Removal of Ciprofloxacin from Wastewater by Ultrasound/Electric Field/Sodium Persulfate (US/E/PS)

Ciprofloxacin (CIP), as a common antibiotic used in human clinical and livestock farming, is discharged into natural water bodies and its concentration has increased in the last years. Its stable chemical structure is difficult to remove by conventional techniques. Residual ciprofloxacin in the environment has become an emerging micropollutant that promotes the generation of resistance genes of bacteria and endangers ecosystem balance and human health. Removal of ciprofloxacin from water by the system of ultrasound/electric field/sodium persulfate (US/E/PS) was investigated. Firstly, CIP degradation affects by different oxidation methods, such as ultrasonic oxidation, electro-oxidation, and persulfate oxidation, and their four combined oxidation methods (ultrasound-activated persulfate oxidation, electro-activated persulfate oxidation, ultrasound-enhanced electro-oxidation, and ultrasound-enhanced electro-activated persulfate oxidation), on the target contaminants were compared. Secondly, the influences of parameters on the CIP degradation by an ultrasound-enhanced electro-activation-persulfate reaction system were investigated. Thirdly, the possible free radical species in the ultrasound-enhanced electro-activation-sulfate reaction system were identified and the dominant free radical species in the system were analyzed. Finally, the samples of CIP in the US/E/PS system were tested by liquid mass spectrometry, and the possible intermediate products and degradation path were speculated. The results indicate that the US/E/PS system is of great potential application value in the removal of organic pollution and environmental purification.

Sodium Persulfate (Na2S2O8)

Sodium persulfate is an environmentally friendly inorganic compound commonly used as an oxidizing agent in chemistry. This reagent undergoes homolytic cleavage in solutions, affording sulfate radical anions that can present several applications. Recently, the SO4.- has been applied in diverse processes, such as the degradation of antibiotics and dyes in wastewater treatment. 1 In organic synthesis, sodium persulfate can be used as an oxidant in transition-metal catalyzed reactions or as an oxidative species in crucial steps in metal-free reactions.2,3 Na2S2O8 is an inexpensive oxidant that is stable and easy to handle, making it a good reagent choice for several strategic synthetic transformations.4 It is synthesized industrially through an electrolytic oxidation process from sodium hydrogen sulfate,5 and recent applications for this compound are presented herein.