Visible-light-driven photocatalytic degradation of tetracycline hydrochloride by Z-scheme Ag3PO4/1T@2H-MoS2 heterojunction: Degradation mechanism, toxicity assessment, and potential applications.

Residual antibiotics in wastewater threaten living organisms and the ecosystem, while the photocatalytic process is recognized as one of the most eco-friendly and promising technologies for the treatment of antibiotic wastewater. In this study, a novel Z-scheme Ag3PO4/1T@2H-MoS2 heterojunction was synthesized, characterized, and used for the visible-light-driven photocatalytic degradation of tetracycline hydrochloride (TCH). It was found that Ag3PO4/1T@2H-MoS2 dosage and coexisting anions had significant effects on the degradation efficiency, which could reach up to 98.9 % within 10 min under the optimal condition. Combing experiments and theoretical calculations, the degradation pathway and mechanism were thoroughly investigated. The excellent photocatalytic property of Ag3PO4/1T@2H-MoS2 was achieved attributed to the Z-scheme heterojunction structure, which remarkably inhibited the recombination of photoinduced electrons and holes. The potential toxicity and mutagenicity for TCH and generated intermediates were evaluated, which revealed the ecological toxicity of antibiotic wastewater was reduced effectively during the photocatalytic degradation process.

Nitrogen-doped mesoporous carbon material (NCMK-3) as a catalyst for the removal of 4-chlorophenol during persulfate oxidation and its efficiency after reuse.

Persulfate (PS) oxidation of 4-chlorophenol (4CP) is mostly catalysed by relatively expensive metal substrates. In this study, we investigated the influence of nitrogen-doped and non-doped mesoporous carbon materials (NCMK-3 and CMK-3) during persulfate (PS) oxidation of 4CP in water. Batch experiments were conducted such that PS was added to simulated contaminant mixture after 1 h agitation with NCMK-3 and CMK-3. Further, the experiment was carried out at different temperatures, pH ranges, concentrations of persulfate (PS), and different doses of NCMK-3, since it recorded better removal rates compared to CMK-3. The results revealed that NCMK-3 and CMK-3 aided the removal of 4CP from water during persulfate oxidation. When persulfate was added after an hour of equilibration with CMK-3 and NCMK-3, 83% and 92% of 4CP were removed within 20 min, respectively, whereas lower removal rates (≤40) were recorded in the absence of persulfate (PS). The removal rates of 4CP increased with an increase in temperature but reduced in the alkaline medium in the NCMK-3/PS system. The efficiency of the NCMK-3 reduced significantly after it was reused three times. Based on the results, NCMK-3 influences the activity of PS oxidation of 4-chlorophenol (4CP) and exhibited a synergistic effect in the removal of the organic contaminant from water.