Sorption of heavy metals on blast furnace sludge

Abstract

An investigation into the use of sludge, a by-product of the steel industry, as an adsorbent for the removal of heavy metals from liquid e uents was carried out. Gases produced in the blast fur- nace were washed and led towards a Dorr thickener where the sludge was obtained as a suspension. The sorption of Pb2+, Zn2+, Cd2+, Cu2+ and Cr3+ on the sludge was investigated by determination of adsorption isotherms. The e ects of time, equilibrium temperature and concentration of metal sol- ution on sludge adsorption e ciency was evaluated. The adsorption process was analyzed using the the- ories of Freundlich and Langmuir and the thermodynamic values of DG, DH and DS corresponding to each adsorption process were calculated. Blast furnace sludge was found to be an e ective sorbent for Pb, Zn, Cd, Cu and Cr±ions within the range of ion concentrations employed