CA1339973C - Process for the production of an electrolyte for the production of alkali dichromates and chromic acid - Google Patents
Process for the production of an electrolyte for the production of alkali dichromates and chromic acidInfo
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- CA1339973C CA1339973C CA000609438A CA609438A CA1339973C CA 1339973 C CA1339973 C CA 1339973C CA 000609438 A CA000609438 A CA 000609438A CA 609438 A CA609438 A CA 609438A CA 1339973 C CA1339973 C CA 1339973C
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-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G37/00—Compounds of chromium
- C01G37/14—Chromates; Bichromates
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G37/00—Compounds of chromium
- C01G37/02—Oxides or hydrates thereof
- C01G37/033—Chromium trioxide; Chromic acid
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
- C22B3/42—Treatment or purification of solutions, e.g. obtained by leaching by ion-exchange extraction
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
- C25B1/01—Products
- C25B1/28—Per-compounds
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
Polyvalent cations can be selectively and almost completely removed from alkali monochromate solutions by bead polymers based on crosslinked polystyrene containing chelating groups, the chelating groups being the substituents ; ; - CH2-N(CH2COOH)2;
; ;
; ;
Description
133~973 A PROCESS FOR THE PRODUCTION OF AN ELECTROLYTE FOR THE
PRODUI~TION OF ALKALI DICHROMATES AND CHROMIC ACID
This invention relates to a process for the removal of polyvalent cations from monochromate solutions, to the monoc]~romate solutions obtainab~e by this process and t:o the u!,e of these solut.ions as electrolyte for the electro-chemical production of dichromates and chromic acid (CrO3).
.~ccording ~o US 3,305,463 and CA-A 739,447, the elect:rolytic production of dichromates and chromic aci.d ta~es place in electrolysis cells of which the electrode compa:rtments are separated by cation exchanger membranes.
In the production of alkali dichromates, alkali mono-chromate solutions or suspensior~s are introduced into the anode compartme~t of the cell anll converted into an alkal.i dichromate solution by the selective transfer of alkal.i ions 1:hrough the membrane to the cathode compartment. For the production of chromic acid, alkali dichromate or alkali monochromate or a mixture of alkali dichromate and monochromate is introduced into the anode compart-ment and converted into solutions containing chromic acid. Sodium dichromate and/or sodium monochromate are generally used for these processes. In both processes, an alkaline solution containing alkali ions is obtained in the cathode compartment, consisting for example of an aqueous sodium hydroxide solution or, as described in CA-A-739,447, of an aqueous solution containing sodium carbonate.
In the operation of these processes, precipitations of compounds of polyvalent ions, particularly alkaline earth ions, are formed in the membrane, reducing its efficiency after only a short time tG the point where the membrane fails altogether. The precipitations are attributable to small quantitieci of polyvalent cations, particular]y cal-Le A 26 310 133!3~73 cium a.nd strontium ions, in the alkali mono- or dichromate soluti.ons used as electrolyte which are obtainable in indust.rial processes as described in Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, Volume A7, 1986, pages 67-97.
~ccording to EP-A 47 799, ca.lcium ions can be removed from alkali monochromate soluti.ons by precipitation as calcium carbonate and filtration. According to Example 13 of thls patent application, a monochromate solution con--tainir,g 4 ppm calcium is obtained. A calcium ion content:
such as this is too high for the long-term operation of A
cation exchanger membrane.
Ihe object of the present invention is to pro~ide electrolytes for the electrochemical production of alkal:i dichromates and chromic acid which enable electrolysis tc~
be carried out continuously for long periods.
It has now surpri.singly been found that polyvalent:
cations can be selectively and almost completely removed from alkali monochromate solutions by bead polymers based on crosslinked polystyrene containing chelating groups, the chelating groups being substituents from the series -P-(OH)2 ; ~ CH2-N(CH2COOH)2;
O o H
-CH2-N-CH2COOH ; -CH2-N [ CH2-ll-(~H)2]2 ; and IH
-CH2-N-CH2-ll-(OH)2 Le A 26 310 2 13~ 973 Bead polymers of the type in question acting as cat;ion exchangers are described, for example, in Ullmann's Encyclopedia der techn:Lschen CherT~ie, 4t:h Edition, Vol. 13, 1977, pages 29'i-297.
According to one aspect of the present invention there :Ls provided a process for the removal of polyvalent cations i-rom monochromate solutions which is characterized in that the polyvalenl cations are removed by bead polymers based on crosslinked polystyrene co:ntaining chelating groups, the che]ating groups be:Lng substituents from the series ~ H)2 ; ~ \ ; -CH2-N(CH2COOH)2;
H ~ OH
-CH --N-CH COOH ; -CH2-N t CH2-P-(OH)~2; and H O
-CH2-N-cH2-ll (OH)2 o According to another aspect of the present inventlon 1:here is provided a sodium monochromate solution containing 300 to :L,OOO g/l Na2CrO4, wherein the content of alkaline earth ions is below 1 ppm.
The H atoms of t:he acidic groups ln the substituent:s mentioned may also be completely or partly replaced by alkali, particularly sodium, ions.
The polyvalent cations are removed by known processes, for examp:Le in ion exchang~e columns. It is of advantage to adjust lhe temperature of the monochromate solutions to below 90~C t;o 1~3~197~
avoid or minimize oY.idative damlage to the bead polymers.
The process according to the invention may be appli.ed to solutions having different alka.li monochromate contents in the range from 1 g~l to 960 g/l.
3a 133!197~
:Bead polymers in which the chelating groups are the substituents -cH~-N~H2 1l ~oH~212 and -cH2-N-cH2-p-(oH)2 the crosslinked polystyrene being substituted by one of the two sl~bstituents or by a mixture of both substituents, are prefe:rably used in the process according to the invention.
Bead polymers of this t.ype are commercially available under the n~me of Duolite~R~ ES 467, Dow Chemical, USA.
.rn the case of the.crosslinked polystyrene substituted by a mixture of both substituents, bead polymers in which the molar ratio of the. P atoms to the N atoms is from 1:1 to 1.3:1 are particularly preferred.
:rt is of advantage to use bead polymers in which the H ions of the acid groups in the substituents are compl,etely or partly replaced by sodium ions.
The bead polymers according to the invention may be used both in the gel form and in the macroporous form, the macroporous form being preferred.
:rt has proved to be of advantage to use the bead polymer in monodisperse form.
~ ne particularly advantageous embodiment of the proce-s according to the invention is characterized by the use of an alkali monochromate solution containing 100 to 600 g,/l alkali monochromate which has been freed from most of the alkaline earth i.ons by precipitation with carbonates at 50 to lOO-C and at a pH value of from 9 to 12 using a two- 1:o ten-fold excess of carbonate, based on the quantity of alkaline earth ions.
:rn the operation of the process according to the invention, monochromate solutions are obtained in which the Le A :26 310 4 1339~73 content of polyvalent cations, such as calcium, magnesium, stronl_ium, barium and iron ions, is below l ppm and, i.n some cases, considerably below that value. Solutions such as these are eminentl.y suitable as electrolyte for the electrochemical production of dichromates and chromic acid By virtue of the very small contents of polyvalent cations, the ].ife of the membrane is considerably lengthened, enabl:ing electrolysis to be carried out continuously over long periods.
:Cn addition, high-purity chromates, dichromates and chrom:ic acid may be obtained by the process according t.o the invention and may be used, for example, in analysis, in the e.lectrolytic production of high-purity chromium metal and in the production of high-purity pigments.
:[n addition to monochromate ions, the solutions to be freed from polyvalent: cations in accordance with th.e inven1:ion may of course also contain other anions such as, for example, OH , co~2~, HCO3, Cr2072 etc. without any adverse effect on the process.
After the cation exchangers have been fully charged-with polyvalent cations, they may be regenerated in known manner with acids, preferably hydrochloric acid, and optionally with subsequent replacement of the H ions of the acid groups by sodium .ions using sodium hydroxide.
rrhe bead polymers to be used in accordance with the inven1:ion are distinguished by a. high uptake capacity for polyvalent cations, particularly calcium ions, and by good mechanical and osmotic stability in alkali monochromate solutions .
l'he process according to the invention is illustrated by the following Examp:Les.
';odium monochromate solutions obtainable in a typical produc:tion process as described in Ullmann's Encyclopedia of Industrial Chemist:ry, 5th Edition, Volume A7, 1986, pages 67-97 were used in the Examples. The sodium mono-Le A ~6 310 5 ~ 339~73 chromate solutions used in Examples 3 to 5 were freed' beforehand from most of the alkaline earth ions by precip-itation with sodium carbonate produced ia ,situ.
The following bead polymers were used as cation exchangers in the Examples:
Bead t~olymer A
Macroporous bead polymer based on polystyrene crosslinked with divinyl benzene in which the styrene nucleii are substituted by CH2 N ~ H2~ll~(ONa)2]2-groups and H
-cH2-N-cH2-ll-(oNa)2-groups the molar ratio of t:he P atoms to the N atoms being approximately 1.6:1Ø
A bead polymer of this type is described, for example, in the journal Chemia Anal: Tyczna, Vol. 18, page 1019, 1973.
Bead polYmer B
Macroporous bead polymer based on polystyrene crosslinked with divinyl benzene in which the styrene nucleii are substi.tuted by -CH2-N(CH2COONa)2-groups and Le A 26 310 6 -CH2 -N-CH2-COONa -groups Trade name: Lewatit~R~ TP 207, a product of Bayer AG, Leverkusen.
Bead l~olYmer C
Macroporous bead polymer based on polystyrene crosslinked with divinyl benzene in which the styrene nucleii are substituted by -S03Na groups.
Trade name: Lewatit~R~ SP 112, a product of Bayer AG, Leverkusen.
ExamP].e 1 The 34% sodium monochromate solution (462 g/l Na2CrO4~
used :in this Example had the following contents of poly-valent: cations: calcium 10.3 ppm, magnesium 0.4 ppm~
stront:ium 5.1 ppm. One liter of this solution was stirred with :~00 ml bead polymer A for 27 hours at 89~C. The pH
value of the solution was 11.5. At the end of the test~
the contents of the cations mentioned had fallen to the following levels: calcium < 0.4 ppm, magnesium < 0.05 ppm, stront:ium 0.7 ppm. Examination of the polymer after the test showed that the polymer skeleton had remained intact.
In add~ition, elemental analyses showed that there had been no significant degradation of the aminomethyl phosphonic acid groups. Accordingly, the bead polymer is suitable for the removal of polyvale!nt cations from sodium monochromate solutions.
Exam~le 2 350 ml bead polymer A were introduced into a heatable glass column 3 cm in diameter which gave a filling level of Le A 26 310 7 1~39973 approx. 50 cm. A 25.5% sodium monochromate solution (318 g/l Na2CrO4) having th,e following contents of polyvalent cations was passed through this column calcium 2.7 ppm, magne,ium < 0.5 ppm, strontium 16.8 ppm, iron 0.09 ppm.
The column was charged upwards at a throughflow rate of 2.25 1 per hour and at a temperature of 88~C.
rn the test, the following contents of polyvalent cations were established in the column eluate:
After ppm Mg ppm Ca ppm Sr ppm Fe passage of 0.1 1 < 0.4 < 0.4 < 0.4 0.05 0.7 1 < 0.4 < 0.4 < 0.4 0.02 1.5 1 < 0.4 < 0.4 < 0.4 0.03 2.25 1 < 0.4 < 0.4 < 0.4 0.03 3.0 L < 0.4 < 0.4 < 0.4 0.03 ExampLes 3 to 5 'rwO sodium monochromate solutions pretreated by the following process were used for the following tests (Examples 3 to 5):
8.44 kg 45% sodium hydroxide and 14 kg carbon dioxide were added in portions with stirring at 80~C to c~uantities of 350 1 of a 35.15~ sodium monochromate solution (483 g/l Na2CrC~4) containing 393 ppm calcium, 11 ppm strontium, 1.5 ppm barium and 1 ppm ma,gnesium. The addition of the sodium hydroxide and carbon dioxide was selected so that the solut:ion always had a pH value of approximately 10, the addit:ion time being 2 hours. During this time, a total of 5 kg sodium carbonate was formed n situ, corresponding to a 10-Eold molar excess, based on the c~uantity of alkaline earth ions of the sodium monochromate solution.
After the addition of sodium hydroxide and carbon dioxicle, the mixtures were stirred for 1 hour at 80~C and then filtered. After this carbonate precipitation, the clear filtrates had the following contents of polyvalent Le A ;'6 310 8 cations:
Precipitation 1Precipitation 2 Calcium 1.8 ppm 2.5 ppm Strontium 1 ppm 1 ppm Barium < 0.4 ppm < 0.4 ppm Magnesium < 0.4 ppm < 0.4 ppm ExamPle 3 The filtrate of the precipitation 1 and bead polymer A were used in this test. 3'~0 ml bead polymer A were introduced into a heatable glass column 3 cm in diameter which gave a filling level of apprcximately 50 cm. Sodium monochromate solution was passed through this column at a rate of 10.6 15 1 per hour. The column was charged upwards at a temper-ature of 80~C.
The following contents of polyvalent cations were established in the column eluate:
After Passage ofPPm Ca ppm Sr 1 < 0.4 c 0.4 1 < 0.4 < 0.4 1 < 0.4 < 0.4 1 < 0.4 0.6 25138 1 0.4 0.7 180 1 0.4 0.9 212 1 0.4 0.9 Exam~le 4 350 ml bead polymer B were introduced into a heatable glass column 3 cm in d:iameter which gave a filling level of approximately 50 cm. The filtrate of prec;ipitation 2 was passed through this column at 80~C at a rate of 2.25 1 per hour. The column was charged upwards.
rhe following contents of polyvalent cations were established in the column eluate:
Le A 26 310 9 1:339~7~
After Passage of p~m Ca ppm Sr 2.25 1 < 0.4 < 0.4 4.5 1 < 0.4 < 0.4 6.75 1 < 0.4 < 0.4 9.0 1 < 0.4 < 0.4 11.25 1 < 0.4 < 0.4 ExamPle 5 ~3ead polymer C was used in this test. The other test parameters were the sa~me as in Example 4.
The following contents of poly~alent cations were established in the column eluate:
After passage of PPm Ca ppm Sr 2.25 1 2 4.50 1 2 6.75 1 2 9.00 1 2 11.25 1 2 ]~n this test, there was only a slight reduction in the calci~lm contents of the solution.
Le A 26 310 10
PRODUI~TION OF ALKALI DICHROMATES AND CHROMIC ACID
This invention relates to a process for the removal of polyvalent cations from monochromate solutions, to the monoc]~romate solutions obtainab~e by this process and t:o the u!,e of these solut.ions as electrolyte for the electro-chemical production of dichromates and chromic acid (CrO3).
.~ccording ~o US 3,305,463 and CA-A 739,447, the elect:rolytic production of dichromates and chromic aci.d ta~es place in electrolysis cells of which the electrode compa:rtments are separated by cation exchanger membranes.
In the production of alkali dichromates, alkali mono-chromate solutions or suspensior~s are introduced into the anode compartme~t of the cell anll converted into an alkal.i dichromate solution by the selective transfer of alkal.i ions 1:hrough the membrane to the cathode compartment. For the production of chromic acid, alkali dichromate or alkali monochromate or a mixture of alkali dichromate and monochromate is introduced into the anode compart-ment and converted into solutions containing chromic acid. Sodium dichromate and/or sodium monochromate are generally used for these processes. In both processes, an alkaline solution containing alkali ions is obtained in the cathode compartment, consisting for example of an aqueous sodium hydroxide solution or, as described in CA-A-739,447, of an aqueous solution containing sodium carbonate.
In the operation of these processes, precipitations of compounds of polyvalent ions, particularly alkaline earth ions, are formed in the membrane, reducing its efficiency after only a short time tG the point where the membrane fails altogether. The precipitations are attributable to small quantitieci of polyvalent cations, particular]y cal-Le A 26 310 133!3~73 cium a.nd strontium ions, in the alkali mono- or dichromate soluti.ons used as electrolyte which are obtainable in indust.rial processes as described in Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, Volume A7, 1986, pages 67-97.
~ccording to EP-A 47 799, ca.lcium ions can be removed from alkali monochromate soluti.ons by precipitation as calcium carbonate and filtration. According to Example 13 of thls patent application, a monochromate solution con--tainir,g 4 ppm calcium is obtained. A calcium ion content:
such as this is too high for the long-term operation of A
cation exchanger membrane.
Ihe object of the present invention is to pro~ide electrolytes for the electrochemical production of alkal:i dichromates and chromic acid which enable electrolysis tc~
be carried out continuously for long periods.
It has now surpri.singly been found that polyvalent:
cations can be selectively and almost completely removed from alkali monochromate solutions by bead polymers based on crosslinked polystyrene containing chelating groups, the chelating groups being substituents from the series -P-(OH)2 ; ~ CH2-N(CH2COOH)2;
O o H
-CH2-N-CH2COOH ; -CH2-N [ CH2-ll-(~H)2]2 ; and IH
-CH2-N-CH2-ll-(OH)2 Le A 26 310 2 13~ 973 Bead polymers of the type in question acting as cat;ion exchangers are described, for example, in Ullmann's Encyclopedia der techn:Lschen CherT~ie, 4t:h Edition, Vol. 13, 1977, pages 29'i-297.
According to one aspect of the present invention there :Ls provided a process for the removal of polyvalent cations i-rom monochromate solutions which is characterized in that the polyvalenl cations are removed by bead polymers based on crosslinked polystyrene co:ntaining chelating groups, the che]ating groups be:Lng substituents from the series ~ H)2 ; ~ \ ; -CH2-N(CH2COOH)2;
H ~ OH
-CH --N-CH COOH ; -CH2-N t CH2-P-(OH)~2; and H O
-CH2-N-cH2-ll (OH)2 o According to another aspect of the present inventlon 1:here is provided a sodium monochromate solution containing 300 to :L,OOO g/l Na2CrO4, wherein the content of alkaline earth ions is below 1 ppm.
The H atoms of t:he acidic groups ln the substituent:s mentioned may also be completely or partly replaced by alkali, particularly sodium, ions.
The polyvalent cations are removed by known processes, for examp:Le in ion exchang~e columns. It is of advantage to adjust lhe temperature of the monochromate solutions to below 90~C t;o 1~3~197~
avoid or minimize oY.idative damlage to the bead polymers.
The process according to the invention may be appli.ed to solutions having different alka.li monochromate contents in the range from 1 g~l to 960 g/l.
3a 133!197~
:Bead polymers in which the chelating groups are the substituents -cH~-N~H2 1l ~oH~212 and -cH2-N-cH2-p-(oH)2 the crosslinked polystyrene being substituted by one of the two sl~bstituents or by a mixture of both substituents, are prefe:rably used in the process according to the invention.
Bead polymers of this t.ype are commercially available under the n~me of Duolite~R~ ES 467, Dow Chemical, USA.
.rn the case of the.crosslinked polystyrene substituted by a mixture of both substituents, bead polymers in which the molar ratio of the. P atoms to the N atoms is from 1:1 to 1.3:1 are particularly preferred.
:rt is of advantage to use bead polymers in which the H ions of the acid groups in the substituents are compl,etely or partly replaced by sodium ions.
The bead polymers according to the invention may be used both in the gel form and in the macroporous form, the macroporous form being preferred.
:rt has proved to be of advantage to use the bead polymer in monodisperse form.
~ ne particularly advantageous embodiment of the proce-s according to the invention is characterized by the use of an alkali monochromate solution containing 100 to 600 g,/l alkali monochromate which has been freed from most of the alkaline earth i.ons by precipitation with carbonates at 50 to lOO-C and at a pH value of from 9 to 12 using a two- 1:o ten-fold excess of carbonate, based on the quantity of alkaline earth ions.
:rn the operation of the process according to the invention, monochromate solutions are obtained in which the Le A :26 310 4 1339~73 content of polyvalent cations, such as calcium, magnesium, stronl_ium, barium and iron ions, is below l ppm and, i.n some cases, considerably below that value. Solutions such as these are eminentl.y suitable as electrolyte for the electrochemical production of dichromates and chromic acid By virtue of the very small contents of polyvalent cations, the ].ife of the membrane is considerably lengthened, enabl:ing electrolysis to be carried out continuously over long periods.
:Cn addition, high-purity chromates, dichromates and chrom:ic acid may be obtained by the process according t.o the invention and may be used, for example, in analysis, in the e.lectrolytic production of high-purity chromium metal and in the production of high-purity pigments.
:[n addition to monochromate ions, the solutions to be freed from polyvalent: cations in accordance with th.e inven1:ion may of course also contain other anions such as, for example, OH , co~2~, HCO3, Cr2072 etc. without any adverse effect on the process.
After the cation exchangers have been fully charged-with polyvalent cations, they may be regenerated in known manner with acids, preferably hydrochloric acid, and optionally with subsequent replacement of the H ions of the acid groups by sodium .ions using sodium hydroxide.
rrhe bead polymers to be used in accordance with the inven1:ion are distinguished by a. high uptake capacity for polyvalent cations, particularly calcium ions, and by good mechanical and osmotic stability in alkali monochromate solutions .
l'he process according to the invention is illustrated by the following Examp:Les.
';odium monochromate solutions obtainable in a typical produc:tion process as described in Ullmann's Encyclopedia of Industrial Chemist:ry, 5th Edition, Volume A7, 1986, pages 67-97 were used in the Examples. The sodium mono-Le A ~6 310 5 ~ 339~73 chromate solutions used in Examples 3 to 5 were freed' beforehand from most of the alkaline earth ions by precip-itation with sodium carbonate produced ia ,situ.
The following bead polymers were used as cation exchangers in the Examples:
Bead t~olymer A
Macroporous bead polymer based on polystyrene crosslinked with divinyl benzene in which the styrene nucleii are substituted by CH2 N ~ H2~ll~(ONa)2]2-groups and H
-cH2-N-cH2-ll-(oNa)2-groups the molar ratio of t:he P atoms to the N atoms being approximately 1.6:1Ø
A bead polymer of this type is described, for example, in the journal Chemia Anal: Tyczna, Vol. 18, page 1019, 1973.
Bead polYmer B
Macroporous bead polymer based on polystyrene crosslinked with divinyl benzene in which the styrene nucleii are substi.tuted by -CH2-N(CH2COONa)2-groups and Le A 26 310 6 -CH2 -N-CH2-COONa -groups Trade name: Lewatit~R~ TP 207, a product of Bayer AG, Leverkusen.
Bead l~olYmer C
Macroporous bead polymer based on polystyrene crosslinked with divinyl benzene in which the styrene nucleii are substituted by -S03Na groups.
Trade name: Lewatit~R~ SP 112, a product of Bayer AG, Leverkusen.
ExamP].e 1 The 34% sodium monochromate solution (462 g/l Na2CrO4~
used :in this Example had the following contents of poly-valent: cations: calcium 10.3 ppm, magnesium 0.4 ppm~
stront:ium 5.1 ppm. One liter of this solution was stirred with :~00 ml bead polymer A for 27 hours at 89~C. The pH
value of the solution was 11.5. At the end of the test~
the contents of the cations mentioned had fallen to the following levels: calcium < 0.4 ppm, magnesium < 0.05 ppm, stront:ium 0.7 ppm. Examination of the polymer after the test showed that the polymer skeleton had remained intact.
In add~ition, elemental analyses showed that there had been no significant degradation of the aminomethyl phosphonic acid groups. Accordingly, the bead polymer is suitable for the removal of polyvale!nt cations from sodium monochromate solutions.
Exam~le 2 350 ml bead polymer A were introduced into a heatable glass column 3 cm in diameter which gave a filling level of Le A 26 310 7 1~39973 approx. 50 cm. A 25.5% sodium monochromate solution (318 g/l Na2CrO4) having th,e following contents of polyvalent cations was passed through this column calcium 2.7 ppm, magne,ium < 0.5 ppm, strontium 16.8 ppm, iron 0.09 ppm.
The column was charged upwards at a throughflow rate of 2.25 1 per hour and at a temperature of 88~C.
rn the test, the following contents of polyvalent cations were established in the column eluate:
After ppm Mg ppm Ca ppm Sr ppm Fe passage of 0.1 1 < 0.4 < 0.4 < 0.4 0.05 0.7 1 < 0.4 < 0.4 < 0.4 0.02 1.5 1 < 0.4 < 0.4 < 0.4 0.03 2.25 1 < 0.4 < 0.4 < 0.4 0.03 3.0 L < 0.4 < 0.4 < 0.4 0.03 ExampLes 3 to 5 'rwO sodium monochromate solutions pretreated by the following process were used for the following tests (Examples 3 to 5):
8.44 kg 45% sodium hydroxide and 14 kg carbon dioxide were added in portions with stirring at 80~C to c~uantities of 350 1 of a 35.15~ sodium monochromate solution (483 g/l Na2CrC~4) containing 393 ppm calcium, 11 ppm strontium, 1.5 ppm barium and 1 ppm ma,gnesium. The addition of the sodium hydroxide and carbon dioxide was selected so that the solut:ion always had a pH value of approximately 10, the addit:ion time being 2 hours. During this time, a total of 5 kg sodium carbonate was formed n situ, corresponding to a 10-Eold molar excess, based on the c~uantity of alkaline earth ions of the sodium monochromate solution.
After the addition of sodium hydroxide and carbon dioxicle, the mixtures were stirred for 1 hour at 80~C and then filtered. After this carbonate precipitation, the clear filtrates had the following contents of polyvalent Le A ;'6 310 8 cations:
Precipitation 1Precipitation 2 Calcium 1.8 ppm 2.5 ppm Strontium 1 ppm 1 ppm Barium < 0.4 ppm < 0.4 ppm Magnesium < 0.4 ppm < 0.4 ppm ExamPle 3 The filtrate of the precipitation 1 and bead polymer A were used in this test. 3'~0 ml bead polymer A were introduced into a heatable glass column 3 cm in diameter which gave a filling level of apprcximately 50 cm. Sodium monochromate solution was passed through this column at a rate of 10.6 15 1 per hour. The column was charged upwards at a temper-ature of 80~C.
The following contents of polyvalent cations were established in the column eluate:
After Passage ofPPm Ca ppm Sr 1 < 0.4 c 0.4 1 < 0.4 < 0.4 1 < 0.4 < 0.4 1 < 0.4 0.6 25138 1 0.4 0.7 180 1 0.4 0.9 212 1 0.4 0.9 Exam~le 4 350 ml bead polymer B were introduced into a heatable glass column 3 cm in d:iameter which gave a filling level of approximately 50 cm. The filtrate of prec;ipitation 2 was passed through this column at 80~C at a rate of 2.25 1 per hour. The column was charged upwards.
rhe following contents of polyvalent cations were established in the column eluate:
Le A 26 310 9 1:339~7~
After Passage of p~m Ca ppm Sr 2.25 1 < 0.4 < 0.4 4.5 1 < 0.4 < 0.4 6.75 1 < 0.4 < 0.4 9.0 1 < 0.4 < 0.4 11.25 1 < 0.4 < 0.4 ExamPle 5 ~3ead polymer C was used in this test. The other test parameters were the sa~me as in Example 4.
The following contents of poly~alent cations were established in the column eluate:
After passage of PPm Ca ppm Sr 2.25 1 2 4.50 1 2 6.75 1 2 9.00 1 2 11.25 1 2 ]~n this test, there was only a slight reduction in the calci~lm contents of the solution.
Le A 26 310 10
Claims (6)
1. A process for the removal of polyvalent cations from a monochromate solution, comprising removing the polyvalent cations using a bead polymer based on a. crosslinked polystyrene containing chelating groups, the chelating groups being the substituents ; ; - CH2-N(CH2COOH)2;
; ;
; ;
2. A process according to claim 1, wherein the chelating groups are the substituents or the crosslinked polystyrene being substituted by one of the two substituents or by a mixture of both substituents.
3. A process according to claim 2, wherein the crosslinked polystyrene is substituted by a mixture of the two substituents, the molar ratio of the P atoms to the N atoms in the bead polymer is from 1:1 to 1.8:1.
4. A process according to claim 1, wherein the H ions of the acid groups in the substituents are completely or partly replaced by sodium ions.
5, A process according to claim 1, wherein the crosslinked polystyrene is a macroporous bead polymer.
6. A process according to claim 1, wherein the alkali monochromate solutions containing 100 to 600 g/l alkali monochromate is freed from most of the alkaline earth ions by precipitation with carbonates at 50 to 100°C and at a pH value in the range from 9 to 12 using a two- to ten-fold carbonate excess, based on the quantity of alkaline earth ions.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3829120.7 | 1988-08-27 | ||
| DE3829120A DE3829120A1 (en) | 1988-08-27 | 1988-08-27 | METHOD FOR PRODUCING AN ELECTROLYTE FOR GENERATING ALKALIDICHROMATES AND CHROME ACID |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1339973C true CA1339973C (en) | 1998-07-28 |
Family
ID=6361720
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000609438A Expired - Fee Related CA1339973C (en) | 1988-08-27 | 1989-08-25 | Process for the production of an electrolyte for the production of alkali dichromates and chromic acid |
Country Status (13)
| Country | Link |
|---|---|
| EP (1) | EP0356803B1 (en) |
| JP (1) | JP2901190B2 (en) |
| KR (1) | KR970002899B1 (en) |
| AR (1) | AR245429A1 (en) |
| BR (1) | BR8904287A (en) |
| CA (1) | CA1339973C (en) |
| DD (1) | DD287409A5 (en) |
| DE (2) | DE3829120A1 (en) |
| ES (1) | ES2052844T3 (en) |
| MX (1) | MX169749B (en) |
| RO (1) | RO103832B1 (en) |
| RU (1) | RU1830051C (en) |
| ZA (1) | ZA896496B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3829121A1 (en) * | 1988-08-27 | 1990-03-01 | Bayer Ag | ELECTROCHEMICAL METHOD FOR THE PRODUCTION OF CHROME ACID |
| EP1078690B1 (en) | 1999-08-27 | 2011-10-12 | LANXESS Deutschland GmbH | Method for producing monodisperse ion exchangers with chelating groups |
| DE10023970A1 (en) * | 2000-05-16 | 2001-11-22 | Bayer Ag | Process for gas adsorption using aminomethylated polymer beads |
| CN112811468B (en) * | 2020-12-25 | 2023-05-23 | 四川省绵阳市华意达化工有限公司 | Method for improving quality of chromic anhydride |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2279453A1 (en) * | 1974-07-24 | 1976-02-20 | Dia Prosim | SELECTIVE ION EXCHANGERS FOR SEPARATING AND FIXING METALS |
| US4157298A (en) * | 1975-07-18 | 1979-06-05 | Akzona Incorporated | Method for the removal of ferric ions from a concentrated aqueous zinc solution |
| DE3704307A1 (en) * | 1987-02-12 | 1988-08-25 | Dow Chemical Gmbh | COMPLEX-FORMING RESIN OF THE GELTYPS AND ITS USE TO REDUCE THE CONCENTRATION OF MULTI-VALUE EARTH ALKALI AND / OR HEAVY METAL IONS IN SOLUTIONS |
-
1988
- 1988-08-27 DE DE3829120A patent/DE3829120A1/en not_active Withdrawn
-
1989
- 1989-08-07 MX MX017094A patent/MX169749B/en unknown
- 1989-08-10 RO RO141224A patent/RO103832B1/en unknown
- 1989-08-15 DE DE8989115031T patent/DE58902682D1/en not_active Expired - Lifetime
- 1989-08-15 EP EP89115031A patent/EP0356803B1/en not_active Expired - Lifetime
- 1989-08-15 ES ES89115031T patent/ES2052844T3/en not_active Expired - Lifetime
- 1989-08-23 RU SU894614831A patent/RU1830051C/en active
- 1989-08-23 JP JP1215128A patent/JP2901190B2/en not_active Expired - Lifetime
- 1989-08-25 BR BR898904287A patent/BR8904287A/en not_active Application Discontinuation
- 1989-08-25 KR KR1019890012118A patent/KR970002899B1/en not_active IP Right Cessation
- 1989-08-25 DD DD89332096A patent/DD287409A5/en not_active IP Right Cessation
- 1989-08-25 CA CA000609438A patent/CA1339973C/en not_active Expired - Fee Related
- 1989-08-25 ZA ZA896496A patent/ZA896496B/en unknown
- 1989-08-25 AR AR89314750A patent/AR245429A1/en active
Also Published As
| Publication number | Publication date |
|---|---|
| MX169749B (en) | 1993-07-22 |
| EP0356803A2 (en) | 1990-03-07 |
| RU1830051C (en) | 1993-07-23 |
| DD287409A5 (en) | 1991-02-28 |
| AR245429A1 (en) | 1994-01-31 |
| KR900003066A (en) | 1990-03-23 |
| JP2901190B2 (en) | 1999-06-07 |
| ES2052844T3 (en) | 1994-07-16 |
| KR970002899B1 (en) | 1997-03-12 |
| DE3829120A1 (en) | 1990-03-01 |
| EP0356803A3 (en) | 1990-03-28 |
| RO103832B1 (en) | 1992-04-26 |
| RO103832A2 (en) | 1991-12-09 |
| ZA896496B (en) | 1990-05-30 |
| EP0356803B1 (en) | 1992-11-11 |
| BR8904287A (en) | 1990-04-17 |
| JPH02107526A (en) | 1990-04-19 |
| DE58902682D1 (en) | 1992-12-17 |
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