Extraction of arsenic(III) from chloride-iodide solutions by diphenyl(2-pyridyl)methane and benzene

The variation of the partition coefficient of arsenic(III) between chloride-iodide solutions and diphenyl(2-pyridyl)methane in benzene has been studied. The effect of the concentration of hydrochloric acid and iodide in the aqueous phase has been assessed. The partition coefficients are maximal for concentrated acid solutions which are 0.02-0.1 M in potassium iodide. Slope-analysis studies were used to elucidate the composition of the extracted species. Polymerization of the solvent species tends to decrease the distribution coefficients of arsenic with increasing concentration of diphenyl(2-pyridyl)methane, especially with trace concentrations of the element. Arsenic can be selectively separated from copper, cobalt, nickel, iron, chromium and antimony, which are usually associated with it in various ores.