Removal of chromium (VI) from aqueous solution using chemically modified corncorb-activated carbon: Equilibrium and kinetic studies

Removal of Cr(VI) ions from aqueous solution was investigated using activated carbon obtained from acid modified (AMCAC) and unmodified corncorb (UMCAC) by batch adsorption technique at 30 degrees C. H2SO4 acid of 10N, 20N, and 30N concentrations were used for the modification of activated carbon. The effect of different adsorption parameters, such as pH, initial Cr(VI) ion concentration, contact time, and adsorbent dosage were studied. The 10N acid modified activated carbon (AMCAC) was effective for the maximum removal of Cr(VI) at pH 6.0, and equilibrium was attained in 60 min. Kinetic studies show that the pseudo-second-order kinetic equation was best suited for removal of Cr(IV) ions from aqueous solution. Adsorption equilibrium data were fitted to Langmuir, Freundlich, and Redlich-Peterson adsorption isotherms. The maximum adsorption capacities of UMCAC and AMCAC with respect to Cr(VI) ions were calculated from Langmuir isotherm, and found to be 22.82, and 54.11 mg/g respectively. FTIR spectra of the adsorbent before and after adsorption with Cr(VI) indicated that hydroxyl, halide, and aldehyde groups are present in the major binding sites which play an important role in the removal of Cr(VI) ions. (c) 2012 American Institute of Chemical Engineers