National Postgraduate Conference (NPC2009, Universiti Technology PETRONAS (March 25-26, 2009) Degradation of Some Antibiotics in Aqueous Solution Using UV/ZnO Process Emad Elmolla 1* , Malay Chaudhuri 2 1 PhD Student, Department of Civil Engineering, UNIVERSITI TEKNOLOGI PETRONAS, MALAYSIA 2 Professor of Civil Engineering, UNIVERSITI TEKNOLOGI PETRONAS, MALAYSIA *Corresponding author , Tel.: +6017-538 5242 E-mail : em_civil@yahoo.com Abstract-Antibiotics are emerging contaminants in the aquatic environment because of their adverse effects on aquatic life and humans. The study examined the effect of operating conditions (zinc oxide concentration, pH and reaction time) of UV/ZnO on degradation of amoxicillin, ampicillin, cloxacillin in aqueous solution. The UV/ZnO photocatalysis is more effective for degradation of cloxacillin compared to ampicillin and amoxicillin degradation. pH has a great effect on amoxicillin , ampicillin and cloxacillin degradation. Complete degradation of all studied antibiotics was achieved at basic condition. The optimum operating conditions for degradation of antibiotics aqueous solution were observed to be ZnO concentration 0.5 g/L, pH 11 and irradiation time 180 min. Under optimum operating conditions, complete degradation of amoxicillin, ampicillin, cloxacillin. Finally, UV/ZnO photocatalysis can be used as a pretreatment process for amoxicillin, ampicillin, and cloxacillin degradation. Keywords: Amoxicillin, Ampicillin, Cloxacillin, Photocatalysis , UV/ZnO I. INTRODUCTION From environmental engineering point of view, pharmaceuticals including antibiotics are a new group of man made chemicals of concern entering the environment at concentrations such that the health effects are unknown. Problem that may be created by the presence of antibiotics at low concentrations in the environment is the development of antibiotic resistant bacteria. In recent years, the incidence of antibiotic resistant bacteria has increased and many people believe the increase is due to the use of antibiotics [1].Amoxicillin, ampicillin and cloxacillin are semi-synthetic penicillin obtaining its antimicrobial properties from the presence of a beta-lactam ring. They are widely used in human and veterinary medicine. Some authors have found amoxicillin and clxacillin in wastewater [2, 3]. Heterogeneous photocatalysis mechanism is based on the use of a semiconductor as a catalyst and UV radiation. When a semiconductor is illuminated with photons, whose energy is equal to or higher than the energy corresponding to the band-gap of the semiconductor. Due to the absorption of these photons by semiconductors, some electrons (e - ) may jump from the valence to the conduction band. Simultaneously, a photo hole is generated in the valance band (h + ). The electron/hole pairs migrate to the surface of the catalyst, where they can whether recombine and dissipate the input energy as heat, or react with the molecules object of degradation [4]. Daneshvar et al. [5] reported that the ZnO appears as a suitable alternative to TiO 2 since its photodegradation mechanism has been proven to be similar to that of TiO 2 . ZnO can absorb a large fraction of solar spectrum than TiO2 so, ZnO photocatalyst is consider more suitable for photocatalytic degradation in the presence of sunlight [6]. There are many reported studies used ZnO as catalysis in photocatalytic degradation of many organic pollutants such as, kraft black liquor [7], 2-Phenylphenol fungicide [8], phenol and chlorophenols [9], lignin [10]. Also degradation of some dyes like azo dye acid red 14 [5], C.I. Acid Yellow 23[11], Rhodamine 6G (R6G) and Methyl Orange (MO) [12]. There are a few researches on studying the degradation of Amoxicillin by different AOPs [13], [14], [15] and [16]. No studies on ampicillin and cloxacillin degradation by homogenous or heterogonous advanced oxidation processes have been reported. In addition, there are a few studies on degradation of different antibiotics such as sulfamethoxazole [17], Lincomycin [18]. The objective of this paper is to study the degradation of amoxicillin (AMX), ampicillin (AMP), cloxacillin (CLX) in aqueous solution using photocatalytic process based on ZnO (UV/ZnO). In addition, to study the effect of operating conditions like ZnO concentration, pH and reaction time on degradation of selected antibiotics. II. MATERIAL AND METHODS A. Chemicals and antibiotics Zinc oxide (ZnO) was purchased from R & M Marketing, Essex, U.K. Analytical grade of amoxicillin (AMX) and ampicillin (AMP) were purchased from (Sigma) and cloxacillin (CLX) from (Fluka) to construct HPLC analytical curves for the determination and quantification of these antibiotics. AMX, AMP and CLX used to prepare simulated antibiotics wastewater were obtained from a commercial source (Farmaniage Company). The commercial products were used as received without any further purification. Sodium hydroxide and sulfuric acid were purchased from