Effect of speciation and composition on the kinetics and precipitation of arsenic sulfide from industrial metallurgical wastewater

Precipitation of arsenic as As2S3 produces little waste sludge, has the potential for low chemical consumption and selective metal(loid) removal. In this study, removal from acidic (pH 2), metallurgical wastewater was tested in industrially relevant conditions. Sulfides added at a S:As molar ratio 2.5 5 resulted 99% 84% As(III) As(V). industrial containing 17% As(V) nearly instantaneous. For synthetic solution, reduction to rate limiting step. At 20 an observed (k2 = 4.8 (mol L?1) h?1), two hours were required remove 93% 1 g As L?1 solution. case samples time lag not observed, showing that components affected arsenate. Speciation also flocculation coagulation characteristics particles: poor flocculation. Selective precipitation possible, but depended on speciation, other metals present.