Removal of Pb2+, Ag+, Cs+ and Sr2+ from aqueous solution by brewery's waste biomass

Heavy metal pollution is becoming a more and more serious environmental problem, posing threat to biota life. Biosorption is an alternative technology for the treatment of wastewater containing metal ions. In this paper, the removal of four metal ions, i.e., Pb2+, Ag+, Sr2+ and Cs+ by waste biomass of brewery was studied. The experimental results showed that metal uptake is a rapid process, which can be described by pseudosecond order kinetic model. The Langmuir adsorption isotherm was applied to correlate the equilibrium data and fitted quite well. The maximum biosorption capacities for four metal ions were 0.413 mmol Pb2+/g, 0.396 mmol Ag+/g, 0.091 mmol Sr2+/g and 0.076 mmol Cs+/g, respectively. The binding of metals was also discussed in term of several factors. The order of accumulated metal ions at equilibrium state on the molar basis was as follows: Pb2+ > Ag+ > Sr2+ > Cs+, which positively correlated with their covalent index and electronegative and reversely correlated with dissociation constant.