Method for the arsenic decontamination of aqueous solutions

摘要

In the method described for the arsenic decontamination of water, arsenic(III) is first oxidised to arsenic(V), the pH is adjusted to 8-10 and then, after addition of a water-soluble polymeric anion exchange reagent, filtration through a membrane is carried out under pressure. In this case, the arsenic is enriched above the membrane and the decontaminated solution arises as filtrate. For example, an aqueous solution containing 9.2 mg of arsenic(V) per litre is decontaminated in this process by 98.8%. An aqueous solution containing 100 mg of arsenic(V) per litre can be decontaminated to the permitted arsenic concentration by three filtration steps. The regeneration of the polymer reagent is carried out by washing with a 0.1 molar acid solution (eg. hydrochloric acid). The arsenic-containing solution arising in this case can serve for the preparation of arsenic compounds. The process can also be used for separating various oxidation stages of arsenic(III and V). In addition, simultaneous decontamination from other elements, such as chromium(VI), selenium(IV), cobalt(II), copper(II) and zinc(II), together with arsenic is possible, or else removing arsenic(V) and leaving the other elements in the water.