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Not AvailableThis paper describes the use of a lignocellulosic biosorbent for the adsorption and ion exchange of nine different heavy metals ions. Batch isothermal equilibrium and continuous column adsorption experiments were carried out in an effort to evaluate the maximum adsorption capacity, pH dependence and to study the mechanism of removal of metal ions onto the biosorbent. Bio-sorption data were interpreted using Langmuir isotherm which reflect the influence of metal concentration on the uptake of the metal ion. Potentiometric titrations were used to determine the contents of total functional groups. The biosorbent showed the strongest affinity for Pb2+, Hg2+ and Cu2+. The metal ions such as Cd2+, Cu2+, Ni2+, Co2+, and Mn2+ seemed to be exclusively involved in ion-exchange mechanism with Ca2+ ions. The column adsorption experiment of multiple metals revealed the role of another cation in effective removal of Pb2+, Hg2+ and Zn2+. The biosorbent has been found to be a good electron donor for the reduction of Cr(VI) in an acidic medium.Not Availabl

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Not AvailableA biomatrix was prepared from rice husk, a lignocellulosic waste from agro-industry, for the removal of several heavy metals as a function of pH and metal concentrations in single and mixed solutions. The biomatrix was characterized using scanning electron microscope and Fourier transform infrared spectroscopy, which indicated the presence of several functional groups for binding metal ions. Different experimental approaches were applied to show mechanistic aspects, especially the role of calcium and magnesium present in the biomatrix in ion exchange mechanism. The ultimate maximum adsorption capacity obtained from the Langmuir isotherm increases in the order (mmol/g): Ni (0.094), Zn (0.124), Cd (0.149), Mn (0.151), Co (0.162), Cu (0.172), Hg (0.18) and Pb (0.28). The sorption of Cr(III) onto biomatrix at pH 2 was 1.0 mmol/g. Speciation of chromium, cadmium and mercury loaded on the biomatrix was determined by X-ray photoelectron spectroscopy. The biomatrix has adsorption capacity comparable or greater to other reported sorbents.Not Availabl