SU1502080A1 - Method of regenerating weak-base ion exchanger - Google Patents

Abstract

The invention relates to methods for the regeneration of ion exchangers and can be used on ion-exchange desalting plants having in their composition anion-exchange filters loaded with a weakly basic anion exchange resin. The aim of the invention is to increase the degree of regeneration of a weakly basic anion exchange resin. The method is carried out as follows. Sulfate or ammonium chloride is introduced into the magnesium oxide suspension to a component ratio of 1.00: 0.33 ÷ 1.00. Then the anion exchange resin is treated with the suspension obtained, at a consumption of magnesium oxide of 0.5-0.75 g-eq per 1 g-eq of sorbed anions. After that, the anion exchange resin is treated with ammonia solution, taken in an amount of 0.25-0.5 g-eq per 1 g-eq of sorbed anions. The method allows to obtain the degree of regeneration of 84.0-89.5%, table 2.

Description

The invention relates to methods for the regeneration of ion exchangers and can be used on ion-exchange desalting plants that contain anion-exchange filters loaded with a weakly basic anion exchange resin.

The aim of the invention is to increase the degree of regeneration of a weakly basic anion exchange resin.

Example. The studies were carried out under static conditions. Anion exchanger AH-31 is pre-saturated with sulfuric acid to a working capacity of 1,470 g-eq / dm. A 600 cm glass beaker is charged with 50 cm of wet saturated anion exchanger and treated with stirring.

150 cm of a suspension of magnesium oxide in water, into which ammonium sulphate or ammonium chloride is injected to a component ratio of 1.00: (O, 33-1.00). The consumption of magnesium oxide is 0.5-0.75 g-eq per 1 g-eq of sorbed anions. Visually fix the dissolution or precipitation. The completeness of the process is determined by the reduction of excess alkalinity, pH, calcium and magnesium concentrations in the solution. After 3 hours of stirring, the solution is drained. Then the anion exchanger is treated with an ammonia solution for an hour, taking in an amount of 0.25-0.5 g-eq per 1 g-eq of sorbed anions (II stage of processing). Yes3, 150 more then the anion exchanger is washed with water to a pH of 9 or until the specific conductivity is O, 1 μS / cm. Portions of wash water — 150 cm each, contact time 1 hour. Excess alkalinity, pH, calcium and magnesium concentrations, and specific conductivity are determined in the wash water.

The data on the regeneration of the AN-31 anion exchanger saturated with NgZO in different modes are presented in the table (experiments 1-7), here a comparative analysis with a known method is presented (experiment 8).

When implementing the proposed method, the degree of regeneration of anion exchangers is 84-89.5%, while the residual capacity of the anion exchanger for sulfate ions is 11.2-11.7 g / dm.

The optimal ratio in the regenerating solution of magnesium oxide and ammonium sulfate is 1.0: (0.33-1.0) (experiments 2-4). An increase in magnesium hydroxide of more than 0.75 g-eq per 1 g-eq of sorbed anions (experiment 1) leads to the fact that part of it does not dissolve in the process of regeneration of the anion exchanger and complicates the subsequent separation of the ion exchanger and the solution. A decrease in magnesium hydroxide to less than 0.5 g-eq per 1 g-eq of sorbed anions reduces the efficiency of the regeneration process (test 5).

The mechanism of the process of regeneration of anion exchanger by the proposed method can be explained by a combination of two processes occurring simultaneously:

(NH) (OH) 2 - 2NH40H + MgS04; (RH) 4S04 + 2NHj, (NH4).

The regeneration of the anion exchanger is carried out at a consumption of magnesium oxide of 0.5-0.75 g-eq per 1 g-eq of sorbed anions. This ensures that waste solutions that do not contain solids are obtained, which facilitates the separation of the ion exchanger and the solution. For almost 100% regeneration of anion exchange resin as

an auxiliary regenerating solution, ammonia solutions are used with a flow rate of 0.25-0.5 g-eq per I g-eq of sorbed anions. The absence or slight excess of ammonia in such waste solutions ensures the washing of the anionite from the products

regeneration (up to, 0) with a small amount of wash water (3-6 m / m of wet sorbent)

The proposed mixture of regenerating solutions allows the process to be carried out at elevated temperatures (-vbO C), since in this case the free ammonia formed during the interaction of magnesium hydroxide and ammonium sulfate is immediately spent on the regeneration of the anion exchanger and the solution is not degassed.

The replacement of ammonium sulfate with chloride does not affect the efficiency of the regeneration of the anion exchanger (experiments 6 and 7) by the proposed method.

Comparative analysis of the degree of regeneration of anion exchange resin by known and proposed methods indicates an increase in the degree of regeneration of weakly basic anion exchange resin from 62.0% to 84.0-89.5%.

Claims (1)

Invention Formula The method of regeneration of a weakly basic anion exchanger, including its treatment with a suspension of magnesium oxide, characterized in that, in order to increase the degree of regeneration, sulfate or ammonium chloride is introduced into the suspension of magnesium oxide to a component ratio of 1.00: 0.33-1.00; anionite will lead at a magnesium oxide consumption of 0.50-0.75 g-eq per 1 g-eq of sorbed anions, followed by treatment of the anion exchanger with ammonia, taken in an amount of 0.25-0.50 g-eq per 1 g-eq of adsorbed anions .