CS215936B1 - Process for producing polyampholytes - Google Patents

Abstract

This invention relates to selective ion exchangers and in particular to a process for the preparation of polyampholytes. The polyampholytes are prepared by reacting an aqueous solution of formaldehyde and phosphomane with an aminated cross-linked chloromethylated styrene copolymer.

Description

The present invention relates to selective ion exchangers, and in particular to a process for producing polyampholytes

Polyampholytes containing oC-aminophosphinic acid groups can be used to selectively separate heavy and non-ferrous metal cations and anions, such as tungsten, from technical solutions and sludges in hydrometallurgy, for example, sulfite leaching of tungsten molybdenum concentrates, nonferrous metals, galvanic solutions and seawater .

Several processes are known for producing nitrogen and phosphorus containing polyampholytes. In one known method, the copolymerization of a vinyl monomer containing functional groups of one type or a copolymerization of a monomer containing functional groups of this type with another reactive monomer and crosslinker, for example divinylbenzene, is introduced to introduce other types of functional groups that are capable of according to this scheme

CHg

Another known method consists in multistage synthesis, in which functional groups are introduced into various polymer chains during the synthesis, for example as follows:

PCI and A1C1

H ₂ ° í ÚOJ ^? hno ₃ jh ₂ sat ₄ Snfli ₂ i ser

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In addition, it is known to produce polyampholytes by sequentially converting polymer-analogous functional groups to produce a given structure or introducing a polyfunctional group into a polymer in the form of reactive complexes or derivatives thereof, followed by conversion to a polymeric complexone.

The disadvantages of the first and second processes mentioned above are the difficulties associated with the β-ion exchange process, which has an almost steohlometrioc ratio of groups of one and the same type and an uneven distribution of functional groups both in the polymer chain and in the volume of granule-f ion exchanger. by reducing the utilization of the operating properties of the groups and the sioe capacity of the ion exchanger, the strength of the complexes of the absorbed metals and the selectivity of sorpo

If the polyampholytes are obtained by the third process described, a satisfactory property value is obtained. When the products are allowed to react completely in all stages of the synthesis, side reactions do not occur and the number of polymer-analogue conversion steps is minimal.

It is also known to produce polyampholytes by using a halomethylated copolymer of styrene and divinylbenzene cross-linked using various crosslinking agents. The method consists in interacting said copolymer and phosphoric acid in an aqueous formaldehyde solution according to the equation

Res - NHg + CH ₂ O + H 3 POg-3 * Res - NIL ·, - CHg - P0 (0H) ₂ where

Res means

at a temperature of 80 to 100 ° C.

A polyampholyte with α-aminophosphinic acid groups is obtained, but the phosphomic acid is oxidized spontaneously with air, and the phosphoric acid is disproportionated to phosphine and orthophosphoric acid. the capacity of the sorbents obtained is 100 mg / g at pH 3 in the presence of an indifferent sodium sulphite electrolyte in a concentration of 50 g per liter.

It is also known to use andnopolystyrene obtained by the reduction of divinylbenzene cross-linked nitropolystyrene, which is reacted with an aqueous solution of formaldehyde and sodium hypophosphite in an acidic medium as expressed by the reaction scheme.

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In the preparation of the starting anion exchanger, in this case, the styrene-divinylbenzene copolymer is nitrated and then reduced with stannous chloride in the presence of hydrochloric acid. The filtration reactions in the first step are accompanied by secondary reactions and carboxy groups and phenols are formed in the product, as well as oxidative degradation of the polymer. All of this leads to a reduction in the useful properties of the lontomere. Observations have shown that the amino group in the polyampholyte obtained is conjugated to the aromatic nucleus, as a result of which it is poorly basic and therefore has a reduced tendency to form complex compounds.

The purpose of the present invention is to overcome these disadvantages.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a process for producing polyampholites having a structure which, in addition to the high sorpoe capability for tungstate ions, provides good polyampholite desorption capacity.

This object is achieved by making polyampholite a reacoaminated, halomethylated crosslinked styrene copolymer containing primary or secondary amino groups with an aqueous solution of formaldehyde and a phosphorus compound in an acidic environment, using an alkali metal or alkali metal phosphomane in the process of the invention soil.

Due to the proposed process, it is possible to achieve a high tungsten eorpoe capacity which is between 500 and 900 mg / g over a wide range of hydrogen ion concentrations.

The high kinetic properties of the polyampholyte produced by the proposed process (the highest eorpoe with statiocyte conditions being achieved within 3-5 hours) can increase the performance of the sorption device. The present invention allows complete desorption of tungstate ions from the polyampholyte (residual capacity is 0.5 to 0.7%), with desorpoe being carried out with a weak ammonia solution.

Other objects and advantages of the present invention will become apparent from the following detailed description of the process for producing polyampholytes and from the examples.

The process according to the invention is based on the use of industrially manufactured ion exchangers of low basicity having suitable physicochemical and operational properties and consisting, for example, of aliphatic amines or ammonium ammonia and polyamines cross-linked with a halomethylated styrene copolymers. For the manufacture of the above-mentioned ion exchange resins, the ion-exchange synthesis theology known for the suspension copolymerization of styrene copolymer with divinylbenzene, dilsopropenylbenzene or divinylpyridine, diethylene glycol dimethacry4

215 936, a cross-linked substance to obtain a three-dimensional crosslinked copolymer in the form of spherical granules which are non-fusible and insoluble in water and organic solvents. The copolymer is then subjected to chloromethyl

and then the amine is a primary or secondary aliphatic amine or polyamines

CH ₂ NR ₄ R ₂

where the sum of man is 100% vol, n is 2 to 30% vol,

R ₁ represents hydrogen,

R ₂ is hydrogen, -C (OH ₂ ) ₂ -OH, - (O ') _n -NH ₂ , in which n is 2 or 6, or and R-, have the same meaning and are / - (CH ₂ ) ₂ - NH- / _m - (CH ₂ ) ₂ NH ₂ in which m is 0, 1 or 2.

The process according to the invention consists in reacting the above-mentioned low-base ion exchanger with an aqueous solution of formaldehyde with phosphorane, which is carried out in an acidic medium, for example hydrochloric acid.

It is proposed that phosphomans such as sodium phosphonate, potassium hypophosphite and barium phosphonate be used. In the presence of a mineral acid, equilibrium is adjusted in the solution of said salt

MeHgPOg + - »H ₃ PO ₂ + Me ⁺ oo makes it possible to produce the phosphoma acid required for the reaction immediately in the reaction mixture.

For the reaction, it is recommended to use 35 to 37% aqueous formaldehyde solution. It may also be used paraformaldehyde of the formula (CH ₂ 0) _of which extends in an acidic medium with heating to give formaldehyde.

The reaction of said low-base ion exchanger with aqueous formaldehyde solution and phosphomane is carried out in an acidic medium (below pH 3) which is achieved by adding any mineral acid such as sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid.

The reaction temperature usually does not exceed 100 ° C when formalin is added. However, the reaction heat may be as high as 140 ° C (140 ° C) when a high boiling organic solvent and paraformaldehyde are used.

The functional group of the produced polyampholyte obeona is represented by the pattern

where

R is hydrogen, alkyl, - (CH ₂ ) ₂ OH or - / (CH ₂ ) ₂ NH / _m (CH ₂ ) ₂ NH ₂ , wherein u is 0, 1, or 2;

The polar hydroxymethyl group attached to the phosphorus atom increases the acidity of the phosphorous acid as well as the pH range within which the polyampholyte can form complex compounds. Due to said polar group, the hydrophilicity of the polymer increases, which facilitates the entry of water into the ion exchanger granules together with the substances dissolved therein and improves the sorption and desorption kinetics.

The structure of the compounds produced by the process of the invention is determined by elemental analysis, on the basis of aeidobasic properties and IR spectroscopy methods.

Example 1

To a flask equipped with a stirrer and a reflux condenser was added 80 g (0.5 mol) of a styrene-divinylbenzene halomethylated copolymer, aminated with ethylenediamine and then charged with 1500 ml of 37% aqueous formaldehyde solution. Then 2 moles of calcium hypophosphite and 2 moles of concentrated hydrochloric acid are added to the mixture. After stirring for one to two hours, the reaction mixture is heated to a temperature between 90 and 95 ° C and maintained for 15 hours.

The synthesized polyampholyte is washed with water until slightly acidic reaction, then with 3% alkaline solution, again with water and 3% hydrochloric acid solution and again with water until chlorine ions disappear. Phosphorus content 7.1% ·

WO3 ^-2 - the capacity is between 450 and 500 mg / g, the Cu ⁺² -capacity is 60 mg / g. Desorpoe with ammonia solution (3 volumes per 1 volume polyampholyte) is 96% · Residual capacity equals 0.5%.

Example 2

2.4 g (0.01 mol) of polyvinylbenzylamine obtained by amination of the macroporous halomethylated ethylene-divinylbenzene copolymer with urotropin and 20 to a 37% aqueous formaldehyde solution and then 5.6 g (0.06 mol) were added to a flask equipped with a stirrer and a re-smoother.

215 936 of sodium phosphomannan and 0.06 mol of concentrated hydrochloric acid. The reaction mixture is heated to 90 ° C and held at this temperature for 20 hours. The polyampholyte obtained is washed as described in Example 1.

- • 2

The phosphorus content of the obtained polyampholite is 10.2%, the WO ^ capacity is 800 mg / g and the residual capacity is 0.6%. '

Example 3

To a flask equipped with a stirrer and reflux condenser was added 350 ml of 37% aqueous formaldehyde solution, 0.3 moles of barium phosphomane and 0.3 moles of concentrated hydrochloric acid, followed by 12.5 g (0.05 moles) of a chloromethylated copolymer of styrene and diethylene glycol dimethacrylate aminated with monoethanolamine. .

The reaction mixture was stirred for 1 to 2 hours without heating and then heated to 90-95 ° C for 15 hours.

The polyampholyte obtained is washed as described in Example 1.

The phosphoxide content of the product obtained was 6.8%, the V0 -capacity was 420 mg / g and the residual capacity was 0.7%.

Example 4

To a flask equipped with a stirrer and a reflux condenser was added 50 g of a chloromethylated copolymer of styrene and diisopropenylbenzene aminated with ethylenediamine, followed by 1500 ml of 37% aqueous formaldehyde solution. The reaction mixture was kept at room temperature for 15 hours. At the end of this time, 176 g of sodium phosphomane were added to the mixture and acidified to pH 3. The reaction mixture was kept at room temperature with stirring, then heated to 90 ° C for 15 hours. The polyampholyte obtained is washed successively with water until slightly acidic, with a 5% sulfuric acid solution and again with water. The phosphorus content of the product obtained is 7.1%, the W ² -capacity of 450 mg / g at pH 5.2 and 900 mg / g at pH 6.0.

Claims (1)

SUBJECT OF THE INVENTION A process for the preparation of polyampholytes by reacting an aqueous solution of formaldehyde and a phosphorus compound with aminated crosslinked chloromethylated styrene copolymers containing primary or secondary amino groups in an acid medium, characterized in that the phosphorus compound used is an alkali metal or alkaline earth metal phosphoman.