Cadmium sorption by EPSs produced by anaerobic sludge under sulfate-reducing conditions

This study showed that EPS produced by anaerobic sludge under sulfate-reducing bacteria was effective in removing Cd2+ from solution. The sorption data could be described by the Freundlich isotherm model. The qm derived from the Langmuir isotherm model was up to 2720 mg/g EPSs. The presence of copper and nickel ions had significantly reduced the cadmium sorption by EPS and the presence of zinc had little effect. Analysis of FTIR spectra demonstrated that C-O-C of polysaccharides at 1150-1030 cm−1, group of the amide(I), CH2 group of the lipids, carboxyl and -OH groups of proteins and polysaccharides were involved in cadmium binding, of which the -OH groups and the C-O-C group of polysaccharides played a major role in cadmium sorption by EPSs.