JP6516317B2 - Method and apparatus for decontaminating soil contaminated with radioactive cesium - Google Patents
Method and apparatus for decontaminating soil contaminated with radioactive cesium Download PDFInfo
- Publication number
- JP6516317B2 JP6516317B2 JP2013261750A JP2013261750A JP6516317B2 JP 6516317 B2 JP6516317 B2 JP 6516317B2 JP 2013261750 A JP2013261750 A JP 2013261750A JP 2013261750 A JP2013261750 A JP 2013261750A JP 6516317 B2 JP6516317 B2 JP 6516317B2
- Authority
- JP
- Japan
- Prior art keywords
- soil
- cesium
- decontamination
- radioactive cesium
- vessel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000002689 soil Substances 0.000 title claims description 127
- 229910052792 caesium Inorganic materials 0.000 title claims description 125
- TVFDJXOCXUVLDH-UHFFFAOYSA-N caesium atom Chemical compound [Cs] TVFDJXOCXUVLDH-UHFFFAOYSA-N 0.000 title claims description 124
- 230000002285 radioactive effect Effects 0.000 title claims description 65
- 238000000034 method Methods 0.000 title claims description 32
- 238000005202 decontamination Methods 0.000 claims description 78
- 230000003588 decontaminative effect Effects 0.000 claims description 54
- 239000003463 adsorbent Substances 0.000 claims description 47
- 239000007788 liquid Substances 0.000 claims description 43
- DCYOBGZUOMKFPA-UHFFFAOYSA-N iron(2+);iron(3+);octadecacyanide Chemical class [Fe+2].[Fe+2].[Fe+2].[Fe+3].[Fe+3].[Fe+3].[Fe+3].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-] DCYOBGZUOMKFPA-UHFFFAOYSA-N 0.000 claims description 41
- 239000000835 fiber Substances 0.000 claims description 38
- 239000002253 acid Substances 0.000 claims description 32
- 238000001179 sorption measurement Methods 0.000 claims description 29
- 238000000605 extraction Methods 0.000 claims description 28
- 229910019142 PO4 Inorganic materials 0.000 claims description 27
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 22
- 239000010452 phosphate Substances 0.000 claims description 22
- 238000003756 stirring Methods 0.000 claims description 20
- 229960003351 prussian blue Drugs 0.000 claims description 18
- 239000013225 prussian blue Substances 0.000 claims description 18
- 238000005406 washing Methods 0.000 claims description 16
- 239000000758 substrate Substances 0.000 claims description 14
- 239000000463 material Substances 0.000 claims description 12
- 239000004927 clay Substances 0.000 claims description 11
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical group O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 10
- 229910017604 nitric acid Inorganic materials 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 9
- 239000002585 base Substances 0.000 claims description 8
- 229910052783 alkali metal Inorganic materials 0.000 claims description 6
- 150000001340 alkali metals Chemical class 0.000 claims description 5
- 229920002678 cellulose Polymers 0.000 claims description 5
- 239000001913 cellulose Substances 0.000 claims description 5
- 239000004745 nonwoven fabric Substances 0.000 claims description 4
- 238000013019 agitation Methods 0.000 claims description 3
- 238000012545 processing Methods 0.000 claims description 3
- 235000021317 phosphate Nutrition 0.000 description 25
- 229910052723 transition metal Inorganic materials 0.000 description 20
- 239000000243 solution Substances 0.000 description 19
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 18
- 238000003795 desorption Methods 0.000 description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 17
- -1 transition metal salts Chemical class 0.000 description 16
- 238000002474 experimental method Methods 0.000 description 15
- 239000007864 aqueous solution Substances 0.000 description 14
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 13
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 12
- UETZVSHORCDDTH-UHFFFAOYSA-N iron(2+);hexacyanide Chemical compound [Fe+2].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-] UETZVSHORCDDTH-UHFFFAOYSA-N 0.000 description 12
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 11
- 229910052751 metal Inorganic materials 0.000 description 11
- 239000002184 metal Substances 0.000 description 11
- 150000003839 salts Chemical class 0.000 description 11
- 229910010272 inorganic material Inorganic materials 0.000 description 10
- 150000002484 inorganic compounds Chemical class 0.000 description 9
- 229910017053 inorganic salt Inorganic materials 0.000 description 9
- 238000006243 chemical reaction Methods 0.000 description 8
- 239000010949 copper Substances 0.000 description 8
- LWIHDJKSTIGBAC-UHFFFAOYSA-K potassium phosphate Substances [K+].[K+].[K+].[O-]P([O-])([O-])=O LWIHDJKSTIGBAC-UHFFFAOYSA-K 0.000 description 8
- 239000000203 mixture Substances 0.000 description 7
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 6
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 6
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 6
- 235000011130 ammonium sulphate Nutrition 0.000 description 6
- 239000011651 chromium Substances 0.000 description 6
- 150000004677 hydrates Chemical class 0.000 description 6
- 239000011572 manganese Substances 0.000 description 6
- 229910021645 metal ion Inorganic materials 0.000 description 6
- 150000007522 mineralic acids Chemical class 0.000 description 6
- 229910000402 monopotassium phosphate Inorganic materials 0.000 description 6
- 235000019796 monopotassium phosphate Nutrition 0.000 description 6
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 5
- 239000003513 alkali Substances 0.000 description 5
- 229910017052 cobalt Inorganic materials 0.000 description 5
- 239000010941 cobalt Substances 0.000 description 5
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 5
- 239000003337 fertilizer Substances 0.000 description 5
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 5
- GNSKLFRGEWLPPA-UHFFFAOYSA-M potassium dihydrogen phosphate Chemical compound [K+].OP(O)([O-])=O GNSKLFRGEWLPPA-UHFFFAOYSA-M 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 239000012857 radioactive material Substances 0.000 description 5
- 239000002901 radioactive waste Substances 0.000 description 5
- 239000006228 supernatant Substances 0.000 description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 4
- NIPNSKYNPDTRPC-UHFFFAOYSA-N N-[2-oxo-2-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)ethyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 NIPNSKYNPDTRPC-UHFFFAOYSA-N 0.000 description 4
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 4
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical group [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 4
- TVFDJXOCXUVLDH-RNFDNDRNSA-N cesium-137 Chemical compound [137Cs] TVFDJXOCXUVLDH-RNFDNDRNSA-N 0.000 description 4
- 229910052802 copper Inorganic materials 0.000 description 4
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 description 4
- 229910052759 nickel Inorganic materials 0.000 description 4
- 239000000941 radioactive substance Substances 0.000 description 4
- 239000001488 sodium phosphate Substances 0.000 description 4
- 238000003860 storage Methods 0.000 description 4
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 4
- JBQYATWDVHIOAR-UHFFFAOYSA-N tellanylidenegermanium Chemical compound [Te]=[Ge] JBQYATWDVHIOAR-UHFFFAOYSA-N 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 239000010936 titanium Substances 0.000 description 4
- VZSRBBMJRBPUNF-UHFFFAOYSA-N 2-(2,3-dihydro-1H-inden-2-ylamino)-N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]pyrimidine-5-carboxamide Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)C(=O)NCCC(N1CC2=C(CC1)NN=N2)=O VZSRBBMJRBPUNF-UHFFFAOYSA-N 0.000 description 3
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 3
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 3
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 229910001413 alkali metal ion Inorganic materials 0.000 description 3
- 229910052804 chromium Inorganic materials 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 239000010419 fine particle Substances 0.000 description 3
- 229910052748 manganese Inorganic materials 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 150000007524 organic acids Chemical class 0.000 description 3
- 239000000049 pigment Substances 0.000 description 3
- 229910052700 potassium Inorganic materials 0.000 description 3
- 239000011591 potassium Substances 0.000 description 3
- 230000005855 radiation Effects 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 239000013049 sediment Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 150000003624 transition metals Chemical class 0.000 description 3
- 229920000742 Cotton Polymers 0.000 description 2
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 2
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 2
- 229920000433 Lyocell Polymers 0.000 description 2
- 229920000297 Rayon Polymers 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 2
- 150000001342 alkaline earth metals Chemical class 0.000 description 2
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- FUFJGUQYACFECW-UHFFFAOYSA-L calcium hydrogenphosphate Chemical compound [Ca+2].OP([O-])([O-])=O FUFJGUQYACFECW-UHFFFAOYSA-L 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- TVFDJXOCXUVLDH-OUBTZVSYSA-N cesium-134 Chemical compound [134Cs] TVFDJXOCXUVLDH-OUBTZVSYSA-N 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 125000004093 cyano group Chemical group *C#N 0.000 description 2
- MHJAJDCZWVHCPF-UHFFFAOYSA-L dimagnesium phosphate Chemical compound [Mg+2].OP([O-])([O-])=O MHJAJDCZWVHCPF-UHFFFAOYSA-L 0.000 description 2
- ZPWVASYFFYYZEW-UHFFFAOYSA-L dipotassium hydrogen phosphate Chemical compound [K+].[K+].OP([O-])([O-])=O ZPWVASYFFYYZEW-UHFFFAOYSA-L 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 150000004820 halides Chemical class 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 2
- LHOWRPZTCLUDOI-UHFFFAOYSA-K iron(3+);triperchlorate Chemical compound [Fe+3].[O-]Cl(=O)(=O)=O.[O-]Cl(=O)(=O)=O.[O-]Cl(=O)(=O)=O LHOWRPZTCLUDOI-UHFFFAOYSA-K 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- 239000004137 magnesium phosphate Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 229910000403 monosodium phosphate Inorganic materials 0.000 description 2
- 235000019799 monosodium phosphate Nutrition 0.000 description 2
- KBJMLQFLOWQJNF-UHFFFAOYSA-N nickel(ii) nitrate Chemical compound [Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O KBJMLQFLOWQJNF-UHFFFAOYSA-N 0.000 description 2
- 235000005985 organic acids Nutrition 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- VLTRZXGMWDSKGL-UHFFFAOYSA-N perchloric acid Chemical compound OCl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-N 0.000 description 2
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 description 2
- 239000002964 rayon Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229910052706 scandium Inorganic materials 0.000 description 2
- SIXSYDAISGFNSX-UHFFFAOYSA-N scandium atom Chemical compound [Sc] SIXSYDAISGFNSX-UHFFFAOYSA-N 0.000 description 2
- AJPJDKMHJJGVTQ-UHFFFAOYSA-M sodium dihydrogen phosphate Chemical compound [Na+].OP(O)([O-])=O AJPJDKMHJJGVTQ-UHFFFAOYSA-M 0.000 description 2
- 159000000000 sodium salts Chemical class 0.000 description 2
- 239000002344 surface layer Substances 0.000 description 2
- AWDBHOZBRXWRKS-UHFFFAOYSA-N tetrapotassium;iron(6+);hexacyanide Chemical compound [K+].[K+].[K+].[K+].[Fe+6].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-] AWDBHOZBRXWRKS-UHFFFAOYSA-N 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- PNDPGZBMCMUPRI-HVTJNCQCSA-N 10043-66-0 Chemical compound [131I][131I] PNDPGZBMCMUPRI-HVTJNCQCSA-N 0.000 description 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- 244000025254 Cannabis sativa Species 0.000 description 1
- 235000012766 Cannabis sativa ssp. sativa var. sativa Nutrition 0.000 description 1
- 235000012765 Cannabis sativa ssp. sativa var. spontanea Nutrition 0.000 description 1
- 229910021580 Cobalt(II) chloride Inorganic materials 0.000 description 1
- 239000005696 Diammonium phosphate Substances 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- MKYBYDHXWVHEJW-UHFFFAOYSA-N N-[1-oxo-1-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propan-2-yl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(C(C)NC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 MKYBYDHXWVHEJW-UHFFFAOYSA-N 0.000 description 1
- AFCARXCZXQIEQB-UHFFFAOYSA-N N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CCNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 AFCARXCZXQIEQB-UHFFFAOYSA-N 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- 229910021586 Nickel(II) chloride Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 239000004952 Polyamide Substances 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 229920001328 Polyvinylidene chloride Polymers 0.000 description 1
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 230000002745 absorbent Effects 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 229910000272 alkali metal oxide Inorganic materials 0.000 description 1
- 229910001860 alkaline earth metal hydroxide Inorganic materials 0.000 description 1
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 description 1
- 229910000387 ammonium dihydrogen phosphate Inorganic materials 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000010426 asphalt Substances 0.000 description 1
- 235000011132 calcium sulphate Nutrition 0.000 description 1
- 235000009120 camo Nutrition 0.000 description 1
- 235000005607 chanvre indien Nutrition 0.000 description 1
- GVPFVAHMJGGAJG-UHFFFAOYSA-L cobalt dichloride Chemical compound [Cl-].[Cl-].[Co+2] GVPFVAHMJGGAJG-UHFFFAOYSA-L 0.000 description 1
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical compound [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 0.000 description 1
- 229910000335 cobalt(II) sulfate Inorganic materials 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 150000004696 coordination complex Chemical class 0.000 description 1
- MNNHAPBLZZVQHP-UHFFFAOYSA-N diammonium hydrogen phosphate Chemical compound [NH4+].[NH4+].OP([O-])([O-])=O MNNHAPBLZZVQHP-UHFFFAOYSA-N 0.000 description 1
- 229910000388 diammonium phosphate Inorganic materials 0.000 description 1
- 235000019838 diammonium phosphate Nutrition 0.000 description 1
- 235000019700 dicalcium phosphate Nutrition 0.000 description 1
- 229910000395 dimagnesium phosphate Inorganic materials 0.000 description 1
- 235000019791 dimagnesium phosphate Nutrition 0.000 description 1
- 229910000396 dipotassium phosphate Inorganic materials 0.000 description 1
- 235000019797 dipotassium phosphate Nutrition 0.000 description 1
- BNIILDVGGAEEIG-UHFFFAOYSA-L disodium hydrogen phosphate Chemical compound [Na+].[Na+].OP([O-])([O-])=O BNIILDVGGAEEIG-UHFFFAOYSA-L 0.000 description 1
- 229910000397 disodium phosphate Inorganic materials 0.000 description 1
- 235000019800 disodium phosphate Nutrition 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000003651 drinking water Substances 0.000 description 1
- 235000020188 drinking water Nutrition 0.000 description 1
- 238000004043 dyeing Methods 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 230000005251 gamma ray Effects 0.000 description 1
- 239000011487 hemp Substances 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000003100 immobilizing effect Effects 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 238000012432 intermediate storage Methods 0.000 description 1
- NJWYTAHMQKIIQQ-UHFFFAOYSA-N iron(3+);hydrate Chemical compound O.[Fe+3] NJWYTAHMQKIIQQ-UHFFFAOYSA-N 0.000 description 1
- YHGPYBQVSJBGHH-UHFFFAOYSA-H iron(3+);trisulfate;pentahydrate Chemical compound O.O.O.O.O.[Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O YHGPYBQVSJBGHH-UHFFFAOYSA-H 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 229910000360 iron(III) sulfate Inorganic materials 0.000 description 1
- 244000144972 livestock Species 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 239000006012 monoammonium phosphate Substances 0.000 description 1
- 235000019837 monoammonium phosphate Nutrition 0.000 description 1
- 229910000401 monomagnesium phosphate Inorganic materials 0.000 description 1
- 235000019785 monomagnesium phosphate Nutrition 0.000 description 1
- QMMRZOWCJAIUJA-UHFFFAOYSA-L nickel dichloride Chemical compound Cl[Ni]Cl QMMRZOWCJAIUJA-UHFFFAOYSA-L 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- VLTRZXGMWDSKGL-UHFFFAOYSA-M perchlorate Inorganic materials [O-]Cl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-M 0.000 description 1
- PJNZPQUBCPKICU-UHFFFAOYSA-N phosphoric acid;potassium Chemical compound [K].OP(O)(O)=O PJNZPQUBCPKICU-UHFFFAOYSA-N 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 229920002239 polyacrylonitrile Polymers 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920000098 polyolefin Polymers 0.000 description 1
- 229920006306 polyurethane fiber Polymers 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- 239000005033 polyvinylidene chloride Substances 0.000 description 1
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 description 1
- 239000004323 potassium nitrate Substances 0.000 description 1
- 235000010333 potassium nitrate Nutrition 0.000 description 1
- 159000000001 potassium salts Chemical class 0.000 description 1
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 description 1
- 229910052939 potassium sulfate Inorganic materials 0.000 description 1
- 235000011151 potassium sulphates Nutrition 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000004627 regenerated cellulose Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- CBXWGGFGZDVPNV-UHFFFAOYSA-N so4-so4 Chemical class OS(O)(=O)=O.OS(O)(=O)=O CBXWGGFGZDVPNV-UHFFFAOYSA-N 0.000 description 1
- GTSHREYGKSITGK-UHFFFAOYSA-N sodium ferrocyanide Chemical compound [Na+].[Na+].[Na+].[Na+].[Fe+2].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-] GTSHREYGKSITGK-UHFFFAOYSA-N 0.000 description 1
- 235000012247 sodium ferrocyanide Nutrition 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 235000011152 sodium sulphate Nutrition 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 1
- 229920002994 synthetic fiber Polymers 0.000 description 1
- 239000012209 synthetic fiber Substances 0.000 description 1
- 229920006304 triacetate fiber Polymers 0.000 description 1
- ILJSQTXMGCGYMG-UHFFFAOYSA-N triacetic acid Chemical compound CC(=O)CC(=O)CC(O)=O ILJSQTXMGCGYMG-UHFFFAOYSA-N 0.000 description 1
- 229910000404 tripotassium phosphate Inorganic materials 0.000 description 1
- 235000019798 tripotassium phosphate Nutrition 0.000 description 1
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 description 1
- 229910000406 trisodium phosphate Inorganic materials 0.000 description 1
- 235000019801 trisodium phosphate Nutrition 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
- DIMMBYOINZRKMD-UHFFFAOYSA-N vanadium(5+) Chemical class [V+5] DIMMBYOINZRKMD-UHFFFAOYSA-N 0.000 description 1
- 210000002268 wool Anatomy 0.000 description 1
Landscapes
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Description
本発明は、放射性物質、特に放射性セシウムで汚染された土壌の除染方法及び除染装置に関する。 The present invention relates to a method and apparatus for decontaminating soil contaminated with radioactive material, particularly radioactive cesium.
２０１１年３月１１日に発生した東日本大震災による福島第一原子力発電所における未曾有の事故は、今もなお、農業、水産業、畜産業はもとより、周辺住民の生活に深刻な影響を及ぼしている。原発事故そのものの収束はもちろんのこと、事故により環境中に放出されたヨウ素（131Ｉ）、セシウム（134Ｃｓ、137Ｃｓ）、ストロンチウム（90Ｓｒ）等の放射性物質の除去は、現在、我が国の喫緊の課題となっている。特に主要な放射性物質であって、約３０年という長い半減期を有するセシウム１３７（137Ｃｓ）の環境中、特に、土壌からの除染については、現在、各種機関により様々なアプローチが検討されている。 An unprecedented accident at the Fukushima Daiichi Nuclear Power Station due to the Great East Japan Earthquake that occurred on March 11, 2011 has serious influence on the life of the surrounding people as well as agriculture, fisheries industry and livestock industry . As well as the convergence of the nuclear accident itself, removal of radioactive substances such as iodine ( 131 I), cesium ( 134 Cs, 137 Cs), and strontium ( 90 Sr) released into the environment by accident is of course currently It is an urgent issue. In particular, various approaches have been considered by various agencies for decontamination from the soil, especially in the environment of cesium 137 ( 137 Cs), which is a major radioactive substance and has a long half-life of about 30 years. There is.
現況、土壌の除染方法は、放射性物質の濃度が高い表層の土壌を剥ぎ取って、仮置き場や中間貯蔵設備に移動させ保管することである。この方法の最大の問題点は、膨大な量の汚染土壌の保管場所の確保が困難なことであり、このことが、土壌除染が加速されない最大の要因である。そこで、汚染土壌から放射性物質だけを分離回収する技術がいくつか提案されている。例えば、有機酸や無機酸等を用いて汚染土壌から放射性物質を抽出する方法や、高温高圧水や亜臨界水を用いて抽出する方法が提案されている。 At present, the method of soil decontamination is to remove the soil in the surface layer where the concentration of radioactive material is high, and move it to a temporary storage site or an intermediate storage facility for storage. The biggest problem with this method is the difficulty in securing a large amount of contaminated soil storage, which is the largest factor that prevents soil decontamination. Therefore, several techniques for separating and recovering only radioactive substances from contaminated soil have been proposed. For example, methods of extracting radioactive materials from contaminated soil using organic acids, inorganic acids, etc., and methods of extracting them using high temperature high pressure water or subcritical water have been proposed.
しかし、チェルノブイリ原発事故により放出された放射性物質の土壌での分布状態や存在形態についての継続調査結果では、セシウム１３７の大部分（７０−９９％）は表層５ｃｍに残っているものの、その大部分（７９−９９％）は、土壌に固定化された形態（例えば、土壌中鉱物と結合しているもの、ホットパーティクル内に存在しているもの）で存在していることが報告されている（例えば、非特許文献１参照）。このような固定化が、土壌からセシウムを効率よく抽出することを困難にしており、例えば、通常の水、酸、アルカリ洗浄では、土壌からのセシウム除去率は１０〜３０％程度に留まるとの報告もなされている。そこで、放射性セシウム汚染土壌を、フッ素イオンを含む処理液と接触させ、固定化されたセシウムの抽出効率を向上させた除染方法等も提案されている（例えば、特許文献１参照）。 However, according to the continuous survey results on the distribution state and the form of radioactive material released from the Chernobyl nuclear accident in the soil, the majority (70-99%) of cesium 137 remains in the surface 5 cm, but the majority It is reported that (79-99%) exists in a form fixed to the soil (for example, one bound to a mineral in the soil, one present in a hot particle) ( See, for example, Non-Patent Document 1). Such immobilization makes it difficult to extract cesium from the soil efficiently, and for example, with ordinary water, acid and alkali washing, the cesium removal rate from the soil remains at about 10 to 30%. Reports have also been made. Then, the decontamination method etc. which made radioactive cesium contamination soil contact the process liquid containing a fluorine ion, and improved the extraction efficiency of the fixed cesium are proposed (for example, refer patent document 1).
このように、現在一般的に行われている土壌の除染方法（表層土壌剥ぎ取り法）では、大量の汚染土壌を移動、集積、保管する必要があり、その場所の確保が困難であり；また、放射性物質を土壌から除去する既存の除染方法でも、人体や生態系への影響が懸念される化学物質が使用され、その結果として除染した土壌でも環境中に戻せないといった課題がある。さらに、放射性物質の土壌からの抽出に高濃度の酸を使用する場合は、除染装置に特殊な材料を必要とするため、除染装置が高価となること；高濃度の酸の取り扱いが困難であること；専門的な知識や技術を要し、専門家でなければ従事できない場合があるといった課題もある。 Thus, the currently generally practiced soil decontamination method (surface soil stripping method) requires the movement, accumulation, and storage of a large amount of contaminated soil, which makes it difficult to secure the place; In addition, existing decontamination methods for removing radioactive substances from soil use chemical substances that may have an impact on human bodies and ecosystems, and as a result there is a problem that even decontaminated soil can not be returned to the environment . Furthermore, when using a high concentration of acid to extract radioactive materials from the soil, the decontamination device becomes expensive because special materials are required for the decontamination device; handling of high concentration acids is difficult There is also the problem that it requires specialized knowledge and skills, and that it may be impossible to engage without experts.
したがって、現行の除染事業だけではなく、汚染土壌を集積せず、且つ低コストで専門家の立ち会い不要な小規模分散型土壌除染システムの構築が求められている。 Therefore, in addition to the current decontamination projects, there is a need to construct a small-scale decentralized soil decontamination system that does not accumulate contaminated soil and does not require the presence of experts at low cost.
本発明者らは、これまでに、「プルシアンブルー類縁体を担持した親水性繊維基材からなるセシウム吸着材」に係る発明を完成させた（国際公開第２０１３／０２７６５２号パンフレット）。かかるセシウム吸着材は、プルシアンブルー類縁体を、親水性繊維基材に固定化したものであり、安全かつ取扱いが容易である。また安価で入手が容易な材料から、簡便な製造方法により得ることが出来るため、経済的な側面からも、広範囲に亘る環境浄化への適用に優れたものである。さらには、除染の対象に応じて、セシウム吸着材を最適な態様へと容易に加工することができる点、また環境中の放射性セシウムを吸着させた後、（セシウムが吸着した）プルシアンブルー類縁体の遷移金属塩を環境中に取り残すことなく、吸着材のみを容易に回収することができるため、表土を取り除くような物理的な除染方法と比較して、放射性廃棄物の量を抑制することもできる点で有利である。 The inventors of the present invention have completed the invention relating to “a cesium adsorbent composed of a hydrophilic fiber substrate carrying a Prussian blue analogue” (WO 2013/027652 pamphlet). The cesium adsorbent is obtained by immobilizing Prussian blue analogue on a hydrophilic fiber substrate, and is safe and easy to handle. In addition, since it can be obtained by a simple manufacturing method from inexpensive and easily available materials, it is excellent in application to environmental purification over a wide range also from an economical aspect. Furthermore, depending on the target of decontamination, the cesium adsorbent can be easily processed into an optimum mode, and after adsorbing radioactive cesium in the environment, Prussian blue affinity (cesium adsorbed) Since only the adsorbent can be easily recovered without leaving the body transition metal salts in the environment, the amount of radioactive waste can be reduced compared to physical decontamination methods that remove the overburden. It is advantageous in that it can also be done.
本発明者らは、上記課題を解決するために鋭意検討した結果、人体や生態系への影響が少なく、農地に還元しても差し支えない成分として、農地等で使われている肥料の成分に着目し、該成分を含む処理液による、放射性セシウムの汚染土壌からの効率的な抽出方法を確立した。さらにかかる抽出方法と、本発明者らが開発した前記セシウム吸着材とを組合せ、低コストで専門家の立ち会い不要な小規模分散型土壌除染システムを構築し、本発明を完成させた。 As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have found that, as components of fertilizers used in agricultural land etc., there is little influence on human bodies and ecosystems and there is no problem even if they are returned to agricultural land. Attention was focused on the efficient extraction method of radioactive cesium from the contaminated soil by the treatment liquid containing the component. Furthermore, the extraction method and the cesium adsorbent developed by the present inventors were combined to construct a small-scale distributed soil decontamination system at a low cost without the presence of an expert, thereby completing the present invention.
本発明は、以下のとおりである：
［１］放射性セシウムで汚染された土壌を、リン酸塩及び硫酸塩からなる群より選択される少なくとも一種の成分を含み、且つｐＨが４以下である処理液と接触させ、土壌から放射性セシウムを抽出する工程を含む、放射性セシウムで汚染された土壌の除染方法。
［２］抽出工程後の処理液を、プルシアンブルー類縁体を担持した親水性繊維基材からなるセシウム吸着材と接触させ、放射性セシウムをセシウム吸着材へ吸着させる工程を含む、前記［１］に記載の除染方法。
［３］リン酸塩及び硫酸塩が、アルカリ金属、アルカリ土類金属及びアンモニアのリン酸塩及び硫酸塩である、前記［１］又は［２］に記載の除染方法。
［４］処理液が、リン酸塩及び硫酸塩からなる群より選択される少なくとも一種の成分と、硝酸とを含む水溶液である、前記［１］〜［３］のいずれかに記載の除染方法。
［５］抽出工程前の処理として、放射性セシウムで汚染された土壌から粘土分を除去する工程を含む、前記［１］〜［４］のいずれかに記載の除染方法。
［６］処理液が、吸着工程後に回収した処理液である、前記［２］〜［５］のいずれかに記載の除染方法。
［７］放射性セシウムで汚染された土壌からセシウムを除去する除染装置であって、
前記土壌及び処理液を受け入れる中空の容器；
前記容器の外壁若しくは前記容器内に配設され、前記容器内に受け入れた前記土壌及び処理液を加熱するための加熱手段；及び
前記容器内に受け入れた前記土壌及び処理液を撹拌するための撹拌手段
を備える撹拌洗浄槽を含み、
前記処理液が、リン酸塩及び硫酸塩からなる群より選択される少なくとも一種の成分を含み、且つｐＨが４以下である、除染装置。
［８］前記撹拌洗浄槽から排出される放射性セシウムを含む処理液及びプルシアンブルー類縁体を担持した親水性繊維基材からなるセシウム吸着材を受け入れる中空の容器
を備える吸着槽を含む、前記［７］に記載の除染装置。
［９］前記セシウム吸着材が、プルシアンブルーを担持したセルロース系長繊維不織布である、前記［８］に記載の除染装置。
The invention is as follows:
[1] Contacting soil contaminated with radioactive cesium with a treatment solution containing at least one component selected from the group consisting of phosphate and sulfate and having a pH of 4 or less; A method of decontaminating soil contaminated with radioactive cesium comprising the step of extracting.
[2] The treatment liquid after the extraction step is brought into contact with a cesium adsorbent composed of a hydrophilic fiber substrate supporting a Prussian blue analogue, and the step of adsorbing radioactive cesium to the cesium adsorbent is included in the above [1] Decontamination method described.
[3] The decontamination method according to the above [1] or [2], wherein the phosphate and sulfate are phosphates and sulfates of an alkali metal, an alkaline earth metal and ammonia.
[4] The decontamination according to any one of the above [1] to [3], wherein the treatment liquid is an aqueous solution containing at least one component selected from the group consisting of phosphate and sulfate, and nitric acid. Method.
[5] The decontamination method according to any one of the above [1] to [4], which includes the step of removing the clay content from the radioactive cesium-contaminated soil as the treatment prior to the extraction step.
[6] The decontamination method according to any one of the above [2] to [5], wherein the treatment liquid is a treatment liquid recovered after the adsorption step.
[7] A decontamination apparatus for removing cesium from soil contaminated with radioactive cesium,
A hollow container for receiving the soil and the treatment liquid;
Heating means disposed in the outer wall of the vessel or in the vessel for heating the soil and the treatment solution received in the vessel; agitation for stirring the soil and the treatment solution received in the vessel Means for stirring the washing tank,
The decontamination apparatus, wherein the treatment liquid contains at least one component selected from the group consisting of phosphate and sulfate, and has a pH of 4 or less.
[8] The adsorption vessel according to the above [7], comprising a hollow vessel for receiving a cesium adsorbent composed of a treatment solution containing radioactive cesium discharged from the stirring and washing vessel and a hydrophilic fiber base material carrying Prussian blue analogue. The decontamination apparatus as described in].
[9] The decontamination apparatus according to [8], wherein the cesium adsorbent is a cellulose-based long-fiber non-woven fabric carrying Prussian blue.
本発明の放射性セシウムで汚染された土壌の除染方法により、汚染土壌から固定化された放射性セシウムを効率よく抽出することができる。また本発明の除染方法で使用する試薬は、いずれも既に農地等で使われている肥料の成分であり、人体や生態系への影響の懸念がなく、除染された土壌を環境中に戻すことができる。したがって、従前の表層土壌剥ぎ取り法のように、汚染土壌の移動、集積、保管は不要である。さらに本発明の除染装置は、特別な材料を必要としないので低コストであり、また専門家による操作を必要としないので、地域住民やボランティア等による自らの手による土壌除染が可能となる。本発明の除染方法及び除染装置により、汚染土壌の除染の加速が期待できる。 By the method for decontaminating soil contaminated with radioactive cesium of the present invention, it is possible to efficiently extract the radioactive cesium immobilized from the contaminated soil. In addition, the reagents used in the decontamination method of the present invention are all components of fertilizers that are already used in farmland and the like, and there is no concern about the effects on human bodies and ecosystems, and decontaminated soil can be used in the environment. It can be returned. Therefore, it is not necessary to move, accumulate and store contaminated soil as in the conventional surface soil stripping method. Furthermore, the decontamination apparatus of the present invention is low in cost because it does not require any special material, and it does not require an operation by a specialist, so it is possible for the local residents and volunteers to decontaminate the soil by their own hands. . The decontamination method and the decontamination apparatus of the present invention can be expected to accelerate the decontamination of contaminated soil.
［放射性セシウムで汚染された土壌の除染方法］
＜抽出工程＞
本発明は、放射性セシウムで汚染された土壌を、リン酸塩及び硫酸塩からなる群より選択される少なくとも一種の成分を含み、且つｐＨが４以下である処理液と接触させ、土壌から放射性セシウムを抽出する工程を含む、放射性セシウムで汚染された土壌の除染方法に関する。
[Method of decontaminating soil contaminated with radioactive cesium]
<Extraction process>
According to the present invention, radioactive cesium contaminated soil is contacted with a treatment solution containing at least one component selected from the group consisting of phosphate and sulfate and having a pH of 4 or less, and radioactive cesium from the soil The present invention relates to a method of decontaminating soil contaminated with radioactive cesium, which comprises the step of extracting
本発明において、「放射性セシウムで汚染された土壌」は、放射性セシウム（134Ｃｓ、137Ｃｓ）を含む土壌を指す。特には、放射性セシウム濃度が８０００Ｂｑ／ｋｇ超のものを指す。８０００Ｂｑ／ｋｇは、廃棄物を安全に処分するために法律で定められた目安であり、例えば、放射性セシウム濃度が８０００Ｂｑ／ｋｇ以下であれば、一般廃棄物と同様の埋め立て処分等ができる。また「土壌」は、居住地、農地等から採取したもののみならず、汚泥、焼却灰、又は河川や湖沼等の堆積物等であってもよい。 In the present invention, "a soil contaminated with radioactive cesium" refers to a soil containing radioactive cesium ( 134 Cs, 137 Cs). In particular, it refers to the one whose radioactive cesium concentration is over 8000 Bq / kg. 8000 Bq / kg is a standard defined by the law for safely disposing of waste. For example, if the radioactive cesium concentration is 8000 Bq / kg or less, the same landfill disposal as general waste can be performed. The "soil" may be not only those collected from residential areas, farmland, etc., but also sludge, incinerated ash, or sediments such as rivers and lakes.
本発明に係る処理液は、リン酸塩及び硫酸塩からなる群より選択される少なくとも一種の成分を含み、且つｐＨが４以下の水溶液である。ここで、リン酸塩及び硫酸塩としては、アルカリ金属、アルカリ土類金属及びアンモニアのリン酸塩及び硫酸塩を挙げることができる。リン酸塩の例としては、リン酸一ナトリウム、リン酸二ナトリウム、リン酸三ナトリウム、リン酸一カリウム、リン酸二カリウム、リン酸三カリウム、リン酸一カルシウム、リン酸一水素カルシウム、リン酸二カルシウム、リン酸一マグネシウム、リン酸二マグネシウム、リン酸一アンモニウム、リン酸二アンモニウム等を挙げることができる。好ましくは、リン酸一ナトリウム及びリン酸一カリウムであり、より好ましくはリン酸一カリウムである。硫酸塩の例としては、硫酸ナトリウム、硫酸カリウム、硫酸カルシウム、硫酸アンモニウム（硫安）等を挙げることができる。好ましくは、硫酸アンモニウムである。 The treatment liquid according to the present invention is an aqueous solution containing at least one component selected from the group consisting of phosphate and sulfate and having a pH of 4 or less. Here, examples of the phosphate and sulfate include phosphates and sulfates of alkali metals, alkaline earth metals and ammonia. Examples of phosphates include monosodium phosphate, disodium phosphate, trisodium phosphate, monopotassium phosphate, dipotassium phosphate, tripotassium phosphate, calcium monophosphate, calcium monohydrogenphosphate, phosphorus Examples include dicalcium acid, monomagnesium phosphate, dimagnesium phosphate, monoammonium phosphate, diammonium phosphate and the like. Preferably, it is monosodium phosphate and monopotassium phosphate, more preferably monopotassium phosphate. Examples of the sulfate include sodium sulfate, potassium sulfate, calcium sulfate, ammonium sulfate (ammonium sulfate) and the like. Preferably, it is ammonium sulfate.
本発明に係る「リン酸塩及び硫酸塩からなる群より選択される少なくとも一種の成分」は、１種又は２種以上のリン酸塩、１種又は２種以上の硫酸塩、あるいは１種のリン酸塩及び１種の硫酸塩の組み合わせであってよく、好ましくは、１種のリン酸塩であるか、１種のリン酸塩及び１種の硫酸塩の組み合わせであり、より好ましくリン酸一カリウムであるか、リン酸一カリウム及び硫酸アンモニウムの組み合わせである。処理液におけるリン酸塩及び硫酸塩の濃度（合計）は、セシウムの除去率の点から、好ましくは０．５０Ｍ〜５．０Ｍであり、より好ましくは０．６０Ｍ〜２．５Ｍであり、特に好ましくは０．９０Ｍ〜２．２Ｍである。 The “at least one component selected from the group consisting of phosphate and sulfate” according to the present invention is one or more phosphates, one or more sulfates, or one or more phosphates and sulfates. It may be a combination of phosphate and one type of sulfate, preferably one type of phosphate or a combination of one type of phosphate and one type of sulfate, more preferably phosphoric acid It is monopotassium or a combination of monopotassium phosphate and ammonium sulfate. The concentration (total) of phosphate and sulfate in the treatment solution is preferably 0.50 M to 5.0 M, more preferably 0.60 M to 2.5 M, from the viewpoint of cesium removal rate. Preferably it is 0.90M-2.2M.
本発明に係る処理液は、水にリン酸塩及び硫酸塩からなる群より選択される少なくとも一種の成分を所望の濃度となるよう添加した後、ｐＨが４以下となるよう酸成分を添加することにより調整される。ｐＨは、セシウムの除去率の点から、好ましくは１〜３であり、より好ましくは１．５〜２．５であり、特に好ましくは約２である。酸成分は、有機酸又は無機酸のいずれであってもよい。有機酸の例としては、酢酸、クエン酸、シュウ酸等を挙げることができ、無機酸の例としては、塩酸、硫酸、硝酸等を挙げることができる。環境負荷の点から、酸成分は、好ましくは無機酸であり、セシウムの除去率の点から、より好ましくは硝酸である。なお硝酸は、ステンレスの腐食作用が比較的小さいことから、除染装置への負荷が小さくて済む点、さらには、反応後に塩基を投入することで硝酸カリウム等の肥料成分に変化させ、無害化することが可能である点からも好ましい。 In the treatment liquid according to the present invention, at least one component selected from the group consisting of phosphate and sulfate is added to water to a desired concentration, and then an acid component is added to a pH of 4 or less. It is adjusted by. The pH is preferably 1 to 3, more preferably 1.5 to 2.5, and particularly preferably about 2 in view of the cesium removal rate. The acid component may be either an organic acid or an inorganic acid. Examples of organic acids include acetic acid, citric acid, oxalic acid and the like, and examples of inorganic acids include hydrochloric acid, sulfuric acid, nitric acid and the like. From the point of environmental impact, the acid component is preferably an inorganic acid, and from the point of cesium removal rate, more preferably nitric acid. Nitric acid has a relatively small corrosive action of stainless steel, so the load on the decontamination apparatus can be small. Furthermore, by adding a base after the reaction, it is changed to a fertilizer component such as potassium nitrate and detoxified. It is preferable also from the point that it is possible.
本発明の除染方法は、汚染土壌を、処理液と接触させ、土壌から放射性セシウムを抽出する工程を含む。汚染土壌と処理液とを接触させる手段は特に限定されないが、典型的には、汚染土壌を処理液中で撹拌・懸濁させる。これにより、汚染土壌から、固定化された放射性セシウムが処理液に抽出される。汚染土壌と処理液の比（固液比（質量基準））は、汚染土壌の量、その放射能濃度等に応じて適宜設定されるが、２：１〜1：１００、好ましくは１：２〜５０、より好ましくは１：５〜２０である。撹拌条件もまた、汚染土壌の量、その放射能濃度等に応じて適宜設定されるが、例えばセシウム除去率の点から、周囲温度〜１００℃の温度、好ましくは５０℃〜１００℃の温度、より好ましくは８０℃〜１００℃の温度で、０．５時間から１０時間、好ましくは１〜５時間、より好ましくは１〜３時間行う。 The decontamination method of the present invention comprises the steps of contacting contaminated soil with a treatment solution and extracting radioactive cesium from the soil. The means for bringing the contaminated soil into contact with the treatment liquid is not particularly limited, but typically the contaminated soil is stirred and suspended in the treatment liquid. As a result, the immobilized radioactive cesium is extracted from the contaminated soil into the treatment solution. The ratio of the contaminated soil to the treatment liquid (solid-liquid ratio (mass basis)) is appropriately set according to the amount of the contaminated soil, its radioactivity concentration, etc., but 2: 1 to 1: 100, preferably 1: 2 50 to 50, more preferably 1: 5 to 20. Stirring conditions are also appropriately set according to the amount of contaminated soil, its radioactivity concentration, etc. For example, from the point of cesium removal rate, ambient temperature to 100 ° C., preferably 50 ° C. to 100 ° C., More preferably, it is carried out at a temperature of 80 ° C. to 100 ° C. for 0.5 hour to 10 hours, preferably 1 to 5 hours, more preferably 1 to 3 hours.
本発明の除染方法は、汚染土壌を、処理液と接触させ、土壌から放射性セシウムを抽出する工程の前に、放射性セシウムで汚染された土壌から粘土分（ここで「粘土分」とは、直径２μｍ未満の微粒子を指す）を除去する工程を含んでもよい。かかる除去工程は特に限定されないが、簡便には、汚染土壌を水中で撹拌・懸濁させ、静置させた後、粘土分を含む上澄みを除去することにより実施される。汚染土壌と水の比（固液比（質量基準））は、汚染土壌の量、その放射能濃度等に応じて適宜設定されるが、例えば１：１〜１００、好ましくは１：２〜５０、より好ましくは１：５〜２０である。撹拌条件もまた、汚染土壌の量、その放射能濃度等に応じて適宜設定されるが、例えば周囲温度〜１００℃の温度、好ましくは周囲温度〜５０℃の温度、より好ましくは周囲温度で、３０秒から１時間、好ましくは１〜２０分、より好ましくは１〜５分行う。なお、既往の研究では、土壌中の粘土分を回収することで放射能濃度を大幅に低減した報告も存在するが、本発明者らの検討では、最大で４５％程度の放射能濃度の低減が見られたが、粘土分を除去する工程単独では、十分な除染効果は得られなかった。 The decontamination method of the present invention comprises contacting the contaminated soil with a treatment solution and extracting the radioactive cesium from the soil, prior to the step of extracting the radioactive cesium from the soil from the soil contaminated with the radioactive cesium (here, "clay component" means Removing the particles having a diameter of less than 2 μm). The removal step is not particularly limited, but is conveniently carried out by stirring and suspending the contaminated soil in water and letting it stand, and then removing the supernatant containing the clay component. The ratio of contaminated soil to water (solid-liquid ratio (mass basis)) is appropriately set according to the amount of contaminated soil, its radioactivity concentration, etc., but it is, for example, 1: 1 to 100, preferably 1: 2 to 50. And more preferably 1: 5 to 20. The stirring conditions are also appropriately set according to the amount of contaminated soil, the radioactivity concentration thereof, etc., for example, at a temperature of ambient temperature to 100 ° C., preferably at a temperature of ambient temperature to 50 ° C., more preferably at ambient temperature It is carried out for 30 seconds to 1 hour, preferably 1 to 20 minutes, more preferably 1 to 5 minutes. In the previous research, there are also reports that the radioactivity concentration is greatly reduced by recovering the clay content in the soil, but in the study of the present inventors, the radioactivity concentration is reduced by about 45% at the maximum. However, the step of removing the clay component alone did not provide a sufficient decontamination effect.
＜吸着工程＞
本発明の除染方法は、前述の抽出工程に加え、抽出工程後の処理液を、プルシアンブルー類縁体を担持した親水性繊維基材からなるセシウム吸着材と接触させ、放射性セシウムをセシウム吸着材へ吸着させる工程を含んでもよい。本発明に係る「プルシアンブルー類縁体を担持した親水性繊維基材からなるセシウム吸着材」は、繊維の内部にプルシアンブルー類縁体が固定化していることを特徴とするものである。
<Adsorption process>
In the decontamination method of the present invention, in addition to the above-mentioned extraction step, the treatment liquid after the extraction step is brought into contact with a cesium adsorbent composed of a hydrophilic fiber base material carrying Prussian blue analogue, and radioactive cesium is a cesium adsorbent You may include the process made to adsorb | suck to. The “cesium adsorbent composed of a hydrophilic fiber substrate carrying a Prussian blue analogue” according to the present invention is characterized in that the Prussian blue analogue is immobilized in the inside of a fiber.
本発明に係る、プルシアンブルー類縁体とは、ヘキサシアノ金属酸イオンを構築素子としたシアノ架橋型金属錯体の一種であり、一般式：ＭＡ ｍ［ＭＢ（ＣＮ）６］ｎ・ｈＨ２Ｏで示される化合物であり、この金属イオン（ＭＡ、ＭＢ）がシアノ基で交互に架橋した面心立方構造をしていると解される。ここで、ＭＡは、第一遷移金属である。したがって、本発明に係るプルシアンブルー類縁体は、ヘキサシアノ金属酸の遷移金属塩であると言い換えてもよい。第一遷移金属としては、スカンジウム（Ｓｃ）、チタン（Ｔｉ）、バナジウム（Ｖ）、クロム（Ｃｒ）、マンガン（Ｍｎ）、鉄（Ｆｅ）、コバルト（Ｃｏ）、ニッケル（Ｎｉ）、銅（Ｃｕ）及び亜鉛（Ｚｎ）が挙げられる。好ましくは、鉄（Ｆｅ）、コバルト（Ｃｏ）、ニッケル（Ｎｉ）、銅（Ｃｕ）及び亜鉛（Ｚｎ）、より好ましくは、鉄（Ｆｅ）、特に第二鉄（Ｆｅ（III））が挙げられる。 According to the present invention, the Prussian blue analogue, is a kind of cyano bridged metal complex was constructed element hexacyano metal ion, the general formula: M A m [M B ( CN) 6] n · hH 2 O It is understood that the metal ion (M A , M B ) has a face-centered cubic structure in which the metal ions (M A , M B ) are alternately cross-linked by cyano groups. Here, M A is a first transition metal. Therefore, the Prussian blue analogue according to the present invention may be rephrased to be a transition metal salt of hexacyano metal acid. As the first transition metal, scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu) And zinc (Zn). Preferably, iron (Fe), cobalt (Co), nickel (Ni), copper (Cu) and zinc (Zn), more preferably iron (Fe), especially ferric iron (Fe (III)) can be mentioned. .
前記一般式において、ＭＢは、八面体６配位構造をとりうる金属種であればよく、好ましくは、クロム（Ｃｒ）、マンガン（Ｍｎ）、鉄（Ｆｅ）、コバルト（Ｃｏ）であり、より好ましくは、鉄（Ｆｅ）、特に第一鉄（Ｆｅ（II））である。なお前記一般式において、ｍ、ｎ及びｈの値は、ＭＡおよびＭＢの酸化数に応じて定まる。 In the above general formula, M B may be any metal species capable of having an octahedral six-coordinated structure, preferably chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), More preferably, it is iron (Fe), particularly ferrous iron (Fe (II)). Note in the general formula, m, the values of n and h is determined according to the oxidation number of M A and M B.
本発明に係るプルシアンブルー類縁体（すなわち、ヘキサシアノ金属酸の遷移金属塩）は、ヘキサシアノ金属酸の無機塩と、遷移金属元素を含む無機化合物との反応により得られる生成物であって、前記一般式で表されるものを含むものであればよい。なお、本発明に係るプルシアンブルー類縁体は、そのヘキサシアノ金属酸の遷移金属塩の一部の金属イオンが、原料由来のアルカリ金属イオン等で置換されているものを含んでいてもよい。 The Prussian blue analogue (ie, transition metal salt of hexacyano metal acid) according to the present invention is a product obtained by the reaction of an inorganic salt of hexacyano metal acid with an inorganic compound containing a transition metal element What is necessary is just to include the one represented by the formula. The Prussian blue analogue according to the present invention may include one in which a part of metal ions of the transition metal salt of hexacyano metal acid is substituted by alkali metal ions or the like derived from the raw material.
例えば、本発明に係るプルシアンブルー類縁体の一態様である、ヘキサシアノ鉄（II）酸の遷移金属塩としては、そのスカンジウム（Ｓｃ）塩、チタン（Ｔｉ）塩、バナジウム（Ｖ）塩、クロム（Ｃｒ）塩、マンガン（Ｍｎ）塩、鉄（Ｆｅ）塩、コバルト（Ｃｏ）塩、ニッケル（Ｎｉ）塩、銅（Ｃｕ）塩及び亜鉛（Ｚｎ）塩が挙げられる。好ましくは、ヘキサシアノ鉄（II）酸の鉄（Ｆｅ）塩、コバルト（Ｃｏ）塩、ニッケル（Ｎｉ）塩、銅（Ｃｕ）塩及び亜鉛（Ｚｎ）塩が挙げられ、より好ましくは、鉄（Ｆｅ）塩、特に第二鉄（Ｆｅ（III））塩が挙げられる。なお、本発明に係るヘキサシアノ鉄（II）酸の遷移金属塩は、ヘキサシアノ鉄（II）酸の無機塩と、遷移金属元素を含む無機化合物との反応により得られる生成物であって、前記一般式（但し、ＭＢが、特に第一鉄（Ｆｅ（II））である）で表されるものを含むものであればよいが、その一部の金属イオンが、原料由来のアルカリ金属イオン等で置換されているものを含んでいてもよい。 For example, as a transition metal salt of hexacyanoferrate (II), which is one embodiment of Prussian blue analogue according to the present invention, scandium (Sc) salt, titanium (Ti) salt, vanadium (V) salt, chromium ( And Cr) salts, manganese (Mn) salts, iron (Fe) salts, cobalt (Co) salts, nickel (Ni) salts, copper (Cu) salts and zinc (Zn) salts. Preferably, iron (Fe) salt, cobalt (Co) salt, nickel (Ni) salt, copper (Cu) salt and zinc (Zn) salt of hexacyanoferrate (II) can be mentioned, and more preferably iron (Fe) ) Salts, in particular ferric (Fe (III)) salts. The transition metal salt of hexacyanoferrate (II) according to the present invention is a product obtained by the reaction of an inorganic salt of hexacyanoferrate (II) with an inorganic compound containing a transition metal element Any metal ion may be used as long as it contains a compound represented by the formula (wherein M B is particularly ferrous iron (Fe (II))), but some of the metal ions are alkali metal ions derived from the raw material, etc. And the like may be substituted.
本発明に係るプルシアンブルー類縁体の最も好適な例である、ヘキサシアノ鉄（II）酸の第二鉄（Ｆｅ（III））塩は、プルシアンブルー又は紺青等とも称され、古くから顔料として用いられている。その理想的な化学組成はＦｅ（III）４［Ｆｅ（II）（ＣＮ）６］３・ｘＨ２Ｏ（ｘ＝１４〜１６）（すなわち「ヘキサシアノ鉄（II）酸鉄（III）水和物」）であるが、その製法等に応じて一部の鉄イオンが置換されていることもある。本発明に係るプルシアンブルーは、ヘキサシアノ鉄（II）酸の無機塩と、第二鉄（III）を含む無機化合物との反応により得られるものであって、前記化学組成を有するものを含むものであればよいが、一部の鉄イオンが、原料由来のアルカリ金属イオン等で置換されているものを含んでいてもよい。 The ferric (Fe (III)) salt of hexacyanoferrate (II), which is the most preferable example of the Prussian blue analogue according to the present invention, is also referred to as Prussian blue or bitumen, etc. ing. Its ideal chemical composition Fe (III) 4 [Fe ( II) (CN) 6] 3 · xH 2 O (x = 14~16) ( i.e. "hexacyanoferrate (II) iron (III) hydrate However, depending on the production method etc., some iron ions may be substituted. Prussian blue according to the present invention is obtained by the reaction of an inorganic salt of hexacyanoferrate (II) with an inorganic compound containing ferric (III), and includes one having the above-mentioned chemical composition. Although it is sufficient, a part of iron ions may include those substituted with alkali metal ions and the like derived from the raw material.
ヘキサシアノ金属酸の無機塩は、水溶性であって、かつ遷移金属元素を含む無機化合物との反応により、本発明に係るプルシアンブルー類縁体（すなわち、ヘキサシアノ金属酸の遷移金属塩）を形成しうるものであれば特に限定はない。例としては、ヘキサシアノ金属酸のアルカリ金属塩（ナトリウム塩、カリウム塩等）またはその水和物が挙げられる。具体的には、ヘキサシアノクロム（III）酸、ヘキサシアノマンガン（II）酸、ヘキサシアノ鉄（II）酸若しくはヘキサシアノコバルト（III）酸のアルカリ金属塩（ナトリウム塩、カリウム塩等）、又はそれらの水和物が挙げられる。 An inorganic salt of hexacyano metal acid is water soluble and can form Prussian blue analogue (that is, a transition metal salt of hexacyano metal acid) according to the present invention by reaction with an inorganic compound containing a transition metal element. If it is a thing, there will be no limitation in particular. Examples include alkali metal salts (sodium salts, potassium salts and the like) of hexacyano metal acids or hydrates thereof. Specifically, an alkali metal salt (sodium salt, potassium salt, etc.) of hexacyanochromic acid (III), hexacyanomanganate (II) acid, hexacyanoferrate (II) acid or hexacyanocobalt (III) acid, or their hydration The thing is mentioned.
例えば、ヘキサシアノ金属酸が、ヘキサシアノ鉄（II）酸である場合、ヘキサシアノ鉄（II）酸の無機塩は、水溶性であって、かつ遷移金属元素を含む無機化合物との反応によりヘキサシアノ鉄（II）酸の遷移金属塩を形成しうるものであれば特に限定はない。具体例としては、ヘキサシアノ鉄（II）酸カリウム、ヘキサシアノ鉄（II）酸ナトリウム又はそれらの水和物が挙げられる。ヘキサシアノ鉄（II）酸カリウム又はその水和物の使用が好ましい。 For example, when the hexacyanometalic acid is hexacyanoferrate (II), the inorganic salt of hexacyanoferrate (II) is water soluble and is reacted with an inorganic compound containing a transition metal element to form hexacyanoferrate (II). There is no particular limitation as long as it can form a transition metal salt of an acid. Specific examples include potassium hexacyanoferrate (II), sodium hexacyanoferrate (II) or their hydrates. The use of potassium hexacyanoferrate (II) or its hydrates is preferred.
遷移金属元素を含む無機化合物は、水溶性であって、かつヘキサシアノ金属酸の無機塩との反応により、本発明のプルシアンブルー類縁体（すなわち、ヘキサシアノ金属酸の遷移金属塩）を形成しうるものであれば特に限定はない。そのような遷移金属元素を含む無機化合物としては、前記第一遷移金属のハロゲン化物、硝酸塩、硫酸塩、過塩素酸塩又はそれらの水和物等が挙げられる。例えば、塩化第二鉄（III）、塩化コバルト（II）、塩化ニッケル（II）等のハロゲン化物；硝酸第二鉄（III）、硝酸コバルト（II）、硝酸ニッケル（II）等の硝酸塩；硫酸第二鉄（III）、硫酸コバルト（II）等の硫酸塩；過塩素酸第二鉄（III）等の過塩素酸塩；又はそれらの水和物が挙げられる。 An inorganic compound containing a transition metal element is water soluble and capable of forming the Prussian blue analogue of the present invention (that is, a transition metal salt of hexacyano metal acid) by reaction with an inorganic salt of hexacyano metal acid There is no particular limitation as long as As an inorganic compound containing such a transition metal element, the halide of the said 1st transition metal, nitrate, a sulfate, perchlorate, or those hydrates etc. are mentioned. For example, halides such as ferric chloride (III), cobalt (II) chloride and nickel (II) chloride; nitrates such as ferric nitrate (III), cobalt (II) nitrate and nickel (II) nitrate; sulfuric acid Sulfates such as ferric (III) and cobalt (II) sulfate; perchlorates such as ferric perchlorate (III); and hydrates thereof.
例えば、第二鉄（III）を含む無機化合物は、水溶性であって、かつヘキサシアノ鉄（II）酸の無機塩との反応によりプルシアンブルーを形成しうるものであれば特に限定はない。例えば、塩化第二鉄（III）、硝酸第二鉄（III）、硫酸第二鉄（III）、過塩素酸第二鉄（III）又はそれらの水和物が挙げられる。 For example, the inorganic compound containing ferric (III) is not particularly limited as long as it is water soluble and can form Prussian blue by reaction with an inorganic salt of hexacyanoferrate (II). For example, ferric chloride (III), ferric nitrate (III), ferric sulfate (III), ferric perchlorate (III) or their hydrates can be mentioned.
本発明に係るセシウム吸着材の基材としては、親水性繊維基材が使用される。本発明に係る親水性繊維は、吸水性繊維と言い換えてもよい。親水性繊維は、一般に水分子を取り込みやすい繊維の総称であり、例としては、羊毛、綿、絹、麻、パルプなどの天然繊維、レーヨン、ポリノジック、キュプラ（ベンベルグ（登録商標））、リヨセル（テンセル（登録商標））等のセルロース系再生繊維が挙げられる。またアセテート、トリアセテートなどの半合成繊維、あるいはポリアミド系、ポリビニルアルコール系、ポリ塩化ビニリデン系、ポリ塩化ビニル系、ポリエステル系、ポリアクリロニトリル系、ポリオレフィン系またはポリウレタン系繊維等の合成繊維を公知の方法で改質し、親水性を付与したものであってもよい。価格や入手の容易さから、親水性繊維としては天然繊維又はセルロース系再生繊維、特に綿、レーヨン又はキュプラが好ましい。 A hydrophilic fiber substrate is used as a substrate of the cesium adsorbent according to the present invention. The hydrophilic fiber according to the present invention may be reworded as a water absorbent fiber. Hydrophilic fiber is a generic term for fibers that are generally easy to take up water molecules, and examples include natural fibers such as wool, cotton, silk, hemp, and pulp, rayon, polynozic, cupra (Benberg (registered trademark)), lyocell Cellulose-based regenerated fibers such as Tencel (registered trademark) can be mentioned. In addition, semisynthetic fibers such as acetate and triacetate, or synthetic fibers such as polyamide, polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, polyester, polyacrylonitrile, polyolefin or polyurethane fibers, etc. It may be modified to impart hydrophilicity. Natural fibers or regenerated cellulose-based fibers, in particular, cotton, rayon or cupra are preferred as hydrophilic fibers in view of cost and availability.
また親水性繊維基材は、上述のような親水性繊維よりなる織物、編物若しくは不織布製品または紙製品であってよい。その形状は、目的とする用途、すなわち除染の対象に応じて適宜選択し、加工すればよい。例えば、水の除染を目的とする場合には、ペレット状、フィルタ状、シート状等であってよく、土壌の除染を目的とする場合は、広範囲をカバーすることができるシート状等であってよい。そのような基材の加工は、基材へのプルシアンブルー類縁体の担持前に行うことができるが、以下に述べるように、本発明のセシウム吸着材は、プルシアンブルー類縁体が繊維の内部および表面に安定的に固定化しているので、担持後に行うこともできる。 The hydrophilic fiber substrate may also be a woven, knitted or non-woven product or a paper product consisting of hydrophilic fibers as described above. The shape may be appropriately selected and processed in accordance with the intended application, that is, the target of decontamination. For example, in the case of decontamination of water, it may be in the form of pellet, filter or sheet, etc. In the case of decontamination of soil, it may be in the form of sheet which can cover a wide range. May be there. Such processing of the substrate can be carried out before loading the Prussian blue analogue on the substrate, but as described below, the cesium adsorbent of the present invention is a Prussian blue analogue having a fiber interior and As it is stably immobilized on the surface, it can be carried out after loading.
本発明に係るセシウム吸着材は、プルシアンブルー類縁体、特に好ましくはプルシアンブルーを担持した親水性繊維基材からなるものであって、繊維の表面のみならず内部にプルシアンブルー類縁体が固定していることを特徴とするものである。特に、プルシアンブルーのような「顔料」は、水や有機溶媒などの媒質に不溶で、基質に対して染着性がない。したがって、顔料により繊維基材を染色（捺染）する場合、通常、バインダー樹脂などで後処理し、顔料を繊維の表面に付着した形で固定化することを要する。一方、本発明のセシウム吸着材では、プルシアンブルー類縁体は、ヘキサシアノ金属酸の無機塩と遷移金属元素を含む無機化合物との反応によりin situで形成され、繊維の表面および内部に微粒子として存在するため、バインダー樹脂などによらず安定的に繊維に固定している。 The cesium adsorbent according to the present invention is a hydrophilic fiber base material carrying Prussian blue analogue, particularly preferably Prussian blue, and the Prussian blue analogue is immobilized not only on the surface of the fiber but also on the inside thereof. It is characterized by In particular, a "pigment" such as Prussian blue is insoluble in a medium such as water or an organic solvent, and is not dyeable to a substrate. Therefore, when the fiber substrate is dyed (printed) with a pigment, it is usually necessary to post-treat with a binder resin or the like to fix the pigment in the form of being attached to the surface of the fiber. On the other hand, in the cesium adsorbent of the present invention, the Prussian blue analogue is formed in situ by the reaction of the inorganic salt of hexacyano metal acid and the inorganic compound containing the transition metal element, and exists as fine particles on the surface and inside of the fiber Therefore, they are stably fixed to the fiber regardless of the binder resin and the like.
本発明に係るセシウム吸着材は、国際公開第２０１３／０２７６５２号パンフレットに記載の方法に従い製造することができる。典型的には、（ａ）親水性繊維よりなる基材をヘキサシアノ金属酸の無機塩の水溶液で処理する工程；及び（ｂ）工程（ａ）で処理した基材を、遷移金属元素を含む無機化合物の水溶液で処理する工程を含む製造方法により作製される。また、本発明に係るセシウム吸着材は、例えば小津産業(株)から放射性セシウム除染布（商品名：五大力ＰＢ；プルシアンブルーを担持したセルロース系長繊維不織布）として入手することができる。 The cesium adsorbent according to the present invention can be produced according to the method described in WO 2013/027652. (A) treating the substrate comprising hydrophilic fibers with an aqueous solution of an inorganic salt of hexacyanometallic acid; and (b) treating the substrate treated in step (a) with a transition metal element-containing inorganic material It is produced by a production method comprising the step of treating with an aqueous solution of a compound. In addition, the cesium adsorbent according to the present invention can be obtained, for example, from Ozu Sangyo Co., Ltd. as a radioactive cesium decontaminated cloth (trade name: Five-Strength PB; a cellulose long-fiber non-woven fabric carrying Prussian blue).
抽出工程後の処理液とセシウム吸着材とを接触させる手段は特に限定されないが、例えば、抽出工程後の処理液中に、ペレット状又はシート状のセシウム吸着材を浸漬させる。これにより、処理液中の放射性セシウムが、セシウム吸着材に吸着される。浸漬条件は、処理液の量、その放射能濃度等に応じて適宜設定されるが、例えば周囲温度〜１００℃の温度、好ましくは周囲温度〜５０℃の温度、より好ましくは周囲温度で、０．５時間から１０時間、好ましくは１〜５時間、より好ましくは１〜３時間行う。 The means for bringing the treatment liquid after the extraction step into contact with the cesium adsorbent is not particularly limited. For example, the pellet-like or sheet-like cesium adsorbent is dipped in the treatment liquid after the extraction step. Thereby, the radioactive cesium in the treatment liquid is adsorbed to the cesium adsorbent. Immersion conditions are appropriately set according to the amount of treatment liquid, its radioactivity concentration, etc., for example, a temperature of ambient temperature to 100 ° C., preferably a temperature of ambient temperature to 50 ° C., more preferably 0 at ambient temperature It is carried out for 5 hours to 10 hours, preferably 1 to 5 hours, more preferably 1 to 3 hours.
セシウム吸着剤による吸着工程に付した後の処理液は、回収して、土壌から放射性セシウムを抽出する工程に再利用することができる。すなわち、回収した処理液を、汚染土壌の２回目以降の抽出工程で用いてもよく、また新たな汚染土壌の１回目の抽出工程で用いてもよい。再利用の際、リン酸塩及び硫酸塩の添加や、ｐＨの調整を、必要に応じて適宜行うことができる。抽出のための処理液を回収、再利用することにより、最終的に生じる放射性廃棄物の総量を減容することができる。 The treatment liquid after being subjected to the adsorption step with a cesium adsorbent can be recovered and reused in the step of extracting radioactive cesium from the soil. That is, the recovered treatment liquid may be used in the second and subsequent extraction steps of the contaminated soil, or may be used in the first extraction step of new contaminated soil. At the time of reuse, addition of phosphate and sulfate and adjustment of pH can be appropriately performed as needed. By recovering and reusing the processing solution for extraction, the total volume of radioactive waste that is ultimately generated can be reduced.
＜脱着工程＞
また、本発明の除染方法は、吸着工程で使用し、放射性セシウムが吸着したセシウム吸着剤から放射性セシウムを脱着及び濃縮する工程を含んでもよい。脱着及び濃縮工程は、酸処理により吸着剤から放射性セシウムを脱着することにより、あるいはアルカリ処理によりセシウム吸着剤から担持されたプルシアンブルー類縁体自体と共に放射性セシウムを脱離することにより実施することができる。これらは、放射性セシウムが吸着したセシウム吸着剤を、それぞれ酸又はアルカリ水溶液に浸漬することにより、実施することができる。脱着液（酸又はアルカリ水溶液）を繰り返し使用することにより、最終的に生じる放射性廃棄物の総量を減容することができる。一方、放射性セシウムが脱着した親水性繊維基材は、非放射性廃棄物として焼却処理することが可能である。この点からも、最終的に生じる放射性廃棄物の総量を大幅に減容することができる。
<Desorption process>
In addition, the decontamination method of the present invention may include a step of desorbing and concentrating radioactive cesium from the cesium adsorbent which is used in the adsorption step and which radioactive cesium is adsorbed. The desorption and concentration steps can be carried out by desorbing the radioactive cesium from the adsorbent by acid treatment, or by desorbing the radioactive cesium together with the Prussian blue analogue itself supported from the cesium adsorbent by alkali treatment . These can be implemented by immersing the cesium adsorbent to which radioactive cesium is adsorbed, in an acid or alkaline aqueous solution, respectively. By repeatedly using the desorbing solution (acid or alkaline aqueous solution), the total volume of the radioactive waste which is finally generated can be reduced. On the other hand, the hydrophilic fiber base material from which radioactive cesium desorbed can be incinerated as non-radioactive waste. Also from this point of view, the total volume of radioactive waste that is finally generated can be significantly reduced.
脱着工程で使用される酸又はアルカリは、特に限定されないが、好ましくは無機酸又は無機アルカリであり、無機酸の例としては、塩酸、硫酸、リン酸等が挙げられ、無機アルカリの例としては、アルカリ金属又はアルカリ土類金属の水酸化物、特には水酸化ナトリウム、水酸化カリウム等が挙げられる。脱着及び濃縮条件は、セシウム吸着剤の容量等に応じて適宜設定されるが、例えば周囲温度〜１００℃の温度、好ましくは周囲温度〜５０℃の温度、より好ましくは周囲温度で、０．５時間から１０時間、好ましくは１〜５時間、より好ましくは１〜３時間行う。 The acid or alkali used in the desorption step is not particularly limited, but is preferably an inorganic acid or inorganic alkali, and examples of the inorganic acid include hydrochloric acid, sulfuric acid, phosphoric acid and the like, and examples of the inorganic alkali And alkali metal or alkaline earth metal hydroxides, particularly sodium hydroxide, potassium hydroxide and the like. Desorption and concentration conditions are appropriately set according to the capacity of the cesium adsorbent etc., for example, a temperature of ambient temperature to 100 ° C., preferably a temperature of ambient temperature to 50 ° C., more preferably 0.5 at ambient temperature It is carried out for 10 hours, preferably 1 to 5 hours, more preferably 1 to 3 hours.
［放射性セシウムで汚染された土壌からセシウムを除去する除染装置］
本発明はまた、放射性セシウムで汚染された土壌からセシウムを除去する除染装置に関する。本発明の除染装置は、
− 放射性セシウムで汚染された土壌及び処理液を受け入れる中空の容器；
− 前記容器の外壁若しくは前記容器内に配設され、前記容器内に受け入れた前記土壌及び処理液を加熱するための加熱手段；及び
− 前記容器内に受け入れた前記土壌及び処理液を撹拌するための撹拌手段
を備える撹拌洗浄槽を含むものであって、且つ前記処理液が、リン酸塩及び硫酸塩からなる群より選択される少なくとも一種の成分を含み、且つｐＨが４以下であるものである。
[Decontamination equipment to remove cesium from soil contaminated with radioactive cesium]
The present invention also relates to a decontamination apparatus for removing cesium from soil contaminated with radioactive cesium. The decontamination apparatus of the present invention is
-A hollow container for receiving radioactive cesium contaminated soil and treatment liquid;
-Heating means disposed in the outer wall of the vessel or in the vessel for heating the soil and treatment solution received in the vessel; and-for stirring the soil and treatment solution received in the vessel And the treatment liquid contains at least one component selected from the group consisting of phosphate and sulfate, and has a pH of 4 or less. is there.
本発明の除染装置は、前記撹拌洗浄槽に加えて、吸着槽を備えることもできる。すなわち、本発明の除染装置は、
− 前記撹拌洗浄槽から排出される放射性セシウムを含む処理液及びプルシアンブルー類縁体を担持した親水性繊維基材からなるセシウム吸着材を受け入れる中空の容器
を備える吸着槽を含んでもよい。
The decontamination apparatus of the present invention can also be provided with an adsorption tank in addition to the stirred washing tank. That is, the decontamination apparatus of the present invention is
-The adsorption tank provided with the hollow vessel which receives the cesium adsorption material which consists of a process liquid containing the radioactive cesium discharged | emitted from the said stirring washing tank, and the hydrophilic fiber base material which carry | supported Prussian blue analogue may be included.
本発明の除染装置において、好ましくは、前記セシウム吸着材はプルシアンブルーを担持したセルロース系長繊維不織布である。 In the decontamination apparatus of the present invention, preferably, the cesium adsorbent is a cellulose-based long-fiber non-woven fabric carrying Prussian blue.
図１は、本発明の除染装置の１つの構成例を示した概略図である。以下、図１を参照しながら、本発明の除染装置を用いた、本発明の除染方法について概説する。この実施形態では、除染装置は、撹拌洗浄槽及び吸着槽から構成されている。前述の本発明の汚染土壌の除染方法において、抽出工程は、撹拌洗浄槽で実施され、吸着工程は、吸着槽で実施される。 FIG. 1 is a schematic view showing one configuration example of the decontamination apparatus of the present invention. Hereinafter, the decontamination method of the present invention using the decontamination apparatus of the present invention will be outlined with reference to FIG. In this embodiment, the decontamination apparatus is composed of a stirring washing tank and an adsorption tank. In the aforementioned decontamination method for contaminated soil of the present invention, the extraction step is carried out in a stirred washing tank, and the adsorption step is carried out in an adsorption tank.
例えば抽出工程では、撹拌洗浄槽の容器１で、水と、リン酸塩及び硫酸塩からなる群より選択される少なくとも一種の成分とにより処理液を調製し、そこに放射性セシウムで汚染された土壌を加え、撹拌手段２により両者を接触させる。ここで、放射性セシウムで汚染された土壌は、予め粘土分を除去したものであってもよい。続いて、そこに酸を加え、ｐＨ４以下に調整する。加熱手段３により所定の温度に加熱し、所定の時間、撹拌手段２により両者を接触させ、土壌から放射性セシウムを抽出する。冷却手段４により周囲温度まで冷却後、撹拌手段２を停止し、土壌が十分に沈殿するまで静置し、次いで処理液循環ライン５により上澄み部（抽出液）を吸着槽の容器６に移す。 For example, in the extraction step, a treatment liquid is prepared with water and at least one component selected from the group consisting of phosphate and sulfate in container 1 of the stirred washing tank, and soil contaminated with radioactive cesium there Is brought into contact with each other by the stirring means 2. Here, the soil contaminated with radioactive cesium may be one from which the clay component has been removed in advance. Subsequently, an acid is added thereto to adjust to pH 4 or less. The mixture is heated to a predetermined temperature by the heating means 3 and brought into contact with each other by the stirring means 2 for a predetermined time to extract radioactive cesium from the soil. After cooling to ambient temperature by the cooling means 4, the stirring means 2 is stopped and left to stand until the soil is sufficiently precipitated, and then the supernatant (extract) is transferred to the vessel 6 of the adsorption tank by the treatment liquid circulation line 5.
吸着工程では、吸着槽の容器６に移された放射性セシウムを含む処理液（抽出液）中に、プルシアンブルー類縁体を担持した親水性繊維基材からなるセシウム吸着材７を導入／回収手段８を用いて導入し、所定の時間、両者を接触させ、放射性セシウムをセシウム吸着材７へ吸着させる。吸着工程に付した処理液は、処理液循環ライン５により回収され、吸着槽の容器６から撹拌洗浄槽の容器１に移され、汚染土壌の２回目以降の抽出工程に、あるいは新たな汚染土壌の１回目の抽出工程に再利用することができる。 In the adsorption step, a cesium adsorbent 7 comprising a hydrophilic fiber base material carrying a Prussian blue analogue is introduced / collected in a treatment liquid (extract) containing radioactive cesium transferred to the vessel 6 of the adsorption tank. The radioactive cesium is adsorbed onto the cesium adsorbent 7 by bringing the two into contact with each other for a predetermined time. The treatment liquid subjected to the adsorption step is recovered by the treatment liquid circulation line 5 and transferred from the container 6 of the adsorption tank to the container 1 of the stirring / washing tank for the second or subsequent extraction step of the contaminated soil or Can be reused in the first extraction step of
以下、本発明の具体的態様を実施例として示すが、これらは例示であって、本発明を限定することを意図するものではない。 Hereinafter, specific embodiments of the present invention will be shown as examples, but these are examples and are not intended to limit the present invention.
［放射能濃度測定］
実施例における放射能濃度の測定は、γ線測定器であるＮａＩ（Ｔｌ）検出器（ＡＴＯＭＴＥＸ，ＲＫＧ−ＡＴ１３２０Ａ）を用い、ソフトウェア（ＡＴＯＭＴＥＸ, ＡＴＭＡ）で解析を行った。
[Radioactivity concentration measurement]
The measurement of the radioactivity concentration in an Example analyzed using software (ATOMTEX, ATMA) using the NaI (Tl) detector (ATOMTEX, RKG-AT1320A) which is a gamma ray measuring instrument.
［土壌試料］
実施例における土壌試料は、地権者の了承を得て福島県相馬郡飯舘村の水田にて、深さ５ｃｍまでを許容深度として表層の土壌を採取し、環境試料採取法（文部科学省，１９８３）に基づき１０５℃に設定した乾燥器内で乾燥させたものである。
[Soil sample]
The soil samples in the example were obtained from the soil in the surface layer at a depth of up to 5 cm as an acceptable depth in the paddy field of Iijima village in Soma-gun, Fukushima with the consent of the owner of the land, and the environmental sampling method (Ministry of Education, MEXT, 1983) And dried in a drier set at 105 ° C.).
実施例１−１：抽出工程
［実験手順］
（i）土壌試料６０g（乾燥時の放射能濃度：２７,４４０Ｂｑ／ｋｇ）に水１０００ｍＬを加え、周囲温度で１分撹拌し、次いで２分静置した後、上澄み液を回収し、上澄み液と共に土壌中の粘土分（微粒子）を除去した。
（ii）撹拌洗浄槽で、リン酸１カリウムの１Ｍ水溶液６００ｍＬを調製し、（i）の粘度分を除去した土壌を加えて撹拌した（固液比１：１０）。
（iii）次いで（ii）に硝酸（１３Ｎ）を滴下してｐＨ２ に調整した。
（iv）約１００℃に加熱し、撹拌しながら２時間保温した。
（v）土壌が十分に沈殿するまで静置して、上澄み部（抽出液）を回収した。
（vi）沈殿部（処理土壌）を洗浄後、一部を採取・乾燥して放射能濃度を測定した。
［実験結果］
得られた土壌の放射能濃度は４,４７０Ｂｑ／ｋｇであり、除染率は８４％であった。なお、セシウムの除染率は以下の式で定義し、その結果を図２に示す。
Example 1-1 Extraction Process [Experimental Procedure]
(I) 1000 mL of water is added to 60 g of soil sample (radioactivity concentration at the time of drying: 27,440 Bq / kg), stirred for 1 minute at ambient temperature, and then allowed to stand for 2 minutes. Together with the removal of clay (fine particles) in the soil.
(Ii) In a stirred washing tank, 600 mL of a 1 M aqueous solution of potassium monobasic phosphate was prepared, and the soil from which the viscosity component of (i) was removed was added and stirred (solid-liquid ratio 1:10).
(Iii) Subsequently, nitric acid (13 N) was added dropwise to (ii) to adjust to pH 2.
(Iv) Heat to about 100 ° C. and keep warm for 2 hours while stirring.
(V) The mixture was allowed to stand until the soil was sufficiently precipitated to recover the supernatant (extract).
(Vi) After washing the sediment portion (treated soil), a part was collected and dried to measure the radioactivity concentration.
[Experimental result]
The radioactivity concentration of the obtained soil was 4,470 Bq / kg, and the decontamination rate was 84%. In addition, the decontamination rate of cesium is defined by the following formula, and the result is shown in FIG.
実施例１−２：抽出工程
手順（ii）のリン酸１カリウムの１Ｍ水溶液を、硫酸アンモニウム１Ｍ水溶液に換えた以外は、実施例１−１と同様の実験手順を実施した。得られた土壌の放射能濃度は１３,９５０Ｂｑ／ｋｇであり、除染率は４９％であった。結果を図２に示す。
Example 1-2 Extraction step The same experimental procedure as in Example 1-1 was carried out except that the 1 M aqueous solution of potassium monobasic phosphate in step (ii) was changed to a 1 M aqueous solution of ammonium sulfate. The radioactivity concentration of the obtained soil was 13,950 Bq / kg, and the decontamination rate was 49%. The results are shown in FIG.
実施例１−３：抽出工程
手順（ii）のリン酸１カリウムの１Ｍ水溶液を、硫酸アンモニウム１Ｍ及びリン酸１カリウム１Ｍの水溶液に換えた以外は、実施例１−１と同様の実験手順を実施した。得られた土壌の放射能濃度は６,７６０Ｂｑ／ｋｇであり、除染率は７５％であった。結果を図２、３に示す。
Example 1-3 Extraction step The same experimental procedure as in Example 1-1 is carried out except that the 1 M aqueous solution of potassium monophosphate in step (ii) is replaced with an aqueous solution of 1 M ammonium sulfate and 1 M potassium monobasic phosphate. did. The radioactivity concentration of the obtained soil was 6,760 Bq / kg, and the decontamination rate was 75%. The results are shown in FIGS.
実施例１−４：抽出工程
手順（iii）の硝酸（１３Ｎ）を、塩酸（１２Ｎ）に換えた以外は、実施例１−３と同様の実験手順を実施した。得られた土壌の放射能濃度は１０,１５０Ｂｑ／ｋｇであり、除染率は６３％であった。結果を図３に示す。
Example 1-4 Extraction Step The same experimental procedure as in Example 1-3 was carried out except that the nitric acid (13N) in step (iii) was changed to hydrochloric acid (12N). The radioactivity concentration of the obtained soil was 10,150 Bq / kg, and the decontamination rate was 63%. The results are shown in FIG.
実施例１−５：抽出工程
手順（iii）の硝酸（１３Ｎ）を、硫酸（３６Ｎ）に換えた以外は、実施例１−３と同様の実験手順を実施した。得られた土壌の放射能濃度は１１,５２０Ｂｑ／ｋｇであり、除染率は５８％であった。結果を図３に示す。
Example 1-5 Extraction step The same experimental procedure as in Example 1-3 was carried out except that nitric acid (13N) in step (iii) was changed to sulfuric acid (36N). The radioactivity concentration of the obtained soil was 11,520 Bq / kg, and the decontamination rate was 58%. The results are shown in FIG.
比較例１：抽出工程
手順（iii）を除いた以外は、実施例１−３と同様の実験手順を実施した。得られた土壌の放射能濃度は２２,２３０Ｂｑ／ｋｇであり、除染率は１９％であった。結果を図３に示す。
Comparative Example 1: Extraction step The same experimental procedure as in Example 1-3 was performed except that procedure (iii) was omitted. The radioactivity concentration of the obtained soil was 22,230 Bq / kg, and the decontamination rate was 19%. The results are shown in FIG.
実施例２：吸着工程
（１）土壌からのセシウム抽出液の作成
土壌試料５４０ｇ（乾燥時の放射能濃度：５７，６００Ｂｑ／ｋｇ）にリン酸二水素カリウム１Ｍの水溶液５．４ｋｇを加え、さらにこれに硝酸を加えてｐＨ２ になるよう調整した。この後、１００℃付近で２時間攪拌し、冷却した。その後、一晩静置し土壌が完全に沈降させることによって上澄み５．３Ｌ（セシウム１３７の濃度：４７１Ｂｑ／ｋｇ、セシウム１３４ の濃度：２６２Ｂｑ／ｋｇ）を得てこれを吸着実験に供した。
Example 2: Adsorption process
(1) Preparation of cesium extract solution from soil 5.4 kg of an aqueous solution of 1 M potassium dihydrogenphosphate is added to a soil sample of 540 g (radioactivity concentration at drying: 57,600 Bq / kg), and nitric acid is further added thereto The pH was adjusted to 2. After this, the mixture was stirred at about 100 ° C. for 2 hours and cooled. Thereafter, the mixture was allowed to stand overnight to allow the soil to completely settle, thereby obtaining 5.3 L of the supernatant (concentration of cesium 137: 471 Bq / kg, concentration of cesium 134: 262 Bq / kg), which was subjected to an adsorption experiment.
（２）吸着実験
抽出液５．３ｋｇ（セシウム１３７の濃度：４７１Ｂｑ／ｋｇ、セシウム１３４ の濃度：２６２Ｂｑ／ｋｇ）に１７７．６ｇ のプルシアンブルーが担持された繊維状のセシウム吸着剤（小津産業(株)製、五大力ＰＢ）を１５時間接触させることによって放射性セシウムを吸着させた後、これを５０℃のオーブンで乾燥させた。吸着実験終了後の抽出液とプルシアンブルー担持繊維の放射線量を、ＡＴ１３２０Ａ（ＡＴＯＭＴＥＸ 社）で測定し、抽出液からの放射性セシウムの除去率の評価を行った。なお、セシウムの除去率は以下の式で定義した。
(2) Adsorption experiment A fibrous cesium adsorbent in which 177.6 g of Prussian blue is supported on 5.3 kg of extract (concentration of cesium 137: 471 Bq / kg, concentration of cesium 134: 262 Bq / kg) After making radioactive cesium adsorb | suck by making the Co., Ltd. product and five large force PB) contact for 15 hours, it was made to dry with a 50 degreeC oven. The radiation dose of the extract and Prussian blue-loaded fiber after the end of the adsorption experiment was measured with AT1320A (ATOMTEX) to evaluate the removal rate of radioactive cesium from the extract. In addition, the removal rate of cesium was defined by the following formula.
表１に吸着実験前の測定値、表２に吸着実験後の測定値を示す。抽出液中の放射性セシウム量を９７％以上除去できたことがわかる。吸着後の抽出液に残留した放射性セシウムの総量は１９Ｂｑ／ｋｇ であり、飲料水の基準値である１０Ｂｑ／Ｌ（≒ｋｇ）以下までにはならなかったが、近い値にはなったことから、精密にセシウム吸着剤の量を制御すれば、上記基準値はクリアできるものと考えられる。 Table 1 shows measured values before the adsorption experiment, and Table 2 shows measured values after the adsorption experiment. It can be seen that the amount of radioactive cesium in the extract could be removed by 97% or more. The total amount of radioactive cesium remaining in the extract after adsorption was 19 Bq / kg, which did not reach 10 Bq / L (≒ kg) or less, which is the standard value for drinking water, but it was a close value. If the amount of cesium adsorbent is precisely controlled, it is considered that the above reference value can be cleared.
実施例３：脱着工程
実施例２で得られた、放射性セシウムを吸着させたプルシアンブルーが担持された繊維状のセシウム吸着剤のうちの４６．２ｇ（乾重量）を１．１Ｎ の水酸化ナトリウム水溶液（脱着液）に２０分接触させて放射性セシウムを脱着させた。更に脱着液の繰り返し利用の可能性を検討するため、上記で一度使用した脱着液に、別の放射性セシウムを吸着させたプルシアンブルーが担持された繊維状のセシウム吸着材４３．１ｇ（乾重量）を２０分接触させて放射性セシウムを脱着させた。１回目及び２回目の脱着後の脱着液とセシウム吸着材の放射線量を、ＡＴ１３２０Ａ（ＡＴＯＭＴＥＸ 社）で測定し、吸着材からの放射性セシウムの脱着率と、脱着後に吸着材に残留する放射性セシウム量を評価した。なお、脱着率は以下のように定義した。
Example 3 Desorption Step 46.2 g (dry weight) of the fibrous cesium adsorbent loaded with Prussian blue adsorbed with radioactive cesium, obtained in Example 2, was added to 1.1 N sodium hydroxide The radioactive cesium was desorbed by contacting the aqueous solution (desorbed solution) for 20 minutes. Furthermore, in order to examine the possibility of repeated use of the desorbed liquid, 43.1 g (dry weight) of fibrous cesium adsorbent in which Prussian blue having another radioactive cesium adsorbed thereon is supported on the desorbed liquid used once. Were contacted for 20 minutes to desorb the radioactive cesium. The radiation dose of the desorption solution and cesium adsorbent after the first and second desorption was measured with AT1320A (ATOMTEX), and the desorption rate of radioactive cesium from the adsorbent and the amount of radioactive cesium remaining in the adsorbent after desorption Was evaluated. The desorption rate was defined as follows.
表３に、１回目及び２回目脱着後の脱着液中の放射線量を示す。また表４に脱着実験前の測定値、表５に２回目脱着実験後の測定値を示す。繰り返し脱着を行うことによって脱着液中の放射性セシウムを濃縮できることがわかった。なお、２回目脱着実験後の脱着液を滴定することにより、使用された水酸化ナトリウム量を算出したところ、９０g−ＮａＯＨ／ｋｇ−セシウム吸着材であることがわかった。また、セシウム吸着材からのプルシアンブルーの脱着率として９７％を得ることができた。 Table 3 shows the radiation dose in the desorption solution after the first and second desorption. Table 4 shows measured values before the desorption experiment, and Table 5 shows measured values after the second desorption experiment. It was found that the radioactive cesium in the desorption liquid can be concentrated by performing repeated desorption. In addition, when the amount of sodium hydroxide used was calculated by titrating the desorbed liquid after 2nd desorption experiment, it turned out that it is 90g-NaOH / kg-cesium adsorbent. Moreover, 97% could be obtained as the desorption rate of Prussian blue from the cesium adsorbent.
実施例４：実用化スケールでの除染試験
本発明の除染方法の実用化に向けたスケールに設計されたプロトタイプの除染装置（図１）を用い、以下の手順に従い、除染試験を実施した。
［実験手順］
（i）土壌試料５６ｋｇ（dry：放射能濃度：４３，０００Ｂｑ／ｋｇ）に水１００Ｌを加え、周囲温度で２分撹拌し、次いで５分静置した後、上澄み液を回収し、上澄み液と共に土壌中の粘土分（微粒子）を除去した。
（ii）撹拌洗浄槽で、リン酸１カリウムの１Ｍ水溶液５６０Ｌを調製し、（i）の粘度分を除去した土壌を加えて撹拌した（固液比１：１０）。
（iii）次いで（ii）に硝酸（１３Ｎ）を滴下してｐＨ２ に調整した。
（iv）約１００℃に加熱し、撹拌しながら２時間保温した。
（v）土壌が十分に沈殿するまで一晩静置して、上澄み部（抽出液）を吸着槽に移動させると共に、一部を採取して放射能濃度を測定した。
（vi）沈殿部（処理土壌）を洗浄後、一部を採取・乾燥して放射能濃度を測定した。
（vii）次いで（v）で得られた抽出液にプルシアンブルーが担持された繊維状のセシウム吸着剤（小津産業(株)製、五大力ＰＢ）を約２ｋｇ投入し、４時間浸漬させた。抽出液の一部を採取して放射能濃度を測定した。
Example 4: Decontamination test in practical scale Using the prototype decontamination apparatus (FIG. 1) designed on a scale for practical use of the decontamination method of the present invention, the decontamination test was carried out according to the following procedure. Carried out.
[Experimental procedure]
(I) 100 L of water is added to 56 kg of soil sample (dry: activity concentration: 43,000 Bq / kg), stirred at ambient temperature for 2 minutes, and then allowed to stand for 5 minutes. The clay component (fine particles) in the soil was removed.
(Ii) In a stirred washing tank, 560 L of 1 M aqueous solution of monopotassium phosphate was prepared, and the soil from which the viscosity component of (i) was removed was added and stirred (solid-liquid ratio 1:10).
(Iii) Subsequently, nitric acid (13 N) was added dropwise to (ii) to adjust to pH 2.
(Iv) Heat to about 100 ° C. and keep warm for 2 hours while stirring.
(V) The mixture was allowed to stand overnight until the soil was sufficiently precipitated, and the supernatant (extract) was transferred to the adsorption tank, and a part was collected to measure the radioactivity concentration.
(Vi) After washing the sediment portion (treated soil), a part was collected and dried to measure the radioactivity concentration.
(Vii) Next, about 2 kg of a fibrous cesium adsorbent (manufactured by Ozu Sangyo Co., Ltd., five power PB) carrying Prussian blue was added to the extract solution obtained in (v), and immersed for 4 hours. A portion of the extract was collected to measure the radioactivity concentration.
［実験結果］
上記の手順（i）〜（v）に従い、抽出後に一晩かけて土壌を沈降させたところ、抽出液が分離されることが確認できた。得られた土壌抽出液の放射能濃度は１，２６０Ｂｑ／ｋｇ、体積は約５６０Ｌであった。この濃度は、ビーカーサイズの抽出試験によって得られる抽出液と同等であった。従って、プロトタイプ装置でもビーカーサイズに近い精度でセシウム抽出及び抽出液の回収が可能であることが明らかになった。また、この抽出液を手順（vii）で吸着剤によって除染した結果、１２０Ｂｑ／ｋｇまで放射能濃度を低減できた（除去率：約９０％）。これは、吸着の条件を調製することによって更に低濃度まで下げることができると考えられる。
次に、処理前土壌の放射能濃度は４３０００Ｂｑ／ｋｇであったが、これを手順（i）〜（vi）に従って除染した結果、土壌の放射能濃度は１８０００Ｂｑ／ｋｇまで低減された（除染率：約５８％）。この土壌を更に肥料溶液１５００Ｌで再抽出を行ったところ、回収した土壌の放射能濃度は４８００Ｂｑ／ｋｇまで低減された（除染率：８９％）。除染率５８％はビーカーサイズ試験の除染率に比べて低い結果であったが、これはプロトタイプ装置の土壌撹拌能力や加熱能力に改善の余地があるためと思われる。以上の実験結果から、本発明の除染方法及び装置は、除染困難とされる土壌にも対応可能であり、そのプロセスが５０ｋｇ−土壌の規模にスケールアップした場合でも適用できることを示した。
[Experimental result]
When soil was allowed to settle overnight after extraction according to the above procedures (i) to (v), it could be confirmed that the extract was separated. The radioactivity concentration of the obtained soil extract was 1,260 Bq / kg, and the volume was about 560 L. This concentration was equivalent to the extract obtained by the beaker size extraction test. Therefore, it has become clear that even with the prototype device, cesium extraction and extraction of the extract can be performed with an accuracy close to the beaker size. Moreover, as a result of decontaminating this extract with an adsorbent in procedure (vii), the radioactivity concentration could be reduced to 120 Bq / kg (removal rate: about 90%). It is believed that this can be further reduced to lower concentrations by adjusting the conditions of adsorption.
Next, the radioactivity concentration in the soil before treatment was 43000 Bq / kg, but as a result of decontamination according to procedures (i) to (vi), the radioactivity concentration in soil was reduced to 18000 Bq / kg ( Dyeing rate: about 58%). When this soil was further reextracted with 1500 L of fertilizer solution, the radioactivity concentration of the recovered soil was reduced to 4800 Bq / kg (decontamination rate: 89%). The decontamination rate of 58% was lower than that of the beaker size test, which seems to be due to the possibility of improvement in the soil stirring ability and heating ability of the prototype device. From the above experimental results, it was shown that the decontamination method and apparatus of the present invention can cope with soils that are considered to be difficult to decontaminate, and that the process can be applied even when the process is scaled up to 50 kg-soil.
本発明の放射性セシウムで汚染された土壌の除染方法により、汚染土壌から固定化された放射性セシウムを効率よく抽出することができる。また本発明の除染方法で使用する試薬は、いずれも既に農地等で使われている肥料の成分であり、人体や生態系への影響の懸念がなく、除染された土壌は環境中に戻すことができる。したがって、従前の表層土壌剥ぎ取り法のように、汚染土壌の移動、集積、保管は不要である。さらに本発明の除染装置は、特別な材料を必要としないので低コストであり、また専門家による操作を必要としないので、地域住民やボランティア等による自らの手による土壌除染が可能となる。本発明の除染方法及び除染装置により、汚染土壌の除染の加速が期待できる。 By the method for decontaminating soil contaminated with radioactive cesium of the present invention, it is possible to efficiently extract the radioactive cesium immobilized from the contaminated soil. In addition, the reagents used in the decontamination method of the present invention are all components of fertilizers already used in farmland and the like, and there is no concern about the influence on human bodies and ecosystems, and decontaminated soil is in the environment It can be returned. Therefore, it is not necessary to move, accumulate and store contaminated soil as in the conventional surface soil stripping method. Furthermore, the decontamination apparatus of the present invention is low in cost because it does not require any special material, and it does not require an operation by a specialist, so it is possible for the local residents and volunteers to decontaminate the soil by their own hands. . The decontamination method and the decontamination apparatus of the present invention can be expected to accelerate the decontamination of contaminated soil.
１ 撹拌洗浄槽の容器
２ 撹拌手段
３ 加熱手段
４ 冷却手段
５ 処理液循環ライン
６ 吸着槽の容器
７ セシウム吸着材
８ セシウム吸着材の導入／回収手段
DESCRIPTION OF SYMBOLS 1 Container 2 of stirring washing tank 2 Stirring means 3 Heating means 4 Cooling means 5 Treatment liquid circulation line 6 Container 7 adsorption tank Cesium adsorbent 8 Cesium adsorbent introduction / collection means
Claims (7)
前記土壌及び処理液を受け入れる中空の容器；
前記容器の外壁若しくは前記容器内に配設され、前記容器内に受け入れた前記土壌及び処理液を加熱するための加熱手段；及び
前記容器内に受け入れた前記土壌及び処理液を撹拌するための撹拌手段
を備える撹拌洗浄槽を含み、
前記土壌が、粘土分が除去された土壌であり、
前記処理液が、１種のアルカリ金属のリン酸塩を含み、且つ酸成分でｐＨが４以下に調整されたものである、除染装置。 A decontamination apparatus for removing cesium from been soil contaminated with radioactive cesium,
A hollow container for receiving the soil and the treatment liquid;
Heating means disposed in the outer wall of the vessel or in the vessel for heating the soil and the treatment solution received in the vessel; agitation for stirring the soil and the treatment solution received in the vessel Means for stirring the washing tank,
The soil is a soil from which clay content has been removed,
It said processing liquid comprises one phosphate of alkali metals, it is and what pH in the acid component is adjusted to 4 or less, the decontamination apparatus.
を備える吸着槽を含む、請求項５に記載の除染装置。 6. The adsorption vessel according to claim 5 , further comprising: an adsorption vessel comprising a hollow vessel for receiving a cesium adsorbent composed of a treatment liquid containing radioactive cesium and a hydrophilic fiber base material carrying Prussian blue analogue, which is discharged from the agitation washing vessel. Decontamination equipment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2013261750A JP6516317B2 (en) | 2013-12-18 | 2013-12-18 | Method and apparatus for decontaminating soil contaminated with radioactive cesium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2013261750A JP6516317B2 (en) | 2013-12-18 | 2013-12-18 | Method and apparatus for decontaminating soil contaminated with radioactive cesium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2015118010A JP2015118010A (en) | 2015-06-25 |
| JP6516317B2 true JP6516317B2 (en) | 2019-05-22 |
Family
ID=53530857
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2013261750A Active JP6516317B2 (en) | 2013-12-18 | 2013-12-18 | Method and apparatus for decontaminating soil contaminated with radioactive cesium |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP6516317B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105047538A (en) * | 2015-07-31 | 2015-11-11 | 江苏奥能光电科技有限公司 | Silicon wafer cleaning method and cleaning device |
| JP6543134B2 (en) * | 2015-08-19 | 2019-07-10 | 国立大学法人福島大学 | How to separate cesium |
| JP2017181337A (en) * | 2016-03-31 | 2017-10-05 | Ｊｆｅエンジニアリング株式会社 | Method for decontamination of radioactive cesium-containing material |
| KR102042487B1 (en) * | 2018-06-12 | 2019-11-11 | 한국원자력연구원 | Apparatus for Treating Uranium-Containing Liquid Waste and Method for Treating Uranium-Containing Liquid Waste |
| CN115026120A (en) * | 2022-05-23 | 2022-09-09 | 中国人民解放军63653部队 | Polluted sandy soil ex-situ chemical leaching system and plutonium polluted sandy soil ex-situ leaching method |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9455054B2 (en) * | 2011-08-19 | 2016-09-27 | The Foundation For The Promotion Of Industrial Science | Radioactive cesium adsorbent, method for producing the same, and method for removing radioactive cesium in environment with said adsorbent |
| JP5904757B2 (en) * | 2011-10-20 | 2016-04-20 | 株式会社東芝 | Soil purification system |
| JP5755548B2 (en) * | 2011-10-20 | 2015-07-29 | 株式会社東芝 | How to remove cesium from soil |
| JP6220114B2 (en) * | 2011-11-30 | 2017-10-25 | 荏原工業洗浄株式会社 | Decontamination method and apparatus for radioactive cesium solid contamination |
| JP2013134055A (en) * | 2011-12-22 | 2013-07-08 | Osamu Yamada | Method for separating cesium from cesium adsorbed solid substance and system for separating cesium by utilizing the method |
| JP2013178132A (en) * | 2012-02-28 | 2013-09-09 | Hitachi Ltd | Removal method of radioactive substance |
| JP2013228324A (en) * | 2012-04-26 | 2013-11-07 | Nippon Kasei Chem Co Ltd | Method for removing radioactive cesium |
-
2013
- 2013-12-18 JP JP2013261750A patent/JP6516317B2/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| JP2015118010A (en) | 2015-06-25 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US9455054B2 (en) | Radioactive cesium adsorbent, method for producing the same, and method for removing radioactive cesium in environment with said adsorbent | |
| Alahabadi et al. | Activated carbon from wood wastes for the removal of uranium and thorium ions through modification with mineral acid | |
| Alkherraz et al. | Removal of Pb (II), Zn (II), Cu (II) and Cd (II) from aqueous solutions by adsorption onto olive branches activated carbon: equilibrium and thermodynamic studies | |
| JP6516317B2 (en) | Method and apparatus for decontaminating soil contaminated with radioactive cesium | |
| Gao et al. | Highly-effective removal of Pb by co-pyrolysis biochar derived from rape straw and orthophosphate | |
| Pan et al. | Removal of uranium contaminant from aqueous solution by chitosan@ attapulgite composite | |
| Awual et al. | Radioactive cesium removal from nuclear wastewater by novel inorganic and conjugate adsorbents | |
| CN104741076A (en) | Magnetic zeolite, and preparation method and application thereof | |
| Tang et al. | High-efficient scavenging of U (VI) by magnetic Fe3O4@ gelatin composite | |
| Chattanathan et al. | Remediation of uranium-contaminated groundwater by sorption onto hydroxyapatite derived from catfish bones | |
| Sun et al. | Treatment of Pb (II) pollution in livestock wastewater by MgFe2O4 modified manure-biochar derived from livestock itself: Special role of endogenous dissolved organic matter and P species | |
| JP2013160666A (en) | Method for safely disposing burned ash containing radioactive cesium | |
| Tian et al. | Removal of surface cesium ion contamination by peelable composite coating with a highly effective magnetic adsorbent | |
| CN107282626A (en) | A kind of lead-contaminated soil stabilizes restorative procedure | |
| JP2015169633A (en) | Cesium adsorbent formed of fiber on which prussian blue is supported, manufacturing method thereof, and method for adsorbing and removing radioactive cesium by using cesium adsorbent | |
| JP2013061220A (en) | Radioactive cesium adsorptive cloth | |
| JP6180838B2 (en) | Soil decontamination method and apparatus | |
| Danila et al. | Removal of Cd, Cu, Ni, and Pb from nanoscale zero-valent iron amended soil using 0.1 M acetic acid solution | |
| JP2015064310A (en) | Metallic element containment method | |
| CN109351322A (en) | A kind of preparation method for the micro-nano MFH composite material handling lead-contaminated soil | |
| Ortiz-Oliveros et al. | Titanium pyrophosphate for removal of trivalent heavy metals and actinides simulated by retention of europium | |
| KR101618346B1 (en) | Manufacturing method of soil fixation agents with adhesion of radionuclide | |
| Vivas et al. | Fiber-supported layered magnesium phosphate exhibits high caesium (I) capture capacity in water | |
| KR101579795B1 (en) | Method of Removing Cesium from Wastewater by the Solidified Sericite | |
| Kim et al. | Magnetic flocculants and selective adsorbents for the decontamination of radioactive and acidic soil-washing effluent |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| RD04 | Notification of resignation of power of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7424 Effective date: 20150318 |
|
| RD04 | Notification of resignation of power of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7424 Effective date: 20160222 |
|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20161118 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20170814 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20170822 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20171020 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20180320 |
|
| A601 | Written request for extension of time |
Free format text: JAPANESE INTERMEDIATE CODE: A601 Effective date: 20180510 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20180719 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20190108 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20190311 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20190319 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20190412 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 6516317 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |