Kinetics and Isotherm Studies of Mercury and Iron Biosorption Using Sargassum Sp

Biosorption is a process in which solids of natural origin are employed for binding heavy metals. It is a promising alternative method to treat industrial effluents, mainly because of its low cost and high metal binding capacity. In this work, the mercury and iron biosorption process by Sargassum sp. seaweed biomass was studied. The work considered the parameters of mercury and iron sorption such as pH, temperature, agitation and biomass size. The optimal conditions were : pH 4, temperature 30oc, agitation 100 rpm and biomass size 0.7mg and the maximum metal uptake was 67.094mg/g, 64.32mg/g, 53.735mg/g, 41.883mg/g respectively for mercury. For iron the pH was 3, temperature 30oc, agitation 150 rpm, biomass size 0. 3mg and the maximum metal uptake was 16.63mg/g,16.23 mg/g, 24.78mg/g and 14.62mg/g. The mercury and iron uptake was also quantitatively evaluated using adsorption isotherms. Results indicated that for iron, Langmuir model gave a better fit and for mercury Freundlich gave a better fit to the experimental data in comparison with the other isotherm models. Kinetic models such as pseudo first order and pseudo second order was also evaluated. The adsorption process follows pseudo second order kinetics for both the metals.