Ag@Ag₂O-graphene (Ag@Ag₂O-G) with different concentrations of graphene was synthesized using a facile in situ precipitation method. The photocatalysts were characterized by field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (DRS). The antibioticsulfamethoxazole (SMX) degradationunder simulated solar light and visible light irradiationwas investigated to evaluate photocatalytic performance. The composite photocatalyst Ag@Ag₂O-G with 2.5 wt% graphene presented the highest activity among all the prepared composite photocatalysts. The coupling of graphene and Ag⁰ increased the photocatalyticactivity and stability of pure Ag₂O. Under higher SMX concentrations, the adsorption, not the photocatalytic ability, playeda crucial role during the SMX removal process. On the basis of the characterization and reactive oxygen species (ROS) scavenging experiments, a separation and transfer mechanism of photogenerated carriers was proposed. In the photocatalytic degradation of SMX, the major active species wereidentified as photogenerated holes; photogenerated electrons in the conduction band (CB) of Ag₂O could not transfer to graphene through Ag⁰due to the more negative reduction potential of graphene. This is an important result regardinggraphene and Ag⁰ roles which isdifferent from that for the photocatalytic degradation of dyes. This researchmay provide new insights into photocatalytic processes for the degradation of non-dye pollutants bycomposite materials to guidethe design of highly efficient reaction systems.

Black TiO₂ with doped nitrogen and modified carbon (b-N-TiO₂/C) were successfully prepared by sol-gel method in the presence of urea as a source of nitrogen and carbon. The photocatalysts were characterized by field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, electron paramagnetic resonance (EPR), and UV-vis diffuse reflectance spectra (DRS). The doped nitrogen, introduced defects, and modified carbon played a synergistic role in enhancing photocatalytic activity of b-N-TiO₂/C for the degradation of chlorophyll-a in algae cells. The sample, with a proper amount of phase composition and oxygen vacancies, showed the highest efficiency to degrade chlorophyll-a, and the addition of H₂O₂ promoted this photocatalysis degradation. Based on the trapping experiments and electron spin resonance (ESR) signals, a photocatalytic mechanism of b-N-TiO₂/C was proposed. In the photocatalytic degradation of chlorophyll-a, the major reactive species were identified as OH and O₂⁻. This research may provide new insights into the photocatalytic inactivation of algae cells by composite photocatalysts.

This study investigates the synergistic enhancement of molecular oxygen activation (MOA) in silver phosphate (Ag₃PO₄) photocatalysts modified with oxygen vacancies (OVs) and silver nanoparticles (Ag⁰). The vacuum-calcined Ag₃PO₄ exhibited a 2.05-fold increase in the degradation efficiency of cylindrospermopsin (CYN), reaching 88.00% within 5 min, compared to its pristine counterpart. This work proposes a novel dual-modification approach—rarely explored in previous MOA studies—by introducing OVs and Ag⁰ simultaneously. The characterization results confirmed that OVs improved the charge transfer and adsorption of molecular oxygen, while the Ag⁰ nanoparticles facilitated electron–hole separation and interfacial charge transfer. Reactive oxygen species (ROS) such as ·O₂⁻, ¹O₂, H₂O₂, and ·OH were confirmed via ESR analysis and chemical assays. A detailed mechanism was proposed and illustrated, showing how OVs and Ag⁰ synergistically promote MOA. These findings highlight a cost-effective method for enhancing photocatalysis and environmental remediation.

Excessive N and P discharges into aquatic environments contribute to water pollution and eutrophication. Thus, there is an urgent need for low-cost and sustainable adsorbents for contaminant removal. In this study, biochar was prepared from date palm fronds, leaves, and pits through slow pyrolysis followed by MgFe-LDH modification at a Mg/Fe molar ratio of 3:1. The FTIR results demonstrate that the MgFe-LDH modification added more hydroxyl groups, interlayer carbonate species, and metal–oxygen bonds. The removal efficiency of the investigated nutrients increased considerably with increasing sorbent dosage, with MgFe-LDH modification being most effective. Generally, sorption followed typical hyperbolic adsorption patterns, approaching equilibrium after 120–180 min. Both Langmuir and Freundlich isotherms adequately described nutrient sorption on unmodified biochars, while the Freundlich model provided a better fit on MgFe-LDH. LDH/BC derived from pits exhibited excellent adsorption capacities, i.e., 105 mg/g for NO3-, 103 mg/g for NH₄⁺, and 135 mg/g for PO₄³⁻. Pseudo-second-order kinetics best described NH₄⁺ adsorption, while both pseudo-first-order and pseudo-second-order models were well fitted to NO₃⁻ and PO₄³⁻ adsorption. Overall, MgFe-LDH modification offers a promising engineering strategy for converting date palm residues into multifunctional adsorbents and offers insight into the design of waste-derived materials for nutrient recovery and eutrophication control.

The limited nitrogen and phosphorus concentration reduction performance of wetlands during cold weather is a global concern. To address the challenge of low nutrient removal efficiency in winter, this study introduces a hollow fiber membrane module integrated into paddy soil, enabling the in situ formation of a hydrogen-based bacterial–algal biofilm. Over a 60-day experiment at water temperatures of 6.2–15.0 °C, the biofilm-enhanced system (HS) reduced aqueous ${\mathrm{NH}}_4^{+}$-N from 25 mg/L to 0.2 mg/L by day 30 and maintained this low level through day 60, whereas the S system still had 5.5 mg/L ${\mathrm{NH}}_4^{+}$-N. Moreover, the HS system consistently maintained lower ${\mathrm{NO}}_3^{-}$-N and total phosphorus (TP) concentrations than the S system. Microbial communities were characterized using third-generation 16S full-length sequencing and 18S rRNA V4 amplicon sequencing. The biofilm was dominated by Geminocystis_PCC_6308, Rikenellaceae_RC9_gut_group, and Rhodobacter, while eukaryotic green algae, mainly Botryococcus sp., were also abundant. In the paddy soil, Terrimonas and unclassified_AKYH767 were identified as potential key taxa associated with nitrogen and phosphorus concentration reduction. Overall, the hydrogen-based bacterial–algal biofilm effectively improves the nitrogen and phosphorus concentration reduction of paddy soil wetlands, offering a promising strategy for cold-weather eutrophic water remediation.