Biosorption of heavy metals and radionuclide from aqueous solutions by pre-treated arca shell biomass

In this study biosorption potential of pre-treated arca shell biomass for lead, copper, nickel, cobalt and cesium was explored from the artificially prepared solution containing known amount of metals. The effects of pH, initial concentration, biosorbent dosage and contact time were studied in batch experiments. Effects of common ions like sodium, potassium, calcium and magnesium on the sorption capacity of pre-treated arca biomasses were also studied. To analyse the homogeneity of the biomaterial, experiments were performed for eight lots arca shell biomass for all the studies elements and it was observed that relative standard deviation in uptake capacity was within 10% for all elements. At equilibrium, the maximum total uptake by shell biomaterial was 18.33 +/- 0.44, 17.64 +/- 0.31, 9.86 +/- 0.17, 3.93 +/- 0.11 and 7.82 +/- 0.36 mg/g for lead, copper, nickel, cesium and cobalt, respectively, under the optimised condition of pH, initial concentration, biosorbent dose and contact time. Effect of all the common ions jointly up to concentration of 50 ppm was negligible for all the elements but at higher levels the cations affects the uptake capacity. Sorption isotherms were studied to explain the removal mechanism of both elements by fitting isotherms data into Lagergren, Freundlich and Langmuir equations. Halls separation factor estimated under optimised condition also favours the sorption potential of these elements using area shell biomass. Arca shell biomass can be effectively and efficiently employed for removal of studied elements after optimisation of parameters. (c) 2007 Published by Elsevier B.V.