Search Results (102)

Chlorophenols (CPs), such as 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP), are persistent and toxic organic pollutants commonly found in industrial effluents. This study investigates their photocatalytic degradation using a TiO₂-based heterogeneous catalyst under UV irradiation, in the presence of hydrogen peroxide. The degradation kinetics were analyzed using both pseudo-first order and nonlinear Langmuir–Hinshelwood (L–H) models, accounting for competitive adsorption and successive oxidation of intermediates. Gas chromatography–mass spectrometry (GC–MS) identified key intermediates, including hydroquinone, catechol, chlorocatechols, and benzoquinone. Nonlinear kinetic modeling of coupled differential equations accurately reproduced the temporal profiles of both the parent compounds and their intermediates, providing mechanistic insights into multi-step hydroxylation, dechlorination, and oxidation processes. The results demonstrate that photocatalytic oxidation effectively mineralizes chlorophenols within 500–600 min, and the developed kinetic model offers a predictive tool for optimizing photocatalytic remediation strategies for chlorinated aromatic pollutants. The novelty of this study lies in the development of a nonlinear Langmuir–Hinshelwood kinetic model integrating experimentally identified degradation intermediates, competitive adsorption phenomena, and parallel photocatalytic reaction pathways for both 4-chlorophenol and 2,4-dichlorophenol oxidation systems. Full article

Industrial and municipal wastewater may contain substances that inhibit biological processes in wastewater treatment plants (WWTPs), posing risks to operational stability and environmental protection. The aim of this study is to evaluate the practical suitability of the ISO 8192:2007 respiration inhibition test for assessing the toxicity of wastewater. Nitrified activated sludge from a municipal WWTP was used to analyze wastewater from three industrial companies, wastewater from several discharge locations at a hospital, and WWTP influent. Oxygen consumption and inhibition were determined at sample-specific dilution levels and the reference substance 3,5-dichlorophenol. Two samples from the dental department of the hospital showed toxic effects on activated sludge respiration (inhibition > 50%), while no toxic effects were observed in the remaining samples. Several samples exhibited stimulatory effects (inhibition < 0%), indicating the presence of readily biodegradable organic matter. However, inhibitory effects (0–50% inhibition) were detected in individual wastewater samples at higher concentrations. This demonstrates that the method can detect toxicological changes in wastewater and is suitable for routine monitoring and early warning in WWTPs. Full article

Two novel cocrystals of zwitterionic trimethylglycine (TMG) with 2,6-dichlorophenol [TMG•2,6-dichlorophenol] (1:1) and 2,6-dibromophenol [TMG•2,6-dibromophenol] (1:2) are synthesized and structurally characterized using single crystal X-ray diffraction. To estimate the energy of various intermolecular interactions, periodic DFT calculations were performed followed by Bader analysis of the crystalline electron density. TMG molecules form dimers in [TMG•2,6-dichlorophenol] (1:1). Its supramolecular structure is governed by the primary charge-assisted H-bonds (~60 kJ/mol) and supported by C–H∙∙∙O contacts (~12 kJ/mol). Cl/Br substitution introduces a more potent halogen-bonding donor. The Br∙∙∙O⁻ interaction (~10 kJ/mol) is strong enough to reorganize the packing into a catemeric motif. As a result, TMG molecules form infinite chains in [TMG•2,6-dibromophenol] (1:2). This illustrates that “fine tuning” is not merely about changing distances, but about shifting the entire energy hierarchy of the crystal. Two-dimensional fingerprint diagrams (2D diagrams) obtained from the Hirshfeld surface and Bader’s analysis of the crystalline electron density give significantly different values of the contributions of the H∙∙∙H contacts, 28% vs. 5% respectively. The main reason for this discrepancy is the large number of relatively short intermolecular H∙∙∙H contacts without a critical bond point in trimethylglycine cocrystals. Full article

The oxidation of chlorophenolic compounds is essential for converting these persistent and toxic pollutants into less harmful products, thereby reducing their environmental and health impacts. In this study, a p-coumaric acid ester derivative was employed as the starting material to synthesize the corresponding phthalonitrile precursor (EnCA-CN), followed by the preparation of non-peripherally substituted Co(II) and Cu(II) phthalocyanine complexes (EnCA-Copc and EnCA-CuPc). These complexes were subsequently characterized using a range of spectroscopic techniques and designed to engage in π–π interactions with graphitic carbon nitride to form efficient photocatalytic materials. The structures of the two effective catalysts were characterized by FT-IR, SEM, and XRD analyses, after which their photocatalytic performance and recyclability in the degradation of 2-chlorophenol, 2,3-dichlorophenol, and 2,3,6-trimethylphenol were evaluated. The optimum catalyst loading for the MPc/g-C₃N₄ composites was determined to be 0.5 g/L, yielding the highest photocatalytic efficiency. The EnCA-CoPc/g-C₃N₄ catalyst achieved 90.8% product selectivity and 82.6% conversion in the oxidation of 2-chlorophenol, whereas the EnCA-CuPc/g-C₃N₄ catalyst exhibited approximately 80.0% pollutant removal. The degradation efficiencies followed the order 2-CP > 2,3-DCP > 2,3,6-TCP, with benzoquinone derivatives identified as the major oxidation products. In recyclability tests, both catalysts retained more than 50% of their activity after five cycles; EnCA-CoPc/g-C₃N₄ maintained 68% conversion in the 5th cycle, while EnCA-CuPc/g-C₃N₄ retained 60% conversion in the 4th cycle. Full article

Detailed studies were conducted on the photooxidation of salicylic acid (SA) in the presence of sodium hypochlorite (NaOCl), which is important in the context of water disinfection processes. It was shown that NaOCl alone causes slow degradation of SA (<10% after 60 min), while its combination with UV radiation significantly increases the efficiency of the process, especially at pH 7.5–10 (up to 30% degradation in 60 min). Eleven chlorinated transformation products have been identified, including 2,6-dichlorophenol and 2,4,6-trichlorophenol, which are characterized by high environmental persistence (>96 days) and the ability to travel distances exceeding 4000 km. QSAR analyses and ecotoxicological tests (Microtox^®, Daphtoxkit F^®, Lemna sp.) confirmed the significant toxicity of some compounds to fish, daphnia, and algae. It was found that the post-reaction mixture after the NaOCl/UV process exhibits higher toxicity than SA photolysis alone, indicating a significant contribution of chlorinated intermediates to environmental risk. The results highlight the need to develop alternative methods for removing pharmaceuticals that minimize the formation of persistent and toxic by-products, and indicate directions for further research on their monitoring in the aquatic environment. Full article

The activation of persulfate (PS) to oxidize and degrade 2,4-dichlorophenol (2,4-DCP) in aqueous solution represents a prevalent advanced oxidation technology. This study established a PS activation system using sulfide-modified nanoscale zero-valent iron supported on biochar (S-nZVI@BC). The optimal conditions included a PS:2,4-DCP mass ratio of 70:1 and S-nZVI@BC:PS of 1.5:1. The activator had excellent stability after being reused five times, which lead to high cost-effectiveness and sustainable usability. This system exhibited broad pH adaptability (3–11), with enhanced efficiency under acidic/neutral conditions. Chloride ion, nitrate, and carbonate had effects during the degradation. During the initial degradation phase, S-nZVI@BC played a primary role, with a greater contribution rate of adsorption than reduction. Fe⁰ played a dominant role in the PS activation process; reactive species—including HO•, SO₄•⁻, and O₂•⁻—were identified as key agents in subsequent degradation stages. The overall degradation processes comprised three distinct stages: dechlorination, ring-opening, and mineralization. Full article

2,2′,4,4′-Tetrabromodiphenyl ether (BDE-47) is a refractory organic pollutant that is characterized by its persistence, toxicity and potential for bioaccumulation. As a typical biocontrol bacteria, Pseudomonas protegens has not been reported to degrade organic pollutants in the environment. A single strain of Pseudomonas protegens was isolated and acclimated from municipal sludge, and its ability to degrade BDE-47 was investigated. The enhancing effects of different carbon sources and inducers on Pseudomonas protegens were also examined. Through the reinforcement of bacterial enhancers, Pseudomonas protegens was applied to remediate soil and water contaminated with BDE-47. Based on colony characteristics, physiological and biochemical properties, and 16S rDNA gene sequence homology analysis, the strain was identified as Pseudomonas protegens and named YP1. This marks the first discovery of Pseudomonas protegens being capable of degrading BDE-47. Strain YP1 utilized BDE-47 as a carbon source and achieved a degradation rate of 69.57% after 75 h of incubation under conditions of 37 °C, pH 7, and constant temperature in a dark shaking incubator. After comparing the actual enhancement effects, glucose was selected as the carbon source and 2,4-dichlorophenol as the inducer to improve the environmental remediation capability of Pseudomonas protegens. After 14 days of remediation, the degradation rates of BDE-47 in contaminated soil and water reached 48.26% and 52.60%, respectively. The Pseudomonas protegens strain obtained from municipal sludge through screening, acclimation, and enhancement processes exhibits excellent environmental remediation capabilities and promising practical application prospects. Full article

Biocatalytic nanomembranes have emerged as promising platforms for micropollutant remediation, yet their practical application is hindered by limitations in removal efficiency and operational stability. This study presents an innovative approach for fabricating highly stable and efficient biocatalytic nanomembranes through the co-immobilization of horseradish peroxidase (HRP) and glucose oxidase (GOx) within a covalent organic framework (COF) nanocrystal. Capitalizing on the dynamic covalent chemistry of COFs during their self-healing and self-crystallization processes, we achieved simultaneous enzyme immobilization and framework formation. This unique confinement strategy preserved enzymatic activity while significantly enhancing stability. HRP/GOx@COF biocatalytic membrane was prepared through the loading of immobilized enzymes (HRP/GOx@COF) onto a macroporous polymeric substrate membrane pre-coated with a polydopamine (PDA) adhesive layer. At HRP and GOx dosages of 4 mg and 4.5 mg, respectively, and a glucose concentration of 5 mM, the removal rate of bisphenol A (BPA) reached 99% through the combined functions of catalysis, adsorption, and rejection. The BPA removal rate of the biocatalytic membrane remained high under both acidic and alkaline conditions. Additionally, the removal rate of dyes with different properties exceeded 88%. The removal efficiencies of doxycycline hydrochloride, 2,4-dichlorophenol, and 8-hydroxyquinoline surpassed 95%. In this study, the enzyme was confined in the ordered and stable COF, which endowed the biocatalytic membrane with good stability and reusability over multiple batch cycles. Full article

This study discussed the influence of acetate and sodium chloride concentration on monitoring 2,4-dichlorophenol(2,4-DCP) by electroactive bacteria. The performance of the reactor was represented by power density, and the electrochemical activity was represented by redox capacity. At the same time, micro-electrodes were used to detect the redox potential between biofilms, and the changes in extracellular polymers and microbial community structure under different conditions were also explored. With acetate concentration of 1 g/L and sodium chloride concentration of 0.0125 g/L, the electroactive microorganisms were more sensitive to toxic substances and responded fast. The biofilm also evenly covered on the surface of the carrier, which aided in the diffusion of substances. Although the maximum power density monotonically increased with acetate concentration, high concentration of substrate may mask the inhibitory effect and affect the judgment of inhibitory results. The content of protein and polysaccharide increased monotonically with sodium chloride concentration. However, more polysaccharides would lead to high resistance to electron transfer. Compared to sodium chloride, the microbial content was more affected by acetate. The electroactive microorganisms had strong adaptability to salinity. In practical application, it is conducive to increase the sensitivity of MFCs to reasonably reduce the concentration of acetic acid and sodium chloride. Full article

Mismanagement of rural wastewater can lead to environmental contamination with the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). Fungi with bioremediating potential constitute a sustainable alternative to decontaminate such wastewater before its reuse. This study evaluated the ability of Aspergillus oryzae pellets to remove 2,4-D from natural and sterile rural wastewater (i.e., with/without native microbiota). The pellets were produced by incubating conidial solutions of A. oryzae strains RCA2, RCA4, RCA5, and RCA10 in synthetic wastewater for 21 days at 25 °C. The wastewater samples were characterized physicochemically and microbiologically upon arrival at the laboratory. Afterwards, they were supplemented with 1, 2.5, or 5 mmol L⁻¹ of 2,4-D and inoculated with the pellets. Physicochemical characterization was repeated throughout the experiment. Herbicide removal and the presence of 2,4-D degradation intermediate, 2,4-dichlorophenol (2,4-DCP), were assessed through high-pressure liquid chromatography with UV/Vis detection (HPLC-UV) and mass spectrometry. At the beginning of the assay, the macro- and micronutrient content in the samples were suitable to sustain fungal growth. By the end, pH had increased and sodium and nitrate levels decreased in comparison with the control. RCA2, RCA4, and RCA10 removed over 80% of 2,4-D after 7 days of incubation, at the three herbicide concentrations tested. Moreover, wet fungal biomass had increased by the end of the assay. These findings demonstrate that RCA2, RCA4, and RCA10 can grow, form pellets, and remove 2,4-D in natural rural wastewater, which makes them potential candidates for bioremediation strategies aimed at improving the quality of water set to be reused. Full article

Copper nanoparticles (CuNPs) are increasingly used in agriculture either alone or in combination with pesticides. Recognizing the potential hazards of CuNPs in soil environments, our study evaluated their effects on the metabolic activity of Nitrobacter winogradskyi ATCC 2539, a chemolithoautotrophic bacterium crucial for the nitrification process, which involves the oxidation of nitrite to nitrate in soil ecosystems. This study evaluated the effects of concentration ranges of CuNPs (2.5 to 162.7 mg L⁻¹), CuONPs (3.2 to 203.6 mg L⁻¹), and various pesticides (iprodione, carbendazim, and 2,4-D) and their derivatives (3,5-dichloroaniline, catechol, and 2,4-dichlorophenol) at concentrations ranging from 0.04 to 2.56 mM. CuSO₄ was also used as a control for comparative purposes. Our findings indicated that the CuNPs significantly inhibited the metabolic activity of N. winogradskyi, resulting in a reduction of up to 95% at concentrations of ≥2.5 mg L⁻¹. The CuONPs were less toxic, while the pesticides and their derivatives generally showed lower toxicity. Notably, combinations of CuNPs with pesticides or their derivatives maintained high toxicity levels comparable to those of the CuNPs alone. According to the Loewe additivity model, these effects were largely additive and primarily associated with CuNPs or CuONPs. Protein profiling using matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF)/TOF mass spectrometry (MS) revealed that carbendazim induced noticeable changes in protein profiles. These findings underscore the detrimental impacts of CuNPs and CuONPs on the metabolic activity of N. winogradskyi, posing a considerable risk to the health of agricultural soils. Overall, this research provides crucial insights into the risks associated with using CuNPs in agriculture, particularly regarding their potential threat to nitrifying microorganisms in soils. Full article

Peroxymonosulfate (PMS)-based advanced oxidation technology has emerged as an effective means for removing organic pollutants from water due to its strong oxidizing ability. However, enhancing the activation efficiency of PMS represents a key challenge at present. SrTiO₃, a typical perovskite metal oxide, holds potential in the field of the photocatalytic degradation of pollutants, yet its application is limited by the wide bandgap and fast carrier recombination rates. This study optimized the photocatalytic performance of SrTiO₃ by regulating its electronic structure and optical properties through cobalt (Co) doping. Experimental results (TRPL, TPV, UV–Vis DRS, ESR, etc.) and DFT calculations (GGA-PBE) demonstrated that Co doping shifted the d-band center of SrTiO₃ upwards, optimized the adsorption energy of SO₄⁻, enhanced the sunlight response range, and significantly improved carrier extraction efficiency. Under visible light irradiation, 2,4-dichlorophenol (2,4-DCP) could be effectively degraded within 60 min in a wide pH range. Through Fukui function calculation (B3LYP/6-31G*) and experimental characterization analysis (HPLC-MS and IC), the possible degradation pathways of 2,4-DCP and the mechanism for photocatalysis were investigated. The toxicity analysis (T.E.S.T) confirmed the reduced toxicity of the degradation products of 2,4-DCPs. This study provides a reference for the catalyst design and optimization strategy of PMS-based advanced oxidation technology. Full article

This study presents a microbial sensing device that employs a poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) matrix to immobilize viable and metabolically Escherichia coli cells. This device enables the monitoring of microorganism metabolic activity in response to external stimuli such as variations in carbon sources or exposure to inhibitory or toxic compounds. PEDOT:PSS, a conductive and chemically stable polymer, was electrodeposited onto screen-printed electrodes, successfully entrapping approximately 1.26 × 10⁷ cells per electrode. The confocal microscopy of Live/Dead-stained samples confirmed a uniform cell distribution and an average viability of ~78%. Ferricyanide respirometry validated the metabolic activity of the immobilized cells. The biosensor’s performance was evaluated using 3,5-dichlorophenol (3,5-DCP) as a reference toxicant. The observed inhibition of microbial activity correlated with 3,5-DCP concentration, yielding a half-maximal effective concentration (EC₅₀) of 9 ppm, consistent with the literature values. Full article

Background: Chemosensation in ticks opens a novel and unique field for scientific research. This study highlights ticks’ chemosensory system to comprehend its host-searching behavior and other integrated chemistry and biology involving Haller’s structure. Methodology: This study combines microanatomical, electrophysiological, and behavioral experiments to investigate the role of Haller’s organ in adult ticks in response to different classes of organic compounds. Results: We showed the microscopic anatomy of Haller’s organ in Haemaphysalis darjeeling, present at the terminal segment of the first pair of appendages. Haller’s structure serves a vital function in perceiving odor. The electrophysiological activity of adult ticks to different classes of organic compounds via electroscutumography was explored at five different concentrations: w/v 0.001, 0.01, 0.1, 1.0, and 2.0%. Among 55 organic compounds, moderate to high stimulation was recorded with pyruvate (13.28 mv at 2%), ammonia (12.26 mv at 2%), benzoic acid (1.99 mv at 0.001%), isobutyric acid (1.39 mv at 0.001%), 2,6-dichlorophenol (1.34 mv at 0.001%), p-Tolualdehyde (1.26 mv at 2%), tetradecane (1.23 mv at 2%), docosane (1.17 mv at 2%), citronellal (1.13 mv at 0.1%), isopropyl acetate (1.05 mv at 0.01%), cyclohexanol (1.03 mv at 2%), 1-octane-3-ol (1.02 mv at 2%), and 1-octanol (1.01 mv at 0.001%). Olfactometric bioassays at w/v 2.0% concentration further confirmed that ammonia, pyruvate, 1-octane-3-ol, hematin porcine, p-Tolualdehyde, methyl salicylate, uric acid, tetradecane, carbon dioxide, propanoic acid, 3-hexanol, hexanoic acid, adenine, 2,6-dichlorophenol, hexadecane, heptanoic acid, pentanoic acid, octadecane, guanine, and nonanoic acid acted as strong attractants, while citronellal, eugenol, butyric acid, geraniol, benzaldehyde, and tiglic aldehyde showed an active repellent effect against the tick species. Conclusions: This investigation provides knowledge of the olfactory sensilla of Haller’s structure as biosensors behind tick olfaction and the possibility for chemical detection of diverse attractants and repellents for future development of anti-tick compounds. Full article

Rapid industrialization has escalated environmental pollution caused by organic compounds, posing critical challenges for wastewater treatment. Advanced oxidation processes based on peroxymonosulfate (PMS) suffer from metal leaching and catalyst recycling challenges. To address these limitations, this study developed a nitrogen-doped biochar aerogel (NBA) derived from poplar wood powder as an eco-friendly and easily recoverable PMS activator. The NBA catalyst, optimized by tuning the calcination temperature to achieve a specific surface area of 297.5 m² g⁻¹, achieved 97% bisphenol A (BPA) removal within 60 min with a catalyst dosage of 0.3 g/L and 1.0 mM PMS under mild conditions. The material exhibited broad pH adaptability (pH 3.5–9), recyclability (>94% efficiency after thermal treatment), and versatility in degrading seven pollutants (BPA, phenol, 4-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, rhodamine 6G, and levofloxacin) through synergistic radical (•OH, SO₄^•−, O₂^•−) and non-radical (¹O₂) pathways. X-ray photoelectron spectroscopy (XPS) analyses revealed that nitrogen doping enhanced PMS activation by optimizing electronic structures. This study highlights the potential of waste biomass-derived carbon aerogels as eco-friendly, efficient, and reusable catalysts for advanced oxidation processes in wastewater treatment. Full article