A new acridine-based photosensitizer with ultra-low light requirement efficiently inactivates carbapenem-resistant Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus and degrades their antibiotic resistance genes.

The spread of antibiotic resistant pathogens and antibiotic resistance genes (ARGs) in the environment poses a serious threat to public health. However, existing methods are difficult to effectively remove antibiotic resistant pathogens and ARGs from the environment. In this study, we synthesized a new acridine-based photosensitizer, 2,7-dibromo-9-mesityl-10-methylacridinium perchlorate (YM-3), by the heavy atom effect, which could photodynamically inactivate antibiotic resistant pathogens and reduce ARGs by generating singlet oxygen (1O2) in an aqueous environment. The 1O2 yield of YM-3 was 4.9 times that of its modified precursor. YM-3 could reduce the culturable number and even the viable counts of methicillin-resistant Staphylococcus aureus and carbapenem-resistant Acinetobacter baumannii to 0 (inactivation rate > 99.99999%) after 2 and 8 h of low-intensity blue light (15 W/m2) irradiation, respectively. After 20 h of light exposure, the copy numbers of ARGs in both bacteria were reduced by 5.80 and 4.48 log, respectively, which might indicate that ARGs had been degraded. In addition, YM-3 still had an efficient bactericidal effect after five inactivation cycle. These characteristics of ultra-low light intensity requirement and efficient bactericidal ability make YM-3 have good application prospects for disinfection in indoor and sunlight environment.

Inhibition of Phenol from Entering into Condensed Freshwater by Activated Persulfate during Solar-Driven Seawater Desalination.

Recently, solar-driven seawater desalination has received extensive attention since it can obtain considerable freshwater by accelerating water evaporation at the air-water interface through solar evaporators. However, the high air-water interface temperature can cause volatile organic compounds (VOCs) to enter condensed freshwater and result in water quality safety risk. In this work, an antioxidative solar evaporator, which was composed of MoS2 as the photothermal material, expandable polyethylene (EPE) foam as the insulation material, polytetrafluoroethylene (PTFE) plate as the corrosion resistant material, and fiberglass membrane (FB) as the seawater delivery material, was fabricated for the first time. The activated persulfate (PS) methods, including peroxymonosulfate (PMS) and peroxodisulfate (PDS), were applied to inhibit phenol from entering condensed freshwater during desalination. The distillation concentration ratio of phenol (RD) was reduced from 76.5% to 0% with the addition of sufficient PMS or PDS, which means that there was no phenol in condensed freshwater. It was found that the Cl- is the main factor in activating PMS, while for PDS, light, and heat are the dominant. Compared with PDS, PMS can make full utilization of the light, heat, Cl- at the evaporator's surface, resulting in more effective inhibition of the phenol from entering condensed freshwater. Finally, though phenol was efficiently removed by the addition of PMS or PDS, the problem of the formation of the halogenated distillation by-products in condensed freshwater should be given more attention in the future.

MoS2 boosts the Fe2+/PMS process for carbamazepine degradation.

Activation of peroxymonosulfate (PMS) by Fe2+ is a green oxidation process for degradation of organic contaminants. However, the formation of iron mud and low PMS utilization lead to the decreased oxidation efficiency. In this work, commercial MoS2 particles were used as the catalyst for boosting the Fe2+/PMS process for carbamazepine (CBZ) removal. The CBZ removal efficiency by the MoS2/Fe2+/PMS process was significantly enhanced, increasing to 6.5 times that of the Fe2+/PMS process. The Fe3+ was reduced to Fe2+ by the exposed Mo4+ on the surface of MoS2, leading to the enhanced PMS utilization rate and increased Fe2+ concentration. The relative intensity of DMPO-HO• and DMPO- SO4-• followed the order of MoS2/PMS < Fe2+/PMS < MoS2/Fe2+/PMS, also suggesting the enhanced oxidation activity with the addition of MoS2 in the process of Fe2+/PMS. The commercial MoS2 had good stability shown by the CBZ removal efficiency remaining almost unchanged during 8-time cycling use. Finally, a possible CBZ degradation pathway was proposed for helping understand the oxidation mechanism of the MoS2/Fe2+/PMS process.