RU2111173C1 - Method for sorption purification of water from iron - Google Patents

Abstract

FIELD: water treatment, namely, purification of water from iron. SUBSTANCE: method involves sorption with the help of cationite followed by regeneration of dead sorbent. Special cationite in Na- and H-form which is preliminary treated by iron salt solution and then is treated by sodium hydroxide solution used cationite. Catalytic film of iron hydroxide which promotes deep deferritization of water is produced overall cationite layer, not only on its filtering surface. Cationite is regenerated with the help of sodium carbonate, iron salts and sodium hydroxide. EFFECT: improved efficiency. 2 tbl

Description

 The invention relates to the field of water treatment, in particular to a technology for purifying industrial condensate and feed water for high and low pressure boilers.

 A known method of sorption water purification from iron by filtering it through a sorbent, in particular through a layer of filter dirt [1].

 The disadvantage of this method is the low degree of iron removal (70-80%), which does not provide a standard concentration of iron in purified water. The residual iron content in purified water is 81-97 μg / L.

 Closest to the proposed method is a method of sorption water purification from iron by filtration through sulfonated coal in H-form, followed by regeneration of the spent sorbent with an acid reagent [2].

 The disadvantages of this method include the low degree of iron deferrization (60-70%) with an initial iron content in water of 150 - 350 μg / L, as well as the use of an aggressive acid reagent at the stage of regeneration of the spent sorbent.

 The main objective of the invention is to create a method of iron deferrization that allows for deep water purification from iron (less than 50 μg / l), as well as the exclusion of the acid reagent from the process of regeneration.

 To solve the problem in a method of sorption water purification from iron, including sorption by KU-2-8 cation exchanger and subsequent regeneration of the spent sorbent, the cleaning is carried out by strongly acidic KU-2-8 cation exchanger in Na- or H-form, which is pre-treated with a solution of iron salt (e.g. ferric chloride or ferrous sulfate), and then sodium hydroxide solution. In this case, a catalytic film of iron hydroxides is formed in the entire layer of cation exchange resin, and not only on its filtering surface, which contributes to the deep iron removal of water.

 The spent sorbent is regenerated first by washing with water the precipitate of iron compounds from the surface of cation exchanger grains, and then sequentially with solutions of sodium bicarbonate, iron salts and sodium hydroxide. The treatment of cation exchange resin with sodium bicarbonate solution removes the iron ions absorbed by the cation exchange resin and partially charges the cation exchange resin in the Na, H form, which, when treated with the iron salt solution, transforms into the Fe form, and when the sodium hydroxide solution is passed through the cation exchange resin, it again acquires the ability to effectively water purification from iron.

 The method is as follows. The swollen KU-2-8 cation exchanger in the H- or Na-form is loaded into the sorption column and a solution of ferrous or trivalent iron salt is passed through it. Then the cation exchange resin is washed with water, a solution of sodium hydroxide is passed through it and washed again. Then, feed water to be purified is passed through the column. After the breakthrough of iron in purified water (more than 50 μg / l), the spent cation exchanger is subjected to regeneration: first, the precipitate of iron compounds is washed with water, then sodium bicarbonate solution is passed through, washed again with water and the sodium salt solution is passed through, then sodium hydroxide solution. After washing with water, cation exchange resin is prepared for a new cycle of water purification from iron.

 In the table. 1 and 2 show the results of experiments on the prototype and the proposed method. As can be seen from the above data, water purification from iron by the proposed method allows to obtain a high degree of iron purification and to exclude the regeneration of the sorbent with an acid reagent. So, when treating cation exchange resin in H-form with solutions of ferric chloride and sodium hydroxide, the depth and degree of iron removal of water were 10 μg / L and 99.4%, respectively. The sorption capacity of the resin was 24.7 mg / g.

 When treating cation exchange resin in Na - form with solutions of ferrous sulfate and sodium hydroxide, the cleaning depth was 30 μg / L, the degree of iron removal was 99.0%, and the sorption capacity of cation exchange resin was 25.0 mg / g. After complete regeneration of cation exchanger, the above indicators are practically unchanged.

Claims (1)

 A method of sorption water purification from iron, including sorption by KU-2-8 cation exchanger and subsequent regeneration of spent sorbent, characterized in that the cation exchanger is pretreated with a solution of ferrous or ferric iron salt and sodium hydroxide solution, and the spent cation exchanger is regenerated by its sequential treatment with water, a solution of sodium bicarbonate, solutions of salts of iron and sodium hydroxide.

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