Abstract: Nitric acid activated carbon is prepared from barks of Ficus Racemosa plant and it is characterized for various parameters to assess its suitability as adsorbent for the removal of Al (III) ions from polluted water. By adopting batch methods, the effect of various major parameters such as pH, contract time, initial Al(III) ion concentration, adsorbent dosage, particle size and temperature, on the affinity of the active carbon towards Al(III), is investigated and optimized for the maximum removal of Al(III) ions. The influence of co-ions on the extraction is investigated. Various adsorption isotherms such as Freundlich, Langmuir, Temkin and Dubinin-Radushkevich are analyzed and correlation coefficient (R2 = 0.998) and dimensionless separation factor (RL = 0.0035174) values, confirm that the sorption process obeys Langmuir adsorption, indicating monolayer formation. Further, the Temkin heat of sorption, B = 2.227 J/mol and the Dubinin-Radushkevich mean free energy, E = 7.071 kJ/mol indicate that the adsorption is ‘physisorption’ in nature. Pseudo-first-order, pseudo-second-order, Weber and Morris intraparticle diffusion, Bangham’s pore diffusion and Elovich equations are applied to identify the rate and kinetics of adsorption process. The adsorption process has good correlation coefficient values with pseudo-second-order model. FTIR studies indicate the involvement of some surface functional groups in Al(III) adsorption. The methodology developed is applied to real Al(III) contaminated water samples and found to be successful.
Keywords: Al(III) ions, barks of Ficus Racemosa plant, adsorption, adsorption isotherms and kinetics, characterization studies, applications
