Sources and transformations of chlorophenols in the natural environment

The Impact of Microplastics on Adsorption of Chlorophenols by River-Suspended Sediments

Although microplastics (MPs) are widely recognized as carriers of environmental pollutants, their impact on the adsorption behavior of chlorophenols (CPs) by river-suspended sediments (SS) remains poorly understood. This study systematically investigated the effects of three common MPs (PVC, PS, and PE) on the adsorption of 4-chlorophenol (MCP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) by SS from the Yellow River. Adsorption isotherms revealed that PVC significantly promoted CP adsorption, fitting well with the Langmuir model (R² > 0.95), whereas PS and PE showed better agreement with the Freundlich model (R² > 0.96). The enhancement effect varied with MP type and CP species, with PVC demonstrating the most pronounced promotion (65% increase for 2,4,6-TCP). Conversely, PS and PE hindered 2,4-DCP adsorption due to its higher partition coefficient in SS (36.83 ± 6.3 L/kg) compared to MPs (1.85 ± 0.01 L/kg for PS and 2.03 ± 0.05 L/kg for PE). Environmental factor analysis revealed that ionic strength exerted dual effects by initially enhancing CP adsorption through reduced solubility and later inhibiting it via electrostatic repulsion. Humic acid (HA) promoted TCP adsorption but inhibited DCP adsorption through aggregation and dispersal mechanisms on SS surfaces. Acidic conditions (pH 2-6) significantly enhanced CP adsorption by maintaining their molecular states, while alkaline conditions reduced adsorption due to electrostatic repulsion. Mechanistically, MPs altered SS surface properties and formed aggregates that either facilitated or competed for CP adsorption sites. This study provides a theoretical basis for ecological risk assessment of combined microplastic-pollutant contamination in sediment-laden rivers.

A review of enhancement of chlorophenol bioremediation using synergistic effects between zero-valent iron and microorganisms

Chlorophenols (CPs) are a class of synthetic organic chemicals that are widely distributed in soil and groundwater, posing significant risks to human health and the environment due to persistence, acute toxicity, and potential carcinogenicity. Zero-valent iron (ZVI) has emerged as a promising remediation technique for CPs, but its efficacy is often hindered by surface passivation, non-target competition, and limited mobility in the subsurface. While CPs are inherently biodegradable, their high toxicity and the lack of functional enzymes in indigenous microbial systems restrict the effectiveness of bioremediation. Recently, a hybrid system integrating ZVI with microbial degradation draws increasingly research interests, paving out a new path for sustainable degradation of CPs. These systems leverage the synergistic interactions between ZVI and microorganisms to enhance CP biodegradation. This review provides a comprehensive analysis of the advancement. Key topics include the enhancement of electron transfer, alterations to microbial communities, mitigation of toxicity, and the interplay between other processes. Operation modes, ZVI dosage, and interactions with naturally occurring iron minerals, are also discussed in the context of applications in soil and groundwater remediation. Despite research efforts and successful implementations, critical knowledge gaps remain, particularly in regard to the characterization of microbial processes in natural systems, highlighting the need for future research.

The Potential of Transgenic Hybrid Aspen Plants with a Recombinant Lac Gene from the Fungus Trametes hirsuta to Degrade Trichlorophenol

Objective: Laccases are known to be able to degrade phenolic compounds to simpler components. The main objective of our study was to analyze this property in transgenic aspen plants carrying the laccase gene Lac from Trametes hirsuta which can be potentially used in soil phytoremediation. Methods: We created transgenic aspen plants carrying the laccase gene Lac from Trametes hirsute using the agrobacterial transformation of stem explants with the pBI-Lac vector containing the Lac gene from the white rot fungus T. hirsuta 072 (NCBI GenBank accession number KP027478). Transgenic plants were micropropagated and cultivated in vitro in lines. The degradation of 2,4,6-trichlorophenol (2,4,6-TCP) by plant roots was analyzed by mass-spectrometry with electron ionization using a gas chromatograph. Results: Although plants have their own laccases, those of fungal origin are more effective. All transgenic plants that expressed the recombinant gene degraded 2,4,6-TCP more effectively than non-transformed plants in the control (the degradation efficiency ranged 92 to 98% versus 82% in non-transformed control). Line 47Lac8 demonstrated a 16% higher efficiency than the non-transformed plants in the control. There was also an inverse relationship between the viability of a transgenic line and its level of expression of the recombinant gene. Thus, line 47Lac4 was not viable under native conditions, probably due to lignin synthesis disruptions during the initiation of secondary tissues. This is confirmed by changes in the expression of native genes of lignin biosynthesis. The rest of the transgenic lines did not differ significantly from control in wood growth and biochemistry. The transgenic plant roots were shown to preserve the ability to express the Lac gene ex vitro. Conclusions: Three transgenic lines (47Lac5, 47Lac8, and 47Lac23) with the Lac gene can be recommended for use in soil phytoremediation.

The Role of Natural Organic Matter in the Degradation of Phenolic Pollutants by Sulfate Radical Oxidation: Radical Scavenging vs Reduction

Dissolved natural organic matter (NOM) significantly influences the performance of water treatment processes. It is generally recognized that NOM acts as a radical scavenger, thus inhibiting the degradation of organic pollutants in advanced oxidation processes (AOPs). This study examined the impacts of 8 different NOM isolates on the degradation of 4-chlorophenol (CP), a representative phenolic pollutant, in sulfate radical (SO4•-)-based AOPs. We developed an improved probe method to measure the steady-state concentration of SO4•- ([SO4•-]ss) in both the absence and presence of NOM. Results show that adding 1.00 mgC L-1 NOM resulted in only a 1.3-3.4% decrease in [SO4•-]ss. However, the apparent rate constants of CP degradation decreased by 76-88%. This discrepancy indicates that radical scavenging cannot be the primary mechanism for observed inhibition. We proposed NOM primarily acts as a reducing agent, reacting with the phenoxy radical intermediates generated from the single-electron oxidation of CP by SO4•-. Based on this hypothesis, we developed and validated a kinetic model using experimental data. The reductive capacity of NOM, as determined by the kinetic model, correlates positively with its electron-donating capacity. These findings enhance the understanding of NOM's role in SO4•--based AOPs and provide a foundation for developing strategies to mitigate its adverse effects.

Palladium Nanosheet Enables Synergistic Electrocatalytic Dehalogenation via Direct and Indirect Electron Transfer Mechanisms

Electrocatalytic dehalogenation is a promising method for the remediation of chlorinated organic pollutants. The dehalogenation performance is controlled by catalytic activity, and the underlying electrocatalytic dehalogenation mechanisms need to be carefully investigated for guiding the design of catalyst. Here we report the preparation of a new Pd-based catalyst with a nanosheet structure (Pd NS) by a simple wet-chemical reduction method. This Pd NS catalyst showed a superior electrocatalytic activity toward the reductive dehalogenation of a chlorinated organic pollutant (e.g., 4-chlorophenol) with the dehalogenation rate of 0.324 h-1. Importantly, the obtained Pd NS catalyst had a good durability that could operate well over 30 h under high concentration of 4-chlorophenol with removal efficiency beyond 82%. Experimental results confirmed the simultaneous occurrence of direct electrocatalytic dehalogenation and H*-mediated indirect electron transfer mechanisms in the dehalogenation process, and their quantitative contributions to the dehalogenation performance were established based on the cyclic voltammetry and quenching experiments. This study provides a promising dehalogenation catalyst and sheds light on the mechanism of electrocatalytic dehalogenation as well as the development of a dual-functional electrocatalyst.

The microbiota of cork and yellow stain as a model for a new route for the synthesis of chlorophenols and chloroanisoles from the microbial degradation of suberin and/or lignin

BACKGROUND

The main application of cork is the production of stoppers for wine bottles. Cork sometimes contains 2,4,6-trichloroanisole, a compound that, at a concentration of ng/L, produces an unpleasant musty odor that destroys the organoleptic properties of wine and results in enormous economic losses for wineries and cork industries. Cork can exhibit a defect known as yellow stain, which is associated with high levels of 2,4,6-trichloroanisole. We describe how the microbiota of cork and yellow stain define a novel mechanism that explains the formation of chlorophenols and chloroanisoles (including 2,4,6-trichloroanisole) from p-hydroxybenzoate produced during lignin and/or suberin breakdown.

RESULTS

Electron microscopy revealed that cork affected by yellow stain exhibited significant structural degradation. This deterioration was attributed to the presence of higher microbial populations compared to those found in standard cork. Cork microbiota is rich in filamentous fungi able to metabolize lignin. A metataxonomic analysis confirmed that yellow stain contained significantly greater populations of fungal species belonging to Absidia, Geomyces, Mortierella, Mucor, Penicillium, Pseudogymnoascus, Talaromyces, and Umbelopsis. It also contained significantly greater amounts of bacteria belonging to Enterobacterales, Streptosporangiales, Tepidisphaerales, Pseudomonas, and several members of Burkholderiaceae, particularly species of the Burkholderia-Caballeronia-Paraburkholderia group. The extraction of aromatic compounds from cork samples allowed the identification of several compounds typically observed following lignin depolymerization. Notably, p-hydroxybenzoic acid and phenol were detected. Two strains of the genus Streptomyces isolated from yellow stain were able to biotransform p-hydroxybenzoate into phenol in resting cell assays. Phenol could be efficiently chlorinated in vitro to produce 2,4,6-trichlorophenol by a fungal chloroperoxidase, an enzymatic activity commonly found in filamentous fungi isolated from cork. Finally, as has been widely demonstrated before, 2,4,6-trichlorophenol can be efficiently O-methylated to 2,4,6-trichloroanisole by many of fungi that inhabit cork.

CONCLUSIONS

Chlorophenols and chloroanisoles can be produced de novo in cork from p-hydroxybenzoate generated by the microbial biodegradation of lignin and/or suberin through the participation of different types of microorganisms present in cork. The natural origin of these compounds, which are of great interest for the chlorine cycle and represent a new source of environmental contamination that differs from that caused by human activity, is described. Video Abstract.

Supported liquid phase extraction using wetted nanofiber discs as a simple approach for in-vial extraction of chlorophenols and insecticides from river water prior to HPLC-DAD analysis

BACKGROUND

A novel supported liquid extraction approach using small polymeric nanofibrous discs was demonstrated and applied to the analysis of real river water. Nanofibrous discs were tested to extract model mixture of 9 common water contaminants 4-nitrophenol, various chlorophenols, bisphenol A, permethrin, and fenoxycarb featuring a wide range of log P values (1.9-6.5). Polyacrylonitrile, polyhydroxybutyrate, and polylactic acid nanofibers were selected as adsorptive materials. One-step desorption was performed directly in HPLC vials, to avoid time-consuming evaporation and reconstitution steps. The discs were allowed to sediment to the bottom of the vial before injection into the chromatographic system.

RESULTS

Various parameters affecting the extraction efficiency including 1-octanol volume, extraction time, ionic strength, and sample volume were investigated and optimized. Wetting the nanofiber discs with 1-octanol resulted in up to 20-fold increase in enrichment factor when compared to non-wetted polymer counterparts. The highest enrichment factors were observed for analytes with a log P range of 3.3-4.5. Our developed method showed good linearity in the range 20-200 μg/L for all analytes tested. Satisfactory repeatability with RSD <13 % were achieved covering all steps including disc preparation, wetting, extraction/elution, and chromatography analysis, and recoveries ranged from 58.93 to 121.43 %.

SIGNIFICANCE

This work represents novel simple supported liquid extraction approach using impregnated polymer nanofiber discs. Using only 50 μL 1-octanol, we reduced the organic solvent compared to other extraction methods. There was no need for any plastic cartridge to hold the sorbent and direct in-vial desorption reduced the unnecessary, time-consuming steps and simplified the sample preparation protocol.

Neighboring Catalytic Sites Are Essential for Electrochemical Dechlorination of 2-Chlorophenol

The electrocatalytic reduction process is a promising technology for decomposing chlorinated organic pollutants in water but is limited by the lack of low-cost catalysts that can achieve high activity and selectivity. In studying electrochemical dechlorination of 2-chlorophenol (2-CP) in aqueous media, we find that cobalt phthalocyanine molecules supported on carbon nanotubes (CoPc/CNT), which is a highly effective electrocatalyst for breaking the aliphatic C-Cl bonds in 1,2-dichloroethane (DCA) and trichloroethylene (TCE), are completely inactive for reducing the aromatic C-Cl bond in 2-CP. Detailed mechanistic investigation, including volcano plot correlation between dechlorination rate and atomic hydrogen adsorption energy on various transition metal surfaces, kinetic measurements, in situ Raman spectroscopy, and density functional theory calculations, reveals that the reduction of the aromatic C-Cl bond in 2-CP goes through a hydrodechlorination mechanism featuring a bimolecular reaction between adsorbed atomic hydrogen and 2-CP on the catalyst surface, which requires neighboring catalytic sites, whereas the aliphatic C-Cl bonds in DCA and TCE are cleaved by direct electron transfer from the catalyst, which can occur on isolated single sites. This investigation leads to the discovery of metallic Co as a highly selective and active electrocatalyst for 2-CP dechlorination. This work provides new insights into the fundamental chemistry and catalyst design of electrochemical dechlorination reactions for wastewater treatment.

Magnetic multi-template molecularly imprinted polymers for selective simultaneous extraction of chlorophenols followed by determination using HPLC

Magnetic multi-template molecularly imprinted polymers (M-mt-MIPs) were successfully synthesized by surface imprinting and multi-template imprinting strategy, using polydopamine coated magnetic multi-walled carbon nanotubes as supporting materials, five typical chlorophenols (CPs) as templates, methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross-linker. Compared to non-imprinted polymers (NIPs), the as-prepared M-mt-MIPs showed high adsorption capacity (32.58‒80.63 mg g-1), rapid mass transfer and specific selectivity for the five targeted CPs, which were applied as magnetic solid-phase extraction (MSPE) adsorbents. Parameters affecting MSPE efficiency were detailed investigated, such as adsorbents dosage, sample pH, extraction time, type and volume of desorption solvent and salt effect. Combined with HPLC-DAD, a simple, rapid and sensitive method was established, showing good linearity (2‒200 μg L-1), low limits of detection (0.32‒0.49 μg L-1), and high enrichment factors (35.2‒108). The developed M-mt-MIPs-MSPE-HPLC method was applied to enrich and determine CPs in tannery wastewater, wet-blue and crust leather, and satisfactory spiking recoveries were attained in the range of 73.95‒109.7% with relative standard deviations (RSDs) of 2.13-8.48%. This study provided a new alternative material and method to rapid simultaneously extract and analyze low concentration of typical CPs in complicated matrices.

Weak static magnetic fields facilitated highly efficient 2,4,6-trichlorophenol removal by sulfurized nanoscale zero-valent iron supported on biochar (BC-SNZVI) at neutral pH

Sulfurized nanoscale zero-valent iron supported on biochar (BC-SNZVI) has been successfully synthesized for 2,4,6-trichlorophenol (2,4,6-TCP) removal, while was only effectively under acidic conditions. To obtain highly efficient removal of 2,4,6-TCP within a broader pH range, weak static magnetic fields (WMF) was applied in BC-SNZVI/2,4,6-TCP aqueous systems. Results showed 30 mT WMF supported the most extensive 2,4,6-TCP removal, and 87.4% of 2,4,6-TCP (initial concentration of 30 mg/L) was removed by 0.5 g/L BC-SNZVI at neutral pH (pH = 6.8) within 180 min, which was increased by 54.4% compared to that without WMF. The observed rate constant (Kobs) under 30 mT WMF was 2.1-fold greater than that without WMF. Although three typical anions (NO3- (0.5-10.0 mM), H2PO4- (0.05-0.5 mM), and HCO3- (0.5-5.0 mM)) still inhibited 2,4,6-TCP removal, WMF could efficiently alleviate the inhibitory effects. Moreover, 73.1% of 2,4,6-TCP was successfully removed by BC-SNZVI under WMF in natural water. WMF remarkably boosted the dechlorination of 2,4,6-TCP, increasing the 2,4,6-TCP dechlorination efficiency from 45.2% (in the absence of WMF) to 83.8% (in the presence of WMF) by the end of 300 min. And the complete dechlorination product phenol appeared within 10 min. Force analysis confirmed the magnetic field gradient force (FB) moved paramagnetic Fe2+ at the SNZVI surface along the direction perpendicular to the external applied field, promoting the mass-transfer controlled SNZVI corrosion. Corrosion resistance analysis revealed WMF promoted the electron-transfer controlled SNZVI corrosion by decreasing its self-corrosion potential (Ecorr). With the introduction of sulfur, the magnitude of FB doubled and the Ecorr decreased comparing with NZVI. Our findings provide a facile and viable strategy for treating chlorinated phenols at neutral pH.

Correlation between urinary rare earth elements and liver function in a Zhuang population aged 35-74 years in Nanning

BACKGROUND

Animal studies have shown that exposure to REEs can cause severe liver damage, but evidence from population studies is still lacking. Therefore, we investigated the relationship between REEs concentrations in urine and liver function in the population.

METHODS

We conducted a cross-sectional study on 1024 participants in Nanning, China. An inductively coupled plasma mass spectrometer (ICP-MS) was used to detect the concentrations of 12 REEs in urine. The relationship between individual exposure to individual REE and liver function was analyzed by multiple linear regression. Finally, the effects of co-exposure to 5 REEs on liver function were assessed by a weighted sum of quartiles (WQS) regression model and a Bayesian kernel machine regression (BKMR) model.

RESULTS

The detection rate of 5 REEs, lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), and dysprosium (Dy), is greater than 60%. After multiple factor correction, La, Ce, Pr, Nd, and Dy were positively correlated with serum ALP, Ce, Pr, and Nd were positively correlated with serum AST, while Ce was negatively correlated with serum TBIL and DBIL. Both WQS and BKMR results indicate that the co-exposure of the 5 REEs is positively correlated with serum ALP and AST, while negatively correlated with serum DBIL. There were potential interactions between La and Ce, La and Dy in the association of co-exposure of the 5 REEs with serum ALP.

CONCLUSIONS

The co-exposure of the 5 REEs was positively correlated with serum ALP and AST, and negatively correlated with serum DBIL.

Electrochemical sensors based on molecularly imprinted polymers for the detection of chlorophenols as emergent distributing chemicals (EDCs): a review

Environmental pollutants like chlorophenol chemicals and their derivatives are commonplace. These compounds serve as building blocks in the production of medicines, biocides, dyes, and agricultural chemicals. Chlorophenols enter the environment through several different pathways, including the breakdown of complex chlorinated hydrocarbons, industrial waste, herbicides, and insecticides. Chlorophenols are destroyed thermally and chemically, creating dangerous chemicals that pose a threat to public health. Water in particular is affected, and thorough monitoring is required to find this source of pollution because it can pose a major hazard to both human and environmental health. For the detection of chlorophenols, molecularly imprinted polymers (MIPs) have been incorporated into a variety of electrochemical sensing systems and assay formats. Due to their long-term chemical and physical stability as well as their simple and affordable synthesis process, MIPs have become intriguing synthetic alternatives over the past few decades. In this review, we concentrate on the commercial potential of the MIP technology. Additionally, we want to outline the most recent advancements in their incorporation into electrochemical sensors with a high commercial potential for detecting chlorophenols.

Molecularly imprinted polymer-based electrochemical sensors for monitoring the persistent organic pollutants chlorophenols

Because of the serious risks they pose to the environment and public health, chlorophenols (CPs), a typical class of the most persistent organic pollutants, have drawn increasing attention. Monitoring CPs effectively has become a pressing and difficult problem. The rapidly increasing need for onsite and real-time CP detection has led to the consideration of electrochemical sensing as a workable solution. Molecularly imprinted polymer (MIP)-based electrochemical sensing has emerged as a promising area for environmental monitoring in response to this analytical problem. MIPs, in conjunction with miniature electrochemical transducers, provide the opportunity to detect target analytes in situ. These devices have the advantages of great chemical and physical stability, cheap production costs, good selectivity, and quick response times. Most studies suggest that these sensors use nanoparticles to improve their analytical properties, especially sensitivity. Furthermore, these sensors have successfully used real water samples without the need for time-consuming pretreatment procedures. This article provides an overview of electrochemical MIP-based sensors reported to detect CPs in water samples. To obtain the highest sensitivity, special consideration is given to the fabrication of the sensors, which includes the use of various functional monomers, sensing platforms, and materials. Several other parameters are also discussed, including the linear concentration range, limit of detection, and the types of water samples that were examined.

Associations of dichlorophenols, trichlorophenols, and ortho-phenylphenol with the risk and prognosis of diabetes and prediabetes: A population-based study

2,4-dichlorophenol (2,4-DCP), 2,5-DCP, 2,4,5-trichlorophenol (2,4,5-TCP), 2,4,6-TCP, and ortho-phenylphenol (OPP) are widely present in the environment. However, their associations with risk and prognosis of diabetes and prediabetes remains unclear. We investigated the associations of these five phenols with the risk of diabetes and prediabetes, and with all-cause and cardiovascular disease (CVD) mortality, in adults with diabetes or prediabetes (n=6419). Information on diabetes and prediabetes indicators, and mortality data was collected from the National Health and Nutrition Examination Survey. Logistic and Cox regression models were used to explore the associations of the five phenols with risk and prognosis of diabetes and prediabetes. Participants in the highest urinary 2,4-DCP and 2,5-DCP tertiles had higher odds of diabetes [adjusted odds ratio (aOR), 1.34, 95 % confidence interval (CI): 1.10, 1.62; aOR, 1.29, 95 % CI: 1.07, 1.56, respectively] than those in the lowest tertiles. Participants with urinary OPP concentrations above the limit of detection (LOD), but below median had an aOR of 1.25 (95 % CI: 1.08, 1.46) for prediabetes compared to those with concentrations below the LOD. In adults with diabetes, the highest 2,4-DCP and 2,5-DCP tertiles were associated with all-cause mortality [adjusted hazard ratio (aHR), 1.49; 95 % CI: 1.08, 2.06; aHR, 1.49; 95 % CI: 1.08, 2.05, respectively] and CVD mortality (aHR, 2.58; 95 % CI: 1.33, 4.97; aHR, 1.96; 95 % CI: 1.06, 3.60, respectively) compared with the lowest tertiles. Compared with 2,4,5-TCP concentrations below the LOD, those above median were associated with all-cause mortality (aHR: 1.75; 95 % CI: 1.24, 2.48) and CVD mortality (aHR: 2.34; 95 % CI: 1.19, 4.63) in adults with prediabetes. Furthermore, the associations between these phenols and mortality were strengthened in some subgroups. Environmental exposure to 2,4-DCP, 2,5-DCP, 2,4,5-TCP, and OPP increases the risk or adverse prognosis of diabetes or prediabetes in adults in the US. Further studies are required to confirm these findings.

Harnessing an amide-based covalent organic framework in solid-phase extraction for chlorophenol analysis in industrial wastewaters

An amide-based covalent organic framework (COF) was successfully synthesized using the reaction between 1,3,5-trimesoyl chloride and ethylenediamine. The structure and morphology of the COF were characterized using Fourier-transform infrared spectra, nuclear magnetic resonance spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Brunauer-Emmett-Teller surface area analysis. The COF was employed as a solid-phase extraction adsorbent for the sampling and preconcentration of chlorophenols from industrial wastewater samples prior to high-performance liquid chromatography with ultraviolet detection. The experimental parameters influencing the extraction efficiency including type and volume of eluent solvent, sample solution volume, salt concentration, sample flow rate, and sample solution pH were investigated and optimized using a response surface methodology employing Box-Behnken-design. Under optimized conditions, calibration curves exhibited good linearities over the range of 0.003-10 µg/mL with determination coefficients (R2) ranging from 0.9982 to 0.9999. The method's limits of detection ranged from 0.001 to 0.01 µg/mL. Good repeatability was achieved with relative standard deviations below 4.7%. The developed procedure utilizing the COF adsorbent was successfully applied to determine chlorophenols accurately and precisely in various industrial wastewater samples.

Impacts of o-cresol spill on composition and function of river sediment and soil microbial communities

o-Cresol is a toxic substance with strong irritating and corrosive effects on skin and mucous membranes. To date, information on the effects of o-cresol on microbial communities in the natural environment is very limited. In the present study, 16S rRNA sequencing and metagenomic technique were carried out to elucidate the effects of the o-cresol spill on microbial communities in river sediments and nearby soils. o-Cresol spill induced the increase in the relative abundance of phyla Planctomycetes and Gemmatimonadetes, suggesting their resilience to o-cresol-induced stress. Uncultured Gemmatimonadetes genera and the MND1 genus exhibited enrichment, while the Pseudomonas genus dominated across all samples, indicating their potential pivotal roles in adapting to the o-cresol spill. Moreover, o-cresol spill impaired the metabolic functions of microbes but triggered their defense mechanisms. Under o-cresol pressure, microbial functions related to carbon fixation were upregulated and functions associated with sulfur metabolism were downregulated. In addition, the o-cresol spill led to an increase in functional genes related to the conversion of o-cresol to 3-methylcatechol. Several genes involved in the degradation of aromatic compounds were also identified, potentially contributing to the biodegradation of o-cresol. This study provides fresh insights into the repercussions of an abrupt o-cresol spill on microbial communities in natural environments, shedding light on their adaptability, defense mechanisms, and biodegradation potential.

Bioremediation of Hazardous Pollutants Using Enzyme-Immobilized Reactors

Bioremediation uses the degradation abilities of microorganisms and other organisms to remove harmful pollutants that pollute the natural environment, helping return it to a natural state that is free of harmful substances. Organism-derived enzymes can degrade and eliminate a variety of pollutants and transform them into non-toxic forms; as such, they are expected to be used in bioremediation. However, since enzymes are proteins, the low operational stability and catalytic efficiency of free enzyme-based degradation systems need improvement. Enzyme immobilization methods are often used to overcome these challenges. Several enzyme immobilization methods have been applied to improve operational stability and reduce remediation costs. Herein, we review recent advancements in immobilized enzymes for bioremediation and summarize the methods for preparing immobilized enzymes for use as catalysts and in pollutant degradation systems. Additionally, the advantages, limitations, and future perspectives of immobilized enzymes in bioremediation are discussed.

NmrB (AN9181) expression is activated under oxidative stress conditions acting as a metabolic repressor of Aspergillus nidulans

Aspergilli comprise a diversity of species that have been extensively studied due to their catabolic diversity, biotechnological and ecological value, and pathogenicity. An impressive level of structural and functional conservation has been shown for aspergilli, regardless of many (yet) cryptic genomic elements. We have hypothesized the existence of conserved genes responsive to stress in aspergilli. To test the hypothesis of such conserved stress regulators in aspergilli, a straightforward computational strategy integrating well-established bioinformatic tools was used as the starting point. Specifically, five transcriptome-based datasets on exposure to organic compounds were used, covering three distinct Aspergillus species. Among the identified up-regulated genes, only one gene showed the same response in all conditions, AN9181. This gene encodes a protein containing a phenylcoumaran benzylic ether reductase-like domain and a Nitrogen metabolite repressor regulator domain (NmrA). Deletion of this gene caused significant phenotypic alterations compared to that of the parental strain across diverse conditions. Specifically, the deletion of AN9181 raised the mutant's metabolic activity in different nitrogen sources. The acquired data supports that AN9181 acts by repressing (slowing down) A. nidulans growth when exposed to aromatic compounds in a concentration dependent manner. The same phenotype was observed for amphotericin B. Finally, AN9181 underwent differential upregulation under oxidative stress conditions. Collectively, the data suggest that AN9181, herein assigned as NmrB (Nitrogen Metabolite Repression Regulator B), builds up the genetic machinery of perception of oxidative stress by negatively regulating growth under such conditions.

A new copper nanocluster surface molecular imprinted polymethacrylic acid probe for ultratrace trichlorophenol based on in situ-generated nanogold SPR effects

A new coinage metal nanocluster surface molecularly imprinted polymethacrylic acid nanoprobe (NC@MIP) for the selective determination of 2,4,6-trichlorophenol (TCP) was prepared via microwave synthesis using 2,4,6-trichlorophenol as a template molecule, copper nanoclusters (CuNC) as a nanosubstrate, and methacrylic acid as a polymer monomer. It was found that the copper nanocluster MIP (CuNC@MIP) shows the strongest catalytic performance for the reduction of HAuCl4 by hydrazine hydrate for the on-site generation of gold nanoparticles (AuNPs) with the surface plasmon resonance (SPR) effects of resonance surface-enhanced Raman scattering (SERS) and resonance Rayleigh scattering (RRS) as well as absorption (Abs). When TCP was added, the CuNC@MIP nanoprobe and TCP-formed CuNC@MIP-TCP nanoenzyme with stronger catalytic activity generated more AuNPs, and the trimodal analytical signal was enhanced linearly. Therefore, a new SERS/RRS/Abs trimodal sensing platform for TCP was constructed, which was simple, rapid, sensitive, and selective. For each mode, the linear ranges were 0.0075-0.075, 0.010-0.10, and 0.010-0.10 nmol L-1, and the detection limits were 0.0010, 0.021, and 0.043 nmol L-1, respectively. The relative deviation of TCP in different water quality was 0.47%-2.5% and the recovery rate was 94.6%-108.6%.

Transformation of chlorobenzene by Mn(III) generated in MnO2/organic acid systems

Chlorobenzene (CB) is a prevalent organic contaminant in water and soil environments. It presents high chemical stability and is resistant to both oxidation and reduction. In this study, we showed that CB was substantially removed by soluble Mn(III) produced during the reductive dissolution of colloidal MnO2 by naturally-occurring organic acids such as formate (FOR), oxalate (OX), and citrate (CIT). The removal rate was dependent on the physicochemical properties of organic acids. With strong electron-donating and coordination ability, OX and CIT promoted MnO2 dissolution and Mn(III) generation compared to FOR, but had adverse effects on the stability and reactivity of Mn(III). As a result, CB removal followed the order: MnO2/CIT > MnO2/FOR > MnO2/OX. Analysis of the transformation products showed that Mn(III) complexes acted as strong electrophiles, attacking the ortho/para carbons of the benzene ring and transforming CB to chlorophenols via an electrophilic substitution mechanism. The theoretical foundation of this proposed reaction mechanism was supplemented by quantum mechanical calculations. Together, the findings of this study provide new insights into the transformation of CB in natural environments and hold the potential to offer a novel strategy for the development of manganese oxide/ligand systems for CB elimination.

Dispersive liquid-liquid microextraction as a novel enrichment approach for compound-specific carbon isotope analysis of chlorinated phenols

Compound-specific isotope analysis (CSIA) via gas chromatography-isotope ratio mass spectrometry (GC-IRMS) is a potent tool to elucidate the fate of (semi-)volatile organic contaminants in technical and environmental systems. Yet, due to the comparatively low sensitivity of IRMS, an enrichment step prior to analysis often is inevitable. A promising approach for fast as well as economic analyte extraction and preconcentration prior to CSIA is dispersive liquid-liquid microextraction (DLLME) - a well-established technique in concentration analysis of contaminants from aqueous samples. Here, we present and evaluate the first DLLME method for GC-IRMS exemplified by the analysis of chlorinated phenols (4-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol) as model compounds. The analytes were simultaneously acetylated with acetic anhydride and extracted from the aqueous phase using a binary solvent mixture of acetone and tetrachloroethylene. With this method, reproducible δ13C values were achieved with errors ≤ 0.6‰ (n = 3) for aqueous concentrations down to 100 μg L-1. With preconcentration factors between 130 and 220, the method outperformed conventional liquid-liquid extraction in terms of sample preparation time and resource consumption with comparable reproducibility. Furthermore, we have demonstrated the suitability of the method (i) for the extraction of the analytes from a spiked river water sample and (ii) to quantify kinetic carbon isotope effect for 2,4,6-trichlorophenol during reduction with zero-valent zinc in a laboratory batch experiment. The presented work shows for the first time the potential of DLLME for analyte enrichment prior to CSIA and paves the way for further developments, such as the extraction of other compounds or scaling up to larger sample volumes.

Critical role of zero-valent iron in the efficient activation of H2O2 for 4-CP degradation by bimetallic peroxidase-like

Peroxidase-like based on double transition metals have higher catalytic activity and are considered to have great potential for application in the field of pollutant degradation. First, in this paper, a novel Fe0-doped three-dimensional porous Fe0@FeMn-NC-like peroxidase was synthesized by a simple one-step thermal reduction method. The doping of manganese was able to reduce part of the iron in Fe-Mn binary oxides to Fe0 at high temperatures. In addition, Fe0@FeMn-NC has excellent peroxidase-like mimetic activity, and thus, it was used for the rapid degradation of p-chlorophenol (4-CP). During the degradation process, Fe0 was able to rapidly replenish the constantly depleted Fe2+ in the reaction system and brought in a large number of additional electrons. The ineffective decomposition of H2O2 due to the use of H2O2 as an electron donor in the reduction reactions from Fe3+ to Fe2+ and from Mn3+ to Mn2+ was avoided. Finally, based on the experimental results of LC-MS and combined with theoretical calculations, the degradation process of 4-CP was rationally analyzed, in which the intermediates were mainly p-chloro-catechol, p-chloro resorcinol, and p-benzoquinone. Fe0@FeMn-NC nano-enzymes have excellent catalytic activity as well as structural stability and perform well in the treatment of simulated wastewater containing a variety of phenolic pollutants as well as real chemical wastewater. It provides some insights and methods for the application of peroxidase-like enzymes in the degradation of organic pollutants.

Degradation of 2, 4-dichlorophenol by peroxymonosulfate catalyzed by ZnO/ZnMn2 O4

In this study, a highly efficient peroxymonosulfate (PMS) activator, ZnO/ZnMn2 O4 , was synthesized using a simple one-step hydrothermal method. The resulting bimetallic oxide catalyst demonstrated a homogenous and high-purity composition, showcasing synergistic catalytic activity in activating PMS for degrading 2, 4-dichlorophenol (2, 4-DCP) in aqueous solution. This catalytic performance surpassed that of individual ZnO, Mn2 O3 , and ZnMn2 O4 metal materials. Under the optimized conditions, the removal efficiency of 2, 4-DCP reached approximately 86% within 60 min, and the catalytic ability remained almost constant even after four cycles of recycling. The developed degradation system proved effective in degrading other azo-dye pollutants. Certain inorganic anions such as HPO4 - , HCO3 - , and NO3 - significantly inhibited the degradation of 2, 4-DCP, while Cl- and SO4 2- did not exhibit such interference. Results from electrochemical experiments indicated that the electron transfer ability of ZnO/ZnMn2 O4 surpassed that of individual metals, and electron transfer occurred between ZnO/ZnMn2 O4 and the oxidant. The primary active radicals responsible for degrading 2, 4-DCP were identified as SO4 •- , OH• and O2 •- , generated through the oxidation and reduction of PMS catalyzed by Zn (II) and Mn (III). Furthermore, X-ray photoelectron spectroscopy (XPS) analysis of the fresh and used catalysts revealed that the exceptional electron transfer ability of ZnO facilitated the valence transfer of Mn (III) and the transfer of electrons to the catalyst's oxygen surface, thus enhancing the catalytic efficiency. The analysis of radicals and intermediates indicates that the two main pathways for degrading 2, 4-DCP involve hydroxylation and radical attack on its aromatic ring. PRACTITIONER POINTS: A bimetallic ZnO/ZnMn2 O4 catalyst was synthesized and characterized. ZnO/ZnMn2 O4 can synergistically activate PMS to degrade 2, 4-DCP compared with single metal oxide. Three primary active radicals, O2 •- , • OH, and SO4 •- , were generated to promote the degradation. ZnO promoted electron transfer among the three species of Mn to facilitate oxidizing pollutants. Hydroxylation and radical attack on the aromatic ring of 2, 4-DCP are the two degradation pathways.

Insights into the Enhanced Photogeneration of Hydroxyl Radicals from Chlorinated Dissolved Organic Matter

Free available chlorine has been and is being applied in global water treatment and readily reacts with dissolved organic matter (DOM) in aquatic environments, leading to the formation of chlorinated products. Chlorination enhances the photoreactivity of DOM, but the influence of chlorinated compounds on the photogeneration of hydroxyl radicals (•OH) has remained unexplored. In this study, a range of chlorinated carboxylate-substituted phenolic model compounds were employed to assess their •OH photogeneration capabilities. These compounds demonstrated a substantial capacity for •OH production, exhibiting quantum yields of 0.1-5.9 × 10-3 through direct photolysis under 305 nm and 0.2-9.5 × 10-3 through a triplet sensitizer (4-benzoylbenzoic acid)-inducing reaction under 365 nm LED irradiation. Moreover, the chlorinated compounds exhibited higher light absorption and •OH quantum yields compared to those of their unchlorinated counterparts. The •OH photogeneration capacity of these compounds exhibited a positive correlation with their triplet state one-electron oxidation potentials. Molecular-level compositional analysis revealed that aromatic structures rich in hydroxyl and carboxyl groups (e.g., O/C > 0.5 with H/C < 1.5) within DOM serve as crucial sources of •OH, and chlorination of these compounds significantly enhances their capacity to generate •OH upon irradiation. This study provides novel insights into the enhanced photogeneration of •OH from chlorinated DOM, which is helpful for understanding the fate of trace pollutants in chlorinated waters.

Tourmaline guiding the electric field and dechlorination pathway of 2,3-dichlorophenol by Desulfitobacterium hafniense

The dehalogenation of organohalides has been a research hotspot in bioremediation field; however, the influence of tourmaline, a natural ore that can generate spontaneous electric field, on organohalide-respiring bacteria (OHRB) and their dechlorination process is not well known. In this study, the effect and mechanism of tourmaline on the reductive dechlorination of 2,3-dichlorophenol (2,3-DCP) by Desulfitobacterium hafniense DCB-2T were explored. The characterization results confirmed that tourmaline had good stability and the optimal dosage of tourmaline was 2.5 g/L, which shortened the total time required for dechlorination reaction to 72 hr. Besides, tourmaline amendment also increased the proportion of 2-chlorophenol (2-CP) from 18% to 30% of end products, while that of 3-CP decreased correspondingly. The theoretical calculations showed that the bond charge of the ortho-substituted chlorine declined from -0.179 to -0.067, and that of meta-substituted chlorine increased from -0.111 to -0.129, which indicated that the spontaneous electric field of tourmaline affected the charge distribution of 2,3-DCP and was more conducive to the generation of 2-CP. Overall, tourmaline with the spontaneous electric field affected the reductive dechlorination pathway of Desulfitobacterium,and the tourmaline-OHRB combining system might serve as a novel strategy for the bioremediation of environments polluted with chlorinated phenols.

2,4,6-TCP migrates and transforms in different cultivated soil in China: Kinetic analysis and mechanistic modeling

Organochlorine pesticides are widely used in agriculture, wood preservation, pulp bleaching and other fields, which increased the pollution risk of cultivated land. In this study, a typical organochlorine pesticides-2,4,6-TCP was conducted as the target pollutants to investigated the migration and transformation characteristics in different cultivated soils in China. The results indicated that the adsorption of 2,4,6-TCP in soil samples was in order: black soil＞laterite＞fluvo-aquic soil, and the maximum adsorption was 71.0870, 27.0575 and 6.1292 mg/kg, respectively. The dispersion coefficient of black soil, laterite and fluvo-aquic soil was 0.0329, 0.0501 and 0.0149, and the hysteretic factor R was 5.381, 1.455 and 2.238, respectively, indicating that the migration ability of 2,4,6-TCP in different cultivated soils samples was in order: black soil＞laterite＞fluvo-aquic soil. The fitting results of one-dimensional migration model indicated that the model well reflected the migration and transformation of 2,4,6-TCP in different cultivated soil samples. Meanwhile, the Two-dimensional migration model fitting results indicated that the maximum concentration of 2,4,6-TCP of different cultivated soil samples were found along the longitudinal flow direction, reaching 40% of the initial pollution concentration at 15 m, corresponding to the center of the pollutant plume.

Concentrations and association between exposure to mixed perfluoroalkyl and polyfluoroalkyl substances and glycometabolism among adolescents

BACKGROUND

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are widely used for industrial and commercial purposes and have received increasing attention due to their adverse effects on health.

OBJECTIVE

To examine the relationship of serum PFAS and glycometabolism among adolescents based on the US National Health and Nutrition Examination Survey.

METHODS

General linear regression models were applied to estimate the relationship between exposure to single PFAS and glycometabolism. Weighted quantile sum (WQS) regression models and Bayesian kernel machine regressions (BKMR) were used to assess the associations between multiple PFASs mixture exposure and glycometabolism.

RESULTS

A total of 757 adolescents were enrolled. Multivariable regression model showed that Me-PFOSA-AcOH exposure was negatively associated with fasting blood glucose. WQS index showed that there was marginal negative correlation between multiple PFASs joint exposure and the homeostasis model of assessment for insulin resistance index (HOMA-IR) (β = -0.26, p < .068), and PFHxS had the largest weight. BKMR models showed that PFASs mixture exposure were associated with decreased INS and HOMA-IR, and the exposure-response relationship had curvilinear shape.

CONCLUSIONS

The increase in serum PFASs were associated with a decrease in HOMA-IR among adolescents. Mixed exposure models could more accurately and effectively reveal true exposure.Key MessagesThe detection rates of different PFAS contents in adolescent serum remained diverse.Adolescent serum PFASs had negative curvilinear correlation with INS and HOMA-IR levels.PFHxS had the highest weight in the associations between multiple PFASs and adolescent glycometabolism.

A novel copper oxide/titanium membrane integrated with peroxymonosulfate activation for efficient phenolic pollutants degradation

Herein, a novel CuO catalyst functionalized Ti-based catalytic membrane (FCTM) was prepared via the regulated electro-deposition technique followed with low-temperature calcination. The morphology of CuO catalyst and oxygen vacancy (OV) content can be controlled by adjusting the preparation conditions, under optimal condition (400 °C, electrolyte as sulfuric acid), the fern-shaped CuO catalyst was formed and the OV content was up to its highest level. Under the optimal treatment condition, the 4-chlorophenol (4-CP) removal of the membrane filtration combined with peroxymonosulfate (PMS) activation (MFPA) process was up to 98.2% (TOC removal of 88.2%). Mechanism studying showed that the enhanced performance in this system was mainly due to the increased production of singlet oxygen (1O2) via the co-effect of fern-shaped CuO (increased specific surface area) and its fine-tuned OV (precursor of 1O2), which not only synergistically enhanced adsorption ability but also offered more active sites for PMS activation. Theoretical calculations showed that the OV-rich CuO displayed high adsorption energy for PMS molecule, leading to the change in OO and OH bond (tend to 1O2) of the PMS molecule. Finally, the possible three degradation pathways of 4-CP were formed by the electrophilic attacking of 1O2.

Single and Joint Associations of Polycyclic Aromatic Hydrocarbon Exposure with Liver Function during Early Pregnancy

The individual and combined associations of polycyclic aromatic hydrocarbons (PAHs) metabolites on liver function during pregnancy are still lacking. We aimed to explore the connection between urinary PAH metabolites and liver function in early pregnant women in southwest China based on the Zunyi birth cohort. Ten urinary PAH metabolites and five liver function parameters during early pregnancy were measured. The associations of single PAHs with parameters of liver function were assessed using multiple linear regression. A Bayesian kernel machine regression (BKMR) model was used to evaluate the joint associations of the PAH mixture with outcomes. We found that each 1% increment of urinary 2-hydroxyphenanthrene (2-OH-PHE) was associated with 3.36% (95% CI: 0.40%, 6.40%) higher alanine aminotransferase (ALT) and 2.22% (95% CI: 0.80%, 3.67%) higher aspartate aminotransferase (AST). Each 1% increment in 1-hydroxy-phenanthrene (1-OH-PHE) was significantly associated with 7.04% (95% CI: 1.61%, 12.75%) increased total bile acid (TBA). Additionally, there was a significant positive linear trend between 2-OH-PHE and AST and 1-OH-PHE and TBA. BKMR also showed a significant positive association of PAH mixture with AST. Our results indicate that PAH metabolites were associated with increased parameters of liver function among early pregnant women. Early pregnant women should pay more attention to the adverse relationships between PAHs and liver function parameters to prevent environment-related adverse perinatal outcomes.

Impact of different zero valent iron-based particles on anaerobic microbial dechlorination of 2,4-dichlorophenol: Comparison of dechlorination performance and the underlying mechanism

The integration of iron-based materials and anaerobic microbial consortia has been extensively studied owing to its potential to enhance pollutant degradation. However, few studies have compared how different iron materials enhance the dechlorination of chlorophenols in coupled microbial systems. This study systematically compared the combined performances of microbial community (MC) and iron materials (Fe0/FeS2 +MC, S-nZVI+MC, n-ZVI+MC, and nFe/Ni+MC) for the dechlorination of 2,4-dichlorophenol (DCP) as one representative of chlorophenols. DCP dechlorination rate was significantly higher in Fe0/FeS2 +MC and S-nZVI+MC (1.92 and 1.67 times, with no significant difference between two groups) than in nZVI+MC and nFe/Ni+MC (1.29 and 1.25 times, with no significant difference between two groups). Fe0/FeS2 had better performance for the reductive dechlorination process as compared with other three iron-based materials via the consumption of any trace amount of oxygen in anoxic condition and accelerated electron transfer. On the other hand, nFe/Ni could induce different dechlorinating bacteria as compared to other iron materials. The enhanced microbial dechlorination was mainly due to some putative dechlorinating bacteria (Pseudomonas, Azotobacter, Propionibacterium), and due to improved electron transfer of sulfidated iron particles. Therefore, Fe0/FeS2 as a biocompatible as well as low-cost sulfidated material can be a good alternative for possible engineering applications in groundwater remediation.

A comprehensive review of chlorophenols: Fate, toxicology and its treatment

Chlorophenols represent one of the most abundant families of toxic pollutants emerging from various industrial manufacturing units. The toxicity of these chloroderivatives is proportional to the number and position of chlorine atoms on the benzene ring. In the aquatic environment, these pollutants accumulate in the tissues of living organisms, primarily in fishes, inducing mortality at an early embryonic stage. Contemplating the behaviour of such xenobiotics and their prevalence in different environmental components, it is crucial to understand the methods used to remove/degrade the chlorophenol from contaminated environment. The current review describes the different treatment methods and their mechanism towards the degradation of these pollutants. Both abiotic and biotic methods are investigated for the removal of chlorophenols. Chlorophenols are either degraded through photochemical reactions in the natural environment, or microbes, the most diverse communities on earth, perform various metabolic functions to detoxify the environment. Biological treatment is a slow process because of the more complex and stable structure of pollutants. Advanced Oxidation Processes are effective in degrading such organics with enhanced rate and efficiency. Based on their ability to generate hydroxyl radicals, source of energy, catalyst type, etc., different processes such as sonication, ozonation, photocatalysis, and Fenton's process are discussed for the treatment or remediation efficiency towards the degradation of chlorophenols. The review entails both advantages and limitations of treatment methods. The study also focuses on reclamation of chlorophenol-contaminated sites. Different remediation methods are discussed to restore the degraded ecosystem back in its natural condition.

Polypyrrole-induced active-edge-S and high-valence-Mo reinforced composites with boosted electrochemical performance for the determination of 2,4,6-trichlorophenol in the aquatic environment

With the extensive application of halogenated aromatic compounds, including 2,4,6-Trichlorophenol (2,4,6-TCP), improper treatment or discharge contribute to persistently harmful effects on humans and the ecosystem, rendering the identification and monitoring of 2,4,6-TCP in the aquatic environment urgently required. In this study, a highly sensitive electrochemical platform was developed using active-edge-S and high-valence-Mo rich MoS₂/polypyrrole composites. MoS₂/PPy illustrates superior electrochemical performance and catalytic activity and has not been explored for detecting chlorinated phenols previously. The local environment of polypyrrole induces the richness of active edge S and a high oxidation state of Mo species in the composites, both of which endorse a sensitive anodic current response due to the favored oxidation of 2,4,6-TCP through nucleophilic substitution. Also, the higher complementarity between pyrrole and 2,4,6-TCP with respective electron-rich and electron-poor features through π-π stacking interactions enhances the specific detection capability of 2,4,6-TCP by the MoS₂/polypyrrole-modified electrode. The MoS₂/polypyrrole-modified electrode achieved a linear range of 0.1-260 μM with an ultralow limit of detection of 0.009 μM. Additionally, the structural stability boosted by the linkage of polypyrrole and MoS₂ results in good resistance and satisfactory recovery in real water samples. The compiled results demonstrate that the proposed MoS₂/polypyrrole composite opens up a new potential to advance a sensitive, selective, facile fabrication, and low-cost platform for the on-site determination of 2,4,6-TCP in aquatic systems. The sensing of 2,4,6-TCP is important to monitor its occurrence and transport, and can also serve to track the effectiveness and adjust subsequent remediation treatments applied to contaminated sites.

Catalytic Hydrodechlorination of 4-Chlorophenol by Palladium-Based Catalyst Supported on Alumina and Graphene Materials

Hydrodechlorination (HDC) is a reaction that involves the use of hydrogen to cleave the C-Cl bond in chlorinated organic compounds such as chlorophenols and chlorobenzenes, thus reducing their toxicity. In this study, a palladium (Pd) catalyst, which is widely used for HDC due to its advantageous physical and chemical properties, was immobilized on alumina (Pd/Al) and graphene-based materials (graphene oxide and reduced graphene oxide; Pd/GO and Pd/rGO, respectively) to induce the HDC of 4-chlorophenol (4-CP). The effects of the catalyst dosage, initial 4-CP concentration, and pH on 4-CP removal were evaluated. We observed that 4-CP was removed very rapidly when the HDC reaction was induced by Pd/GO and Pd/rGO. The granulation of Pd/rGO using sand was also investigated as a way to facilitate the separation of the catalyst from the treated aqueous solution after use, which is to improve practicality and effectiveness of the use of Pd catalysts with graphene-based support materials in an HDC system. The granulated catalyst (Pd/rGOSC) was employed in a column to induce HDC in a continuous flow reaction, leading to the successful removal of most 4-CP after 48 h. The reaction mechanisms were also determined based on the oxidation state of Pd, which was observed using X-ray photoelectron spectroscopy. Based on the results as a whole, the proposed granulated catalyst has the potential to greatly enhance the practical applicability of HDC for water purification.

Biochar-supported sulfurized nanoscale zero-valent iron facilitates extensive dechlorination and rapid removal of 2,4,6-Trichlorophenol in aqueous solution

Nanoscale zero-valent iron (NZVI) has been widely used in rapid remediation of contaminants. However, several obstacles such as aggregation and surface passivation hampered NZVI from further application. In this study, sulfurized nanoscale-zero valent iron supported by biochar (BC-SNZVI) was successfully synthesized and utilized for highly efficient 2,4,6-Trichlorophenol (2,4,6-TCP) dechlorination in aqueous solution. SEM-EDS analysis revealed the even distribution of SNZVI on the surface of BC. FTIR, XRD, XPS and N₂ Brunauer-Emmett-Teller (BET) adsorption analyses were carried out to characterize the materials. Results showed that BC-SNZVI with S/Fe molar ratio of 0.088, Na₂S₂O₃ as sulfurization agent, and pre-sulfurization as the sulfurization strategy exhibited the superior performance for 2,4,6-TCP removal. The overall removal of 2,4,6-TCP was well described with the pseudo-first-order kinetics (R² > 0.9), and the observed kinetics constant K_obs was 0.083 min^-1 with BC-SNZVI, which was one order of magnitude higher than that of BC-NZVI (0.0092 min^-1) and SNZVI (0.0042 min^-1), and two orders of magnitude higher than that of NZVI (0.00092 min^-1). Moreover, the removal efficiency of 2,4,6-TCP reached 99.5% by BC-SNZVI with dosage of 0.5 g·L^-1, initial 2,4,6-TCP concentration of 30 mg·L^-1 and initial solution pH of 3 within 180 min. The removal of 2,4,6-TCP by BC-SNZVI was acid-promoted and the removal efficiencies of 2,4,6-TCP decreased with the increase of initial 2,4,6-TCP concentrations. Furthermore, more extensive dechlorination of 2,4,6-TCP was achieved with BC-SNZVI and complete dechlorination product phenol became predominant. The facilitation of sulfur for Fe⁰ utilization and electron distribution in the presence of biochar remarkably enhanced the dechlorination performance of BC-SNZVI for 2,4,6-TCP. These findings provide insights into BC-SNZVI as an alternative engineering carbon based NZVI material for treating chlorinated phenols.

Effective biodegradation of chlorophenols, sulfonamides, and their mixtures by bacterial laccase immobilized on chitin

Coexisting multi-pollutants like sulfonamides (SAs) and chlorophenols (CPs) in the ecological environment pose a potential risk to living organisms. The development of a strategy for the effective removal of multiple pollutants has become an urgent need. Herein, we systematically investigated the potential of immobilized bacterial laccase to remove chlorophenols (CPs), sulfonamides (SAs), and their mixtures. Laccase from Bacillus pumilus ZB1 was efficiently immobilized on chitin and its thermal stability, pH stability, and affinity to substrates were improved. Reusability assessment showed the immobilized laccase retained 75.5% of its initial activity after five cycles. The removal efficiency of CPs and SAs by immobilized laccase was significantly improved compared with that of free laccase. In particular, the removal of 2,4-dichlorophenol and 2,4,6-trichlorophenol reached 96.9% and 89.3% respectively within 8 h. The immobilized laccase could remove 63.70% of 2,4-dichlorophenol after four cycles. The degradation pathways of 2,4-dichlorophenol and sulfamethazine were proposed via LC/MS analysis. When the co-pollutants containing 2,4,6-trichlorophenol and sulfamethoxazole, immobilized laccase showed 100% removal of 2,4,6-trichlorophenol and 38.71% removal of sulfamethoxazole simultaneously. Cytotoxicity and phytotoxicity tests indicated that immobilized laccase can alleviate the toxicity of co-pollutants. The results demonstrate that chitin-based laccase immobilization can be an effective strategy for the removal of SAs, CPs, and their co-pollutants.

Sulfurized nano zero-valent iron prepared via different methods: Effect of stability and types of surface corrosion products on removal of 2,4,6-trichlorophenol

Sulfurization improves the stability and activity of nano zero-valent iron (nZVI). The sulfurized nZVI (S-nZVI) were prepared with ball milling, vacuum chemical vapor deposition (CVD) and liquid-phase reduction techniques and the corresponding products were the mixture of FeS₂ and nZVI (nZVI/FeS₂), well-defined core-shell structure (FeS_x@Fe) or seriously oxidized (S-nZVI(aq)), respectively. All these materials were applied to eliminate 2,4,6-trichlorophenol (TCP) from water. The removal of TCP was irrelevant with the structure of S-nZVI. Both nZVI/FeS₂ and FeS_x@Fe showed remarkable performance for the degradation of TCP. S-nZVI(aq) possessed poor mineralization efficiency to TCP due to its bad crystallinity degree and severe leaching of Fe ions, which retarded the affinity of TCP. Desorption and quenching experiments suggested that TCP removal by nZVI and S-nZVI was based on surface adsorption and subsequent direct reduction by Fe⁰, oxidation by in-situ produced ROS and polymerization on the surface of these materials. In the reaction process, the corrosion products of these materials transformed into crystalline Fe₃O₄ and α/β-FeOOH, which enhanced the stability of nZVI and S-nZVI materials and was conductive to the electron transferring from Fe⁰ to TCP and strong affinity of TCP onto Fe or FeS_x phases. All these were contributed to high performance of nZVI and sulfurized nZVI in removal and minerazilation of TCP in continuous recycle test.

Piperazine-linked metal covalent organic framework-coated fibers for efficient electro-enhanced solid-phase microextraction of chlorophenols

Conductive covalent organic frameworks (COFs) have received considerable attention and are critical in various applications such as electro-enhanced solid-phase microextraction (EE-SPME). In this work, a novel piperazine-linked copper-doped phthalocyanine metal covalent organic framework (CuPc-MCOF) was synthesized with good stability and high electrical conductivity. The synthesized CuPc-MCOF was then used as an EE-SPME coating material for extraction of five trace chlorophenols (CPs), including 2,4-dichlorophenol (2,4-DCP), 2,6-dichlorophenol (2,6-DCP), 2,4,6-trichlorophenol (2,4,6-TCP), 2,4,5-trichlorophenol (2,4,5-TCP) and 2,4,5,6-tetrachlorophenol (2,4,5,6-TCP), exhibiting excellent extraction performance because of various synergistic forces between CuPc-MCOF fibers and CPs. By combining EE-SPME with gas chromatography-tandem mass spectrometry (GC-MS/MS), a sensitive method for CPs detection was established with a low limit of detection (0.8-5 ng L^-1) and good reproducibility (RSD≤8.4%, n = 3). This method was then successfully applied to the analysis of trace CPs in real samples of seawater and seafood. Results showed that the developed CuPc-MCOF coating material possessed superior extraction performance and potential application in extraction of trace polar pollutants from complex samples.

N, N'-methylene bisacrylamide/divinyl benzene based-highly cross-linked hybrid monolithic column: Production and its applications for powerful capture of four chlorophenols

In this paper, the role of the halogen bond in capillary monolithic column microextraction was explored for the first time. Benzene-1,3,5-tricarbohydrazide (BTH) was synthesized as a functional monomer, N, N'-methylene bisacrylamide (MBA) and divinyl benzene (DVB) were used as cross-linking agents, the hybrid monolithic column of poly (BTH-co-DVB-co-MBA) was prepared using methanol and polyethylene glycol as pore-forming agents and azodiisobutyronitrile as the initiator. Due to the existence of BTH, a large number of nitrogen atoms (Lewis base) were introduced into the monolithic column, which could form a halogen bond with chlorine-containing organic pollutants and enhance its adsorption performance. Based on the monolithic column, a sensitive and environment-friendly solid-phase microextraction technology was studied. The monolithic column was integrated with high-performance liquid chromatography (HPLC) to extract and detect four kinds of chlorophenol in real water samples. Under best conditions, the method showed excellent extraction ability and linearity, with a linear correlation coefficient of 0.9958-0.9987, a low detection limit (LOD) of 0.04-0.23 μg L^-1 (S/N = 3), and relative standard deviation (RSD) less than 3.09%. The recovery rate was kept between 87.30% and 123.00%, and the RSD was less than 3.83%, which indicated that the column had powerful capture performance, high precision, and strong anti-matrix interference ability in the real sample, and had potential application value in practical work.

Assessment of the inhibition risk of chlorophenol substances on cytochrome P450 via cocktail inhibition assays

Chlorophenols (CPs) are widespread pollutants in nature. CPs have raised significant concern due to their potential hepatotoxic effects on humans. This research aimed to ascertain the inhibitory potential of eleven CPs (2-CP, 3-CP, 4-CP, 2,4-DCP, 2,3,4-TCP, 2,4,5-TCP, 2,4,6-TCP, 2,3,4,5-TeCP, 2,3,4,6-TeCP, 2,3,5,6-TeCP, and PCP) on nine human CYP isoforms (CYP1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4). The CPs that inhibit the activity of CYP isoforms were detected with human liver microsomes (HLM) using a cocktail approach in vitro. The results demonstrated that trichlorophenols, tetrachlorophenols, and PCP strongly inhibited CYP2C8 and CYP2C9. The half inhibition concentration (IC₅₀) value of 2,3,4,6-TeCP and PCP for CYP2C8 inhibition was 27.3 μM and 12.3 μM, respectively. The IC₅₀ for the inhibition of 2,4,6-TCP, 2,3,4,6-TeCP and PCP towards CYP2C9 were calculated to be 30.3 μM, 5.8 μM and 2.2 μM, respectively. 2,3,4,6-TeCP, and PCP exhibited non-competitive inhibition towards CYP2C8. 2,4,6-TCP, 2,3,4,6-TeCP, and PCP exhibited competitive inhibition towards CYP2C9. The inhibition kinetics parameters (Ki) were 51.51 μM, 22.28 μM, 37.86 μM, 7.27 μM, 0.68 μM for 2,3,4,6-TeCP-CYP2C8, PCP-CYP2C8, 2,4,6-TCP-CYP2C9, 2,3,4,6-TeCP-CYP2C9, PCP-CYP2C9, respectively. This study also defined clear structure-activity relationships (SAR) of CPs on CYP2C8, supported by molecular docking studies. Overall, CPs were found to cause inhibitory effects on CYP isoforms in vitro, and this finding may provide a basis for CPs focused on CYP isoforms inhibition endpoints.

Revisiting UV/sulfite exposed to air: A redox process for reductive dechlorination and oxidative mineralization

2,4-Dichlorophenol (2,4-DCP) widely exists in many industrial wastewaters and is considered a priority pollutant due to its high toxicity. In this work, we proposed a UV/sulfite process without aeration for high-efficiency dechlorination and enhanced mineralization. The UV/sulfite system significantly improved the removal of 2,4-DCP (93.33 % in 60 min) and dechlorination rate (85.13 % in 60 min) compared with UV alone and sulfite alone, and the synergistic factor was 6.59. The UV/sulfite system without aeration improved the mineralization rate (49.80 %) compared with the nitrogen aeration system. UV/sulfite was a reduction-oxidation coupled process and was more suitable for neutral and alkaline conditions. Reducing species (hydrated electrons and H^•) made 2,4-DCP dechlorinate to form dechlorination products such as p-chlorophenol (4-CP), o-chlorophenol (2-CP), and phenol, which were further mineralized by oxidized species (SO₄^•-). UV/sulfite remained highly efficient in the presence of coexisting ions and under different water quality conditions. This process was also suitable for removing a wide range of chlorinated organic compounds. The UV/sulfite process without aeration can achieve high dechlorination and enhanced mineralization with simple operation and low cost (1.78 $·m^-3 order^-1), which has a broad and cost-effective application prospect in removing refractory halogenated organic pollutants.

Bimetallic FeO x -MO x Loaded TiO2 (M = Cu, Co) Nanocomposite Photocatalysts for Complete Mineralization of Herbicides

A series of monometallic and bimetallic cocatalyst(s), comprising FeO _x , CuO _x , CoO _x , FeO _x -CuO _x , and FeO _x -CoO _x loaded TiO₂ catalysts prepared by the surface impregnation method, were investigated for the photocatalytic mineralization of the widely used four herbicides: 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP), 2,4-dichlorophenoxyacetic acid (2,4-D), and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). It was found that FeO _x -CoO _x /TiO₂ showed the highest photocatalytic efficiency toward mineralization of selected herbicides. FeO _x -CoO _x /TiO₂ achieves 92% TOC removal in 180 min, representing nearly three time activity of the benchmark PC50 TiO₂. From XPS analysis, FeOOH, CuO, and CoO were determined to be loaded onto the TiO₂ surface. The outstanding photocatalytic performance of the optimized FeO _x -CoO _x /TiO₂ sample for herbicides mineralization is due to an increased charge separation and enhanced hydroxyl radicals production monitored by diverse spectroscopies. Based on the proposed charge transfer mechanism, FeO _x -CoO _x cocatalyst species accelerate the transfer of photogenerated holes on TiO₂, thus facilitating hydroxyl radicals production.

WO3/rGO nanocomposite-based sensor for the detection and degradation of 4-Chlorophenol

Chlorinated organic compounds are useful chemicals or intermediates that are used extensively in both industry and agriculture. The 4-chlorophenol (4CP) in low concentration poses a serious environmental problem and causes many health issues, including cancer and liver disease. In this work, we demonstrated the detection of 4CP at carbon paste electrodes modified using tungsten oxide (WO₃) nanorods and reduced graphene oxide (rGO) nanoparticles. The significance of pH on the voltammetric response of 4CP was investigated, and it was discovered that an alkaline pH is an optimal condition for detecting substituted phenols. Moreover, parameters like heterogeneous rate constant, accumulation time, temperature effect, Gibb's free energy, scan rate, enthalpy, activation energy, and entropy were studied. The excellent catalytic and bulk properties of tungsten oxide nanostructures make it an effective modifier in electrochemical sensors. The employment of nanostructured WO₃ for the assay of 4CP offers excellent sensitivity, selectivity, and applicability. The WO₃ nanostructures are obtained hydrothermally and characterized in detail to understand the crystalline, quantitative and chemical properties. The electrochemical behavior of 4CP was studied utilizing voltammetry techniques. The CV technique was used to optimize and affect many factors in the electrochemical behavior of 4CP. The scan rate investigation helps to examine the physicochemical characteristics of the electrode process, and the electrooxidation of 4CP included 2 electrons and 2 protons. With 4CP, the modified electrode displayed a broad range of linearity. The limit of detection was determined to be 0.102 nM, while the limit of quantification was 0.3433 nM. The concentration of 4CP ranged between 0.1 × 10^-7 M and 3.5 × 10^-7 M. The fabricated electrode was also used to detect 4CP in soil and water samples. Good recoveries were obtained from the soil and water samples. The proposed electrode was used for analytical applications, including 4CP detection with high selectivity, low detection limit, sensitivity, and rapid response.

Laccase-assisted degradation of emerging recalcitrant compounds - A review

The main objective of this review is to provide up to date, brief, irrefutable, organized data on the conducted experiments on a range of emerging recalcitrant compounds such as Diclofenac (DCF), Chlorophenols (CPs), tetracycline (TCs), Triclosan (TCS), Bisphenol A (BPA) and Carbamazepine (CBZ). These compounds were selected from the categories of pharmaceutical contaminants (PCs), endocrine disruptors (EDs) and personal care products (PCPs) on the basis of their toxicity and concentration retained in the environment. In this context, detailed mechanism of laccase mediated degradation has been conversed that laccase assisted degradation occurs by one electron oxidation involving redox potential as underlying element of the process. Further, converging towards biotechnology, laccase immobilization increased removal efficiency, storage and reusability through various experimentally conducted studies. Laccase is being considered noteworthy as mediators facilitate laccase in oxidation of non-phenolic compounds and thereby increasing its substrate range which is being discussed in further in the review. The laccase assisted degradation mechanism of each compound has been elucidated but further studies to undercover proper degradation mechanisms needs to be performed.

Association between trichlorophenols and neurodegenerative diseases: A cross-sectional study from NHANES 2003-2010

PURPOSE OF THE RESEARCH

To evaluate the association of the exposure of trichlorophenols (TCPs) on the morbidity and mortality of patients with Parkinson's disease (PD) and Alzheimer's disease (AD) using the data from the National Health and Nutrition Examination Survey (NHANES) 2003-2010. Multivariable logistic regression models and COX regression were used to evaluate the association between TCP exposure and the AD and PD risk. Least Absolute Shrinkage and Selection Operator (LASSO) methods were used to screen latent covariates.

PRINCIPAL RESULTS

A total of 6333 participants over the age of 18 years were included in the analysis. After the adjustments for major confounders, participants with higher concentrations of urinary 2,4,6-TCP had higher risk of AD (odds ratios (ORs), 3.19; 95% CI: 1.07, 9.45) than the group below the limit of detection (LOD). Compared to group of below the LOD, higher urinary concentrations of 2,4,5-TCP was associated with higher risk of all-cause mortality in PD patients (log-rank P = 0.022) and all participants (log-rank P < 0.001) without adjustments for confounders. In addition, a higher risk of all-cause mortality in all participants with high urinary concentrations of 2,4,6-TCP (log-rank P = 0.001) was found without adjustments for confounders. With the adjustments for major confounders, participants with higher concentrations of urinary 2,4,5-TCP had a higher risk of death in patients with PD (hazard ratios (HRs), 53.19; 95% CI: 2.82, 1004.13) than in the group below the LOD.

MAJOR CONCLUSIONS

Exposure to high concentration of 2,4,6-TCP may increase the risk of AD, and the level of 2,4,5-TCP may be associated with the risk of death in patients with PD. Our findings reveal the potential toxicity of TCPs, highlight the potential impact of TCPs on neurodegenerative diseases, and express concerns regarding the use of organochlorine pesticides.