Research Article Adsorption of Phenol from Aqueous Solutions on Jojoba Nuts Residue Equilibrium isotherms for the adsorption of phenol from aqueous solutions of three types of Jojoba nuts residue were determined at 30, 40 and 55 C. Types I and II were the residue after extracting the oil by leaching or by a pressing pro- cess, respectively. The third type was obtained by thermally treating the residue remaining after pressing. The phenol concentration ranged from 0–100 ppm in the aqueous solutions. A low adsorption capacity relative to activated carbon was obtained on types I and II, while the adsorption capacity of type III was much higher than types I and II. The results show that Jojoba nuts residue show good potential for adsorption of phenolic compounds if subjected to some type of treatment (activation). As the temperature increased from 30 to 55 C, the adsorption capacity of types I and II decreased, but the increase had a negligible effect on type III. The experimental data were fitted to the appropriate adsorption models. The models used were Langmuir, Freundlich, Koble-Corrigan and Red- lich-Peterson. Keywords: Adsorption, Modeling, Organic pollution, Plants Received: November 29, 2006; revised: December 9, 2006; accepted: January 12, 2007 DOI: 10.1002/ceat.200600378 1 Introduction Adsorption is commonly used to remove pollutants from water because of its simplicity, convenient operation and the relatively low cost for its application [1]. The removal of pollu- tants, such as phenol, from water/wastewater onto activated carbon to obtain reusable water is a well-known technique. Toxic organic compounds increasingly cause severe environ- mental problems because of their resistance to natural degra- dation [2]. They must be dealt with safely and effectively. Phe- nol is one of the major toxic organic compounds that may occur in domestic and industrial wastewater, natural and pota- ble waters supplies. Chlorination of such water may produce odorous and unpleasant tasting chlorophenol. The treatment of polluted water before use is a necessary process. Activated carbon is the most widely used material as an ad- sorbent. It is hydrophobic, has a highly porous structure and a relatively large surface area between 300 and 2500 m 2 /g, which is the largest among all sorbents [3]. However, the interna- tional price of activated carbon is increasing rapidly, and therefore, the availability of substitute adsorbents in order to maintain low treatment costs, is needed. Agricultural residue such as wood sawdust [4] and olive seed residue [5] were found to be of acceptable efficiency for removing colors from aqueous solutions and effluents. Zeolite, clay and gypsum were evaluated for their capability to remove phenol from water and found to be of low capacity [6]. A by-product of Jojoba nuts is the meal remaining after the oil has been extracted. This material constitutes about 50 % of the nuts composition, so any commercial utilization of Jojoba oil should consider the handling of large amounts of meal and its potential uses [7]. Pressing and/or leaching by organic sol- vent can remove the oil. The fact that the nuts contain about 50 % oil suggests that it has high porosity once the oil is ex- tracted. The possibility of using the residue without further treatment or with some treatment (thermal in this study) is considered in this work. Therefore, the objectives of this work were to measure the ability of three different types of Jojoba nuts residue to adsorb phenol from aqueous solutions at three different temperatures, and to fit the experimental data to the appropriate adsorption models. 2 Experimental 2.1 Materials Jojoba nuts from the Jordan University of Science and Tech- nology (JUST) farm were used. All the chemicals used were re-  2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim http://www.cet-journal.com Mousa K. Abu-Arabi 1 Mamdouh A. Allawzi 1 Ahmad S. Al-Zoubi 1 1 Chemical Engineering Department, Jordan University of Science and Technology, Irbid, Jordan. – Correspondence: M. A. Allawzi (mallawzi@just.edu.jo), Chemical Engineering Department, Jordan University of Science and Technology, P.O.Box 3030, Irbid 22110, Jordan. Chem. Eng. Technol. 2007, 30, No. 4, 493–500 493