Separation and Purification Technology 46 (2005) 11–18 Studies on adsorption of propiconazole on modified carbons Olivier Adam a , Maud Bitschen´ e b , Giangiacomo Torri c , Franc ¸ois De Giorgi a , Pierre-Marie Badot a , Gr´ egorio Crini b,∗ a Laboratoire de Biologie Environmentale, EA 3184 USC INRA, Universit´ e de Franche-Comt´ e, Place Leclerc, 25000 Besan¸ con, France b Centre de Spectrom´ etrie, SERAC, Universit´ e de Franche-Comt´ e, 16 route de Gray, 25030 Besan¸ con cedex, France c Istituto Scientifico di Chimica e Biochimica “G. Ronzoni”, 81 Via G. Colombo, 20133 Milano, Italy Received 15 November 2004; received in revised form 30 March 2005; accepted 31 March 2005 Abstract 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 HNO 3 ,H 2 O 2 , 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. © 2005 Elsevier B.V. All rights reserved. Keywords: Activated carbon; Propiconazole; Adsorption 1. Introduction Adsorption is an effective separation process for a wide variety of applications. In particular, adsorption is a well- established technique for treating domestic and industrial effluents. It is now recognized as an efficient and economic method for the removal of pollutants from wastewaters. Although many different adsorbents were tested to remove toxic compounds from wastewaters [1–4], activated carbons, in granular or powdered form, were still the most widely used sorbents to this end [5]. Extensive experimental and modeling studies have been reported to date on the activated carbon adsorption of a broad spectrum of hazardous com- pounds from aqueous solution. The presence of pollutants such as triazole fungicides in waters poses health and environmental risks [6–8]. The tri- ∗ Corresponding author. Tel.: +33 3 81 66 65 64; fax: +33 3 81 66 64 38. E-mail address: gregorio.crini@univ-fcomte.fr (G. Crini). azole fungicides are agrochemicals used world wide in the agricultural industry due to their wide spectrum of action. The European Union has listed the persistent and potentially toxic compounds. Propiconazole (1-(2-(2,4-dichlorophenyl)-4- propyl-1,3-dioxolan-2-ylmethyl)-1H-1,2,4-triazole), a sys- tematic foliar triazole fungicide, is one of them in this pri- ority list. Its toxicity is moderate: the acute oral LD 50 is around 1500 mg/kg in rats (European Commission Docu- ment, SANCO/3049/99, 2003). However, this organic com- pound has been classified as a possible human carcinogen by the U.S. Environmental Protection Agency [9]. The objectives of the present work were to study the adsorption of propiconazole on activated carbon. In this paper, we are describing the complexing properties of untreated and treated carbons toward propiconazole using the bottle-point method. The influence of several parameters (kinetics of sorption, i.e., contact time, effect of the pollu- tant concentration, temperature) on the sorption capacity of these carbons is evaluated. The modifications in the surface 1383-5866/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.seppur.2005.03.012