Authors: Alaa H. Hawari
Addresses: Department of Civil and Architectural Engineering, Qatar University, P.O. Box 2713, Doha, Qatar
Abstract: Untreated anaerobically digested sewage sludge was used for the first time as a biosorbent for removing phenol from aqueous solution. Results showed that adsorption capacity was influenced by the pH of the aqueous solution with an observed maximum phenol removal at pH around 6-8. The adsorption equilibrium of phenolic compounds was obtained after almost two hours with an adsorption of approximately 90% of the phenolic compounds. A sorbent concentration of 1.8 g/L was found to insure the best removal percentage and the best sorbent capacity. Both Langmuir and Freundlich models have provided reasonable fittings for the data of phenol adsorption. The experimental data fitted the pseudo-second-order kinetic model and the intraparticle diffusion model. The values of change in Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were calculated. The thermodynamic study of adsorption process showed that the process was exothermic in nature.
Keywords: phenol adsorption; anaerobically digested sludge; ADS; kinetics; thermodynamics; dried sewage sludge; phenol biosorbent; kinetic modelling; intraparticle diffusion model; Gibbs free energy; enthalpy; entropy; exothermic.
International Journal of Environmental Engineering, 2014 Vol.6 No.1, pp.29 - 42
Received: 19 Sep 2011
Accepted: 08 May 2012
Published online: 11 Nov 2013 *