Recovery and reuse of chromium from tannery wastewaters using Turbinaria ornata seaweed

Brown seaweed (Turbinaria spp) was pre-treated with sulfuric acid, calcium chloride and magnesium chloride and tested for its ability to remove chromium from tannery wastewater. Protonated seaweeds gave better uptake of chromium compared with calcium and magnesium treatments. Chromium uptake was optimal at pH 3.5. Turbinaria weed exhibited maximum uptake of about 31 mg of chromium for one gram of seaweed at an initial concentration of 1000 ppm of chromium. Freundlich and Langmuir adsorption isotherm models were used to describe the biosorption of chromium(III) by Turbinaria spp. The chromium-loaded seaweed was reused as a reductant in the preparation of the tanning agent basic chromium sulfate (BCS). Leathers made from this tanning agent had properties comparable to conventionally processed chrome-tanned leathers. (C) 2004 Society of Chemical Industry.