André Clément

Decontamination of synthetic solutions containing heavy metals using chemically modified sawdusts bearing polyacrylic acid chains

New materials containing carboxylate groups have been synthesized by grafting polyacrylic acid onto sawdust. These new adsorbents were subjected to continuous extraction of different metal ions using packed columns to determine their maximum binding capacities. They exhibit binding capacities 15–40 times higher than unmodified sawdusts for removal of Cu2+, Ni2+, and Cd2+ chosen as representative heavy metal ions. Cation desorption and adsorbent regeneration could be effected by elution with a diluted HCl solution; water as an eluent has no effect on metal desorption.

Synthesis and use of esterified sawdusts bearing carboxyl group for removal of cadmium(II) from water.

Summary Improvement of the reaction of succinic anhydride with wood meal was studied in order to prepare low cost materials for the removal of heavy metals. Without solvent, the use of 1 equivalent of pyridine or triethylamine/succinic anhydride was necessary to obtain high grafting efficiencies at 80 °C. In the presence of small quantities of 1,2-dichloroethane as swelling agent, only 0.1 equivalent of catalyst was needed to obtain satisfactory results. Three more or less modified sawdusts were used after activation with NaHCO3 for the removal of cadmium(II) from water. Metal binding capacity was directly connected with the acid value estimated by titration and can reach 200 mg/g. Strongly modified sawdust showed a cadmium binding capacity lower than expected because of diester formation.