Typical Organic Pollutants Research Articles

Developing a novel polysulfone/chitosan membrane incorporated with green synthesized CuO from aloe vera extract for toxic dye removal

AbstractThe environment and public health have been protected by the simple, non‐destructive, and ecologically benign process used for fabricating membranes. In this study, a low‐cost wastewater treatment membrane is made from raw materials followed by phase inversion approach. A typical organic pollutant that has earned a poor track record for gradually harming aquatic life. Thus, the membrane technology is used to minimize the water contaminated by dyes. To treat wastewater, a membrane was developed by combining green synthesized CuO nanoparticles with polysulfone (PS) and chitosan (CS). The developed membranes were analyzed using x‐ray photoelectron spectroscopy, contact angle, Fourier transform infrared, scanning electron microscopy, transmission electron microscope, and x‐ray diffraction techniques. The developed membrane, along with the nanoparticles and additives, confirmed its crystalline confirmation, hydrophilicity, arrangement of structures, and morphological modifications. CuO nanoparticles were prepared using aloe vera extract, and incorporated into a mixed matrix membrane was utilized for the congo red (CR) and methylene blue (MB) adsorption processes. The absorption capacity was analyzed via UV spectroscopy makes it potentially important for membrane performance. Therefore, the resulting membrane could be used as a substrate for dye removal applications.

Low-temperature hydrothermal self-assembly synthesis of ZnIn2S4/chitosan-graphene aerogels for enhanced aqueous pollutants removal

A novel visible-light-responsive ZnIn2S4/chitosan graphene aerogel (ZCGA) was prepared using a low-temperature hydrothermal self-assembly method for the adsorption and degradation of tetracycline. Infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) indicated interactions between ZnIn2S4 and chitosan graphene aerogel (CGA). Under the irradiation of a 500 W xenon lamp, ZCGA exhibited excellent adsorption and photocatalytic degradation performance for tetracycline, with a removal rate exceeding 90 % within 180 min. This significant performance improvement is attributed to the high carrier transport properties of CGA, which greatly enhanced the activity of the photocatalytic reaction and also showed high efficiency in removing other types of organic pollutants. Radical trapping experiments further confirmed that the superoxide anion (·O2−) is the main active species in the photocatalytic process. In addition, the monolithic aerogel has good recyclability and mechanical stability. This study not only demonstrates the great potential of ZCGA in the field of photocatalysis but also provides new ideas for designing efficient, recyclable, and visible light-responsive photocatalysts.

Activation mechanism of persulfate by Fe3C-based materials for efficient benzo-a-pyrene abatement in wastewater: The reversed direct electron transfer from persulfate to contaminants

Herein, an unusual reserved direct electron transfer (r-DET) process from persulfate (PS) to contaminants was observed on the surface of Fe3C with N-doped C shell supported on carbon nanotubes (Fe3C@CN-CNTs). The Fe3C-based materials were synthesized via a facile sol–gel method employing melamine, glucose, FeCl3, and commercial multi-walled CNTs. The activation mechanisms were fully explored with a comparison of Fe3C@CN-CNTs and other Fe3C-based materials for the effective abatement of benzo-a-pyrene (BaP), a typical persistent organic pollutant in industrial wastewater. Electrochemical measurements, zeta potential monitoring, and Mössbauer spectroscopy indicated that the lack of CN shell result the relatively large particle size of Fe3C on Fe3C-CNTs, leading to more negatively charged surface and abundant OH during PS activation. Nevertheless, the superparamagnetic fraction with a fine particle size on the surface of Fe3C@CN and Fe3C@CN-CNTs potentially leads to a more positively charged surface, enhancing the zeta potential of surface adsorbed BaP and benefiting the r-DET. Through r-DET, oxidized PS and reduced BaP formed as intermediates, accelerating the overall degradation of BaP in Fe3C@CN-CNTs/PS. The degradation pathways, cytotoxicity, and operation conditions of BaP degradation by Fe3C@CN-CNTs/PS were thoroughly investigated. Additionally, Fe3C@CN-CNTs were found to promote the nucleophilic reaction between Cl− and PS, producing free chlorine and enhancing BaP degradation efficiency in chloride-containing wastewater. Overall, this study presents a new insight for the PS-based r-DET process and offers a promising approach for treating organically-contaminated wastewater.

Exploring photocatalytic tetracycline removal performance under simulated sunlight irradiation: Milling time effect on metallic reduction of MnO/ZrO2 mixed oxide

In the present research, it is reported that ball milling technique can be applied to enhance the photocatalytic properties of MnO and ZrO2 metal oxide powders (MZOx) furthermore the fabricated photocatalyst can be used for the degradation of tetracycline (TTC). XRD analyses revealed that increasing the milling time resulted in the formation of a pure metallic Mn crystal phase, which boosted the antibiotic degradation rate. It was confirmed by SEM technique that the morphological structures of the particles were generally small and uniform. The band gap energy was calculated as 3.70 eV for the hybrid metal oxide. Additionally, the adsorptive and photoluminescence features were illuminated via DRS and PL analyses. The effect of milling time had a major impact on the photodegradation rate of TTC, and the 8 h milling sample (MZOx-8h) exhibited the highest catalytic degradation activity (79.4 %). Low photocatalytic activity was obtained at acidic pHs and increased at alkaline pHs. The presence of H2O2 sharply decreased photocatalytic process time (60 min) and 94.3 % of the TTC was degraded at 7.5 mM H2O2. The photocatalytic degradation process proceeded through superoxide radicals and was supported by holes. The stability of MZOx-8h almost remained constant (70.02 %) even after seven cycles. It was determined that the presence of oxalic acid positively affected the progress of TTC degradation reactions. Further, practical application areas were investigated and MZOx-8h doped on support materials was found to be suitable for such applications in proportion to the doping ratio. Finally, it was demonstrated that MZOx-8h exhibited remarkable performance in photocatalytic reactions of different types of organic pollutants. The synergistic nature of MnO and ZrO2 with the contribution of ball milling time effect resulted in high photocatalytic activity.

Drivers of change behind the spatial distribution and fate of typical trace organic pollutants in fresh waste leachate across China

There have been growing concerns regarding the health and environmental impacts of trace organic pollutants (TOPs). However, fresh leachate from municipal solid waste (MSW) has been overlooked as a potential reservoir of TOPs. Therefore, we investigated 90 legacy and emerging TOPs in fresh leachate from 14 provinces and municipalities in China. Additionally, the fate and final discharge impacts of TOPs in 14 leachate treatment systems were analyzed. The results revealed that the detection rate of 90 TOPs was over 50 % in all samples. Notably, polychlorinated biphenyls, banned for 40 years, were frequently detected in fresh leachate. The concentration of pseudo-persistent TOPs (105–107 ng/L) is significantly higher than that of persistent TOPs (102–104 ng/L). Spatial distribution patterns of TOPs in fresh leachate suggest that economy, population, climate, and policies impact TOPs discharge from MSW. For example, economically developed and densely populated areas displayed higher TOPs concentrations, whereas warmer climates facilitate TOPs leaching from MSW. We confirmed that waste classification policies were a key driver of the decline in multiple TOPs in leachate. Mass balance analysis shows that the final effluent and sludge from current dominant leachate treatment systems contain refractory TOPs, especially perfluoroalkyl acids, which must be prioritized for control. This paper was the first comprehensive investigation of multiple TOPs in fresh leachate at a large geographic scale. The factors affecting the occurrence, spatial distribution, and fate of TOPs in fresh leachate were revealed. It provides a valuable reference for the establishment of policies for the management of TOPs in MSW and the associated leachate.

Phenanthrene-induced hyperuricemia with intestinal barrier damage and the protective role of theabrownin: Modulation by gut microbiota-mediated bile acid metabolism

Hyperuricemia is prevalent globally and potentially linked to environmental pollution. As a typical persistent organic pollutant, phenanthrene (Phe) poses threats to human health through biomagnification. Although studies have reported Phe-induced toxicities to multiple organs, its impact on uric acid (UA) metabolism remains unclear. In this study, data mining on NHANES 2001–2016 indicated a positive correlation between Phe exposure and the occurrence of hyperuricemia in population. Subsequently, adolescent Balb/c male mice were orally exposed to Phe at a dosage of 10 mg/kg bw every second day for 7 weeks, resulting in dysfunction of intestinal UA excretion and disruption of the intestinal barrier. Utilizing intestinal organoids, 16S rRNA sequencing of gut microbiota, and targeted metabolomic analysis, we further revealed that an imbalance in bile acid metabolism derived from gut microbiota might mediate the intestinal barrier damage. Additionally, the tea extract theabrownin (TB) effectively improved Phe-induced hyperuricemia and intestinal dysfunction at a dose of 320 mg/kg bw per day. In conclusion, this study demonstrates that Phe exposure is positively associated with hyperuricemia and intestinal damage, which provides new insights into the toxic effects induced by Phe. Furthermore, the present study proposes that supplementation with TB would be a healthy and effective improvement strategy for patients with hyperuricemia and intestinal injury caused by environmental factors.

Organic pollutant degradation over highly efficient Mn–Mo(O,S)2 oxysulfide photocatalyst under visible light illumination

Metal oxide semiconductor photocatalysts have received remarkable consideration as a promising technology for environmental remediation and energy conversion. Oxysulfide semiconductors have narrow band gaps which are appropriate for photocatalytic removal of toxic organic pollutants under visible light illumination. For the elimination purpose of these pollutants, Mo(O,S)2, Mn(O,S)2, and Mn–Mo(O,S)2 oxysulfide catalysts containing various Mn contents were synthesized at low temperatures via a simple method. The structural, morphological, electrochemical, compositional, and optical properties of the as-synthesized catalysts were exhaustively characterized. The photocatalytic degradation activity of the bares Mo(O,S)2, Mn(O,S)2, and other Mn–Mo(O,S)2 compositions were evaluated over different types of organic pollutants under visible light illumination. The addition of Mn in Mo(O,S)2 structure improved the photodegradation activity, and Mn–Mo(O,S)2-30 was found to be the best composition with superior photodegradation performance towards the four cationic, anionic, and neutral dyes. The degradation efficiency of 10 ppm of MB, and MO dyes reach 99.7 % and 98.6 %, within 30 and 120 min, respectively. Mn–Mo(O,S)2-30 catalyst also shows a good photodegradation performance on Rh B and NR organic pollutants. According to the recycling test, the catalyst exhibited excellent performance. The photodegradation follows pseudo-first order kinetics with a rate constant of 0.097 and 0.036 min−1 for MB and MO dyes, respectively. The trapping experiment showed that superoxide anion radicals (O2•-) and holes (h+) are the responsible active species for the degradation on MO and MB, respectively. The novelty of using Mn–Mo(O,S)2-30 for various dyes degradation lies in its remarkable catalytic properties.

Environmental risks of mask wastes binding pollutants: Phytotoxicity, microbial community, nitrogen and carbon cycles

The increasing contamination of mask wastes presents a significant global challenge to ecological health. However, there is a lack of comprehensive understanding regarding the environmental risks that mask wastes pose to soil. In this study, a total of 12 mask wastes were collected from landfills. Mask wastes exhibited negligible morphological changes, and bound eight metals and four types of organic pollutants. Masks combined with pollutants inhibited the growth of alfalfa and Elymus nutans, reducing underground biomass by 84.6 %. Mask wastes decreased the Chao1 index and the relative abundances (RAs) of functional bacteria (Micrococcales, Gemmatimonadales, and Sphingomonadales). Metagenomic analysis showed that mask wastes diminished the RAs of functional genes associated with nitrification (amoABC and HAO), denitrification (nirKS and nosZ), glycolysis (gap2), and TCA cycle (aclAB and mdh), thereby inhibiting the nitrogen transformation and ATP production. Furthermore, some pathogenic viruses (Herpesviridae and Tunggulvirus) were also found on the mask wastes. Structural equation models demonstrated that mask wastes restrained soil enzyme activities, ultimately affecting nitrogen and carbon cycles. Collectively, these evidences indicate that mask wastes contribute to soil health and metabolic function disturbances. This study offers a new perspective on the potential environmental risks associated with the improper disposal of masks.

Efficient degradation of levofloxacin using peroxymonosulfate activated by a novel magnetic catalyst derived from waste walnut shell biomass

Developing an economical and efficient catalyst derived from biochar and metal-organic frameworks (MOFs) for the activation of peroxymonosulfate (PMS) to degrade pollutants holds promise for practical applications. Herein, a simple in-situ synthesis method was designed to generate zeolitic imidazole framework with Co-based (ZIF-67) on the surface of waste walnut shell biomass, and novel derived magnetic catalysts (BC@CobC, Biochar@Co base Carbon) were obtained by high-temperature carbonization. This structure could avoid the drawbacks of structural collapse and particle agglomeration of MOF derivatives, while the presence of biochar could accelerate electron transfer and improve the activation performance. For the degradation of levofloxacin, the removal rate in the 0.5-BC@CobC/PMS system reached 89.88 % in 15 min with a mineralization of 60.43 % when the dosage of catalyst was 0.01 g L−1. Capture experiments and EPR tests showed that SO4−•, •OH, •O2− and 1O2 were jointly participated in the levofloxacin degradation process. Meanwhile, the BC@CobC/PMS system was minimally affected by the pH, co-existing inorganic anions, and natural active substances. It is worth noting that the BC@CobC/PMS system also had excellent removal effect on other typical organic pollutants, and the removal rate could reach 100 %. Cycling experiments showed that BC@CobC maintained high catalytic activity after multiple recycling. The degradation pathway of levofloxacin was also analyzed. Compared to the existing reports, the catalyst is economically superior, with much improved pollutant removal, and boasts a lower catalyst usage. This work will provide a viable idea in terms of reusing biomass waste and activating PMS for wastewater treatment.

Enhanced degradation of methanethiol via operational pH regulation in biofilm reactor: Insight of sulfur metabolism pathways and microbial adaptation mechanism

Methanethiol (CH3SH), a typical organic sulfur pollutant, poses significant risks to both human health and ecological stability due to its high toxicity and corrosive properties. Membrane aerated biofilm reactor (MABR) has been regarded as a promising and eco-friendly solution for removing organic sulfur from wastewater. However, the oxidation of CH3SH might lead to spontaneous acidification, which might affect microbial metabolic activities to influence the CH3SH biotransformation in MABR system. This work demonstrated that operational pH regulation could effectively promote the complete conversion of CH3SH to SO42- in MABR, while the transformation efficiency was only 40.6% under uncontrolled pH condition. Meanwhile, operational pH regulation resulted in 35.2% reduction in the excessive secretion of extracellular polymeric substances, thereby building a stable biofilm structure with sufficient oxygen mass transfer to enhance the CH3SH transformation. Additionally, operational pH regulation favored the enrichment of sulfur-oxidizing microorganisms (e.g., Rhodanobacter and Rhodobacter), while the uncontrolled pH favored the proliferation of microorganisms in harsh environment (e.g., Chitinophagaceae sp. and Sphingobacteriales sp.). Moreover, operational pH regulation enhanced the expression of critical genes involved in sulfur metabolism (e.g., SELENBP1 and SoxA), accompanied with glycolysis (e.g., ppgK and pfkB) and pyruvate metabolism (e.g., ackA and aceE), which could provide sufficient energy and electron. Conversely, these gene expressions were down-regulated in pH unregulation reactor, while the microbial adaptation mechanism was activated through the enhancement of DNA replication, quorum sensing, and two-component system, enabling resistance to extreme acidic conditions. This study would provide the in-depth understanding of operational pH regulation on organic sulfur degradation and transformation in MABR system and offer novel guidance for organic sulfur removal.

Efficient activation of persulfate for tetracycline hydrochloride degradation by biochar prepared from corn stover doped with organic phosphorus sources

Proposed to prepare phosphorus-doped biochar catalyst materials by impregnation pyrolysis method using corn stover and different phosphorus source precursors as raw materials, and the batch-wise research revealed that the phosphorus source precursor, the doping ratio, and the pyrolysis temperature had a significant influence on the biochar properties. The biochar material Pb-C-4–600 prepared with (C4H9)3PO4 as phosphorus source precursor, 1:4 doping ratio, and pyrolysis temperature of 600 ℃ had an ID/IG = 0.914, pore size of 4.91 nm, and specific surface area of 173.9845 m²/g, which was 93.4 times higher than that of the pure biochar. The removal rate of TCH reached 99.77 % in 30 min under the reaction conditions of PMS concentration of 2 g/L, Pb-C-4–600 dosage of 1 g/L, and pH 3. Comparing the efficacy of Pb-C-4–600 and different catalysts for the degradation of TCH by activated PMS under the same reaction conditions, the degradation reaction rate of Pb-C-4–600 was 0.17663 min−1, which was 1.48 times higher than that of N-bio, 1.67 times higher than that of S-bio, and 2.64 times higher than that of B-bio, which further demonstrating the advantages of Pb-C-4–600 in similar composites. The oxidative degradation performance of other typical organic pollutants (BPA, phenol, AO7) was also good. The prominent reactive oxidizing radical in the system of Pb-C-4–600/PMS was SO4·−, and the system could adapt to a wide pH range.

Joule heat mediated by graphite felt enhances peroxymonosulfate activation and carbamazepine degradation: Efficiency and mechanism

Thermal activation of persulfate (PS) is a simple and effective method to generate sulfate radicals (SO4̇‾) for pollutant degradation but its practical application was severely restricted by the excessive energy consumption. In this study, a low energy consumption but efficient Joule heat-activation strategy was developed. The temperature of the reaction solution (TRS) rose to 76.9 °C within 30 min after 5 V external voltage (Uex) was applied onto the two sides of a graphite felt (GF) with the thickness of 6 mm (GF-6). Correspondingly, the peroxymonosulfate (PMS) decomposition ratio and the degradation efficiency of carbamazepine (CBZ) reached 82.6 % and 97.5 %. The catalytic activation of PMS on the surface of GF was the dominant pathway to generate free radicals during the Joule heating process rather than the heat-activation pathway. More importantly, removing per milligram of CBZ only consumed 5.6 kJ electric energy which was significantly lower than that of the common heating methods (namely, 80 °C water bath heating and electrical heating at 5 V using a commercially available ceramic electric heating rod). Impressively, this Joule heating system exhibited wide applicability and prominent reusability. Overall, this work developed an effective PMS thermal activation strategy with low power consumption using the widely available GF and realized efficient degradation of typical organic pollutants.

Enhanced Fenton-like catalysis via interfacial regulation of g-C3N4 for efficient aromatic organic pollutant degradation

For the efficient degradation of organic pollutants with the goal of reducing the water environment pollution, we employed an alkaline hydrothermal treatment on primeval g-C3N4 to synthesize a hydroxyl-grafted g-C3N4 (CN-0.5) material, from which we engineered a novel Fenton-like catalyst, known as Cu–CN-0.5. The introduction of numerous hydroxyl functional groups allowed the CN-0.5 substrate to stably fix active copper oxide particles through surface complexation, resulting in a low Cu leaching rate during a Cu–CN-0.5 Fenton-like process. A sequence of characterization techniques and theoretical calculations uncovered that interfacial complexation induced charge redistribution on the Cu–CN-0.5 surface. Specifically, some of the π electrons in the tris-s-triazine units were transferred to the copper oxide particles along the newly formed chemical bonds (C(π)-O-Cu), forming a π-deficient area on the tris-s-triazine plane near the complexation site. In a typical Cu–CN-0.5 Fenton-like process, a stable π-π interaction was established due to the favorable positive-negative match of electrostatic potential between the aromatic pollutants and π-deficient areas, leading to a significant improvement in Cu–CN-0.5's adsorption capacity for aromatic pollutants. Furthermore, pollutants also delivered electrons to the Cu–CN-0.5 Fenton-like system via a “through-space” approach, which suppressed the futile oxidation of H2O2 in reducing the high-valent Cu2+ and significantly improved the generation efficiency of •OH with high oxidative capacity. As expected, Cu–CN-0.5 not only exhibited an efficient Fenton degradation for several typical aromatic organic pollutants, but also demonstrated both a low metal leaching rate (0.12 mg/L) and a H2O2 utilization rate exceeding 80%. The distinctive Fenton degradation mechanism substantiated the potential of the as-prepared material for effective wastewater treatment applications.

Degradation of tetracycline by combining hydrodynamic cavitation (HC) and ultraviolet (UV)

Abstract Antibiotics have become a new type of organic pollutant. Traditional methods of antibiotic treatment have several problems, including low treatment efficiency, high cost, and low safety. As an emerging process intensification technology, hydrodynamic cavitation (HC) can significantly enhance degradation efficiency coupling with other treatment means. This work studies the degradation effect of a representative antibiotic, tetracycline, by combining HC and UV. The effect of various operating factors, including inlet pressure, initial concentration, pH, and temperature, is analyzed. It is found that HC/UV can obtain 1.7∼4.2 times more effectiveness than that of sole use of HC or UV.

Role of autonomic nervous system in BDE-209 maternal exposure induced immunotoxicity in female offspring.

Decabrominated diphenyl ether (BDE-209) is a typical persistent organic pollutant that can cross the placental barrier, increasing the exposure risk for offspring. Norepinephrine (NE) from nerve terminals and acetylcholine (Ach) can bind to specific receptors on immune cells, inhibit the immune function of the body then cause immunotoxicity. However, whether maternal exposure to BDE-209 could lead to immunotoxicity in the offspring by acting on the sympathetic and parasympathetic nervous systems remains unclear. In view of this, the pregnancy and lactation rat BDE-209 exposure model was established and the results demonstrated that pregnancy and lactation BDE-209 exposure could induce immunotoxicity to female offspring via affecting immunopathology (hematological and biochemical parameters, organ indices, and spleen histopathological), decreasing humoral immunity (serum hemolysin, immunoglobulins, and cytokine productions), damaging cellular immunity (splenic lymphocytes and spleen cytokine productions), and restraining nonspecific immunity. Moreover, a dramatically significant correlation was observed between spleen nerve indices and immunity indices. Additionally, the mechanism revealed that maternal BDE-209 exposure caused offspring immunotoxicity through (1) activating MHC/PKCθ/NF-κB pathway; (2) promoting sympathetic nervous pathway, by upregulating the expression of β2AR protein, which in turn elevating cAMP, following activate PKA and phosphorylate CREB, ultimately leading to immunotoxicity;(3) activating parasympathetic nerve pathway by reducing the binding with Ach and α7nAchR, upregulating the expression of JAK2 and phosphorylating STAT3, induced immunotoxicity of female offspring.

Study of the fouling behavior of typical inorganic-organic foulants in silicates-bearing mine wastewater on reverse osmosis membrane

Inorganic-organic contaminants in mine wastewater treatment constantly challenge the performance of reverse osmosis (RO) membranes. In this work, the main pollutants are calcium ions, soluble silicate, and fulvic acid (FA). We investigate the membrane contamination response of these contaminants in single cases and several composite scenarios. It turns out that membrane fouling is significantly affected by differences in feed composition and content. When all three contaminants coexist, the Lewis acid-base (AB) interaction may dominate the contamination process. When the Ca2+ concentration was raised from 0 to 7 mM, the AB energy between foulants decreased from −77.47 KT to −98.84 KT at the minimum separation distance. This study highlights the impact of typical inorganic and organic pollutants in the RO process, which could help optimize feed conditions while also giving a comparable theory for the water treatment sector.

Contamination Levels and Accumulation Profiles of Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Sediments from South Central Coast of Vietnam

Contamination Levels and Accumulation Profiles of Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Sediments from South Central Coast of Vietnam

Boosting peroxymonosulfate activation over partial Zn-substituted Co3O4 for florfenicol degradation: Insights into catalytic performance, degradation mechanism and routes

Florfenicol (FLO) is a broad-spectrum halogenated antibiotic (containing F and Cl atoms), and the discharged FLO in wastewater exhibits potential biotoxicity. Peroxymonosulfate (PMS) activation can generate reactive oxygen species (ROSs) to realize efficient degradation of organic pollutants. Herein, Zn-substituted Co3O4 (ZnxCo) catalysts were prepared and applied in PMS activation for FLO degradation. The physicochemical properties were systematically studied by combining experiments and density functional theory (DFT) calculation. The Zn partial substitution induced electron rearrangement and promoted oxygen vacancy (OV) formation in Co3O4. Zn0.03Co catalyst exhibited superior FLO removal, achieving a higher reaction rate of 0.112 min−1 than Co3O4 (0.053 min−1). The FLO degradation was highly dependent on the factors of PMS/Zn0.03Co/FLO dosage, temperature, initial pH, and coexisting inorganic anions. The Zn0.03Co also displayed outstanding performance in PMS activation for degradation of various typical organic pollutants. Electron paramagnetic resonance (EPR) spectra and quenching experiments indicated that both radical species (·OH, SO4·-, and ·O2-) and nonradical species (1O2) contribute to FLO removal. The redox cycle of Co3+/Co2+ and OVs played an essential role in PMS activation. The electron structure of FLO and parameters of PMS adsorbed on ZnxCo were calculated. The longer length of CoO and OO bonds for the adsorbed PMS could enhance its activation to generate ROSs. The intermediates were detected, and five degradation pathways were proposed. The acute and chronic toxicities of intermediates suggested that the dechlorination process is important for the toxicity attenuation of FLO. This study clarified the performance enhancement mechanism of Zn substitution on FLO degradation by PMS activation using Co3O4 based catalyst, which favors the development of PMS-based advanced oxidation processes for wastewater treatment.

Accumulation of typical persistent organic pollutants and heavy metals in bioretention facilities: Distribution, risk assessment, and microbial community impact

Bioretention facilities have proven highly effective in removing pollutants from runoff. However, there is a concerning paucity of research on the contamination characteristics and associated risks posed by refractory pollutants in these facilities following long-term operation. This research focuses on the distribution, sources, microbial community impact, and human health risks of pollutants in eight bioretention facilities that have been operational for 5–11 years. The results showed that the distribution of Cu, Zn, and Cd was closely related to anti-seepage measures. PAHs, PCBs, and OCPs primarily accumulated in the surface, with concentrations ranging from 7.42 to 20.34 mg/kg, 31.8–77.3 μg/kg, and 60.5–163.6 μg/kg, respectively. Their concentrations inversely correlate with the depth of the media. Although the majority of contaminants remained below their respective risk thresholds, their concentrations typically exceeded those of background soil values, indicating an enrichment phenomenon. Source analysis revealed that PAHs primarily originate from oil combustion, PCBs were linked to their related industrial products, DDTs had their main sources in technical DDx and residues from the use of dicofol, while HCHs were traced back to historical residues from agricultural activities. Microbial α-diversity (Chao 1 and Shannon) decreased by 8.3–23.4% and 0.8–4.4%, respectively, in different facilities after long-term operation. The most dominant microbial phylum in the facilities was Proteobacteria (all relative abundances >48%). The total relative abundance of dominant genera was 6.7–34.3% higher than the control site, and Pseudomonas, a typical POPs-heavy metal degrading bacterium, had the highest relative abundance (>1.2%). Cu, Zn, and Cd present no non-carcinogenic risks and have low potential ecological risks. However, the lifetime cancer risk for PAHs is 10−6 ∼10−4 in most facilities and is of concern. The cancer risk for PCBs is acceptable, while OCPs pose a low cancer risk only for children.

Gradual effects of gradient concentrations of perfluorooctane sulfonate on the antioxidant ability and gut microbiota of red claw crayfish (Cherax quadricarinatus)

Perfluorooctane sulfonate (PFOS) is a typical persistent organic pollutant that is characterized by environmental persistence, bioaccumulation, and toxicity. In this study, we investigated the gut microbial response of the red claw crayfish Cherax quadricarinatus after 28 days of exposure to 0 ng/L, 1 ng/L, 10 μg/L, or 10 mg/L of PFOS as a stressor. We measured oxidative stress-related enzyme activities and expression of molecules related to detoxification mechanisms to evaluate the toxic effects of PFOS. We found that PFOS disturbed microbial homeostasis in the gut of C. quadricarinatus, resulting in increased abundance of the pathogen Shewanella and decreased abundance of the beneficial bacterium Lactobacillus. The latter especially disturbed amino acid transport and carbohydrate transport. We also found that the activities of glutathione S-transferase and glutathione peroxidase were positively correlated with the expression levels of cytochrome P450 genes (GST1-1, GSTP, GSTK1, HPGDS, UGT5), which are products of PFOS-induced oxidative stress and play an antioxidant role in the body. The results of this study provided valuable ecotoxicological data to better understand the biological fate and effects of PFOS in C. quadricarinatus.