Photoelectrocatalytic coupling system synergistically removal of antibiotics and antibiotic resistant bacteria from aquatic environment.

Antibiotics, antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are ubiquitous in the reclaimed water, posing a potential threat to human and ecological health. Nowadays, the reuse technology of reclaimed water has been widely concerned, but the removal of antibiotics, ARB and ARGs in reclaimed water has not been sufficiently studied. This study used TiO2 nanotube arrays (TNTs) decorated with Ag/SnO2-Sb nanoparticles (TNTs-Ag/SnO2-Sb) as the anode and Ti-Pd/SnO2-Sb as the cathode to construct an efficient photoelectrocatalytic (PEC) system. In this system, 99.9% of ARB was inactivated in 20 min, meanwhile, ARGs was removed within 30 min, and antibiotics were almost completely degraded within 1 h. Furthermore, the effects of system parameters on the removals of antibiotics, ARB and ARGs were also studied. The redox performance of the system was verified by adding persulfate. Escherichia coli, as a representative microorganism in aquatic environments, was used to evaluate the ecotoxicity of PEC treated chloramphenicol (CAP) solution. The ecotoxicity of CAP solution was significantly reduced after being treated by PEC. In addition, transformation intermediates of CAP were identified using liquid chromatography-tandems mass spectrometry (LC-MS/MS) and the possible degradation pathways were proposed. This study could provide a potential alternative method for controlling antibiotic resistance and protecting the quality of reclaimed water.

Photoelectrocatalytic simultaneous removal of 17α-ethinylestradiol and E. coli using the anode of Ag and SnO2-Sb 3D-loaded TiO2 nanotube arrays.

Reclaimed water contains both residual contaminants and pathogenic microorganisms while their simultaneous removal has not been fully addressed. Thus, a photoelectrocatalytical system (PEC) was engineering herein using an innovatively synthesized composite of TiO2 nanotube arrays (TNTs) decorated with antimony doped tin oxide (SnO2-Sb) and silver nanoparticles (Ag) in three dimensions (TNTs-Ag/SnO2-Sb) to realize the simultaneous removal of 17α-ethinylestradiol (EE2) and Escherichia coli (E. coli). The optical and electrochemical properties of TNTs were improved after the loading of Ag and SnO2-Sb with an excellent the stability for reuse. A 68% removal of EE2 and more than 5-log removal of E. coli were achieved in 1 h in PEC. The DNA activity of E. coli was nearly completely lost after PEC treatment and the cytotoxicity of PEC treated EE2 solution was significantly reduced. Reactive species (HO and H2O2) and degradation products of EE2 were identified, and the transformation pathways were proposed accordingly. This study generates valuable information of the transformation kinetics and mechanism for simultaneous removal of EE2 and E coli. It also provides an effective and innovative technology for water reuse.