Removal of ciprofloxacin antibiotic with nano graphene oxide magnetite composite: Comparison of adsorption and photooxidation processes

Abstract

Ciprofloxacin (CIP) is a widely used fluoroquinolone antibiotic, both in aquatic life and agriculture. Graphene has been extensively utilized due to its favorable physical and chemical properties with a large surface area and high chemical and thermal stability. The aim of the study was to investigate the removal of CIP at increasing CIP and nano graphene oxide-magnetite (Nano-GO/M) composite concentrations, contact times and pH values by two different processes, namely adsorption and photooxidation. It was found that CIP removal by adsorption was low (maximum 15%–16.7%) at CIP concentrations between 1 and 1,000 mg/L, and the optimum operational conditions for these yields were 0.5–10 g/L Nano-GO/M composite, 30 min, and a pH of 6.5, respectively. The maximum adsorption capacities were between 2 and 2.2 mgCIP/gNano-GO/M for 1 and 1,000 mg/L CIP concentrations, respectively. The CIP was mainly removed by the photodegradation process. For maximum removal of 1–3 mg/L CIP (93%–94%), the optimum Nano-GO/M composite concentration, contacting time and pH were found as 0.5 g/L, 30 min, and 6.5, respectively, by photooxidation at a power of 300 W. As the Nano-GO/M composite concentrations were increased from 0.5 g/L to 2 and 10 g/L, the CIP yields increased from 93%–94% to 95%–96% and 97%–98%, respectively, at an optimum pH of 6.5 after 30 min irradiation at 300 W. CIP was photodegraded according to the second-order reaction kinetic (0.088 min–1). The calculated OH? radical concentrations were high at maximum CIP photodegradation yields. Under acidic and alkaline pH conditions, low CIP yields were obtained. © 2017 Desalination Publications. All rights reserved.