Synthesis of arsenic sorbent by the reaction of magnesium hydroxide with aqueous iron(III) chloride solution

Abstract

The reaction of magnesium hydroxide with a concentrated aqueous solution of iron(III) chloride yields a mixture of magnesium–iron layered double hydroxide and iron oxide–hydroxide in the akaganeite form. The content of these phases depends on the Mg/Fe atomic ratio in the starting reactant mixture. Iron oxide–hydroxide is the major reaction product at the Mg/Fe atomic ratio in the interval 1.5–1.75, and layered magnesium–iron layered double hydroxide, at Mg/Fe = 3–4. The ability of the synthesized products to take up As(III) from aqueous solutions was studied. These sorbents allow the arsenic concentration to be decreased from 3–5 mg L^–1 to values below MPC (0.01 mg L^–1).