Study on the adsorption of Ca2+, Cd2+ and Pb2+ by magnetic Fe3O4 yeast treated with EDTA dianhydride

Magnetic Fe3O4 baker's yeast biomass (FB) was prepared by combining baker's yeast biomass and nano-Fe3O4 using glutaraldehyde as a cross-link agent, and was chemically treated with ethylenediaminetetraacetic dianhydride (EDTAD). The EDTAD-treated magnetic Fe3O4 baker's yeast biomass (EFB) was investigated by Fourier transform infrared spectroscopy (FTIR), potentiometric titration, zeta potential, and magnetic response analysis. The results revealed that the EFB possessed not only the superparamagnetic characteristic of nano-Fe3O4, but its surface also had plenty of carboxyl and amino groups introduced by the EDTA molecules. The adsorption properties of EFB for Pb2+, Cd2+, and Ca2+ ions were also evaluated. The results showed that the uptakes of EFB for the three metal ions were higher than that of FB, and the adsorption capability of Pb2+, Cd2+, and Ca2+ ions increased with an increase in pH. The adsorption process was followed by the pseudo-second-order kinetic model and Langmuir isotherm equation. The maximum adsorption capacities of 99.26 mg/g for Pb2+ at pH 5.5, 48.70 mg/g for Cd2+ at pH 6.0, and 33.46 mg/g for Ca2+ at pH 6.0 were observed at 30 degrees C. The regeneration experiments showed that the EFB could be successfully reused. (C) 2011 Elsevier B.V. All rights reserved.