Water and Environment Journal. Print ISSN 1747-6585 Water and Environment Journal 0 (2019) 1–12 © 2019 CIWEM. 1 Introduction Today, an increasing tendency is seen in the consumption of drugs especially antibiotics such that the drug produc- tion has reached hundreds of thousands per year (Sun et al. , 2009). As a result of the high rate of drug con- sumption, its residue can enter the environment and lead to problems. The main sources of antibiotic contamination are the discharge of hospital, domestic, pharmaceutical, industrial and animal wastewaters to the environment (Ajoudanian and Nezamzadeh-Ejhieh, 2015; Arabpour and Nezamzadeh-Ejhieh, 2015; Carabin et al. , 2015). The pres- ence of antibiotics in water has caused drug resistance, changes in the structure of aquatic species and interfer- ence with the photosynthesis of plants (Aristilde et al. , 2010; Bottoni et al. , 2010; Dirany et al. , 2010). There are many ways to remove antibiotics from water such as coagulation and precipitation, adsorption, nano- filtration membrane, and biological degradation (Sun et al. , 2009; Zazouli et al. , 2009; Arabpour and Nezamzadeh- Ejhieh, 2015). In adsorption, pollutants are transferred from a liquid to a solid phase without any degradation (Chong et al. , 2010). Biological treatment requires longer times resulting in lower yield (Belghadr et al. , 2015; Lofrano et al. , 2017). Reverse osmosis needs high technology and costs (Afonso-Olivares et al. , 2016). The photocatalytic process is an advanced oxidation method that is capable of removing various poisonous and refractory compounds from water. In photocatalytic treatment, organic pollut- ants are degraded in the presence of metal oxide semi- conductors under UV and sunlight irradiation. The photocatalytic process has the advantages such as the ability to remove pollutants at low concentration, no need to other chemical additives, use of sunlight and produc- tion of no harmful materials (Chong et al. , 2010; Choi et al. , 2014; Ye et al. , 2018). Ciprofloxacin is one of the most widely used antibiotics for the treatment of bacterial infections in hospitals (Vasconcelos et al. , 2009). Ciprofloxacin cannot be degraded biologically but it can be partially adsorbed by biosolids in sewers, and the remainder of it can cause health and environmental problems (Guo et al. , 2013). Recently, many studies have been directed to develop photocatalysts with higher yields and easier operation. Nezamzadeh-Ejhieh and Shirazi (2014) investigated nano- clinoptilotile particles with FeO for photocatalyst degrada- tion for tetracycline under UV light irradiation. The recyclable and stable CdS/C@Fe 3 O 4 photocatalyst was synthesized by Lu et al. (2015) and was used for the photodegradation of ciprofloxacin in water. Vaiano et al. (2015) achieved high values of TOC removal by applying N-doped TiO 2 doped for the treatment of spiramycin wastewater. Yuan et al. (2016) examined TiO 2 doped with Photodegradation of ciprofloxacin in water using photocatalyst of zinc oxide nanowires doped with copper and cerium oxides Maryam Mirzai, Faranak Akhlaghian & Farhad Rahmani Department of Chemical Engineering, Faculty of Engineering, University of Kurdistan, Sanandaj, Iran Keywords cerium oxide; ciprofloxacin wastewater; copper oxide; foil photocatalyst; zinc oxide nanowires. Correspondence Faranak Akhlaghian, Department of Chemical Engineering, Faculty of Engineering, University of Kurdistan, Sanandaj 66177-15175, Iran. Email: akhlaghianfk@gmail.com doi:10.1111/wej.12477 Abstract Antibiotic pollution via wastewaters has led to many environmental problems. In this work, to remove ciprofloxacin which is an antibiotic from water, foil photo- catalyst of zinc oxide nanowires doped with copper and cerium oxides was ap- plied under UV light irradiation. An empirical model was developed to determine the photocatalyst activity using response surface methodology. The independent variables were the concentrations of precursors, copper and cerium nitrates in the coating solution. The F-value and p-value of the model showed the accuracy of the model. The statistical analysis indicated that copper oxide had larger ef- fect on the response than cerium oxide. The optimized catalyst was determined and characterized using ICP, XRD, SEM and MIP techniques. The results of this work which are comparable to those of the previous studies have the advantage of easy separation of the photocatalyst from water without using a centrifuge.