Insights into the radical and nonradical oxidation degradation of ciprofloxacin in peroxodisulfate activation by ultraviolet light

Abstract

Ultraviolet light (UV light) was broadly utilized as persulfate activation source in advanced oxidation process to degrade contaminants in water due to its simple operation and environmental protection. In this paper, the degradation of ciprofloxacin (CIP) was investigated with peroxodisulfate (PDS) as oxidant and UV light as PDS activation source (UV/PDS system). The influence of initial pH, PDS dosage, UV light power, different CIP concentrations and coexisting substances (inorganic anions and natural organic matter) on CIP degradation process were investigated. Under the specific reaction conditions ([pH]0 = 7, [PDS] = 15 mM, UV light power = 3 W, [CIP] = 10 mg L−1), the CIP degradation efficiency reached 94.00 % within 40 min. The quenching experiments demonstrated that 1O2, O2−∙, ∙OH and SO4−∙ were the main active species, especially O2−∙ was the most dominant active species. In addition, CIP degradation in other water qualities (tap water and landscape river water) was explored, metronidazole (MNZ) and tetracycline (TC) were applied as representative pollutants for effective degradation. The above results indicated that the UV/PDS system would be possible to effectively degrade other types of refractory pollutants and less affected by water quality.