WO2006059824A1 - Method of preparation of zeolite for re¬ mediating contaminated materials and method for remediating contaminated materials using thereof - Google Patents
Method of preparation of zeolite for re¬ mediating contaminated materials and method for remediating contaminated materials using thereof Download PDFInfo
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- WO2006059824A1 WO2006059824A1 PCT/KR2005/001479 KR2005001479W WO2006059824A1 WO 2006059824 A1 WO2006059824 A1 WO 2006059824A1 KR 2005001479 W KR2005001479 W KR 2005001479W WO 2006059824 A1 WO2006059824 A1 WO 2006059824A1
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- zeolite
- contaminated materials
- remediating contaminated
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- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 title claims abstract description 169
- 239000010457 zeolite Substances 0.000 title claims abstract description 158
- 229910021536 Zeolite Inorganic materials 0.000 title claims abstract description 157
- 239000000463 material Substances 0.000 title claims abstract description 87
- 238000000034 method Methods 0.000 title claims abstract description 60
- 238000002360 preparation method Methods 0.000 title claims abstract description 26
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical class [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims abstract description 52
- 238000007254 oxidation reaction Methods 0.000 claims description 47
- 230000003647 oxidation Effects 0.000 claims description 46
- 229910001448 ferrous ion Inorganic materials 0.000 claims description 43
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 32
- 235000000396 iron Nutrition 0.000 claims description 25
- 239000007864 aqueous solution Substances 0.000 claims description 21
- 238000003756 stirring Methods 0.000 claims description 21
- 238000005406 washing Methods 0.000 claims description 16
- 239000000356 contaminant Substances 0.000 claims description 14
- 238000002156 mixing Methods 0.000 claims description 11
- 239000012279 sodium borohydride Substances 0.000 claims description 11
- 229910000033 sodium borohydride Inorganic materials 0.000 claims description 11
- 238000001035 drying Methods 0.000 claims description 4
- 150000004677 hydrates Chemical class 0.000 claims description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 77
- 229910052742 iron Inorganic materials 0.000 abstract description 25
- 150000002500 ions Chemical class 0.000 abstract description 11
- 238000010521 absorption reaction Methods 0.000 abstract description 10
- 238000005067 remediation Methods 0.000 abstract description 10
- 238000007796 conventional method Methods 0.000 abstract description 6
- 230000002035 prolonged effect Effects 0.000 abstract description 5
- 150000001875 compounds Chemical class 0.000 abstract description 4
- 238000006243 chemical reaction Methods 0.000 description 38
- 239000000243 solution Substances 0.000 description 24
- 238000006722 reduction reaction Methods 0.000 description 19
- 230000000052 comparative effect Effects 0.000 description 18
- -1 salt compounds Chemical class 0.000 description 16
- 239000002689 soil Substances 0.000 description 12
- 230000035699 permeability Effects 0.000 description 11
- 239000008367 deionised water Substances 0.000 description 9
- 229910021641 deionized water Inorganic materials 0.000 description 9
- 150000002894 organic compounds Chemical class 0.000 description 8
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 7
- 229910001447 ferric ion Inorganic materials 0.000 description 7
- 229960002089 ferrous chloride Drugs 0.000 description 7
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- 238000004458 analytical method Methods 0.000 description 6
- 238000006298 dechlorination reaction Methods 0.000 description 6
- 230000035484 reaction time Effects 0.000 description 6
- 238000004876 x-ray fluorescence Methods 0.000 description 6
- JYIBXUUINYLWLR-UHFFFAOYSA-N aluminum;calcium;potassium;silicon;sodium;trihydrate Chemical compound O.O.O.[Na].[Al].[Si].[K].[Ca] JYIBXUUINYLWLR-UHFFFAOYSA-N 0.000 description 5
- 229910001603 clinoptilolite Inorganic materials 0.000 description 5
- 229910001385 heavy metal Inorganic materials 0.000 description 5
- 238000005342 ion exchange Methods 0.000 description 5
- 235000015097 nutrients Nutrition 0.000 description 5
- 239000011148 porous material Substances 0.000 description 5
- 150000003839 salts Chemical class 0.000 description 5
- 239000012153 distilled water Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 239000012429 reaction media Substances 0.000 description 4
- 230000002829 reductive effect Effects 0.000 description 4
- WSLDOOZREJYCGB-UHFFFAOYSA-N 1,2-Dichloroethane Chemical compound ClCCCl WSLDOOZREJYCGB-UHFFFAOYSA-N 0.000 description 3
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 3
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 3
- MMDJDBSEMBIJBB-UHFFFAOYSA-N [O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[NH6+3] Chemical compound [O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[NH6+3] MMDJDBSEMBIJBB-UHFFFAOYSA-N 0.000 description 3
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 3
- 150000003071 polychlorinated biphenyls Chemical class 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 229910001415 sodium ion Inorganic materials 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- ULGZDMOVFRHVEP-RWJQBGPGSA-N Erythromycin Chemical compound O([C@@H]1[C@@H](C)C(=O)O[C@@H]([C@@]([C@H](O)[C@@H](C)C(=O)[C@H](C)C[C@@](C)(O)[C@H](O[C@H]2[C@@H]([C@H](C[C@@H](C)O2)N(C)C)O)[C@H]1C)(C)O)CC)[C@H]1C[C@@](C)(OC)[C@@H](O)[C@H](C)O1 ULGZDMOVFRHVEP-RWJQBGPGSA-N 0.000 description 2
- MBMLMWLHJBBADN-UHFFFAOYSA-N Ferrous sulfide Chemical compound [Fe]=S MBMLMWLHJBBADN-UHFFFAOYSA-N 0.000 description 2
- CYTYCFOTNPOANT-UHFFFAOYSA-N Perchloroethylene Chemical group ClC(Cl)=C(Cl)Cl CYTYCFOTNPOANT-UHFFFAOYSA-N 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 2
- 229910052793 cadmium Inorganic materials 0.000 description 2
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 239000003638 chemical reducing agent Substances 0.000 description 2
- NEHMKBQYUWJMIP-UHFFFAOYSA-N chloromethane Chemical compound ClC NEHMKBQYUWJMIP-UHFFFAOYSA-N 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 238000010908 decantation Methods 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- 229940052308 general anesthetics halogenated hydrocarbons Drugs 0.000 description 2
- 239000003673 groundwater Substances 0.000 description 2
- 150000008282 halocarbons Chemical class 0.000 description 2
- 239000011133 lead Substances 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000006042 reductive dechlorination reaction Methods 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- 229950011008 tetrachloroethylene Drugs 0.000 description 2
- VZGDMQKNWNREIO-UHFFFAOYSA-N tetrachloromethane Chemical compound ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- 239000011701 zinc Substances 0.000 description 2
- 229910001369 Brass Inorganic materials 0.000 description 1
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 1
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- XSTXAVWGXDQKEL-UHFFFAOYSA-N Trichloroethylene Chemical compound ClC=C(Cl)Cl XSTXAVWGXDQKEL-UHFFFAOYSA-N 0.000 description 1
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910002056 binary alloy Inorganic materials 0.000 description 1
- 239000010951 brass Substances 0.000 description 1
- 150000001768 cations Chemical group 0.000 description 1
- 229960001701 chloroform Drugs 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 150000004820 halides Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 239000012256 powdered iron Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000002269 spontaneous effect Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J39/00—Cation exchange; Use of material as cation exchangers; Treatment of material for improving the cation exchange properties
- B01J39/08—Use of material as cation exchangers; Treatment of material for improving the cation exchange properties
- B01J39/14—Base exchange silicates, e.g. zeolites
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
- B01J20/16—Alumino-silicates
- B01J20/18—Synthetic zeolitic molecular sieves
- B01J20/186—Chemical treatments in view of modifying the properties of the sieve, e.g. increasing the stability or the activity, also decreasing the activity
Definitions
- the present invention relates to a method of preparation of a zeolite for remediating contaminated materials and a method for remediating contaminated materials using the resulted zeolite.
- the present invention relates to a method of preparation of a zeolite for remediating contaminated materials, in which, by using ferrous compounds in the preparation of zeolite for remediating contaminated materials instead of ferric compounds as in the conventional methods, the absorption rate of ions of iron by the zeolite can increase and simultaneously excellent and stable remediation capacity for contaminated materials over a prolonged period can be provided, and to a method for remediating contaminated materials using the resulted zeolite.
- a conventional method using a reactive wall for remediation of contaminated groundwater generally uses a powdered iron as a reaction medium.
- US patent No. 5,575,927 discloses a method using a combination of iron and ferrous sulfide in relative amounts as a reaction medium to reduce halogenated hydrocarbons more rapidly, as compared with a method using iron or ferrous sulfide alone.
- US patent No. 5,543,059 discloses a method in which a solution contaminated with halogenated hydrocarbons is remediated by passing it through a tiered iron wall or column comprising at least three divided zones according to the size of iron particles as a reaction medium.
- iron with an oxidation number of 0 (Fe ) becomes oxidized and thus forms a redox couple.
- This oxidation is somewhat similar to a corrosive reaction caused by spontaneous oxidation in which the oxidation is occurred by the tendency of a metal with an oxidation number of 0 to lose its electrons and to be present as a cation form.
- the redox potential is -0.44V.
- Fig. 1 is a schematic view illustrating the dechlorination process and a standard reduction potential of PCE(C Cl , tetrachloroethylene).
- the dechlorination becomes slower as being moving from B to A.
- At C it shows the highest oxidation state
- at D it shows the lowest oxidation state.
- the main reducing agent which can react with a chlorinated organic compound is Fe o , Fe + , and H .
- FIG. 2 is a schematic view of the reductive dechlorination of a chlorinated organic material by electron exchange upon the corrosion of iron with an oxidation number of 0;
- Fig. 2A is a schematic view of the reduction reaction of a chlorinated organic compound occurred directly by iron with an oxidation number of 0 on the surface thereof;
- Fig. 2B is a schematic view of the reduction reaction of a chlorinated organic compound occurred indirectly by the ferrous ion;
- Fig. 2C is a schematic view illustrating the function of iron with an oxidation number of 0 in the reduction reaction of a chlorinated organic compound by H in the presence of a catalyst.
- a zeolite can remove nutrient salts such as ammonia nitrogen and heavy metals such as cadmium, lead, copper, zinc and the like from contaminated materials by the ion exchange reaction.
- the ion exchange reaction means a selective exchange reaction of ions having electric charge in liquid phase with other ions having the same electric charge in solid phase. By the exchange reaction as such, it is possible to separate or remove specific ions.
- the ion exchange reaction is conducted stoichiometrically, and since the exchange reaction characteristically does not affect to the basic structure of the solid participating in the exchange reaction, regeneration is also possible.
- the iron powder has been used as it is in the form of granules without any treatment or mixing with other ingredients. Therefore, the methods pose a problem that, owing to the limited redox potential of the iron powder, they have only limited applications to limited species of contaminants such as PCE, TCE, DCE, VC, CT and the like, and cannot be applied to the remediation of contaminated materials requiring high redox potential like PCBs, other heavy metals and nutrient salts. Further, since the zeolite has been used generally by being directly added to an aqueous solution, the subject contaminant to be removed is limited to several materials such as heavy metals, nutrient salts and the like.
- 380548 has disclosed a method in which iron is supported on a zeolite and the zeolite is filled into a reactive wall so that heavy metals and nutrient salts which may be removed by zeolite as well as organic salt compounds which may be removed by the conventional reactive wall including an iron powder, may be simultaneously removed.
- the present invention has been designed to solve the problems of prior arts as above. Therefore, the object of the present invention is to provide a method of preparation of a zeolite for remediating contaminated materials, which can increase the absorption rate of ions of iron by the zeolite and simultaneously provide excellent and stable remediation capacity for contaminated materials over a prolonged period, as compared with conventional methods using ferric compounds in the preparation of a zeolite for remediating contaminated materials, and to a method for remediating contaminated materials using the resulted zeolite.
- a method of preparation of a zeolite for remediating contaminated materials comprising the steps of: (1) washing zeolite with water; and (2) mixing the washed zeolite with an aqueous solution containing ferrous ions (Fe + ) with stirring to make the ferrous ions absorbed into the washed zeolite to obtain a zeolite absorbing ferrous ions.
- the zeolite is a material which can remove nutrient salts such as ammonia nitrogen, phosphorus and the like, and heavy metals such as cadmium, lead, copper, zinc and the like, by ion exchange reaction.
- various natural or synthetic zeolites may be used, and preferably used is clinoptilolite which is one of natural zeolites.
- the aqueous solution containing ferrous ions (Fe + ) used in the method of preparation of a zeolite for remediating contaminated materials can be prepared from ferrous halides, for example FeCl , FeF and FeI , or hydrates thereof, and preferably prepared from ferrous chloride (FeCl ) or its hydrate.
- the zeolite is washed with water. It is for preventing a decrease in reaction efficiency by the absorption of impurities into the zeolite, and thus distilled or deionized water may be preferably used for the washing.
- the time and number of washing are not specifically limited, but it is preferred to take 1-10 minutes for every washing and to repeat the washing 1-5 times, taking the total process and the washing efficiency into consideration. In view of the washing efficiency, it is preferred to conduct the washing with moderate stirring rather than too vigorous stirring since too vigorous stirring may cause damages to the structure of the zeolite.
- the washed zeolite is filtered to separate from the washing solution used.
- the washed zeolite is added into an aqueous solution containing ferrous ions and stirred so that the aqueous solution containing ferrous ions can be absorbed into the zeolite.
- the aqueous solution containing ferrous ions can be prepared by using the above-described halogenated ferrous compounds or hydrates thereof, and preferably by dissolving ferrous chloride or its hydrate into distilled water or deionized water.
- the concentration or amount of use of the aqueous solution containing ferrous ions may be varied with the amount of zeolite added thereto, however, from the view of the process efficiency, it is preferred to use 0.5-2L of the aqueous solution containing ferrous ions with the concentration of 0.1-2M, per lOOg of the zeolite.
- a certain reaction condition such as reaction time for the absorption of said aqueous solution containing ferrous ions into said zeolite in the step (2), may be varied by other process conditions such as stirring, however it is preferably carried out for 3-48 hours.
- reaction time is less than 3 hours, the aqueous solution containing ferrous ions would not be sufficiently absorbed into the zeolite.
- reaction time is more than 48 hours, it is not desirable in aspect of the total process efficiency.
- the absorption reaction is preferably conducted under appropriate stirring condition. However, it is desirable to avoid too vigorous stirring since it may cause damages to the structure of the zeolite.
- the reaction mixture is filtered to separate the zeolite and the reaction solution, and the separated zeolite is washed several times with distilled water or deionized water so as to obtain a zeolite which comprises ferrous ions absorbed therein.
- the resulted zeolite comprising absorbed ferrous ions obtained as above can be used as a reaction material for the preparation of a reactive wall for remediating contaminated materials.
- the method of preparation of a zeolite for remediating contaminated materials may further comprises, as a step (3), a step of mixing the zeolite absorbing ferrous ions obtained from the step (2) with an aqueous solution of sodium borohydride(NaBH ) with stirring to reduce said ferrous ions absorbed in the zeolite to obtain a zeolite supporting irons with an oxidation number of 0.
- a step (3) a step of mixing the zeolite absorbing ferrous ions obtained from the step (2) with an aqueous solution of sodium borohydride(NaBH ) with stirring to reduce said ferrous ions absorbed in the zeolite to obtain a zeolite supporting irons with an oxidation number of 0.
- the ferrous ions (Fe + ) absorbed in the zeolite are reduced to irons with an oxidation number of 0 through a reduction reaction represented by the following reaction scheme(l), by mixing the zeolite containing the ferrous irons therein, with the aqueous solution of sodium borohydride (NaBH ) with stirring.
- a reduction reaction represented by the following reaction scheme(l)
- FIG. 3 is a view schematically illustrating the structure of the zeolite prepared according to the method as above-mentioned, on which the particles of irons with an oxidation number of 0 are attached. As seen from Fig. 3, the irons with an oxidation number of 0 (20) is supported by the zeolite as being accumulated on the cage-like structure of the zeolite.
- a certain reaction condition such as reaction time for the reduction of ferrous ion to iron with an oxidation number of 0 in the step (3), may be varied with other process conditions such as stirring and the like, however it is preferred to carry out the reaction for 10 minutes to 2 hours.
- the reaction time is less than 10 minutes, the ferrous ions cannot be sufficiently reduced to irons with an oxidation number of 0, while the reaction time is more than 2 hours, it is possible to cause undesirable structural damages to the zeolite.
- the mixture is filtered to separate the reaction solution and the resulted zeolite.
- the separated zeolite is washed several times with distilled water or deionized water to obtain a zeolite by which irons with an oxidation number of 0 are supported.
- the method of preparation of a zeolite for remediating contaminated materials according to the present invention may further comprises, following after the step (3), a step of drying the zeolite supporting irons with an oxidation number of 0 obtained from the step (3).
- the drying process is preferably conducted by a vacuum dry at 60-120? for 1-lOhours, since the iron with an oxidation number of 0 supported by the zeolite may be oxidized if it contacts with an oxygen in the air at a high temperature.
- the method of preparation of a zeolite for remediating contaminated materials according to the present invention may further comprises various additional steps which could be included in the production of zeolite for remediating contaminated materials, as well as above-said steps, within the scope of achieving the object of the present invention.
- a method for remediating contaminated materials comprises the steps of: preparing a reactive wall comprised of the zeolite for remediating contaminated materials prepared by the method according to any one of claims 1 to 4; placing the reactive wall on a site through which contaminated materials pass; and passing the contaminated materials through the reactive wall to remove contaminants present in the contaminated materials.
- the contaminants which can removed by the method for remediating contaminated materials according to the present invention may include organic compounds for example, nitrate compounds, PCE(C Cl , tetrachloroethylene), TCE(C HCl , tri- choroethylene), DCE(C H Cl , dichloroethylene), VC(C H Cl, vinyl chloride), CT(CCl , carbon tetrachloride), trichloromethane(CHCl ), dichloromethane(CH Cl ), chloromethane(CH Cl), PCBs (poly chlorinated biphenyls) and the like, and in the method for remediating contaminated materials according to the present invention, those contaminants are converted to non-toxic materials such as ethane through a reductive dechlorination replacing Cl ions with H + ions, by means of electrons generated in the course of oxidation of iron with an oxidation number of 0(Fe) or ferrous ion(Fe + ) to ferric ion(
- the reactive wall comprising the zeolite for remediating contaminated materials is placed in a trench excavated by using backhoes and clamshells at the site.
- the zeolite for remediating contaminated materials is mixed with soils and the excavated earth according to the mixing ratio calculated from the results of determining the coefficient of water permeability as described in the following examples.
- the mixture is formed directly in a mixing plant and then poured into the trench.
- steel sheet piles may be optionally penetrated, in order to ensure the stability of the trench while the reaction medium is introduced into the trench as such.
- the reactive wall comprises 5-20wt%, preferably 20wt% of the zeolite for remediating contaminated materials, prepared by the present invention.
- the amount of the zeolite is more than 20wt%, the water permeability of the reactive wall becomes significantly decreased with the lapse of time owing to plugging of pores by the zeolite, while when the amount of the zeolite is less than 5wt%, it has a problem that the contaminants cannot be sufficiently removed.
- the reactive wall comprising the zeolite for remediating contaminated materials may further comprise soil other than zeolite, for example preferably sandy soil, and additional materials which may be conventionally included in a reactive wall for remediating contaminated materials, without departing from the scope of the present invention.
- Fig. 1 is a schematic view illustrating a dechlorination process and a standard reduction potential of PCE (teterachloroethylene),
- Fig. 2A is a schematic view illustrating the reduction reaction of a chlorinated organic compound occurred directly by iron with an oxidation number of 0 on the surface thereof,
- Fig. 2B is a schematic view illustrating the reduction reaction of a chlorinated organic compound occurred indirectly by the ferrous ion
- FIG. 2C is a schematic view illustrating the function of iron with an oxidation number of 0 in the reduction reaction of a chlorinated organic compound by H in the presence of a catalyst
- FIG. 3 is a schematic view illustrating the structure of the zeolite on which the particles of irons with an oxidation number of 0 are attached,
- FIG. 4 is a plot showing, in the test example 1 on the remediation capacity of the present invention, the tendencies of decrease of the concentration of the nitrate nitrogen ions in the reaction solution with the lapse of time, in the presence of the zeolite for remediating contaminated materials, wherein the zeolite for remediating contaminated materials was prepared by Example 2 and Comparative example 2, respectively, and
- Fig. 5 is a plot showing, in the test example 2 on the remediation capacity of the present invention, the tendencies of decrease of the efficiency of the reactive wall in removing PCE with the lapse of time, wherein the reactive wall is prepared by using the zeolite obtained from Example 1 and Comparative example 2, respectively.
- Example 2 [58] 500g of clinoptilolite, as a zeolite, was washed three times with 5L of deionized water for 5 minutes for each run while stirring, and filtered to obtain the washed zeolite separated from the washing solution.
- the washed zeolite was added to 5L of a ferrous chloride solution at the concentration of 350 mM and stirred for 24 hours, and the ferrous chloride solution used in the reaction was removed by decantation.
- the resulted zeolite was washed three times for 10 minutes for each run with 5L of deionized water while stirring and separated from the washing solution to obtain a zeolite, in which ferrous ions were absorbed into the zeolite structure.
- the obtained zeolite was added to 5L of a sodium borohydride solution at the concentration of 2OmM and stirred for 20 minutes, and then the sodium borohydride solution used was decanted.
- the resulted zeolite was washed three times for 10 minutes for each run with 5L of deionized water while stirring, separated from the washing solution, and dried in a vacuum dryer at 9O 0 C for 5 hours to obtain a zeolite for remediating contaminated materials, in which irons with an oxidation number of 0 were supported by the zeolite structure.
- Test example 1 concerning remediating capability: test on nitrate nitrogen removing capacity [76] 2Og of zeolite obtained from the example 2, in which irons with an oxidation number of 0 were supported by the zeolite structure, was added to IL of a nitrate nitrogen solution at the concentration of 5mM, and slowly stirred to carry out a reaction of removing the contaminant, nitrate nitrogen ion (NO ) for 10 hours.
- nitrate nitrogen removing capacity 2Og of zeolite obtained from the example 2, in which irons with an oxidation number of 0 were supported by the zeolite structure, was added to IL of a nitrate nitrogen solution at the concentration of 5mM, and slowly stirred to carry out a reaction of removing the contaminant, nitrate nitrogen ion (NO ) for 10 hours.
- the Fe content in the zeolite obtained from the example 2 is higher than that from the comparative example 2, as it can be seen from above table 1 and table 2. Further, as though it has not been clearly explained yet, it is inferred that, since ferric ions require one and half times more of electrons in reduction to iron with an oxidation number of 0, as compared to the ferrous ions in the same amount, when preparing a zeolite with irons with an oxidation number of 0 by using the same amount of sodium borohydride, the reduction rate of ferric ions to irons with an oxidation number of 0 is lower than the rate of ferrous ions to irons with an oxidation number of 0, and therefore, among the total iron in the zeolite, the ratio of iron with an oxidation number of 0 becomes relatively lower in the comparative example 2 than in the example 2.
- Test example 2 concerning remediating capability test on nitrate nitrogen removing capacity through reactive wall
- reaction material As a reaction material, the zeolite obtained from example 1, in which ferrous ions were absorbed into the zeolite structure, was mixed with soil(sandy soil) with a weight ratio (reaction material:soil) of 1:9, 2:8, 3:7 and 5:5, respectively. The mixture was subjected to a constant head permeability test according to KSF-2322 of Korean Standard to estimate the coefficient of permeability. Detailed test procedure is as follows:
- the coefficient of permeability of the prepared reactive wall which comprises the zeolite having absorbed ferrous ions was 5cm/hr, and the hydraulic gradient was 1/50. Based on these obtained values, Darcy velocity was determined to be 0.1cm/hr, and the maximum velocity of groundwater used in the present reactive wall test was set to be lcm/hr, which is 10 times higher than the darcy velocity.
- a reactive wall having a width of Im, depth of 0.5m and thickness of 0.01m was manufactured by using a mixed soil wherein the zeolite having absorbed ferrous ions and sandy soil were mixed with the ratio of 2:8 based on the weight.
- an aqueous solution having 1OmM of nitrate nitrogen ion (NO ) as a contaminant was allowed to pass through the reactive wall, and the concentration of nitrate nitrogen ion in the passed aqueous solution was measured to obtain a percentage value (%) of the nitrate nitrogen ion concentration removed by the reaction material.
- NO nitrate nitrogen ion
- a zeolite for remediating contaminated materials in which the absorption rate of reactive species by the zeolite can increase and simultaneously excellent and stable remediation capacity for contaminated materials over a prolonged period can be provided, by using ferrous compounds in the preparation of zeolite for remediating contaminated materials instead of using ferric compounds in the preparation of zeolite as in the conventional methods. Therefore, when the resulted zeolite for remediating contaminated materials is used in a reactive wall, it is possible to remediate contaminated materials over a prolonged period in a stable way with good efficiency.
Abstract
Disclosed is a method of preparation of a zeolite for remediating contaminated materials and a method for remediating contaminated materials using the resulted zeolite. Specifically, the present invention relates to a method of preparation of a zeolite for remediating contaminated materials, in which, by using ferrous compounds in the preparation of zeolite for remediating contaminated materials instead of ferric compounds as in the conventional methods, the absorption rate of ions of iron by the zeolite can increase and simultaneously excellent and stable remediation capacity for contaminated materials over a prolonged period can be provided, and to a method for remediating contaminated materials using the resulted zeolite.
Description
Description
METHOD OF PREPARATION OF ZEOLITE FOR REMEDIATING CONTAMINATED MATERIALS AND METHOD FOR REMEDIATING CONTAMINATED MATERIALS USING
THEREOF Technical Field
[1] The present invention relates to a method of preparation of a zeolite for remediating contaminated materials and a method for remediating contaminated materials using the resulted zeolite. Specifically, the present invention relates to a method of preparation of a zeolite for remediating contaminated materials, in which, by using ferrous compounds in the preparation of zeolite for remediating contaminated materials instead of ferric compounds as in the conventional methods, the absorption rate of ions of iron by the zeolite can increase and simultaneously excellent and stable remediation capacity for contaminated materials over a prolonged period can be provided, and to a method for remediating contaminated materials using the resulted zeolite.
[2]
Background Art
[3] A conventional method using a reactive wall for remediation of contaminated groundwater generally uses a powdered iron as a reaction medium. For example, US patent No. 5,575,927 discloses a method using a combination of iron and ferrous sulfide in relative amounts as a reaction medium to reduce halogenated hydrocarbons more rapidly, as compared with a method using iron or ferrous sulfide alone. Also, US patent No. 5,543,059 discloses a method in which a solution contaminated with halogenated hydrocarbons is remediated by passing it through a tiered iron wall or column comprising at least three divided zones according to the size of iron particles as a reaction medium.
[4] In the conventional techniques as mentioned above, it has been found that the mechanism of remediation by iron with an oxidation number of 0 is as follows:
[5] In the mechanism, iron with an oxidation number of 0 (Fe ) becomes oxidized and thus forms a redox couple. This oxidation is somewhat similar to a corrosive reaction caused by spontaneous oxidation in which the oxidation is occurred by the tendency of a metal with an oxidation number of 0 to lose its electrons and to be present as a cation form. In case of iron, the redox potential is -0.44V.
[6] Fe <→ Fe + + 2e~ ...formula (1)
[7] Fig. 1 is a schematic view illustrating the dechlorination process and a standard
reduction potential of PCE(C Cl , tetrachloroethylene). In Fig. 1, the dechlorination becomes slower as being moving from B to A. At C, it shows the highest oxidation state, and at D, it shows the lowest oxidation state. As it may be expected from Fig. 2, the main reducing agent, which can react with a chlorinated organic compound is Fe o , Fe +, and H . For a corrosive reaction, a direct electron exchange between Fe and a chlorinated alkyl adsorbed to the surface [formula (2)] is mainly occurred, but other reactions may also be occurred such as dechlorination by Fe + generated from the corrosive reaction [formula (3)], dechlorination by H [formula (4)], the oxidation of Fe by H O, and the like. The dechlorination process of an alky halide(RX) by such reducing agents may be represented by the following reaction formulas:
[8] Fe0 + RX + H+ <→ Fe2+ + RH + X" ...formula (2)
[9] 2Fe2+ + RX + H+ <→ 2Fe3+ + RH + X" ...formula (3)
[10] H + RX <→ RH + H+ + X" ...formula (4)
[11] Fig. 2 is a schematic view of the reductive dechlorination of a chlorinated organic material by electron exchange upon the corrosion of iron with an oxidation number of 0; Fig. 2A is a schematic view of the reduction reaction of a chlorinated organic compound occurred directly by iron with an oxidation number of 0 on the surface thereof; Fig. 2B is a schematic view of the reduction reaction of a chlorinated organic compound occurred indirectly by the ferrous ion; and Fig. 2C is a schematic view illustrating the function of iron with an oxidation number of 0 in the reduction reaction of a chlorinated organic compound by H in the presence of a catalyst.
[12] It is generally known that a zeolite can remove nutrient salts such as ammonia nitrogen and heavy metals such as cadmium, lead, copper, zinc and the like from contaminated materials by the ion exchange reaction. Herein, the ion exchange reaction means a selective exchange reaction of ions having electric charge in liquid phase with other ions having the same electric charge in solid phase. By the exchange reaction as such, it is possible to separate or remove specific ions. The ion exchange reaction is conducted stoichiometrically, and since the exchange reaction characteristically does not affect to the basic structure of the solid participating in the exchange reaction, regeneration is also possible.
[13] Provided that a binary system comprised of a specific ion (NH +) in liquid phase and another ion (Na+) in solid phase (Z) to be exchanged is used, the mechanism of the ion exchange reaction between Na+ ion in Z and NH + in an aqueous solution can be represented by the following reaction formula, wherein Z is, for example, a zeolite such as clinoptilolite.
[14] ZDNa+ NH 4 + <→ ZDNH 4 + + Na+...formula(5)
[15] The exchange of ions is occurred at the pores of zeolite (see, pores(30) illustrated in
Fig. 3), and in case of clinoptilolite, it is known that the pore size is 4A.
[16] [17]
Disclosure of Invention
Technical Problem
[18] In conventional reactive wall methods using an iron powder, the iron powder has been used as it is in the form of granules without any treatment or mixing with other ingredients. Therefore, the methods pose a problem that, owing to the limited redox potential of the iron powder, they have only limited applications to limited species of contaminants such as PCE, TCE, DCE, VC, CT and the like, and cannot be applied to the remediation of contaminated materials requiring high redox potential like PCBs, other heavy metals and nutrient salts. Further, since the zeolite has been used generally by being directly added to an aqueous solution, the subject contaminant to be removed is limited to several materials such as heavy metals, nutrient salts and the like.
[19] In order to solve the problems mentioned above, a Korean registered patent No.
380548 has disclosed a method in which iron is supported on a zeolite and the zeolite is filled into a reactive wall so that heavy metals and nutrient salts which may be removed by zeolite as well as organic salt compounds which may be removed by the conventional reactive wall including an iron powder, may be simultaneously removed.
[20] In the method disclosed in the above Korean registered patent, a ferric chloride
(FeCl D6FJ0) solution is permeated into zeolite, and then a sodium borohydride (NaBH ) solution is added thereto with stirring so that a reduction reaction can be occurred, thereby the precipitates of iron with an oxidation number of 0 (Fe ) being formed in the inner structure of the zeolite. The reduction reaction can be represented as the following reaction formula:
[21] Fe(H O) 3+ + 3BH " + 3H O ^ Fe°| + 3B(OH) + 10.5H
2 6 4 2 3 2
[22] However, according to the above-mentioned prior art using ferric chloride, it has been found to have problems such as still unsatisfying absorption level of ferric ions to zeolite, great consumption of sodium borohydride (NaBH ) and damages on the zeolite
4 structure naturally occurred owing to the vigorous stirring over a long time during the reduction reaction of ferric ions. Further, another problem has also been found that the iron with an oxidation number of 0 precipitated in zeolite as in the prior art shows a rapidly decrease in remediation capacity for contaminated materials with the lapse of time, therefore it is not suitably used for a long-term application.
[23]
Technical Solution
[24] The present invention has been designed to solve the problems of prior arts as above. Therefore, the object of the present invention is to provide a method of
preparation of a zeolite for remediating contaminated materials, which can increase the absorption rate of ions of iron by the zeolite and simultaneously provide excellent and stable remediation capacity for contaminated materials over a prolonged period, as compared with conventional methods using ferric compounds in the preparation of a zeolite for remediating contaminated materials, and to a method for remediating contaminated materials using the resulted zeolite.
[25] According to one aspect of the present invention, provided is a method of preparation of a zeolite for remediating contaminated materials comprising the steps of: (1) washing zeolite with water; and (2) mixing the washed zeolite with an aqueous solution containing ferrous ions (Fe +) with stirring to make the ferrous ions absorbed into the washed zeolite to obtain a zeolite absorbing ferrous ions.
[26] In the present invention, the zeolite is a material which can remove nutrient salts such as ammonia nitrogen, phosphorus and the like, and heavy metals such as cadmium, lead, copper, zinc and the like, by ion exchange reaction. For the zeolite used in the method of preparation of a zeolite for remediating contaminated materials according to the present invention, various natural or synthetic zeolites may be used, and preferably used is clinoptilolite which is one of natural zeolites.
[27] In the present invention, the aqueous solution containing ferrous ions (Fe +) used in the method of preparation of a zeolite for remediating contaminated materials can be prepared from ferrous halides, for example FeCl , FeF and FeI , or hydrates thereof, and preferably prepared from ferrous chloride (FeCl ) or its hydrate.
[28] Hereinafter, the method of preparation of a zeolite for remediating contaminated materials according to the present invention is further described in detail by each step.
[29] In the step (1) of the method of preparation of a zeolite for remediating contaminated materials according to the present invention, the zeolite is washed with water. It is for preventing a decrease in reaction efficiency by the absorption of impurities into the zeolite, and thus distilled or deionized water may be preferably used for the washing. The time and number of washing are not specifically limited, but it is preferred to take 1-10 minutes for every washing and to repeat the washing 1-5 times, taking the total process and the washing efficiency into consideration. In view of the washing efficiency, it is preferred to conduct the washing with moderate stirring rather than too vigorous stirring since too vigorous stirring may cause damages to the structure of the zeolite. After completing the washing, the washed zeolite is filtered to separate from the washing solution used.
[30] In the step (2) of the method of preparation of a zeolite for remediating contaminated materials according to the present invention, the washed zeolite is added into an aqueous solution containing ferrous ions and stirred so that the aqueous solution containing ferrous ions can be absorbed into the zeolite. The aqueous solution
containing ferrous ions can be prepared by using the above-described halogenated ferrous compounds or hydrates thereof, and preferably by dissolving ferrous chloride or its hydrate into distilled water or deionized water. The concentration or amount of use of the aqueous solution containing ferrous ions may be varied with the amount of zeolite added thereto, however, from the view of the process efficiency, it is preferred to use 0.5-2L of the aqueous solution containing ferrous ions with the concentration of 0.1-2M, per lOOg of the zeolite.
[31] A certain reaction condition such as reaction time for the absorption of said aqueous solution containing ferrous ions into said zeolite in the step (2), may be varied by other process conditions such as stirring, however it is preferably carried out for 3-48 hours. When the reaction time is less than 3 hours, the aqueous solution containing ferrous ions would not be sufficiently absorbed into the zeolite. While, when the reaction time is more than 48 hours, it is not desirable in aspect of the total process efficiency. Further, the absorption reaction is preferably conducted under appropriate stirring condition. However, it is desirable to avoid too vigorous stirring since it may cause damages to the structure of the zeolite. When completing the absorption reaction, the reaction mixture is filtered to separate the zeolite and the reaction solution, and the separated zeolite is washed several times with distilled water or deionized water so as to obtain a zeolite which comprises ferrous ions absorbed therein. The resulted zeolite comprising absorbed ferrous ions obtained as above, can be used as a reaction material for the preparation of a reactive wall for remediating contaminated materials.
[32] The method of preparation of a zeolite for remediating contaminated materials according to the present invention, may further comprises, as a step (3), a step of mixing the zeolite absorbing ferrous ions obtained from the step (2) with an aqueous solution of sodium borohydride(NaBH ) with stirring to reduce said ferrous ions absorbed in the zeolite to obtain a zeolite supporting irons with an oxidation number of 0.
[33] In the step (3) which may be optionally included in the method according to the present invention, the ferrous ions (Fe +) absorbed in the zeolite are reduced to irons with an oxidation number of 0 through a reduction reaction represented by the following reaction scheme(l), by mixing the zeolite containing the ferrous irons therein, with the aqueous solution of sodium borohydride (NaBH ) with stirring.
[34] Fe2+ + 2BH4 " + 6H2O → Fe°| + 2B(OH)3 + 7H2 : reaction scheme(l)
[35] The irons with an oxidation number of 0 generated from said reduction reaction are precipitated as particles in nanometer scale, and supported by the inner structure of the zeolite. Fig. 3 is a view schematically illustrating the structure of the zeolite prepared according to the method as above-mentioned, on which the particles of irons with an
oxidation number of 0 are attached. As seen from Fig. 3, the irons with an oxidation number of 0 (20) is supported by the zeolite as being accumulated on the cage-like structure of the zeolite. [36] As seen from the reaction scheme (1), 1 mole of ferrous ion stoichiometrically requires 2 mole of sodium borohydride (NaBH ) for the reduction, therefore the concentration and the amount of use of the aqueous solution of sodium borohydride (NaBH ) in the step (3) depend on the amount of the corresponding reactant, i.e.
4 ferrous ions. From the view of the process efficiency, it is preferred to use 0.5-2L of an aqueous solution of sodium borohydride with the concentration of 10-50OmM, per lOOg of the above-prepared zeolite containing the ferrous irons therein.
[37] Additionally, a certain reaction condition such as reaction time for the reduction of ferrous ion to iron with an oxidation number of 0 in the step (3), may be varied with other process conditions such as stirring and the like, however it is preferred to carry out the reaction for 10 minutes to 2 hours. When the reaction time is less than 10 minutes, the ferrous ions cannot be sufficiently reduced to irons with an oxidation number of 0, while the reaction time is more than 2 hours, it is possible to cause undesirable structural damages to the zeolite. Further, it is preferred to carry out the absorption reaction under moderate stirring condition, and too vigorous stirring should be desirably avoided, since it could bring about damages to the structure of the zeolite. When completing the reduction reaction, the mixture is filtered to separate the reaction solution and the resulted zeolite. The separated zeolite is washed several times with distilled water or deionized water to obtain a zeolite by which irons with an oxidation number of 0 are supported.
[38] The method of preparation of a zeolite for remediating contaminated materials according to the present invention may further comprises, following after the step (3), a step of drying the zeolite supporting irons with an oxidation number of 0 obtained from the step (3). In the drying step, the drying process is preferably conducted by a vacuum dry at 60-120? for 1-lOhours, since the iron with an oxidation number of 0 supported by the zeolite may be oxidized if it contacts with an oxygen in the air at a high temperature.
[39] The method of preparation of a zeolite for remediating contaminated materials according to the present invention may further comprises various additional steps which could be included in the production of zeolite for remediating contaminated materials, as well as above-said steps, within the scope of achieving the object of the present invention.
[40] According to another aspect of the present invention, a method for remediating contaminated materials is also provided, which comprises the steps of: preparing a reactive wall comprised of the zeolite for remediating contaminated materials prepared by the
method according to any one of claims 1 to 4; placing the reactive wall on a site through which contaminated materials pass; and passing the contaminated materials through the reactive wall to remove contaminants present in the contaminated materials.
[41] The contaminants which can removed by the method for remediating contaminated materials according to the present invention may include organic compounds for example, nitrate compounds, PCE(C Cl , tetrachloroethylene), TCE(C HCl , tri- choroethylene), DCE(C H Cl , dichloroethylene), VC(C H Cl, vinyl chloride), CT(CCl , carbon tetrachloride), trichloromethane(CHCl ), dichloromethane(CH Cl ), chloromethane(CH Cl), PCBs (poly chlorinated biphenyls) and the like, and in the method for remediating contaminated materials according to the present invention, those contaminants are converted to non-toxic materials such as ethane through a reductive dechlorination replacing Cl ions with H+ ions, by means of electrons generated in the course of oxidation of iron with an oxidation number of 0(Fe) or ferrous ion(Fe +) to ferric ion(Fe +).
[42] The reactive wall comprising the zeolite for remediating contaminated materials is placed in a trench excavated by using backhoes and clamshells at the site. The zeolite for remediating contaminated materials is mixed with soils and the excavated earth according to the mixing ratio calculated from the results of determining the coefficient of water permeability as described in the following examples. In the mixing process, the mixture is formed directly in a mixing plant and then poured into the trench. In this while, steel sheet piles may be optionally penetrated, in order to ensure the stability of the trench while the reaction medium is introduced into the trench as such.
[43] In the method for remediating contaminated materials according to the present invention, the reactive wall comprises 5-20wt%, preferably 20wt% of the zeolite for remediating contaminated materials, prepared by the present invention. When the amount of the zeolite is more than 20wt%, the water permeability of the reactive wall becomes significantly decreased with the lapse of time owing to plugging of pores by the zeolite, while when the amount of the zeolite is less than 5wt%, it has a problem that the contaminants cannot be sufficiently removed. In the method for remediating contaminants according to the present invention, the reactive wall comprising the zeolite for remediating contaminated materials may further comprise soil other than zeolite, for example preferably sandy soil, and additional materials which may be conventionally included in a reactive wall for remediating contaminated materials, without departing from the scope of the present invention.
[44]
Brief Description of the Drawings
[45] Fig. 1 is a schematic view illustrating a dechlorination process and a standard reduction potential of PCE (teterachloroethylene),
[46] Fig. 2A is a schematic view illustrating the reduction reaction of a chlorinated organic compound occurred directly by iron with an oxidation number of 0 on the surface thereof,
[47] Fig. 2B is a schematic view illustrating the reduction reaction of a chlorinated organic compound occurred indirectly by the ferrous ion,
[48] Fig. 2C is a schematic view illustrating the function of iron with an oxidation number of 0 in the reduction reaction of a chlorinated organic compound by H in the presence of a catalyst,
[49] Fig. 3 is a schematic view illustrating the structure of the zeolite on which the particles of irons with an oxidation number of 0 are attached,
[50] Fig. 4 is a plot showing, in the test example 1 on the remediation capacity of the present invention, the tendencies of decrease of the concentration of the nitrate nitrogen ions in the reaction solution with the lapse of time, in the presence of the zeolite for remediating contaminated materials, wherein the zeolite for remediating contaminated materials was prepared by Example 2 and Comparative example 2, respectively, and
[51] Fig. 5 is a plot showing, in the test example 2 on the remediation capacity of the present invention, the tendencies of decrease of the efficiency of the reactive wall in removing PCE with the lapse of time, wherein the reactive wall is prepared by using the zeolite obtained from Example 1 and Comparative example 2, respectively.
[52]
[53]
Mode for the Invention
[54] Hereinafter, the invention will be described in more detail, with reference to the following examples and comparative examples, but it should be understood that the scope of the invention is not construed as being limited thereto.
[55] Example 1
[56] 500g of clinoptilolite, as a zeolite, was washed three times with 5L of deionized water for 5 minutes for each run while stirring, and filtered to obtain the washed zeolite separated from the washing solution. The washed zeolite was added to 5L of a ferrous chloride aqueous solution at the concentration of 350 mM and stirred for 24 hours, and the ferrous chloride solution used in the reaction was removed by decantation. The resulted zeolite was washed three times for 10 minutes for each run with 5L of deionized water while stirring and separated from the washing solution to obtain a zeolite for remediating contaminated materials, in which ferrous ions were absorbed
into the zeolite structure.
[57] Example 2 [58] 500g of clinoptilolite, as a zeolite, was washed three times with 5L of deionized water for 5 minutes for each run while stirring, and filtered to obtain the washed zeolite separated from the washing solution. The washed zeolite was added to 5L of a ferrous chloride solution at the concentration of 350 mM and stirred for 24 hours, and the ferrous chloride solution used in the reaction was removed by decantation. The resulted zeolite was washed three times for 10 minutes for each run with 5L of deionized water while stirring and separated from the washing solution to obtain a zeolite, in which ferrous ions were absorbed into the zeolite structure. Then, the obtained zeolite was added to 5L of a sodium borohydride solution at the concentration of 2OmM and stirred for 20 minutes, and then the sodium borohydride solution used was decanted. The resulted zeolite was washed three times for 10 minutes for each run with 5L of deionized water while stirring, separated from the washing solution, and dried in a vacuum dryer at 9O0C for 5 hours to obtain a zeolite for remediating contaminated materials, in which irons with an oxidation number of 0 were supported by the zeolite structure.
[59] For the raw material zeolite used in Examples 1 and 2, the zeolite for remediating contaminated materials obtained from Example 1 in which ferrous ions were absorbed into the zeolite structure, and the zeolite for remediating contaminated materials obtained from Example 2 in which irons with an oxidation number of 0 were supported by the zeolite structure, a composition analysis was carried out by X-ray fluorescence (XRF). The XRF analysis results were represented in the following table 1.
[60] [61] Table 1
[62] Examples: composition of the zeolite through XRF analysis (wt%) [63] [64] As seen from Table 1, the Fe content in the zeolite obtained respectively from Examples 1 and 2 became increased twice as much as the Fe content in the raw material zeolite.
[65] [66] [67] Comparative examples 1 and 2 [68] By using 5L of a ferric chloride solution at the concentration of 35OmM instead of 5L of a ferrous chloride solution at the concentration of 35OmM, a zeolite for remediating contaminated materials in which ferric ions were absorbed into the zeolite structure was obtained in comparative example 1 according to the method of examples 1, and a zeolite for remediating contaminated materials in which irons with an oxidation number of 0 were supported by the zeolite structure was obtained in comparative example 2 according to the method of examples 2.
[69] For each of the zeolite for remediating contaminated materials obtained from comparative example 1 and the zeolite for remediating contaminated materials obtained from comparative example 2, a composition analysis was carried out by XRF as in the examples 1 and 2. The XRF analysis results were represented in the following table 2.
[70] [71] Table 2
[72] Comparative example: composition of zeolite through XRF analysis (wt%) [73] [74] From Tables 1 and 2, it can be seen that each Fe content in the zeolite of comparative example 1 and the zeolite of comparative example 2 did not reach to the increase rate as in the examples 1 and 2, even though it was increased about one and half as much as the Fe content in the raw material zeolite.
[75] Test example 1 - concerning remediating capability: test on nitrate nitrogen removing capacity [76] 2Og of zeolite obtained from the example 2, in which irons with an oxidation number of 0 were supported by the zeolite structure, was added to IL of a nitrate nitrogen solution at the concentration of 5mM, and slowly stirred to carry out a reaction of removing the contaminant, nitrate nitrogen ion (NO ) for 10 hours.
[77] Also, with 2Og of zeolite obtained from the comparative example 2, in which irons with an oxidation number of 0 were supported by the zeolite structure, the same reaction procedure as above was carried out.
[78] During the reaction, a sample of the reaction solution was taken every 2 hours, and the concentration of the nitrate nitrogen ion in the sample was measured. The results are shown in the following table 3, and the tendencies of decrease of the concentration of nitrate nitrogen ion are illustrated in Fig. 4.
[79] [80] Table 3
[81] Concentration of nitrate nitrogen ion in the reaction solution with the lapse of time(mM)
[82] [83] From table 3, it can be seen that the zeolite obtained from the example 2 is superior
to the zeolite obtained from the comparative example 2, in the nitrate nitrogen ion removing capability from the reaction solution.
[84] It may be because the Fe content in the zeolite obtained from the example 2 is higher than that from the comparative example 2, as it can be seen from above table 1 and table 2. Further, as though it has not been clearly explained yet, it is inferred that, since ferric ions require one and half times more of electrons in reduction to iron with an oxidation number of 0, as compared to the ferrous ions in the same amount, when preparing a zeolite with irons with an oxidation number of 0 by using the same amount of sodium borohydride, the reduction rate of ferric ions to irons with an oxidation number of 0 is lower than the rate of ferrous ions to irons with an oxidation number of 0, and therefore, among the total iron in the zeolite, the ratio of iron with an oxidation number of 0 becomes relatively lower in the comparative example 2 than in the example 2.
[85]
[86] Test example 2 concerning remediating capability: test on nitrate nitrogen removing capacity through reactive wall
[87] [Manufacture of a reactive wall]
[88] As a reaction material, the zeolite obtained from example 1, in which ferrous ions were absorbed into the zeolite structure, was mixed with soil(sandy soil) with a weight ratio (reaction material:soil) of 1:9, 2:8, 3:7 and 5:5, respectively. The mixture was subjected to a constant head permeability test according to KSF-2322 of Korean Standard to estimate the coefficient of permeability. Detailed test procedure is as follows:
[89] (1) providing a reaction material as a sample to be measured for the coefficient of permeability and weighing the sample.
[90] (2) measuring the inner diameter of a permeation cylinder to calculate the cross- sectional area(A).
[91] (3) fixing the permeation cylinder onto a porous panel in a container.
[92] (4) laying brass wire net having a mesh size of 74D onto the bottom of the container.
[93] (5) filling the permeation cylinder with the sample to the height of 10 centimeters, compacting the filled sample with a compressing rod so as to be packed uniformly, and then measuring the sample height (L).
[94] (6) calculating the sample weight (wt) in the cylinder by taking the weight of remained sample from the total weight of sample before filling it into the permeation cylinder.
[95] (7) determining specific gravity and water content with the remained sample.
[96] (8) charging the cylinder containing the sample with water to be saturated.
[97] (9) introducing water from the upper part of the cylinder with still and allowing the
water to overflow through the overflow hole in the upper part of the cylinder so as to maintain the water level in the cylinder constant. [98] (10) draining the water with the outlet in the bottom part of the cylinder open until the amount of water overflowed from the container becomes nearly constant. [99] (11) measuring the amount of water (Q) flowing out and time (t).
[100] (12) measuring the difference in head of water (h) between the top and bottom part of the sample.
[101] (13) measuring the water temperature (T).
[102] (14) measuring the water content of the sample which has been gone through the test. [103] (15) determining the coefficient of permeability with the measured values using the formula: [104] k QIiA t QJJhA t
[105] In the formula,
[106] k: coefficient of permeability (cm/sec)
[107] L: height of the sample (cm)
[108] A: cross-sectional area of the sample (cm )
[109] h: difference in head of water (cm)
[110] t: permeation time (sec)
[111] Q: amount of permeated water (cm ).
[112]
[113] Regarding the resulted coefficient of permeability of each sample, when the mixing ratio (reaction material:soil) of the zeolite in which ferrous ions were absorbed with soil is 1:9 or 2:8, the coefficient of permeability was hardly reduced with the lapse of time, however when the mixing ratio is 3:7 or 5:5, the coefficient of permeability was significantly reduced as times elapsed. The reason for this is estimated that the higher the zeolite content, the plugging of pores by the zeolite is more likely to occur. Therefore, in the present test, the reactive wall made with the weight ratio of zeolite to soil (i.e., reaction material:soil) of 2:8 was used.
[114] The coefficient of permeability of the prepared reactive wall which comprises the zeolite having absorbed ferrous ions was 5cm/hr, and the hydraulic gradient was 1/50. Based on these obtained values, Darcy velocity was determined to be 0.1cm/hr, and the maximum velocity of groundwater used in the present reactive wall test was set to be lcm/hr, which is 10 times higher than the darcy velocity.
[115] [Estimation on the efficiency in remediating contaminated materials]
[116] As described above, a reactive wall having a width of Im, depth of 0.5m and
thickness of 0.01m was manufactured by using a mixed soil wherein the zeolite having absorbed ferrous ions and sandy soil were mixed with the ratio of 2:8 based on the weight. In order to determine the efficiency in remediating contaminated materials, an aqueous solution having 1OmM of nitrate nitrogen ion (NO ) as a contaminant was allowed to pass through the reactive wall, and the concentration of nitrate nitrogen ion in the passed aqueous solution was measured to obtain a percentage value (%) of the nitrate nitrogen ion concentration removed by the reaction material. In order to determine the stability of the capacity for remediating contaminated materials over a long period, for the same reactive wall, the above-described test was repeated every week during 10 weeks. The results are shown in the following table 4, and the tendency is plotted in Fig. 5.
[117] Additionally, by using the zeolite obtained from comparative example 2 in which irons with an oxidation number of 0 were supported by the zeolite structure, another reactive wall was manufactured by the same method as described above, and its effect of removing nitrate nitrogen ions over a long period was also estimated by the same method as above. The results are represented tin the following table 4, and the tendency is plotted in Fig. 5.
[118] [119] Table 4
[121] [Note: The concentration of nitrate nitrogen ion before passing the reactive wall was 1OmM in every test.]
[122]
[123] From the table 4, it can be known that, although the reactive wall formed from the zeolite of comparative example 2 showed higher efficiency in removing nitrate nitrogen ion than the reactive wall formed from the zeolite of example 1 during the first 3 weeks, the reactive wall formed from the zeolite of example 1 showed less decrease in the efficiency in removing nitrate nitrogen ion as time elapses after placing the reactive walls, than the reactive wall formed from the zeolite of comparative example 2. It means that the reactive wall formed from the zeolite of example 1 consequently exhibited much stable effects of removing contaminants over a long period, therefore it may be suitably used to remediate underground water with low concentration of contaminants for a long period, in the area where the degree of pollution is not serious.
[124] It has not been clearly explained yet the fact that the zeolite having absorbed ferrous ions shows much stable effects for a long term use. However, it may be inferred that, since irons with an oxidation number of 0 have a relatively unstable oxidization state as compared with ferrous ions, if iron with an oxidation number of 0 is used in the reduction of contaminants, it is more rapidly oxidized by losing electrons with the lapse of time owing to its relatively lower stability than ferrous ion, and therefore, the tendency of ferrous ions to become ferric ions by losing electrons with the lapse of time is lower than that of irons with an oxidation number of 0, although the efficiency of the ferrous ions in removing contaminants at the early period shortly after placing the reactive wall is lower than that of irons with an oxidation number of 0.
[125]
Industrial Applicability
[126] According to the present invention, it is possible to obtain a zeolite for remediating contaminated materials, in which the absorption rate of reactive species by the zeolite can increase and simultaneously excellent and stable remediation capacity for contaminated materials over a prolonged period can be provided, by using ferrous compounds in the preparation of zeolite for remediating contaminated materials instead of using ferric compounds in the preparation of zeolite as in the conventional methods. Therefore, when the resulted zeolite for remediating contaminated materials is used in a reactive wall, it is possible to remediate contaminated materials over a prolonged period in a stable way with good efficiency.
[127]
Claims
(1) washing zeolite with water; and
(2) mixing the washed zeolite with an aqueous solution containing ferrous ions (Fe +) with stirring to make the ferrous ions absorbed into the washed zeolite to obtain a zeolite absorbing ferrous ions.
[2] The method of preparation of a zeolite for remediating contaminated materials according to claim 1, further comprising, as a step (3), a step of mixing the zeolite absorbing ferrous ions obtained from the step (2) with an aqueous solution of sodium borohydride with stirring to reduce said ferrous ions absorbed in the zeolite to obtain a zeolite supporting irons with an oxidation number of 0.
[3] The method of preparation of a zeolite for remediating contaminated materials according to claim 2, further comprising a step of drying the zeolite supporting irons with an oxidation number of 0 obtained from the step (3).
[4] The method of preparation of a zeolite for remediating contaminated materials according to claim 1 or 2, wherein the aqueous solution containing ferrous ions is prepared by using halogenated ferrous compounds or hydrates thereof.
[5] A method for remediating contaminated materials comprising the steps of: preparing a reactive wall comprising the zeolite for remediating contaminated materials prepared by the method according to any one of claims 1 to 4; placing the reactive wall on a site through which the contaminated materials pass; and passing the contaminated materials through the reactive wall to remove contaminants present in the contaminated materials.
[6] The method for remediating contaminated materials according to claim 5, wherein the reactive wall comprises 5-20wt% of the zeolite for remediating contaminated materials.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR10-2004-0099710 | 2004-12-01 | ||
| KR10-2004-0099711 | 2004-12-01 | ||
| KR1020040099710A KR20060060909A (en) | 2004-12-01 | 2004-12-01 | Method of preparation of zeolite anchored iron for remediating contaminated materials using ferrous compound |
| KR1020040099711A KR100594431B1 (en) | 2004-12-01 | 2004-12-01 | Method for remediating contaminated materials using ferrous ion absorbed zeolite |
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| Publication Number | Publication Date |
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| WO2006059824A1 true WO2006059824A1 (en) | 2006-06-08 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/KR2005/001479 WO2006059824A1 (en) | 2004-12-01 | 2005-05-20 | Method of preparation of zeolite for re¬ mediating contaminated materials and method for remediating contaminated materials using thereof |
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| WO (1) | WO2006059824A1 (en) |
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| CN100391590C (en) * | 2006-09-07 | 2008-06-04 | 上海交通大学 | Method for preparing composite assembled object of magnetic ferriferous oxide/ molecular sieve of Nano zeolite |
| CN103007907A (en) * | 2012-12-21 | 2013-04-03 | 清华大学 | Preparation method of high-efficiency quantitative supported nano iron |
| CN103043742A (en) * | 2012-11-30 | 2013-04-17 | 姜英杰 | Environment-friendly and energy-saving ammonia nitrogen removal process |
| CN111056585A (en) * | 2018-10-17 | 2020-04-24 | 武汉市秀谷科技有限公司 | Active infiltration wall filler and preparation method thereof |
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| US5575927A (en) * | 1995-07-06 | 1996-11-19 | General Electric Company | Method for destruction of halogenated hydrocarbons |
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| CN100391590C (en) * | 2006-09-07 | 2008-06-04 | 上海交通大学 | Method for preparing composite assembled object of magnetic ferriferous oxide/ molecular sieve of Nano zeolite |
| CN103043742A (en) * | 2012-11-30 | 2013-04-17 | 姜英杰 | Environment-friendly and energy-saving ammonia nitrogen removal process |
| CN103007907A (en) * | 2012-12-21 | 2013-04-03 | 清华大学 | Preparation method of high-efficiency quantitative supported nano iron |
| CN111056585A (en) * | 2018-10-17 | 2020-04-24 | 武汉市秀谷科技有限公司 | Active infiltration wall filler and preparation method thereof |
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