Ciprofloxacin removal: BDD anode coupled with solid polymer electrolyte and ultrasound irradiation

Ciprofloxacin (CIP) is a broad-spectrum antibiotic of the fluoroquinolone group. The low biodegradability of this compound enhances its accumulation in the environment, with associated interference on non-target pathogens, photosynthesis of plants, alterations in the structure of algae and increasing risk of resistant bacteria development. Production plants and hospitals are the main sources of water contamination. Hence, the development of efficient technologies for the treatment of wastewaters is recommended. Here, ultrasound irradiation coupled with the electrochemical generation of hydroxyl radicals by Nb/BDD anode were investigated to remove CIP from aqueous solutions. A solid polymer electrolyte (SPE) was used to overcome the low conductivity of the solution treated. Response Surface Methodology (RSM) was applied with the aim to evaluate the effects of electric current, ultrasound irradiation and stirring rate on the removal and the energy requirements associated to the treatment. Up to 91.36 % of CIP disappearance was attained within 20 min. at 1.16 A and 520 rpm. Ultrasound irradiation at 40 kHz enhanced the removal of the compound only at low current intensity, while strongly affected the energy demand. A treatment time of 30 min. at 0.642 A and 660 rpm has been suggested to minimize the specific energy consumption, estimated to be <1.91 10−3 kWh mg−1. Further research is encouraged, given the promising potential of a zero-discharge removal of several emerging pollutants as phytosanitary, pharmaceuticals and personal care products.