Adsorptive removal of acrylonitrile by commercial grade activated carbon: kinetics, equilibrium and thermodynamics.

The potential of activated carbons--powdered (PAC) and granular (GAC), for the adsorption of acrylonitrile (AN) at different initial AN concentrations (50<or=C(0)<or=500 mg/l) from aqueous solutions was studied over the temperature range of 303-333 K. The effect of adsorbent dosage, initial AN concentration, contact time, and the change in pH with addition of adsorbents on adsorption was studied. The Langmuir, Freundlich, Tempkin, and Redlich-Peterson (R-P) isotherm equations were used to test their fit with the experimental data, and the model parameters were determined for different temperatures. The Langmuir and R-P models were found to be the best to describe the equilibrium isotherm data of AN adsorption on PAC and GAC, respectively. Error analysis also confirmed the efficacy of the R-P isotherm to best fit the experimental data. The pseudo-second order kinetic model best represents the kinetics of the adsorption of AN onto PAC and GAC. Maximum adsorption capacity of PAC and GAC at optimum conditions of AN removal (adsorbent dose approximately 20 g/l of solution, and equilibrium time approximately 5 h) was found to be 51.72 and 46.63 mg/g, respectively.