Comparing the Bio-Sorption Affinity of Ni and Cd by Bio-Solid with Other Bio-Sorbent

Heavy metals pollution is very important in Environment. Toxicity and accumulation characteristics of these metals are more noticeable for health aspects. Today, using bio-sorbent is more noticeable because these ways are ecofriendly and economic. In this survey, in addition to achieving Ni and Cd bio-sorption by bio-solid, the results of other relative surveys used for comparing the results and bio-sorption affinity discussion. Bio-solid powder produced from municipal excess sludge by drying, grinding and grainsizing. Ni and Cd solutions in 0.25 and 0.75 mille molar have been contacted which 0.5, 1, 2 and 4 grams of biosolid in pH 4, 200 rpm stirring, 24-260C temperature and two hours (continuous 5-420 min in kinetic study) time and samples have been analyzed with atomic absorption spectrophotometer to kinetic and isotherm modeling study and comparing the results. The maximum equilibrium adsorption of metals observed at two hours contact time and increasing of pH up to 4 increased the adsorption rate. The equilibrium data of both metals could be fitted by Langmuir isotherm equation and the maximum adsorption capacity (qmax) for cadmium and nickel are 0.38 and 0.195 mmol/gr dry bio-solid, respectively. The same as other biomasses studied for bio-sorption of heavy metals bio-sorption affinity of bio-solid for Cd is more than Ni. Generally, the bio-sorption affinity of algae and fungi for heavy metals bio-sorption is more than sludge and bacteria that is the result of cellular wall characteristics.