Improvement of Ciprofloxacin Antibiotic Photocatalytic Degradation and Adsorption Ability from Aqueous Solution by Bismuth Oxyiodide

Abstract

Bismuth Oxyiodide (BiOI) hierarchical structures were fabricated from the solution route at room temperature (BiOI-R) and solvothermal synthesis (BiOI-S) in the presence of KI and ethylene glycol to improve the photocatalytic and adsorption ability for the removal of ciprofloxacin from the aqueous environment. In this study, BiOI was characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption-desorption isotherm (BET), UV-Vis absorption spectroscopy, and pH of the point of zero charge (pHpzc). It was observed that the BiOI-S has better adsorption and photocatalysis capacity as a result of having more surface area, higher light absorption ability, and lower band-gap energy than the BiOI-R. The response surface methodology was applied to optimize the conditions of contact time, BiOI dosage, ciprofloxacin initial concentration, and pH for ciprofloxacin adsorption and photocatalytic processes using BiOI-S. The results show that the optimum conditions of ciprofloxacin removal processes obtained as contact time of 90 min, BiOI-S dosage of 2 g/L, and initial ciprofloxacin concentration of 2 mg/L, solution pH of 4.5 for adsorption processes. Meanwhile BiOI-S dosage of 1.5 g/L, initial ciprofloxacin concentration of 3.5 mg/L, and contact time of 108 min were the best condition for photocatalytic degradation. Additionally, the adsorption isotherm and kinetic studies fitted the Freundlich isotherm and pseudo-second-order model, respectively. The ciprofloxacin adsorption capacity value for BiOI-S of 3.799 mg/g was obtained and photocatalytic degradation of ciprofloxacin by BiOI-S followed the pseudo-first-order rate reaction based on Langmuir-Hinshelwood kinetics.