Isotherm and kinetics study for acrylic acid removal using powdered activated carbon

The potential of powdered activated carbon (PAC) for the adsorption of acrylic acid (AA) from aqueous solution was studied at the initial concentration (C-0) in the range of 50-500 mg/l over the temperature range of 303-348 K. The equilibrium adsorption studies were carried out to evaluate the effect of adsorbent dosage and contact time, change in pH by adding adsorbents and the initial concentration. Langmuir, Freundlich and Redlich-Peterson (R-P) equilibrium isotherm models were tested to represent the data. Error functions were used to test their validity to fit of the adsorption data with the isotherm and kinetic models. The Freundlich isotherm equation is found to best represent the equilibrium separation data in the temperature range of 303-348 K. The maximum adsorption capacity of AA onto PAC was obtained as q(m) = 36.23 mg/g with an optimum PAC dosage w = 20 g/l at 303 K for C-0 = 100 mg/l. The pseudo-second-order kinetics is found to represent the experimental AA-PAC data. The negative value of Delta G(ad)(0) (-16.60 to -18.18 kJ/mol K) indicate the feasibility and spontaneity of the adsorption process. (C) 2009 Elsevier B.V. All rights reserved.