Herein, a highly stable and efficient photoelectrocatalytic system was developed for the rapid degradation of tetracycline . The photoelectrocatalytic system comprised two Ag/N-doped TiO 2 nanotube photoanodes, a bipolar membrane, and a P–Pd cathode. The Ag/N-doped TiO 2 nanotube photoanodes were coupled with a P–Pd cathode to enhance the hydroxyl free radical (·OH) generation at the cathode surface. The bipolar membrane can separate tetracycline pollutants and degradation products from the photoanodes, which can minimize the contamination of the photocatalyst by tetracycline or products, thereby enhancing the repeatability and stability of the photoelectrocatalytic system. photoelectrocatalytic uses ultraviolet–visible light as the input energy for the effective removal of tetracycline and total organic carbon . The initial pH in the cathode and photoanode chambers was 7.0. The Na 2 SO 4 concentration in the photoanode chamber and the addition amount of H 2 O 2 were 0.2 M and 4% (v/v), respectively. Under these conditions, 100 mL of 100 mg/L tetracycline was completely degraded within 60 min, and 82.3% total organic carbon was removed within 5 h. The pseudo-first-order reaction rate constant of the Ag/N-doped TiO 2 nanotube with 0.15 M Ag was 0.0637 min-1, which was 12 times higher than that of N-doped TiO 2 nanotube. The mechanisms underlying·OH generation and the tetracycline degradation pathway were also elucidated. The photoelectrocatalytic system, which is an eco-friendly and low-energy system, exhibits excellent stability and reliability toward tetracycline and total organic carbon degradation and significantly aids the development of wastewater remediation.
Zhenjiang Yu,Yuanyuan Zhao,Bing Gao,Xuyang Liu,Liming Jia,Fangbo Zhao,Jun Ma
To improve the anti-biofouling properties of membranes, Ag-embedded nano-sized titanium dioxide (Ag-n-TiO2) particles were utilized as biocidal agents to modify polyvinyl chloride (PVC) membranes. Both Ag-n-TiO2/PVC flat sheet membranes and reinforced hollow fiber membranes were fabricated by a phase inversion method with varying Ag-n-TiO2 particle concentrations. As a result, the hydrophilicity, permeability, and retention capability increased with Ag-n-TiO2 concentrations from 0 to 1.5 wt%. In addition, the in situ antibacterial and anti-formation of biofilm properties of the modified membranes were greatly enhanced in the conventional inhibition zone test, Escherichia coli (E. coli) absorption experiment, fluorescent staining experiment, as well as long-term continuous biofouling test. The best results were obtained for the PVC membrane modified by 1.0 wt% Ag-n-TiO2. The optimized membrane presented not only better permeability and in situ antibacterial properties in the E. coli adhesion test, but also an enhancement in resisting biofilm formation and a more steady permeation flux in long-term filtration than the unmodified membrane.
Plasmon Ag decorated 3D urchinlike N-TiO 2−x photocatalysts are successfully synthesized by a facile hydrothermal treatment (180 °C) and combined with a photo-deposition approach, followed by a reduction treatment. The results show that the resultant Ag/N-TiO 2−x sample possesses a three-dimensional (3D) urchinlike nanostructure with high crystallinity of anatase. Meanwhile, it exhibits the narrow optical band gap (Eg ∼ 2.61 eV) and the excellent visible-light-driven photocatalytic performance. Moreover, the hydrogen generation rate and photocatalytic degradation rate of phenol are up to 186.2 μmol h −1 g −1 and 97.7% under visible light irradiation, which are about 4.2 and 5.4 folds greater than that of N-TiO 2 . The mechanism of photocatalytic process is also proposed, and the enhanced photocatalytic property is mainly due to the synergistic reaction of the Ti 3+ and N codoping, which narrows the band gap and favors the utilization of visible light, and the plasmon effect of Ag nanoparticles and unique 3D urchinlike architecture, which are propitious to the separation and transmission of photogenerated carriers.
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