Removal of Aluminum (III) from waste waters using bio-adsorbents derived from plant materials of Withania somnifera has been investigated by varying various physicochemical parameters such as pH, time of equilibration, sorbent dosage, agitation time, initial concentration of Aluminum ions, temperature and presence of foreign ions using simulated waters and by adopting batch methods of extraction. Optimum conditions for the maximum extraction of Al (III) ions have been investigated. The adsorption process is analyzed with Freundlich, Langmuir, Temkin and Dubinin-Radushkevich (D-R) isotherm models and found that the Langmuir isotherm model better describes the adsorption process emphasizing the mono-layer formation of the Al (III) ions on the adsorbent and further, the mean free energy (E) and heats of sorption (B) of Temkin isotherm and Dubinin-Radushkevich isotherms indicate that the adsorption is ‘physisorption’ in nature. Kinetics of adsorption is quantified using pseudo first-order, pseudo second-order, Weber and Morris intraparticle diffusion, Bangham’s pore diffusion and Elovich equations and found that the adsorption process has good correlation coefficient values with pseudo-second-order model.The endothermic nature of the adsorption is found on the analysis of the thermodynamic parameters, ΔH, ΔS and ΔG. Interference of common co-ions has been studied. The methodologies developed are successfully applied to industrial sewages and polluted natural waters.
