Studies on adsorption of propiconazole on modified carbons

The adsorption capacity and kinetics of propiconazole in aqueous solution using untreated and treated activated carbons as adsorbents have been studied, providing new experimental data at different temperatures which were obtained using the bottle-point method. Untreated carbon was oxidized with HNO3, H2O2, NaOCl and NaOH to produce a series of samples with different surface chemical properties. The surface chemistry was characterized by the determination of the point of zero charge. It was found that the physical morphology of the sample is affected by the strength of the oxidizing agent and the operating conditions. The surface chemistry of the activated carbon plays a key role in pollutant adsorption performance. Results of sorption experiments showed that carbon modified with NaOH is the best material for the adsorption of propiconazole at pH 6.5. Sorption of propiconazole reached equilibrium in 120 min. The maximum adsorption onto untreated activated carbon was 101 mg/g. As expected, the adsorption increased with increasing temperature. Adsorption kinetics obeyed a second-order kinetic model. (C) 2005 Elsevier B.V. All rights reserved.