CS225017B1 - The preparation of sorbents on the base of cellulose - Google Patents

Description

The present invention relates to a process for the preparation of cellulose-based sorbents with diazotized 3-N-aminoarylamino-2-hydroxypropyl groups and subsequent introduction of the functional groups via coupling.

At present, there is an attempt to obtain chelating ion exchangers with the highest performance, which is given by the highest capacity and the highest exchange rate. The capacity of the ion exchange cellulose unit is directly dependent on the concentration of the functional exchange groups present. The exchange rate is strongly influenced by the active surface of the ion exchanger and the accessibility of the exchange functional groups.

The diazotizable p-aminobenzyl functional cellulose derivatives used hitherto have an exchange capacity of 0.15 to 0.20 mol g ^- , which is a low capacity for today's needs.

According to the present invention, it has been found that much higher exchange capacities can be achieved by the process according to the invention, which consists in the formation of cellulose-containing structural units of the general formula:

Cellulose - O-CHg-CH-CHg-NH-Ar-NH-Ac, OH where

Ac is acetyl or formyl

Ar is benzene optionally substituted with alkyl Jedra C, to C * alkoxydem C ₁ to C ^, halogen, aitroskupinou, the position -HN-Ac can be in the 2, 3 or 4, firstly with stirring an aqueous solution of sodium nitrite in dilute hydrochloric acid at 0 to 10 ° C for 1 to 3 hours and after aspirating and washing the diazocellulose with ice water, this is gradually added over 10 to 30 minutes to a stirred solution of the coupling agent capable of forming complexes with metals cooled at 0 to 10 ° C and at the same temperature, the reaction mixture is kept under stirring for a further 1 to 3 hours, then stirred for a further 1 to 3 hours at 15 to 30 ° C and finally the functionalized cellulose is suctioned off and washed.

An advantage of the process according to the invention is that the exchange capacity is higher than 0.20 mol g ^-1 , which is due to the higher concentration of functional groups bound in the cellulose unit. Another advantage is the high exchange rate, especially when using spherical cellulose.

^The starting modified cellulose containing 3-N-aminoarylamino-2-hydroxypropyl groups are prepared by reacting a primary aromatic diamine, one amino group of which is protected with an acyl group, with 1-chloro-2,3-epoxypropane in an environmentally miscible organic solvent environment. with water and subsequent reaction of this crude reaction mixture with a suspension of cellulose and an alkali metal hydroxide in a water-immiscible organic solvent medium. &

the thiazotation is carried out according to known procedures with sodium nitrite in dilute hydrochloric acid, at a temperature of 0 to 10 ° C.

Separation of the diazo-oellulose is accomplished by filtering off the reaction mixture and washing the diazo-oellulose with ice water to prevent its decomposition.

As coupling agents, those coupling agents that are capable of complexing with metals are used. Preference is given to using 8-hydroxyquinoline, salicylic acid, sulfosalicylic acid, chromotropic acid, diphenylthiocarbazone, 1- (2-pyridylazo) -2-naphthol, 4- (2-pyridylazo) resorcinol.

The final product is obtained by filtration of the reaction mixture, and finally the cellulose is washed with a solvent suitable for the respective coupling agent.

He did

5.0 g of cellulose containing 0.796 mmol / g of 1- (N-aminophenyl) -amino-2-hydroxypropyl group are mixed with 16.0 ml of dilute hydrochloric acid (1: 1) at 0-5 ° C. C was diazotized with a solution of 1.1 g of sodium nitrite in 10 ml of water. Stir at the same temperature for 2 hours. The diazo-cellulose is then filtered off with suction, washed with ice-water until the filtrate is acidic. After all the diazo-cellulose was added, it was stirred at the same temperature for 2 hours and at room temperature for a further 2 hours. The sorbate obtained is washed with water until the filtrate is neutral. The ion exchanger thus prepared has a capacity for Fe @ ^{+ +} 0.43 mmol / g at pH = 2.

Example 2

Cellulose containing 1- (N-m-aminophenyl) -amino-2-hydroxypropyl group (0.785 mmol / g) was diazotized as described in Example 1.

The thoroughly aspirated diacellulose is then added in portions to a solution of 1.15 g of 8-hydroxyquinoline in 20 ml of ethanol at a temperature of 5 to 10 ° C. After addition of all the diacellulose, it is stirred at the same temperature for 2 hours and then for a further 3 hours at room temperature. The product obtained is washed with ethyl alcohol until the effluent filtrate is colorless.

The ion exchanger obtained has an exchange capacity for Fe ³⁺ 0.351 mmol / g at pH = 4, for Zn ²⁺ 0.320 mmol / g at pH = 5 and for UO ₂ ⁺ 0.342 mmol / g at pH = 7.

Claims (1)

Process for the preparation of cellulose-based sorbents with diazotized 3-N-aminoarylamino-2-hydroxypropyl groups, characterized in that the cellulose-containing structural units of the general formula: Cellulose - O-CH ₂ -CH-GH ₂ -RH-Ar-NH-Ac, OH where Ac is acetyl or formyl, Ar is a benzene ring optionally substituted with alkyl to C ₁ , C ₁ to C ₁ alkoxy, halogen, nitro, wherein the position of the -NH-Ac group may be 2, 3 or 4, initially acting with dilute aqueous sodium nitrite in a dilute environment hydrochloric acid at 0 to 10 ° C for 1 to 3 hours and after aspirating and washing the diacellulose with ice water, this is gradually added over 10 to 30 minutes to a stirred solution of a coupling agent capable of forming complexes with metals cooled to 0 to 10 ° C and at the same temperature, the reaction mixture is kept under stirring for a further 1 to 3 hours, then stirred for a further 1 to 3 hours at 15 to 30 ° C, and finally the functionalized cellulose is aspirated and washed.