Remoção do microcontaminante ciprofloxacina em água residuária sintética aplicando processo eletrolítico

Abstract

Ciprofloxacin (CIP) is an antibiotic of the fluoroquinolone class, has low biodegradability and possible toxic effects on the environment. Due to its extensive use, it is considering an emerging pollutant present in environmental compartments such as water, sludge and sewage that contributes to the phenomenon of resistance to antimicrobials. This work aimed to study the optimal conditions for the removal of CIP in synthetic wastewater, using electrolytic treatment, through a laboratory scale reactor using aluminum electrodes. The experiments performed using standard solutions with concentrations of 10 mg L1 of CIP. The operational parameters of the reactor initial pH, voltage and NaCl concentration optimized based on the reduction of the CIP concentration, by means of 2³ full factorial design followed by optimization by the response surface methodology employing central composite rotational design (DCCR). After optimization, the removal kinetics evaluated in a time of 120 min with monitoring of CIP concentration, QOD, electrode mass loss, pH, Al3+ concentration in the solution and the evaluation of the sludge generated by infrared spectroscopy (FT - GO). The best operating condition obtained was pH = 7.6; Voltage = 5.6 V and [NaCl] = 0.6 g L-1, with a predicted removal of 78.52% within 30 min. The reaction kinetics fitted to the second-order kinetic model, both for CIP removal and for COD removal, presenting the R2 correlation coefficients of 0.98 and 0.88, respectively. The FT-IR analysis suggests that in addition to the removal of CIP by electrocoagulation mechanism, which are based on adsorption, there is also the occurrence of degradation by the electro-oxidation mechanism, promoted by oxidizing species such as hypochlorite ion and hydroxyl radical. In general terms, the applied electrolytic process proved to be favorable for the removal of CIP in synthetic wastewater.