Ciprofloxacin (CIP) in natural waters has been taken as a serious pollutant because of its hazardous biological and ecotoxicological effects. Here, a 3D nanocomposite photocatalyst g-C₃N₄/La-N-TiO₂ (CN/La-N-TiO₂) was successfully synthesized by a simple and reproducible in-situ synthetic method. The obtained composite was characterized by XRD, SEM, BET, TEM, mapping, IR, and UV-vis spectra. The photocatalytic degradation of ciprofloxacin was investigated by using CN/La-N-TiO₂ nanocomposite. The main influential factors such as pH of the solution, initial CIP concentration, catalyst dosage, and coexisting ions were investigated in detail. The fastest degradation of CIP occurred at a pH of about 6.5, and CIP (5 mg/L starting concentration) was completely degraded in about 60 min after exposure to the simulated solar light. The removal rates were rarely affected by Na⁺ (10 mg·L⁻¹), Ca²⁺ (10 mg·L⁻¹), Mg²⁺ (10 mg·L⁻¹), and urea (5 mg·L⁻¹), but decreased in the presence of NO₃⁻ (10 mg·L⁻¹). The findings indicate that CN/La-N-TiO₂ nanocomposite is a green and promising photocatalyst for large-scale applications and would be a candidate for the removal of the emerging antibiotics present in the water environment.

Microbial fuel cells (MFCs) could achieve the removal of antibiotics and generate power in the meantime, a process in which the bacterial community structure played a key role. Previous work has mainly focused on microbes in the anode, while their role in the cathode was seldomly mentioned. Thus, this study explored the bacterial community of both electrodes in MFCs under sulfadiazine (SDZ) pressure. The results showed that the addition of SDZ had a limited effect on the electrochemical performance, and the maximum output voltage was kept at 0.55 V. As the most abundant phylum, Proteobacteria played an important role in both the anode and cathode. Among them, Geobacter (40.30%) worked for power generation, while Xanthobacter (11.11%), Bradyrhizobium (9.04%), and Achromobacter (7.30%) functioned in SDZ removal. Actinobacteria mainly clustered in the cathode, in which Microbacterium (9.85%) was responsible for SDZ removal. Bacteroidetes, associated with the degradation of SDZ, showed no significant difference between the anode and cathode. Cathodic and part of anodic bacteria could remove SDZ efficiently in MFCs through synergistic interactions and produce metabolites for exoelectrogenic bacteria. The potential hosts of antibiotic resistance genes (ARGs) presented mainly at the anode, while cathodic bacteria might be responsible for ARGs reduction. This work elucidated the role of microorganisms and their synergistic interaction in MFCs and provided a reference to generate power and remove antibiotics using MFCs.

In the present study, PbO₂ electrodes, doped with different doses of Er (0%, 0.5%, 1%, 2%, and 4%), were fabricated and characterized. Surface morphology characterization by SEM-EDS and XRD showed that Er was successfully doped into the PbO₂ catalyst layer and the particle size of Er-PbO₂ was reduced significantly. Electrochemical oxidation of sulfamerazine (SMR) in the Er-PbO₂ anode system obeyed te pseudo first-order kinetic model with the order of 2% Er-PbO₂ > 4% Er-PbO₂ > 1% Er-PbO₂ > 0.5% Er-PbO₂ > 0% PbO₂. For 2% Er-PbO₂, k_SMR was 1.39 h⁻¹, which was only 0.93 h⁻¹ for 0% PbO₂. Effects of different operational parameters on SMR degradation in 2% Er-PbO₂ anode system were investigated, including the initial pH of the electrolyte and current density. Under the situation of an initial pH of 3, a current density of 30 mA·cm⁻², a concentration of SMR 30 mg L⁻¹, and 0.2 M Na₂SO₄ used as supporting electrolyte, SMR was totally removed in 3 h, and COD mineralization efficiency was achieved 71.3% after 6 h electrolysis. Furthermore, the degradation pathway of SMR was proposed as combining the active sites identification by density functional calculation (DFT) and intermediates detection by LC-MS. Results showed that Er-PbO₂ has great potential for antibiotic wastewater treatment in practical applications.

Electrochemical oxidation of landfill leachate after biological treatment by a novel electrochemical system, which was constructed by introducing a corroding electrode of iron (Fe_c) between a boron-doped diamond (BDD) anode and carbon felt (CF) cathode (named as BDD–Fe_c–CF), was investigated in the present study. Response surface methodology (RSM) with Box–Behnken (BBD) statistical experiment design was applied to optimize the experimental conditions. Effects of variables including current density, electrolytic time and pH on chemical oxygen demand (COD) and ammonia nitrogen (NH₃-N) removal efficiency were analyzed. Results showed that electrolytic time was more important than current density and pH for both COD and NH₃-N degradation. Based on analysis of variance (ANOVA) under the optimum conditions (current density of 25 mA·cm⁻², electrolytic time of 9 h and pH of 11), the removal efficiencies for COD and NH₃-N were 81.3% and 99.8%, respectively. In the BDD–Fe_c–CF system, organic pollutants were oxidized by electrochemical and Fenton oxidation under acidic conditions. Under alkaline conditions, coagulation by Fe(OH)₃ and oxidation by Fe(VI) have great contribution on organic compounds degradation. What is more, species of organic compounds before and after electrochemical treatment were analyzed by GC–MS, with 56 kinds components detected before treatment and only 16 kinds left after treatment. These results demonstrated that electrochemical oxidation by the BDD–Fe_c–CF system has great potential for the advanced treatment of landfill leachate.