화학공학소재연구정보센터
Indian Journal of Chemical Technology, Vol.8, No.6, 487-495, 2001
Hexavalent chromium removal using iron bearing industrial sludges
The use of iron bearing metallic and mineral materials for the treatment of highly toxic Cr(VI) containing industrial wastewater have received increased attention for the past decade. In conventional treatment, a large amount of chromium hydroxide generates as secondary solid waste which poses a serious problem of disposal. In the presence of iron bearing materials, Cr(VI) reduces to Cr(III) and Fe(II) oxidises to Fe(III) generating mixed complexes from which separation probability of individual element reduces. Based on this chemical principle it is expected that such industrial solid wastes containing iron as a major constituent have potential to reduce highly toxic Cr(VI) to less toxic Cr(III). In view of this, present investigation was aimed to utilise iron bearing industrial wastes like sludges of steel tube making industry and aluminium industry for removal of Cr(VI). Studies include identification of suitable pH for the Cr(VI) reduction, optimisation of dosage and contact time and determination of reaction kinetics. No Cr(VI) was detected from the reacted wastes and total chromium was measured as Cr(III). Toxicity characteristics leaching procedure(TCLP) has been employed to estimate the leachability of chromium, iron etc from the reacted wastes. TCLP results indicate a negligible amount of chromium as Cr(III) and iron leachability from the reacted wastes.