Journal of Hazardous Materials 172 (2009) 1476–1481 Contents lists available at ScienceDirect Journal of Hazardous Materials journal homepage: www.elsevier.com/locate/jhazmat Degradation of the antibiotics amoxicillin, ampicillin and cloxacillin in aqueous solution by the photo-Fenton process Emad S. Elmolla ∗ , Malay Chaudhuri Department of Civil Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak, Malaysia article info Article history: Received 28 May 2009 Received in revised form 1 August 2009 Accepted 5 August 2009 Available online 11 August 2009 Keywords: Antibiotics Ampicillin Amoxicillin Cloxacillin Photo-Fenton process abstract The study examined degradation of the antibiotics amoxicillin, ampicillin and cloxacillin in aqueous solu- tion by the photo-Fenton process. The optimum operating conditions for treatment of an aqueous solution containing 104, 105 and 103 mg/L amoxicillin, ampicillin, and cloxacillin, respectively was observed to be H 2 O 2 /COD molar ratio 1.5, H 2 O 2 /Fe 2+ molar ratio 20 and pH 3. Under optimum operating condi- tions, complete degradation of amoxicillin, ampicillin and cloxacillin occurred in 2 min. Biodegradability (BOD 5 /COD ratio) improved from ∼ 0 to 0.4, and COD and DOC degradation were 80.8 and 58.4%, respec- tively in 50 min. Photo-Fenton treatment resulted in the release and mineralization of organic carbon and nitrogen in the antibiotic molecule. Increase in ammonia and nitrate concentration, and DOC degradation were observed as a result of organic carbon and nitrogen mineralization. DOC degradation increased to 58.4% and ammonia increased from 8 to 13.5 mg/L, and nitrate increased from 0.3 to 14.2 mg/L in 50 min. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Antibiotics are hazardous contaminants in the aquatic environ- ment because of their adverse effects on aquatic life and humans. Problem that may be created by the presence of antibiotics at low concentrations in the environment is the development of antibiotic resistant bacteria [1]. In recent years, the incidence of antibi- otic resistant bacteria has increased and many people believe the increase is due to the use of antibiotics [2]. Furthermore, the pres- ence of antibiotics in wastewaters has increased in recent years and their abatement will be a challenge in the near future. Amoxicillin, ampicillin and cloxacillin are semi-synthetic penicillin obtaining their 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 cloxacillin in municipal wastewater [3,4]. Antibiotics can reach the aquatic environment though various sources such as antibiotic industry, hospital efflu- ent and excretion from humans and livestock [5–7]. Arslan-Alaton and Dogruel [8] reported that the concentration of penicillin for- mulation in real antibiotics wastewater may be up to 400 mg/L. Antibiotics wastewater has high chemical oxygen demand (COD) and low biochemical oxygen demand (BOD), and hence biological processes are unsuitable for the wastewater treatment. Advanced oxidation processes (AOPs) have proved to be highly effective in the degradation of most of the pollutants in wastewaters [9]. Oxidation ∗ Corresponding author. Tel.: +60 14 9047313; fax: +60 5 365 6716. E-mail address: em civil@yahoo.com (E.S. Elmolla). with Fenton’s reagent is based on hydroxyl radicals (OH • ) produced by catalytic decomposition of hydrogen peroxide in reaction with ferrous ion. In the photo-Fenton process, additional reactions occur in the presence of light that produce hydroxyl radicals or increase the production rate of hydroxyl radicals [10], thus increasing the efficiency of the process. There have been studies on treatment of amoxicillin wastewater and penicillin formulation effluent by AOPs [8,11,12]. Reaction kinetics of amoxicillin ozonation has been studied [13]. However, no studies on degradation of amoxicillin, ampicillin and cloxacillin antibiotics in aqueous solution by the photo-Fenton process have been reported. This study examined the operating conditions (H 2 O 2 /COD molar ratio, H 2 O 2 /Fe 2+ molar ratio, pH and irradiation time) of the photo-Fenton process on degradation of the antibiotics amoxicillin, ampicillin and cloxacillin in aqueous solution. 2. Materials and methods 2.1. Chemicals and antibiotics Hydrogen peroxide (H 2 O 2 ) (30% w/w) and ferrous sulfate (FeSO 4 ·7H 2 O) were purchased from R&M Marketing, Essex, UK. Analytical grade of the antibiotics amoxicillin (AMX) and ampi- cillin (AMP) were purchased from Sigma and cloxacillin (CLX) from Fluka to construct high performance liquid chromatograph (HPLC) analytical curves for the determination and quantification of the antibiotics. AMX, AMP and CLX used to prepare antibiotics aque- ous solution were obtained from a commercial source (Farmaniage Company). The commercial products were used as received with- 0304-3894/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2009.08.015