Activated Carbon for Treatment of Cadmium Wastewater

Abstract

The use of activated carbon for heavy metal removal was exemplified by studying the adsorption characteristics of Cd(II) from Cd(II)-BF₄ plating solution on both granular and powdered activated carbons. The results indicated that at all pH values, powdered activated carbons such as Nuchar SA and Nuchar SN, exhibited greater Cd(II) removal capacity than the granular ones such as Darco HD 3000 and Filtrasorb 400. The powdered activated carbon was bound to spheres (0.6 mm-1 mm) using a suspension-polymerization technique. The adsorption capacity of the aggregated carbons was 85% - 90% of the unbound ones. The rate of Cd(II) removal at pH 7 is proportional to the cadmium concentration, the carbon dose, and the available surface sites. Used activated carbons were regenerated chemically with strong acids such as HCl, HClO₄, and H₂SO₄. Two treatment schemes are proposed with economical analysis for comparison with other common treatment processes.