Journal of hazardous materials最新文献

Coupling heterogeneous photocatalysis with free chlorine (HOCl/ClO^-) emerges as an effective strategy to enhance the yield of reactive species, while the chlorine activation mechanism is yet to be clear. In this study, facet- and morphology-engineered BiVO₄ was synthesized and employed to activate HOCl/ClO^- under visible light irradiation, termed as Vis/BiVO₄/chlorine process. The HOCl/ClO^- activation mechanisms in the Vis/BiVO₄/chlorine process was investigated through use of of oxalate (hole (h_VB⁺) quencher) or Cu²⁺ (electron (e_CB^-) shuttle). e_CB^- and superoxide radicals (O₂^•-) activates HOCl to form hydroxyl radicals (HO•) (one-electron transfer pathways) while only reduces ClO^- to Cl^- (two-electron transfer pathways). O₂ not only promotes HO• production, but also enables more HO• to reach target compound without being scavenged. The reactions between h_VB⁺ and chlorine are both chlorine species- and valance band (VB) potential-dependent. h_VB⁺ activates both HOCl and ClO^- to form ClO•. While at pH 5.0, the more positive VB potential of BiVO₄ than the E°(Cl⁺/HOCl) enables h_VB⁺ to oxidize HOCl to HO• and Cl⁺, which reacts rapidly with H₂O to regenerate HOCl. Using truncated bipyramid-like BiVO₄ at larger exposed area of {110} facet (h_VB⁺-dominated) and plate-like BiVO₄ at larger exposed area of {010} facet (e_CB^-/O₂^•--dominated) favors the h_VB⁺- and e_CB^-/O₂^•--induced HOCl/ClO^- activation pathway, respectively. These findings provide novel insights into the chlorine activation mechanism and the modulation of reaction pathways that HOCl and ClO^- undergo and the corresponding radicals/ions.

Microorganisms critically regulate radionuclide migration through diverse biological mechanisms. Bacillus subtilis (B. subtilis) exhibits strong adsorption capacity, immobilizing radionuclides and limiting their mobility. By contrast, biological colloids predominantly enhance transport via complexation and mobilization. This study systematically investigates the influence of B. subtilis cells, spores, extracellular polymeric substances (EPS), and bentonite colloids (BC) on Eu(III) transport in quartz sand. Integrating advanced microscopy, spectroscopy, and machine learning, we reveal that Eu(III) mobility is governed by intricate interactions among bacterial activity, spores, EPS, and BC. Notably, inactivated B. subtilis colloids exhibited higher mobility yet more pronounced Eu(III) transport inhibition compared to live cells. Under neutral pH/low ionic strength conditions, B. subtilis cells and spores enhanced Eu(III) transport by 63 %, whereas acidic pH/high ionic strength conditions reduced transport by 30 % for cells, with spores maintaining elevated mobility. EPS removal increased both bacterial mobility and Eu(III) transport efficiency by 20 %, particularly under acidic conditions. While B. subtilis elevated Eu(III) mobility by 63 %, BC attenuated this effect by 13 %, primarily through the formation of BC-B. subtilis-Eu(III) ternary pseudo-colloids. Machine learning identified BC concentration and pH as key governing factors. These findings provide critical insights into microbial-mediated radionuclide transport and advance predictive risk assessment models for high-level radioactive waste disposal.

Viable pathogenic microorganisms in atmospheric particles pose notable health risks, while their exposure characteristics and health risks across climate zones remain unclear. This study collected 399 particulate samples from automobile air conditioning filters in eight Chinese cities across five climate zones, analyzing microbial concentration, viability, and pathogenicity via microbial culture, fluorescence staining, and high-throughput sequencing. Health risks were evaluated with quantitative microbial risk assessment (QMRA) method. Results revealed distinct microbial patterns. Proportion of viable microorganisms was highest in tropical monsoon climate region (42.58 %). Conversely, plateau and mountain climate region exhibited lower microbial viability (25.12 %) and bacterial culturability ((1.58 ± 0.41) × 10⁵ CFU/g). Bacterial genera like Acinetobacter were consistent across climate zones. However, dominant fungal genera manifested significant differences while pathogenic fungi such as Aspergillus and Cryptococcus were more abundant in temperate continental climate region. These may be attributed to different sources and microbial biogeographical characteristics, such as latitudinal distribution pattern. Annual infection risk and disease burden exceeds threshold of 10^-4 and 10^-6 in temperate, subtropical and tropical monsoon climate regions. Dermal contact demonstrated higher health risk. These insights into exposure characteristics of viable microorganisms can offer data support and theoretical basis for improving the air quality evaluation system and control of potential health risks.

Although methanogenic archaea are among the oldest microorganisms capable of mercury methylation, their contribution to methylmercury (MeHg) production has only recently gained attention. Studies with laboratory-cultivated methanogens elucidate the transformation of inorganic mercury (Hg) into MeHg, thereby uncovering underlying microbial methylation mechanisms. However, this field faces challenges such as significant Hg loss and unstable culture systems, which impede accurate assessment of these processes. This study aims to develop a reliable low-Hg-loss cultivation protocol for Hg methylation by methanogens, enabling a more accurate evaluation of their contribution to MeHg production. Our findings demonstrate that redox potential is a critical factor for Hg methylation, affecting Hg speciation and microbial growth. Notably, titanium nitrilotriacetate (Ti(III)-NTA), a reducing agent used in prior studies, was identified as a primary cause of Hg loss, reducing 83.2 % of Hg(II) to elemental Hg(0) at 500 μM. Adding cysteine satisfied both the redox and sulfur requirements of methanogens. Under these optimized conditions, Methanospirillum hungatei JF-1 achieved the highest MeHg production of all methanogens, converting 75.7 % of Hg(II) to MeHg and 630.4 pmol MeHg/mg protein. Overall, this study establishes a stable culture system for investigating Hg methylation by methanogens and indicates that the role of methanogens in mercury methylation is more substantial than previously acknowledged.

The engineering application of electro-Fenton process is subject to limited availability of •OH caused by mass transfer limitation and the short lifetime of •OH in water. In this study, an efficient electro-Fenton treatment process is developed by constructing a flow-through micro-nanoscale spatial confinement electrode with NiFe bimetal atom catalyst for oxygen reduction reaction (ORR). The NiN₄-FeN₄ active sites are anchored onto carbon nanotubes grown in the tunnel of carbonized pine wood (NiFe-NCNTs-CP). Efficient generation of •OH is achieved through 3-electron ORR over NiFe-NCNTs-CP. Because of the unique flow-through micron-nanoscale confinement environment, the concentration of accumulated •OH reaches as high as 6092 μmol L^-1 min^-1 even though the water flux is up to 236 L m^-2 h^-1 (equivalent to a retention time of 60 s). The proposed electro-Fenton system achieves 100 % removal of florfenicol, thiamphenicol, chloramphenicol, sulfamethoxazole, and tetracycline in water within just 60 s (C₀=20 mg L^-1, pH=7, 0.7 V vs SCE). The proposed continuous flow process maintains highly stable for treating actual medical wastewater within 8 days, achieving discharge standards and eliminating the antibacterial activity of medical wastewater. Furthermore, the proposed process showed a low energy consumption of only 7.35 kWh kg (COD)^-1. This study presents a highly practical electro-Fenton process for organic wastewater treatment.

Biochar derived from lignocellulosic biomass (LB) has shown broad application prospects in the field of peroxymonosulfate (PMS) catalysis, but the regulation mechanism of its catalytic active sites (e.g., C=O group) and LB components (cellulose, hemicellulose, and lignin) remains to be systematically elucidated. In this study, a laccase-mediated directional regulation strategy of LB components was innovatively proposed to target the design of biochar rich in the C=O group. Using wheat straw (WS) as a model feedstock, the properties and performance of biochar derived from native WS (BC-WS) and laccase-pretreated WS residue (BC-LR) were compared. Laccase pretreatment significantly enhanced the C=O group content of BC-LR by 213 %, achieved through a 27 % reduction in the relative lignin content and a corresponding increase in cellulose proportion. BC-LR demonstrated superior catalytic activity and reactive oxygen species yield than BC-WS in PMS activation, with strong positive correlations observed between its C=O content and phenol degradation kinetics (R²=0.9145) as well as PMS decomposition kinetics (R²=0.9957). Mechanistic investigations revealed that C=O-mediated non-radical pathway (including ¹O₂ and surface electron transfer) and adsorbed carbon transfer pathway dominated the phenol removal process in the BC-LR/PMS system. Notably, the BC-LR/PMS system exhibited broad-spectrum degradation of typical pollutants such as bisphenol F, o-phenylphenol, and naproxen. In addition, the system exhibited robust performance in dynamic remediation experiments under diverse hydrogeological conditions, achieving high efficiency in complex environments. This study elucidates the critical role of LB components in determining the C=O content and catalytic performance of biochar, providing a foundation for the tailored design of high-performance biochar for PMS catalytic environments.

A comprehensive approach combining target analysis, non-target screening, and suspect screening was employed to assess the effectiveness of ozonation in removing micropollutants at their native concentrations from wastewater effluent, using HPLC-HRMS. Eight pharmaceutical micropollutants were monitored during the wastewater ozonation to evaluate their removal efficiency at different ozone doses. A specific transferred ozone dose of 1.10 g_O3.g_C^-1 was sufficient to eliminate over 90 % of seven of the compounds. Non-target screening revealed that the greatest number of ozonation transformation products formed at a low ozone dose of approximately 0.52 g_O3.g_C^-1. Increasing the ozone dose led to further degradation of these transformation products. Suspect screening identified 15 OTPs with confidence levels of 3 or higher. The formation kinetics of these compounds were assessed based on their chromatographic peak areas. Primary transformation products from highly ozone-reactive compounds were most abundant at lower ozone doses, whereas those derived from less reactive compounds formed at higher ozone doses. The integration of multiple analytical approaches highlighted both the effectiveness of ozonation for micropollutant removal at economically sustainable doses and the importance of better understanding and monitoring ozonation transformation products during ozonation and in subsequent treatment processes.

The electrons in environmental persistent free radicals (EPFRs) of aged microplastics (MPs) are highly mobile and reactive, readily interacting with oxygen and water to generate reactive oxygen species, possessing ecological hazards. However, it is still a big challenge to detect the formation of EPFRs and electrons in real-time by using the conventional technologies. Interestingly, the conductive atomic force microscopy (CAFM) can capture local electrical information on the sample surface with high resolution. Based on this, the present work provided an intuitive understanding of the dynamic evolution of surface currents in aged conjugated aromatic ring MPs and alkane chain MPs. The study found that photoexcitation induced electron transitions, promoting interactions between electrons and the chemical bonds of the polymers and ultimately generation of the persistent free radicals. Conjugated structures played a crucial role in the facilitating of electron transfer. And the aged PET MPs primarily generated carbon-centered and oxygen-centered free radicals, while the aged PS and PP MPs mainly produced oxygen-centered free radicals. Ultimately, the free electrons generated by the aged MPs enhanced their removal capacity for cationic dyes. This study provides a novel testing method and perspective to deeply investigate the formation of electrons on the surfaces of aged MPs.

Ibuprofen (IBU) is used as a racemic mixture despite enantiomeric pharmacological differences. However, its stereoselectivity in aquatic ecosystems remains inadequately characterized, leading to potential environmental risk uncertainties. This study presents a comprehensive, integrated, multi-tiered evaluation of the enantioselective ecotoxicity, environmental fate, and ecological risk of IBU in aquatic environments. Chronic toxicity tests with D. magna and recombinant yeast nuclear receptor assays demonstrated significant enantio-selective effects, with S-IBU exhibiting as much as 8-fold greater toxic potency than R-IBU at environmentally relevant concentrations. Using chiral-specific toxicity data from our experiments and the literature, the predicted no-effect concentration (PNEC) for S-IBU was significantly less than those for racemic IBU and R-IBU. Environmental monitoring across the Wenyu River basin revealed prevalent IBU contamination with a detection rate of 96.8 % and maximum concentration of 431.7 ng/L, with predominance of S-IBU with an enantiomeric fraction of 0.57-1.0 in surface waters and wastewater treatment plant effluents. Ecological risk assessment indicated that IBU posed moderate to great risks to aquatic ecosystems, with 93.5 % of sites exceeding PNEC. These findings demonstrate that conventional risk assessments using only racemic IBU substantially underestimate ecological hazards. This highlights the necessity for enantioselective toxicity assessment and monitoring in chiral chemicals risk management.

As emerging contaminants, flame retardants are ubiquitous in water, soil, the atmosphere, and organisms. Brominated (BFRs) and organophosphorus flame retardants (OPFRs) dominate as primary replacements for brominated diphenyl ethers, yet their comparative ecotoxicity and environmental behavior remain critically understudied. This study comprehensively summarizes environmental levels, toxicities, metabolism, and environmental behaviors between BFRs and OPFRs. It is showed that OPFRs have surpassed BFRs by 1 - 2 orders of magnitude in concentration becoming dominant contaminants across environmental matrices. OPFRs exhibit similar toxicity targets yet more complex metabolic pathways than BFRs, indicating that they are not environmentally safer alternatives. Meanwhile, they undergo microbial degradation as carbon substrates, photolysis as photosensitizers, and hydrophobic adsorption onto organic matrices (e.g., dissolved organic matter). These environmental behaviors may enhance or inhibit toxicity risk of flame retardants. In addition, the removal technologies and regulatory measures for flame retardants still require continuous refinement. Future studies should prioritize combined risk assessment of mixtures especially metabolites, environmental behaviors, and identification of the key environmental factors of flame retardants.