Zinc and nickel recovery by Macrocystis pyrifera biomass

PLAZA CAZÓN JOSEFINA; VIERA MARISA; DONATI EDGARDO

Workshop; First Argentine Workshop in Environmental Sciences; 2009

Biosorption is an alternative technology to remove heavy metals from industrial effluents employing non ? living biomass (bacteria, algae, fungi, etc.). Macrocysistis pyrifera is a brown algae that grown in the south of Argentina. This algae forms part the Phaeophyta family, one of its most important characteristic is the alginate content, which represent the 40 % of its dry weight. Alginate is the main responsible for the binding of heavy metals. The objective of this work was to evaluate zinc and nickel biosorption using Macrocystis pyrifera as biosorbent. The assays consisted in: stabilization of the biomaterial, kinetic studies, equilibrium studies in monometallic system of zinc and nickel and bimetallic systems (zinc - nickel). The stabilization of the biomaterial was reached by treating it with 0.2 M CaCl2. Four different pH values (3, 4, and 5) and different contact times between zinc and nickel ions and biomass were considered in order to determinate the optimum pH and the time for reaching the equilibrium. Zinc and nickel biosorption studies were carried out using different zinc and nickel individual concentrations (5 ppm to 400 ppm) at initial pH of 4. Zinc and nickel adsorption in bimetallic systems was also studied. The result of zinc and nickel adsorption fitted very well to Langmuir model. The values of qm (obtained from the Langmuir model) were 0.69 mmol/g and 0.011 mmol/g and the values of b (affinity coefficient) were 0,84 L/mmol and 0,54 L/mmol for zinc and nickel respectively. The adsorption capacity for zinc is really significant compared with the nickel adsorption. The adsorption capacity of zinc was not affected by the presence of nickel. These results are significant for the setting of biosorption experiments in column systems.