Solar-Driven Degradation of Ciprofloxacin in the Aquatic Environment

Ciprofloxacin (CIP), a pharmaceutical compound, -occurs as a micropollutant in various types of environmental matrices including wastewater, because it is resistant to removal via conventional methods – due to its persistent characteristics. For this reason, in this work the efficiency of photodegradation CIP (2 mg L-1) in Milli-Q water (MW) and tap water (TP) was investigated using TiO2 and ZnO at a concentration of 20 mg L-1 each. The tests were performed without and in the presence of SO4 2- ions (250 mg L-1) as one of main components of the aquatic, environmental matrices. Solar-driven photocatalysis using TiO2-P25 and ZnO improved the removal efficiency of CIP compared to its solar photolysis. In all cases approximately 90% removal of CIP was observed after 20 to 30 minutes, but no mineralization processes was achieved. The most efficient degradation was obtained using TiO2 at concentration of 20 mg L-1 in DW without the presence of SO4 2- after 5 minutes. The photodegradation rate constants estimated kt = 0.644 min-1 and kQUV = 0.249 L kJ-1. The complexity of the matrix affected the efficiency of CIP removal, favouring DW. The impact of sulfate anions also depended on the matrix: in distilled water, their impact was negative on the photocatalysis process efficiency, while in tap water, they slightly accelerated a process of CIP decomposition. Taking this into account, photocatalysis is an efficient; however, further research is necessary.