Aluminum-doped, iminoacetic acid group-containing chelate resins

Abstract

The present invention relates to aluminium-doped chelate resins containing iminoacetic acid groups, to a production process for aluminium-doped chelate resins containing iminoacetic acid groups, and to a device comprising at least one layer of at least one aluminium-doped chelate resin containing iminoacetic acid groups, and to the uses of this device and of the chelate resins for removal of fluoride from water.

Claims

1. A chelate resin consisting essentially of functional groups of the formula (I) ##STR00002## bonded to a polymer skeleton via the methylene group via an aromatic radical, wherein the polymer skeleton is a polystyrene copolymer and wherein X is any monovalent anion, n=0.60 to 1.20 per aromatic radical, and m=0.70 to 1.20 per nitrogen atom.

2. The chelate resin according to claim 1, wherein X is selected from the group of nitrate, chloride and bromide.

3. The chelate resin according to claim 1, wherein the chelate resin contains 25 to 35 g of aluminium per litre of resin.

4. The chelate resin according to claim 1, wherein: the polystyrene copolymer has been prepared from styrene and polyvinylaromatic monomers; wherein the polyvinylaromatic compounds comprise crosslinkers selected from the group consisting of divinylbenzene, divinyltoluene, trivinylbenzene, divinylnaphthalene, and trivinyinaphthalene; and the polymer backbone comprises 1%-20% by weight of the polyvinylaromatic compounds, based on the sum total of monomers and crosslinkers.

5. The chelate resin according to claim 1, wherein: X is selected from the group of nitrate, chloride and bromide; and the chelate resin contains 25 to 35 g of aluminium per litre of resin.

6. The chelate resin according to claim 1, wherein n=0.70 to 1.0, and m=0.75 to 0.95.

7. A process for producing the chelate resin according to claim 1, the process comprising: a.) converting monomer droplets composed of styrene, at least one polyvinylaromatic compound, at least one porogen, and at least one initiator to a crosslinked bead polymer, b.) phthalimidomethylating the crosslinked bead polymer from step a) with phthalimide derivatives, wherein the phthalimide derivatives are used in this reaction in a ratio of 0.70 mol to 1.70 mol per mole of bead polymer, c.) converting the phthalimidomethylated bead polymer from step b) to aminomethylated bead polymer, d.) reacting the aminomethylated bead polymer from step c) with chloroacetic acid or salts thereof to give chelate resins having iminoacetic acid groups with m=0.70 to 1.20 and the molar ratio of chloroacetic acid or salts thereof is 0.70:1 to 1.40:1 based on the molar amount of the aminomethyl groups in the bead polymer, and e.) contacting the chelate resin from step d) with a solution of AlX.sub.3 where X is any monovalent anion.

8. The process according to claim 7, further comprising phthalimidomethylating at a temperature of 60 C. to 80 C.

9. The process according to claim 7, wherein the phthalimidomethylating comprises condensation of the phthalimide derivative with the bead polymer in the presence of a catalyst in a molar ratio of 0.1:1 to 0.45:1 in relation to the amount of phthalimide derivatives used.

10. The process for producing the chelate resin according claim 7, wherein the phthalimide derivatives are used in this reaction in a ratio of 0.70 mol to 1.35 mol per mole of bead polymer.

11. The process according to claim 7, wherein the amount of aluminium used in process step e) is 2 to 7 mol of aluminium based on one litre of chelate resin containing iminoacetic acid groups used.

12. The process for producing the chelate resin according to claim 7, wherein: the at least one polyvinylaromatic compound is selected from the group consisting of divinylbenzene, divinyltoluene, trivinylbenzene, divinylnaphthalene, and trivinylnaphthalene; the at least one porogen is selected from the group consisting of hexane, octane, isooctane, isododecane, octanol, and isomers thereof; and the at least one initiator is selected from the group consisting of dibenzoyl peroxide, dilauroyl peroxide, bis(p-chlorobenzoyl) peroxide, dicyclohexyl peroxydicarbonate, tert-butyl peroctoate, tert-butyl peroxy-2-ethylhexanoate, 2,5-bis(2-ethylhexanoylperoxy)-2,5-dimethylhexane, tert-amylperoxy-2-ethylhexane, 2,2-azobis(isobutyronitrile), and 2,2-azobis(2-methylisobutyronitrile); the phthalimidomethylating comprises condensation of the phthalimide derivative with the bead polymer in the presence of a catalyst selected from oleum, sulphuric acid or sulphur trioxide in a molar ratio of 0.2:1 to 0.4:1 in relation to the amount of phthalimide derivatives; the phthalimidomethylating is done at a temperature of 60 C. to 80 C., and the phthalimide derivatives are used in this reaction in a ratio of 0.80 mol to 1.1 mol per mole of bead polymer; the converting of the phthalimidomethylated bead polymer to aminomethylated bead polymer comprises treatment of the phthalimidomethylated bead polymer with aqueous or alcoholic solutions of sodium hydroxide or potassium hydroxide at temperatures of 120 to 190 C.; the reacting of the aminomethylated bead polymer with chloroacetic acid or salts thereof is done at a molar ratio of the chloroacetic acid derivative to the bead polymer containing aminomethyl groups is 0.80:1.0 to 1.1:1.0, based on the molar amount of the aminomethyl groups in the bead polymer to provide a second substitution level of m=0.75 and 0.95; and the solution of AlX.sub.3 is an aluminum salt solution selected from the group consisting of aluminium chloride, aluminium nitrate, aluminium sulphate, aluminium bromide, aluminium iodide, and the hydrates and solvates thereof, and the amount of aluminium used is 2 to 7 mol aluminium per litre of chelate resin containing iminoacetic acid groups.

13. A device for removing fluoride from water, the device comprising at least one chelate resin containing functional groups of the formula (I) according to claim 1.

14. Use of the device according to claim 13 for removing fluoride from water, preferably for producing drinking water.

Description

EXAMPLES

Example 1

(1) a) Preparation of a Heterodisperse Macroporous Bead Polymer Based on Styrene and Divinylbenzene

(2) At room temperature, the reactor is initially charged with 1112 ml of demineralized water. Into this are metered 72 ml of a 2% by weight aqueous Walocel solution. Walocel (DOW Chemical) is a hydroxyethylmethylcellulose. The solution is prepared by introducing the hydroxyethylmethylcellulose solid into an initial charge of water while stirring and then stirring for a further 4 hours. After the aqueous Walocel solution has been metered in, the mixture is stirred for a further 30 minutes. Subsequently, 7.5 grams of disodium hydrogenphosphate*12 H.sub.2O are metered in. The mixture is stirred for a further 30 minutes.

(3) With the stirrer stationary, the organic phase consisting of 865.1 g of styrene, 94.9 g of 80.95% by weight divinylbenzene, 576 g of isododecane and 7.68 g of 75% by weight dibenzoyl peroxide is metered in. The solution had been prepared separately beforehand.

(4) The abovementioned mixture is polymerized to completion with stirring by increasing the temperature in accordance with a temperature programme beginning at 25 C. and ending at 95 C.

(5) The mixture is cooled down, and the suspension is applied to a sieve, washed with demineralized water and dried in a laboratory vacuum cabinet at 80 C. for 48 hours.

(6) Weight yield based on the total amount of monomers used: 957.2 grams

(7) b) Preparation of the Heterodisperse Amidomethylated Bead Polymer

(8) 666 ml of dichloroethane, 353.7 g of phthalimide and 204.5 g of 36% by weight formalin form an initial charge at room temperature. The pH of the suspension is adjusted to 5.5 to 6 using sodium hydroxide solution. The water is then removed by distillation. Then 25.9 g of sulphuric acid are metered in. The water formed is removed by distillation. The mixture is cooled. At 30 C., 94.7 g of 65% oleum and then 252.5 g of bead polymer prepared in accordance with process step a) from Example 1 are metered in. The suspension is heated to 70 C. and stirred at this temperature for a further 6.5 hours. The reaction liquid is drawn off, demineralized water is metered in and residual dichloroethane is removed by distillation.

(9) Yield of amidomethylated bead polymer: 1100 ml

(10) c) Preparation of the Heterodisperse Aminomethylated Bead Polymer

(11) Into 1080 ml of amidomethylated bead polymer are metered 547 ml of demineralized water and 484.8 g of 50% by weight sodium hydroxide solution at room temperature. The suspension is heated to 180 C. and stirred at this temperature for 8 hours.

(12) The resultant aminomethylated bead polymer is washed with demineralized water.

(13) Yield of amidomethylated bead polymer: 835 ml

(14) Amount of aminomethyl groups in mol per litre of aminomethylated bead polymer: 2.31 mol/l.

(15) It can be calculated from this that, on statistical average, per aromatic nucleus, n=0.95 hydrogen atom has been replaced by aminomethyl groups.

(16) d) Production of the Chelate Resin Having Chelating Groups of the Iminoacetic Acid Type

(17) Into 563 ml of demineralized water are metered, at room temperature, 805 ml of aminomethylated bead polymer from example 1c). The suspension is heated to 90 C. Into this suspension are metered, within 6 hours, 241.6 g of an aqueous solution having an 80% by weight content of monochloroacetic acid. At the same time, the pH of the suspension is kept at pH 9.2 by metered addition of 50% by weight sodium hydroxide solution. Subsequently, the mixture is heated to 95 C. and the suspension is adjusted to pH 10.5 with 50% by weight sodium hydroxide solution. The mixture is stirred at pH 10.5 and 95 C. for a further 6 hours.

(18) Thereafter, the suspension is cooled. The resin is washed with demineralized water until it is free of chloride.

(19) Yield: 1240 ml of chelate resin

(20) Second substitution level: m=1.04

(21) According to this, on statistical average, 1.04 of the two hydrogen atoms in the primary amino group have been replaced by acetic acid groups.

(22) e) Doping of the Resins with Aluminium

(23) 110 ml of chelate resin from example d) are installed into a chromatography column having a frit base. A 1 litre beaker is initially charged with 550 ml of a 1 normal solution of AlCl.sub.3 in demineralized water. By means of a peristaltic pump, the aluminium chloride solution is then pumped through the resin bed in downward flow and back into the beaker again for one hour. The rate of pumped circulation is 10 BV/h, i.e. 1.1 litre/h. The resin becomes laden with aluminium and shrinks by 10% in volume to 100 ml.

(24) Thereafter, the aluminium chloride solution is discarded and 1 litre of deionized water is introduced into the beaker. The deionized water is conveyed through the resin into the eluate at a pumping rate of 1 litre per hour (10 BV/h). The deionized water rinses excess aluminium off the chelate resin. Thereafter, the material is ready for operation.

(25) Resin volume: 100 ml

(26) 100 ml of resin contain 3.2 grams of aluminium.

(27) f) Fluoride Adsorption Experiment on an Aluminium-Doped Resin

(28) 100 ml of the aluminium-doped resin from Example 1 e) in the abovementioned chromatography column, for downward flow operation, are connected at the feed via a pump to a 200 litre reservoir vessel and at the drain to a 200 litre collecting vessel.

(29) The 200 litre feed vessel is initially charged with 200 litres of demineralized water and 28 g of CaCl.sub.2, 53 g of Na.sub.2SO.sub.4*6H.sub.2O, 100 g of NaCl and 4.4 g of NaF are dissolved therein. The resulting composition of the solution is shown in Table 1.

(30) TABLE-US-00001 TABLE 1 Composition of the feed solution Ion Concentration [ppm] Concentration [meq/l] Calcium 51 2.54 Sodium 257 11.17 Chloride 393 11.09 Sulphate 102 2.13 Fluoride 10 0.53 Total 813 27.46

(31) At regular time intervals, the fluoride concentrations are measured in the eluate. The volume of filtrate in which an eluate concentration of <1.5 mg/l is measured is used to calculate, via mass balancing, the usable capacity (UC) reported as the mass of fluoride separated out (in g) per litre of chelate exchanger (in the aluminium form initially charged).

(32) The usable capacity is 2.1 g of fluoride per l of resin.

Comparative Example

(33) Fluoride adsorption experiment on an aluminium-doped heterodisperse resin having a second substitution level=1.5

(34) The comparative example was conducted analogously to Example 1 step f).

(35) Resin specimen A (aluminium-doped chelate resin containing iminodiacetic acid groups): first substitution level: n=0.78, second substitution level m=1.5.

(36) The results are shown in Table 2:

(37) TABLE-US-00002 TABLE 2 Usable capacities (UC) of resin A: Resin specimen UC (g of F per l of resin) Resin specimen A (aluminium-doped 1.9 chelate resin containing iminodiacetic acid groups):

(38) Results

(39) Example 2 which has been added to Table 3 was produced analogously and the usable capacity was determined.

(40) TABLE-US-00003 TABLE 3 Usable capacities of the chelate resins from the examples First Second UC [g F/l substitution substitution resin] Example 1 0.95 1.04 2.1 Example 2 0.97 0.85 3.5 Comparative 0.78 1.5 1.9 example

(41) Analytical Methods

(42) Determination of Amount of Basic Aminomethyl Groups in Aminomethylated Crosslinked Polystyrene Bead Polymer

(43) 100 ml of the aminomethylated bead polymer are agitated down in the tamp volumeter and subsequently washed with demineralized water into a glass column. 1000 ml of 2% by weight aqueous sodium hydroxide solution are passed through the column in the course of 1 hour and 40 minutes. Demineralized water is then passed through until 100 ml of eluate with added phenolphthalein have a consumption of 0.1 N (0.1 normal) hydrochloric acid of not more than 0.05 mi.

(44) 50 ml of this resin are admixed in a beaker with 50 ml of demineralized water and 100 ml of 1 N hydrochloric acid. The suspension is stirred for 30 minutes and then filled into a glass column. The liquid is drained off. A further 100 ml of 1 N hydrochloric acid are passed through the resin for 20 minutes. 200 ml of methanol are then passed through. All the eluates are collected and combined and titrated with 1N aqueous sodium hydroxide solution against methyl orange.

(45) The number of aminomethyl groups in 1 litre of aminomethylated resin computes according to the following formula: (200V)*20=mol of aminomethyl groups per litre of resin.

(46) Determination of the Amount of Weakly Acidic Iminoacetic Acid Groups in the Chelate Resin and Determination of the Substitution Level of the Hydrogen Atoms in the Primary Amino Groups by Acetic Acid Group Second Substitution

(47) 100 ml of exchanger are introduced into a filter column and eluted with 500 ml of 3% by weight hydrochloric acid within 1.5 hours. The column is then washed with demineralized water until the eluate is neutral.

(48) 50 ml of resin are taken from the amount of resin remaining and introduced into a column. 0.1 N sodium hydroxide solution is filtered through the resin. The eluate is collected in a 250 ml volumetric flask in each case. This liquid is titrated with 1 N hydrochloric acid against methyl orange. 0.1 N sodium hydroxide solution is filtered through the resin until 250 ml of eluate have a consumption of 24.5 to 25 ml of 1 N hydrochloric acid. Once the test has ended, the volume of exchanger in Na form is determined.
Total capacity (TC)=(X*25sum of V)3 in mol/l of exchanger
X=number of eluate fractions
Sum of V=total consumption in ml of 1 N hydrochloric acid in the titration