Original Articles: 2012 Vol: 4 Issue: 4
Lead removal from aqueous solutions by Bacillus subtilis
The dead biomass of Bacillus subtilis has been used for the removal of lead (II) from an aqueous solution. The effects of various parameters such as contact time, adsorbate concentration, pH of the medium and temperature were examined. Optimum removal at 200C was found to be 98.4 % at pH 6.5, with an initial Pb (II) concentration of 100 mgL-1. Dynamics of the sorption process and mass transfer of Pb (II) to Bacillus subtilis were investigated and the values of rate constant of adsorption, rate constant of intraparticle diffusion and the mass transfer coefficients were calculated. Different thermodynamic parameters viz., changes in standard free energy, enthalpy and entropy were evaluated and it was found that the reaction was spontaneous and exothermic in nature. The adsorption data fitted the Langmuir isotherm. The data were subjected to multiple regression analysis and a model was developed to predict the removal of Pb (II) from an aqueous solution.