Chemosphere最新文献

Polychlorinated dibenzo-p-dioxins (PCDDs) are persistent organic pollutants that pose considerable threats to ecological and human health owing to their high toxicity potential. Understanding the mechanisms for underlying the base-catalyzed hydrolysis of PCDDs in aquatic environments is essential for assessing their environmental behaviour and ecological risks. Herein, we combined quantitative structure-activity relationship (QSAR) models with density functional theory calculations to analyse the base-catalyzed hydrolysis mechanisms of PCDDs. Among the four developed QSAR models, the single-parameter QSAR model based on the lowest unoccupied molecular orbital energy (E_LUMO) demonstrated the best performance, achieving a coefficient of determination of 0.89 and a root mean square error of 0.49, indicating superior overall performance. Results indicate that the second-order rate constants for base-catalyzed hydrolysis (k_OH) of PCDDs are primarily influenced by E_LUMO, molecular polarizability (α), molecular volume (V_m), degree of chlorination (N_Cl), and chlorine position. Specifically, increases in the α and V_m values of PCDDs lead to higher logk_OH values, while an increase in the E_LUMO value results in a lower logk_OH value. This study elucidates the relationship between the molecular structure and the rate of base-catalyzed hydrolysis of PCDDs for the first time, providing valuable insight into their environmental fate. Furthermore, this research offers a novel theoretical perspective on the base-catalyzed hydrolysis of PCDDs, which will aid in regulatory assessments and risk management.

Chlorpyrifos (CLP) and deltamethrin (DTM) are among the most widely utilized organophosphate and pyrethroid insecticides globally. Their simultaneous presence in aquatic environments poses significant threats to fish health and challenges the sustainability of aquaculture practices. Despite their prevalence, the combined toxic effects of CLP and DTM on hook snout carp (Opsariichthys bidens Günther) remain insufficiently understood. In this study, O. bidens were exposed to waterborne treatments of CLP, DTM, or their combination for 30 days, and the biochemical and molecular responses of the liver tissue were systematically assessed. Acute toxicity tests revealed that the combined exposure to CLP and DTM resulted in synergistic toxicity. Significant alterations in the activities of key enzymes, including superoxide dismutase (SOD), catalase (CAT), caspase-3 (CASP-3), and caspase-9 (CASP-9), relative to the control group, demonstrated that co-exposure induced oxidative stress in O. bidens. Additionally, the elevated transcriptional levels of immune-related genes such as cxcl-c1c, il-8, and il-1 suggested a pronounced inflammatory response triggered by the pesticide mixture. Conversely, the significantly reduced expression of p53 and esr indicated that combined exposure disrupted apoptotic regulation and endocrine system function in the fish. In summary, these findings demonstrated that co-exposure to CLP and DTM induced liver damage in O. bidens by impairing antioxidant enzyme activity, disrupting apoptosis regulation, and altering the transcriptional profiles of genes involved in immune and endocrine pathways. These results provided new insights into the physiological and molecular mechanisms of pesticide-induced hepatotoxicity in fish and offered valuable information for evaluating the ecological risks associated with pesticide mixtures in aquatic environments.

N-doped hierarchical porous carbon (N-HPC) is made from waste lignin by a one-pot method, and its mechanisms of Cr (VI) removal was investigated. The specific surface area (S_BET) of N-HPC-Fe3 was 1749.8 m²/g, the experimentally determined equilibrium adsorption capacity (q_e) for Cr (VI) was 386.5 mg/g, and the calculated maximum adsorption capacity (q_m) was 627.1 mg/g, which showed excellent adsorption performance. The adsorption process is consistent with the Langmuir model and the pseudo-second-order model. The removal process of Cr (VI) was proposed: the high specific surface area and positively charged surface of N-HPC enhanced the pore filling and electrostatic adsorption effects; and the high content of nitrogen-oxygen functional groups acted as electron donors and adsorption active sites, which reduced Cr (VI) to Cr (III) and complexed it to the N-HPC surface. The contribution of different mechanisms was quantified and 85.1% reduction was the main removal mechanism. The removal efficiency of N-HPC reached 76.5% after 7 cycles and was minimally affected by coexisting ions, showing excellent reusability, stability and selectivity. This study emphasizes the potential of using cost-effective and sustainable biomass waste carbon for Cr (VI) removal, providing a theoretical and practical basis for environmental remediation.

Air pollution is closely associated with the development of multiple metabolic diseases. Circadian syndrome (CircS), as an extended concept of metabolic syndrome (MetS), has been proven to be a better predictor of metabolic diseases than MetS. However, the relationship between volatile organic compounds (VOCs) and CircS in pre- and postmenopausal remains unclear. This study used data from the National Health and Nutrition Examination Survey (NHANES) 2011-2020, including 520 premenopausal women and 531 postmenopausal women. Generalized linear model (GLM), restricted cubic splines (RCS) model, subgroup analyses, and weighted quantile sum (WQS) model was used to assess the relationship between VOCs and CircS. In addition, sensitivity analyses were performed to evaluate the robustness of the results. Our findings showed that seven VOC metabolites were positively associated with the risk of CircS in postmenopausal women. In premenopausal women, only two VOC metabolites were positively associated with the risk of CircS. The WQS analysis further confirmed that VOC mixtures selected by least absolute shrinkage and selection operator (LASSO) were significantly associated with an increased risk of CircS in postmenopausal women, with HPMMA identified as the primary contributor to the combined effect. This association was not evident in premenopausal women. Meanwhile, in postmenopausal women, individual urinary VOC metabolites and VOC mixtures were observed to be positively associated with elevated glucose and short sleep. Our results highlighted that VOCs exposure was strongly associated with the occurrence of CircS in postmenopausal women. Further research is needed to confirm this conclusion.

Improving the activity of ferrate is one of the main research focus in environmental field. Here, we demonstrate a novel copper oxide (CuO)-Ferrate(VI) system wherein CuO plays a key role in activating Fe(VI) to effectively eliminate phenolic contaminants. The dominant reactive species were determined to be Cu(III) and ¹O₂, confirmed by in situ Raman spectroscopy, quenching experiments, and EPR tests. The results indicated that Fe(VI) preferentially reacts with CuO, forming Cu(III) and ¹O₂. Subsequently, deprotonated 2,4-dichlorophenol (2,4-DCP) was adsorbed with Cu(III) via electrostatic adsorption and was directly oxidized by Cu(III). Co-existing ion experiments demonstrated the strong stability of the CuO/Fe(VI) system against environmental background substances, maintaining effective removal efficiency over multiple cycles. In summary, this study highlights the potential advantages of CuO-assisted Fe(VI) activation, offering a new route for the efficient utilization of Fe(VI) in eliminating phenolic pollutants.

Biofilm formation presents a significant challenge in health care, food industries, water distribution systems, etc. In addition to their inherent resistance to various stresses and biocides, emerging resistance against widely used biocides like chlorine is a growing concern. The strong link between chlorine resistance and the development of antibiotic resistance among microbes further exacerbates this issue. Therefore, it is highly desirable to devise a method to mitigate the problems associated with biofilms formed by Chlorine Resistant Bacteria (CRB). In this study, a highly chlorine resistant, biofilm-forming Klebsiella pneumoniae was isolated from the cooling water system of a nuclear power plant employing continuous chlorination for biofilm control. Interestingly, K. pneumoniae was found to enhance biofilm formation under the influence of increasing concentrations of chlorine, highlighting the limitations of chlorination-based biofilm control measures. As a remedial measure, chlorine resistant bacteriophages specific to K. pneumoniae were successfully isolated from the same water sample. These bacteriophages effectively inhibited planktonic growth biofilm formation and removed preformed biofilms. Whole-genome sequencing of two of the promising bacteriophages confirmed their identity as novel bacteriophages specific to K. pneumoniae. The absence of any antibiotic-resistant gene, virulent factor(s), or gene associated with the lysogenic life cycle further supports their suitability for environmental applications. This study provides valuable insights into the prevalence of chlorine resistant, pathogenic bacteria in cooling water distribution systems. It also highlights the promising application of bacteriophages to mitigate chlorine resistant bacteria and their biofilms.

ZVI-Fenton, which is the combination of zero-valent iron (metallic Fe) and H₂O₂ is a relatively cheap advanced oxidation process for the elimination of contaminants from wastewater. Here we experimentally tested the ZVI-Fenton reaction at pH 4 towards two crucial goals in the treatment of secondary (partially treated) urban wastewater: (i) degradation of pharmaceuticals such as anti-inflammatory drugs (ibuprofen) and antibiotics (cefazolin, sulfamethoxazole), and (ii) elimination of a considerable fraction of bacteria through a combination of acidic pH and strongly oxidising conditions. In detail, ZVI-Fenton at pH 4 achieved degradation of both primary contaminants and potentially problematic transformation intermediates. The latter include toxic 4-isobutylacetophenone from ibuprofen and compounds potentially retaining antibiotic properties, namely cefazolin products with an intact β-lactam ring and sulfamethoxazole products retaining the p-amino sulfonic acid moiety. Furthermore, the ZVI-Fenton process significantly lowered the total abundance of bacteria, greatly aiding the final disinfection stage. Overall, both objectives were successfully achieved demonstrating that ZVI-Fenton at pH 4 is an efficient treatment against chemical and microbiological contaminants.

ZnAlFe mixed metal oxides (ZnAlFe-MMOs) were synthesized from layered double hydroxides (LDHs) prepared by the coprecipitation method at pH 9 using an initial weight composition of Zn²⁺ = 75%, Al³⁺ = 15% and Fe³⁺ = 10%, with or without the addition of citric or oxalic acid. The solids were calcined at 400 °C to obtain the respective MMOs, which exhibited relatively high specific surface areas (165.3-63.8 m² g^-1) and semiconductor properties active in the visible region (bandgap values (E_g) of 2.42-1.77 eV). The synthesized materials were tested for the removal of trivalent arsenic by adsorption and by photocatalysis under visible light irradiation (λ ≥ 420 nm). The best removal of As(III) by adsorption (65.9%) and by photocatalysis (99.9%) was obtained with the ZnAlFe-MMOs prepared in the absence of organic acids. The XPS results indicate the coexistence of As³⁺ and As⁵⁺ over ZnAlFe-MMOs after the photocatalytic reaction and also confirm the formation of Fe²⁺ sites on the hematite surface that enhances the removal of As(III). Raman measurements confirmed that, in the photocatalytic experiments, As is largely retained as As(V) on ZnAlFe-MMOs, bound to Fe. The results of fluorescence of 7-hydroxycoumarin suggest that the photocatalyst produces HO^•, which can be the main species for As(III) oxidation under UV-Vis irradiation. Moreover, ZnAlFe-MMOs exhibited a good reusability after regeneration making ZnAlFe-MMOs a promising material for arsenic decontamination in polluted water.

This systematic review covers the urgent challenges posed by per- and polyfluoroalkyl substances (PFAS) in managing residuals from municipal, industrial, and waste treatment sources. It covers regulatory considerations, treatment technologies, residual management strategies, and critical conclusions and recommendations. A rigorous methodology was employed, utilizing scientific search engines and a wide array of peer-reviewed journal articles, technical reports, and regulatory guidance, to ensure the inclusion of the most relevant and up-to-date information on PFAS management of impacted residuals. The increasing public and regulatory focus underscores the persistence and environmental impact of PFAS. Emerging technologies for removing and sequestrating PFAS from environmental media are evaluated, and innovative destruction methods for addressing the residual media and the concentrated waste streams generated from such treatment processes are reviewed. Additionally, the evolving regulatory landscape in the United States is summarized and insights into the complexities of PFAS in residual management are discussed. Overall, this systematic review serves as a vital resource to inform stakeholders, guide research, and facilitate responsible PFAS management, emphasizing the pressing need for effective residual management solutions amidst evolving regulations and persistent environmental threats.

In the current electrolytic manganese industry, iron separation and reuse from iron-rich manganese ore leachate (IRMOL) has become one of the most pressing challenges. This study aimed to investigate the optimal conditions for iron separation from IRMOL and to assess the economic and practical advantages of iron separation or removal in industrial manufacturing. To identify more cost-effective and technologically advanced production circumstances, we examined five key elements that weaken Fe(OH)₃ colloidal production conditions in enterprises: reaction temperature, pH, crystal species, aging and reaction time. The screening results showed that when the conditions were optimized, the efficiency of reducing manganese loss decreased from 6.15% to 4.69%. Additionally, the generation of iron-rich electrolytic manganese residue (IREMR) was decreased by 44.32%, and the filtration velocity of IREMR increased from 0.0030 to 0.0220 mL/(s·cm²) compared to the production conditions before optimization at the enterprises. Through multiphase equilibria modeling with Visual MINTEQ, we have determined that raising the temperature and pH levels increases the expenses associated with chemicals and energy usage and results in an elevation of Fe(OH)₂⁺ concentration. This can lead to the creation of Fe(OH)₃ colloidal, causing a high water content in IREMR, inefficient filtration, and significant loss of manganese. This strategy is highly significant for the production of electrolytic manganese and the reduction of electrolytic manganese residue.