Recovery of Chromium (III) from tannery wastewater
Awan, M.A.; Baig, M.A.; Javed Iqbal; Aslam, M.R.; Naveed Ijaz
Journal of Applied Science and Environmental Management 7(2): 5-8
2003
Document Number: 259966
Three aqueous oxidants, hydrogen peroxide, sodium hypochlorite and calcium hypochlorite were employed independently in oxidizing chromium (III) containing tannery waste waters to soluble chromate (CrO42-) under alkaline conditions. The actual tanning effluents (1 and 2) were collected in plastic containers from tanneries in Sambrial Road, Sialkot, Pakistan. The amount of recovered chromate was determined via spectrophotometry. Hydrogen peroxide was potentially a suitable oxidant as it could recover chromate (CrO42-) up to 98% (from synthetic Cr3+ solution) and 88% (from effluent 1). The percentage recoveries by the hypochlorites were lower than those by hydrogen peroxide, i.e. for NaOCl the recoveries were up to 94% (from synthetic Cr3+ solution) and 67% (from effluent 1), similarly for Ca(OCl)2 90% (from synthetic Cr3+ solution) and 49% (from effluent 1). For all three oxidants complete (100%) recovery could not be achieved despite different experimental conditions (temperatures and oxidation time). The results clearly indicated that hydrogen peroxide is the most efficient among the three oxidants.