Jenyuk Lohwacharin

The selective photocatalytic cleavage of lignin Cβ-O bonds under mild conditions is vital to sustainable biomass valorization, yet this process continues to face challenges including inefficient visible-light utilization and reliance on organic solvents for lignin dispersion. Herein, an S-scheme Zn0.5Cd0.5S/BiVO4 heterojunction photocatalyst with broad-spectrum response was developed to achieve efficient cleavage of the Cβ-O bond in the β-O-4 model compound 2-phenoxy-1-phenylethanol (PP-ol). Given the hydrophobic nature of PP-ol, an aqueous SDS micellar medium was introduced to promote its contact with the hydrophilic photocatalyst surface. Under N2 atmosphere, the developed photocatalyst coupled with an aqueous SDS-8/CH3COOH (5:1) micellar medium achieves an 87.6% conversion of PP-ol within 1.5 h. The introduction of the aqueous micellar medium increases the yields of phenol and acetophenone by factors of 3.44 and 2.93, respectively, compared with those obtained in the absence of SDS. The construction of the heterojunction, combined with the presence of sulfur vacancy (SV), extends the visible-light response range, yielding an apparent quantum yield (AQY) of 0.68% at 520 nm. DFT calculations and in situ EPR analyses demonstrate that the enhanced charge separation and robust redox ability endowed by the S-scheme pathway efficiently drive the formation of a critical •Cα intermediate, thereby triggering the scission of the adjacent Cβ-O bond. Control experiments with different substrates further confirmed this pathway. This work, through the construction of an S-scheme heterojunction coupled with a multifunctional aqueous micellar medium, opens a green and sustainable pathway for lignin valorization and offers new insights into the development of high-performance heterojunction photocatalysts.

The occurrence, seasonal variation, and removal efficiency of 24 antibiotics across 9 classes in hospital and municipal wastewater treatment plants (WWTPs) were investigated, while evaluating their ecological, human health, and resistance selection risks. Eighteen antibiotics were detected in both influent and effluent (0.24 to 4,794.25 µg/L), and in sewage sludge (<LOD to 1,543.92 µg/kg). Oxytetracycline was the dominant contaminant in water samples, with high concentrations doubling during the dry season. Conversely, sulfamethoxazole exhibited the highest accumulation in sewage sludge. Treatment efficiency varied significantly across all stations. Notably, negative removal efficiencies were observed for certain antibiotics due to inherent structural characteristics resisting degradation. Seasonal analysis revealed a distinct dilution effect during the wet season, leading to lower COD and BOD levels. Pearson correlation and Redundancy Analysis (RDA) identified DO, pH, and temperature as core physicochemical drivers affecting antibiotic behavior, with low-flow dry season conditions concentrating macrolides alongside organic particulate loads. Risk assessments highlighted severe environmental and clinical concerns. Oxytetracycline and ciprofloxacin posed high ecological risks in effluents (maximum risk quotient (RQ) = 1.02 at the RM station). For human health, amoxicillin and oxytetracycline dominated risks for infants (0–6 months), spanning medium-to-high risk levels. Additionally, resistance selection risks (RQAMR) reached critical levels for oxytetracycline (9,588.49), ciprofloxacin (1,599.32), and amoxicillin (1,171.29). In soil-terrestrial and soil-aquatic assessments, ciprofloxacin posed the highest risk, while clarithromycin dominated soil-aquatic risks. This study provides valuable insights into the seasonal dynamics and environmental persistence of antibiotics, underscoring the critical need for improved wastewater treatment technologies to mitigate the risks of ecological toxicity and antimicrobial resistance (AMR) proliferation.

Haloacetaldehydes (HALs) and haloacetonitriles (HANs) are groups of carcinogenic disinfection by products (DBPs) present in water supplies, of which trichloroacetaldehyde (TCAL) and dichloroacetonitrile (DCAN) are frequently detected. The efficiency of ultraviolet (UV) irradiation processes in the removal of DBPs depends strongly on the contribution of direct and indirect photolysis. Significant gaps exist in research regarding kinetics of photodegradation in multi-solute systems. Therefore, in this study the efficiency of vacuum UV (VUV) and UV-C processes was tested on batch photodegradation with synthetic waters containing either TCAL or DCAN and bi-solutes. A radical scavenger test was performed to determine the presence of OH radicals. The VUV (185 + 254 nm) degraded TCAL and DCAN more effectively than UV-C (254 nm), achieving absolute elimination after 30 min (>99.9%, 113 mW/cm²) for TCAL, but only an 84% reduction in DCAN after 120 min of irradiation at fluence of >450 mW/cm². The experimental results demonstrate that the main mechanism in TCAL reduction was indirect photolysis, but for DCAN it was direct photolysis by VUV photolysis. When indirect photolysis dominated, HALs and HANs in the mixture competed for OH radicals under VUV photolysis. A degradation pathway study indicated that TCAL was degraded and transformed to formic acid, while DCAN was dechlorinated by OH radicals. Overall, this study confirms that the VUV process is more effective than UV-C in photodegrading carbonaceous DBPs.