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This study employs density functional theory to investigate whether asymmetric uranyl‐Salophen catalyzes the activation of 2,4‐dichlorophenol, 2,4,6‐trichlorophenol, and pentachlorophenol. Changes in various important parameters such as bond lengths, Wiberg bond indices, infrared vibrational absorption spectra, natural charge distributions, ultraviolet–visible absorption spectra, and 13C NMR chemical shifts of the aromatic rings of chlorophenols before and after forming complexes with asymmetric uranyl‐Salophen are analyzed. This means that asymmetric uranyl‐Salophen indeed activates 2,4‐dichlorophenol, 2,4, 6‐trichlorophenol, and pentachlorophenol, significantly lengthening the aromatic ring bonds of the three chlorophenols and increasing the electrophilicity of the carbon atoms in the aromatic ring. This suggests that the conjugated system of the aromatic ring is also partially disrupted, indicating that these three chlorophenols are indeed catalytically activated. Furthermore, this implies that this asymmetric uranyl‐Salophen may be used to degrade chlorophenols in water. [ABSTRACT FROM AUTHOR]

A method for obtaining effervescent tablets, consisting of magnetic carbon, tartaric acid, sodium carbonate and sodium bicarbonate, and their use for the adsorption of dichlorophenoxycarboxylic acids (DCPA)—2,4-dichlorophenoxyacetic, 2,4-dichlorophenoxypropionic and 2,4-dichlorophenoxybutyric acids and their metabolites—2,4-dichlorophenol and 4-chlorophenol is proposed. The tablets are immersed in an analyzed solution with a neutral reaction medium. To analyze soils, extraction with an alkali solution followed by the neutralization of the extract is carried out. After CO2 separation is completed, the sorbent is removed with a neodymium magnet and the analytes are desorbed with acetone. The acetone extract is evaporated under a stream of nitrogen, and the concentrate is analyzed by gas chromatography–mass spectrometry. The method was tested on model systems—samples of river water and typical chernozem, which were artificially contaminated with DCPA and chlorophenols (CP). In analyzing river waters, the limits of determination for DCPA are 0.7–0.9 μg/L, for CP—40 ng/L. In soils, the limit of detection is 3–4 and 0.1 μg/kg for DCPA and CP, respectively. [ABSTRACT FROM AUTHOR]

Catalytic dechlorination of organic chlorides by palladium (Pd) with HCOOH represents one of the most effective and promising techniques for environmental remediation. In this study, we adopted alkaline-modified porous natural sponge as support of a Pd nanocatalyst (Pd@M-Sponge) and HCOOH as a hydrogen source for the hydrodechlorination of florfenicol (FF), o-chlorophenol (o-CP), and p-chlorophenol (p-CP). Favorable conversion efficiency of FF, o-CP, and p-CP was achieved at 25 °C and atmospheric pressure attributed to the small diameter and high catalytic reactivity of the prepared Pd NPs, in addition to the slight internal mass transfer limitation of the prepared Pd@M-Sponge. High reaction rate constants were obtained even in the conditions of a low molar ratio of HCOOH to p-CP (10:1) and a high concentration of p-CP (500 mg/L). The prepared catalyst also demonstrated superior recyclability without any obvious decrease in catalytic reactivity in 20 successive p-CP dechlorination cycles. This work provides an ideal recyclable and cost-effective catalyst based on renewable and biocompatible natural material for the catalytic hydrodechlorination of chlorinated organic pollutants with formic acid and a new view for the exploration and designing of highly reactive and stable catalysts for hydrodechlorination. [ABSTRACT FROM AUTHOR]

Context: Dioxins, specifically 2,3,7,8-tetrachlorinated dibenzo-p-dioxin (TCDD), are highly toxic dioxins known for their severe health impacts and persistent environmental pollutants. This study focuses on understanding the formation pathways of TCDD from its precursor molecule 2,4,5-trichlorophenol (2,4,5-TCP). In our exploration of reaction pathways from 2,4,5-trichlorophenol (TCP), we delve into three reaction mechanisms: free-radical, direct condensation, and anionic. Our findings highlight the significance of the radical mechanism, particularly propagated by H radicals, with a notable increase in dioxin formation around 900 K. These results are consistent with experimental observations indicating an increase in the conversion of trichlorophenol from 600 to 900 K in the non-catalytic gas phase reaction. Thermodynamic parameters (∆H, ∆S, and ∆G), reaction barriers, and rate constants (k) were calculated across a temperature range of 300–1200 K to support the findings and provide insights into the optimal temperature range for controlling dioxins during the incineration process. Method: In this study, quantum chemical calculations were conducted using density functional theory (DFT) with the B3LYP functional and the 6–311 + + G(d,p) basis set in Gaussian 16 software. Stationary points, including transition states (TS), were confirmed with frequency calculations. Intrinsic reaction coordinate (IRC) calculations ensured minimum energy paths between TS and products, visualized in GaussView 6.0 Program. Single-point energy calculations utilized a more precise basis set, 6–311 + + G(3df,2p), for enhanced energy accuracy, incorporating zero-point vibrational energy (ZPE) and other energy corrections. These calculations were repeated over a temperature range of 298.15–1200 K at 1 atm pressure. Finally, rate constant (k) expressions associated with TCDD formation were determined using transition state theory (TST). [ABSTRACT FROM AUTHOR]

In this study, we evaluated the potential of Lantana camara L. (L. camara L.) fruit extract as a biogenic mediator for the synthesis of enzyme-rich zinc oxide nanoparticles (EZnO) aimed at the detoxification of phenol and its derivatives. The protein extraction yielded a maximum concentration in the 80 % cut fraction, with a protein concentration of 0.96 μg/ml. The highest peroxidase enzyme activity was measured at 41 U/min at 80 % cut using a 250 μg protein concentration, while the highest polyphenol oxidase activity of 7.16 μg/ml was observed in the 40 % cut fraction. The synthesis of EZnO nanoparticles was confirmed through a visible color change and UV–visible spectroscopy with a distinctive absorbance peak at 307. 40 nm. X-ray diffraction (XRD) analysis at 2θ angle indicated the crystalline structure of the nanoparticles, with characteristic peaks corresponding to the planes of the ZnO crystal lattice. Fourier-transform infrared spectroscopy (FTIR) characterization revealed the embedding of the peroxidase enzyme within the nanoparticles, evidenced by absorbance peaks at 1708.62 cm−1 corresponding to amide I, 1604.48 cm−1 corresponding to amide II, and 1380 cm−1 corresponding to amide III. Similarly, the presence of polyphenol oxidase was indicated by absorbance peaks at 3185.83 cm−1 and 2981.41 cm−1. Transmission electron microscopy (TEM) analysis showed the nanoparticles exhibited polydispersity with a size range of 10–100 nm, with an agglomerated morphology, suggesting successful enzyme-nanoparticle hybridization. The histogram was constructed based on the counting of nanoparticles with size which showed highest number of nanoparticles were in the range of between 10 and 20 nm. The BET analysis showed a surface area of 225.1 m2/g. The EZnO nanoparticles demonstrated effective detoxification capabilities, achieving 86 % removal of synthetic phenol, 63 % removal of synthetic 2-chlorophenol, and 69 % removal of their mixture within 24 h. These findings highlights the potential of L. camara L. fruit extract and EZnO nanoparticles for application in the detoxification of hazardous pollutants, offering a sustainable and efficient approach to environmental remediation.

The research on developing a purification technology for 2,4-dichlorophenol (2,4-DCP) polluted water with high efficiency and the low energy consumption is crucial for achieving several Sustainable Development Goals (SDGs). In order to achieve these goals, MWCNTs-Pd/Fe nanocomposites were prepared by Fe nanoparticles modified with multi-walled carbon nanotubes (MWCNTs) and palladium (Pd) in the presence of ultrasonic irradiation. The MWCNTs-Pd/Fe nanocomposites were characterized by using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and X-Ray Diffraction (XRD), and others. Characterization results confirmed that the MWCNTs-Pd/Fe was successfully prepared, with the particle size of 80 nm and the specific surface area of 89.5 m2/g confirmed. We studied the reductive dechlorination of 2,4-Dichlorophenol (2,4-DCP) by MWCNTs-Pd/Fe nanocomposites under different conditions, and the optimized experimental results were found when the Pd loading was 0.4 %, the pH was 3, and the temperature was 30 °C. The phenol yield increased from 76.5 % (without ultrasonic irradiation) to 92.3 % (with ultrasonic irradiation) in 300 min and the 2,4-DCP removal rate reached 98.7 % under the optimal conditions. Therefore, ultrasonic irradiation enhanced the performance of MWCNTs-Pd/Fe nanocomposites for 2,4-DCP removal. We also established the degradation mechanism of chlorophenol by analyzing the intermediates, and proposed the degradation kinetics model. The degradation of 2,4-DCP followed the pseudo-first-order kinetics with the rate constant of 0.05988 min−1. Also, this study demonstrated the potential of using ultrasonic irradiation to improve the properties and recovery of MWCNTs-Pd/Fe nanocomposites, contributing to achievement of the Sustainable Development Goals (SDGs), including SDG-3, SDG-6.

Chlorophenols and their derivatives are persistent environmental pollutants, posing a threat to terrestrial and aquatic life. The biological approach for eliminating toxic contaminants is an effective, sustainable, and environmental friendly method. In this study, the crude enzymes present in the secretome of white-rot fungus (Pycnoporus sp.) were explored for the degradation of 2-chlorophenol. The activity of ligninolytic enzymes in the secretome was analyzed and characterized for their kinetics and thermodynamic properties. Laccase and manganese peroxidase were prevalent ligninolytic enzymes and exhibited temperature stability in the range of 50–65 °C and pH 4–5, respectively. The kinetic parameters Michaelis constant (Km) and turnover number (Kcat) for Lac were 42.54 μM and 45 s−1 for 2,2′-azino-bis (3-ethylben- zothiazoline-6-sulfonic acid), and 93.56 μM and 48 s−1 towards 2,6-dimethoxyphenol whereas Km and Kcat for MnP were 2039 μM and 294 s−1 for guaiacol as substrate. Treatment with the crude enzymes laccase and manganese peroxidase results in the reduction of 2-chlorophenol concentration, confirmed by UV–visible absorption spectra and high-performance liquid chromatography analysis. The detoxification of 2-chlorophenol into less toxic forms was confirmed by the plate toxicity assay. This study demonstrated that crude enzymes produced by Pycnoporus sp. could potentially minimize the toxicity of phenolic compounds in a sustainable way. [ABSTRACT FROM AUTHOR]

In this work, we prepared an eco-friendly, simple, stable new adsorbent SA-Bn-TiO2 NPs hydrogel and Comparative between SA-Bn-TiO2 NPs, SA-Bn, and TiO2 NPs surfaces as adsorbents. The best results of the percentage of removal (E%) of two pollutants including Amoxicillin (AMX) and 4-chlorophenol (CPH) arranged in the order of increasing as SA-Bn-TiO2 NPs > SA-Bn > TiO2 NPs. The good results of the percentage of removal (E%) of SA-Bn-TiO2 NPs were 87.56% and 82.56 for AMX and CPH at the same order. Kinetics adsorption models of two pollutants on SA-Bn-TiO2 NPs was studied and modelled utilizing three adsorptions kinetic. The classification of the kinetic models according to the simulation of the adsorption study is pseudo first order < pseudo-second order > chemisorption. Recyclability and desorption studies indicated the better reusing performance of the prepared composite. Based on the results, the prepared nano-composites can be useful as a promising, cost-effective, environmentally friendly, and efficient material for pollutant decontamination. Studies was carried out utilizing several desorption agents at various concentrations (0.01, 0.05 and 0.1 N) including HNO3, H2SO4, HCl, NaOH, H3PO4, ethanol, acetone and water. The SA-Bn-TiO2 NPs was regeneration with 100% using water. [ABSTRACT FROM AUTHOR]

Biological toxicity testing plays an essential role in identifying the possible negative effects induced by substances such as organic pollutants or heavy metals. As an alternative to conventional methods of toxicity detection, paper-based analytical device (PAD) offers advantages in terms of convenience, quick results, environmental friendliness, and cost-effectiveness. However, detecting the toxicity of both organic pollutants and heavy metals is challenging for a PAD. Here, we show the evaluation of biotoxicity testing for chlorophenols (pentachlorophenol, 2,4-dichlorophenol, and 4-chlorophenol) and heavy metals (Cu2+, Zn2+, and Pb2+) by a resazurin-integrated PAD. The results were achieved by observing the colourimetric response of bacteria (Enterococcus faecalis and Escherichia coli) to resazurin reduction on the PAD. The toxicity responses of E. faecalis-PAD and E. coli-PAD to chlorophenols and heavy metals can be read within 10 min and 40 min, respectively. Compared to the traditional growth inhibition experiments for toxicity measuring which takes at least 3 h, the resazurin-integrated PAD can recognize toxicity differences between studied chlorophenols and between studied heavy metals within 40 min. [ABSTRACT FROM AUTHOR]

Abstract Background 2,4-Dichlorophenol (2,4-DCP) is a very toxic aromatic compound for humans and the environment and is highly resistant to degradation. Therefore, it is necessary to develop efficient remediation and cost-effective approaches to this pollutant. Microbial enzymes such as laccases can degrade phenols, but limited information is known about immobilized bacterial laccase and their reuse. Methods Immobilization of marine halophilic Bacillus subtilis AAK cultures via entrapment and adsorption techniques and degradation of different phenolic compounds by immobilized cells were estimated. Partial purification and immobilization of laccase enzymes were carried out. In addition, the biodegradation of 2,4-DCP and others contaminated by wastewater was investigated. Results Immobilization of cells and partially purified laccase enzymes by adsorption into 3% alginate increased 2,4-DCP biotransformation compared with free cells and free enzymes. In addition, the reuse of both the immobilized culture and laccase enzymes was evaluated. The highest removal of 2,4-DCP from pulp and paper wastewater samples inoculated by immobilized cells and the immobilized enzyme was 90% and 95%, respectively, at 50 h and 52 h of incubation, compared to free cells and free enzyme. Conclusion The results of this study have revealed the immobilization of a biocatalyst and its laccase enzyme as a promising technique for enhancing the degradation of 2,4-DCP and other toxic phenolic and aromatic compounds. The reuse of the biocatalyst and its laccase enzyme enabled the application of this cost-effective bioremediation strategy.

This article aimed to compare the degradation efficiencies of different reactants applicable for the oxidative or reductive degradation of a chlorinated anionic azo dye, Mordant Blue 9 (MB9). In this article, the broadly applied Fenton oxidation process was optimized for the oxidative treatment of MB9, and the obtained results were compared with other innovative chemical reduction methods. In the reductive degradation of MB9, we compared the efficiencies of different reductive agents such as Fe0 (ZVI), Al0, the Raney Al-Ni alloy, NaBH4, NaBH4/Na2S2O5, and other combinations of these reductants. The reductive methods aimed to reduce the azo bond together with the bound chlorine in the structure of MB9. The dechlorination of MB9 produces non-chlorinated aminophenols, which are more easily biodegradable in wastewater treatment plants (WWTPs) compared to their corresponding chlorinated aromatic compounds. The efficiencies of both the oxidative and reductive degradation processes were monitored by visible spectroscopy and determined based on the chemical oxygen demand (COD). The hydrodechlorination of MB9 to non-chlorinated products was expressed using the measurement of adsorbable organically bound halogens (AOXs) and controlled by LC–MS analyses. Optimally, 28 mol of H2SO4, 120 mol of H2O2, and 4 mol of FeSO4 should be applied per one mol of dissolved MB9 dye for a practically complete oxidative degradation after 20 h of action. On the other hand, the application of the Al-Ni alloy/NaOH (100 mol of Al in the Al-Ni alloy + 100 mol of NaOH per one mol of MB9) proceeded smoothly and seven-times faster than the Fenton reaction, consumed similar quantities of reagents, and produced dechlorinated aminophenols. The cost of the Al-Ni alloy/NaOH-based method could be decreased significantly by applying a pretreatment with Al0/NaOH and a subsequent hydrodechlorination using smaller Al-Ni alloy doses. The homogeneous reduction accompanied by HDC using in situ produced Na2S2O4 (by the action of NaBH4/Na2S2O5) was an effective, rapid, and simple treatment method. This reductive system consumed quantities of reagents that are almost twice as low (66 mol of NaBH4 + 66 mol of Na2S2O5 + 18 mol of H2SO4 per one mol of MB9) in comparison with the other oxidative/reductive systems and allowed the effective and fast degradation of MB9 accompanied by the effective removal of AOX. A comparison of the oxidative and reductive methods for chlorinated acid azo dye MB9 degradation showed that an innovative combination of reduction methods offers a smooth, simple, and efficient degradation and hydrodehalogenation of chlorinated textile MB9 dye. [ABSTRACT FROM AUTHOR]

2, 4-Dichlorophenol is a type of chlorophenol that, even at low concentrations, causes adverse effects such as anemia, coma, weakening of the nervous system, and cancer in humans and other organisms. Therefore, the aim of this study was to synthesize the Fe-TiO2@Fe3O4 sonocatalyst and to assess the removal efficiency of 2, 4-dichlorophenol using this sonocatalyst. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), value-stream mapping (VSM), Brunauer Emmett Teller (BET), and diffuse reflectance spectroscopy (DRS) analyses were performed for characterizing the synthesized nanoparticles. The effect of different factors, such as pH (3–9), initial concentration 2, 4-dichlorophenol (20–80 mg/L), and level of nanoparticles (200–600 mg/L) at different time points (15–90 min), was assessed on sonocatalytic removal of 2, 4-dichlorophenol, and then the reaction kinetics, process mechanism, and stability of the synthesized nanoparticles were determined under optimal conditions. The highest removal efficiency of 2, 4-dichlorophenol and constant reaction rate was obtained at pH of 5, the initial concentration of 20 mg/L, and the nanoparticles dose of 400 mg/L under ultrasound with a frequency of 35 kHz following the reaction time of 90 min. The maximum mineralization efficiency (total organic carbon TOC) under optimal conditions was 81%. Analysis of the degradation kinetics indicated that the 2, 4-dichlorophenol degradation can follow a first-order reaction. The stability of the synthesized sonocatalyst decreased by 91% after 5 re-uses. This study confirmed the efficiency of the Fe-TiO2@Fe3O4 sonocatalytic process in the degradation and mineralization of 2, 4-dichlorophenol. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Pd/MXene@Ni-MOF/NF composite with low Pd dosage (0.21 mg cm−2) was prepared. • The Pd/MXene@Ni-MOF/NF composite achieved complete removal of 2-CP within 90 min. • The Pd/MXene@Ni-MOF/NF composite showed wide pH tolerance and long-term stability. • The modification of MXene on Ni-MOF improved the ability to generate active H*. To simultaneously reduce the usage of Pd and enhance the generation of active hydrogen atoms (H*), a novel Pd/MXene@Ni-MOF/NF composite was reported for electrocatalytic hydrodechlorination (EHDC). The synthesized catalyst delivered excellent activity, successfully achieving complete removal of 2-chlorophenol (2-CP) within 90 min and the rate constant was approximately 2.8 times higher than that of Pd/NF catalyst. Additionally, Pd/MXene@Ni-MOF/NF composites also showed a full range of pH tolerance, excellent ion interference resistance and long-term stability. Mechanistic studies suggested that the modification of MXene improved the electrocatalytic properties of Ni-MOF and the generation of H* by its optimized hydrophilicity, electrical conductivity and structural stability, which offered sufficient active species for the conversion of 2-CP to phenol on Pd nanoparticles. [ABSTRACT FROM AUTHOR]

Developing rapid and reliable electrochemical monitoring methods for 4-CP is of great significance to ensure the safety of the water environment. Electrochemical sensing materials with high sensitivity and selectivity are urgently needed. Here, interlaced sheet-like Ni-BDC frameworks (BDC: 1,4-dicarboxybenzene) and multi-walled carbon nanotubes (MWCNTs) composite (Ni-BDC/MWCNTs) are constructed via in-situ self-assembly of Ni-BDC in the presence of MWCNTs at room temperature. Because of the large specific surface area, high electrochemical activity of Ni-BDC, and the outstanding electrical conductivity of MWCNTs, the obtained Ni-BDC/MWCNTs compound had a significant signal enhancement effect for the oxidation of 4-CP based on the large electrochemical active area, fast electron transfer ability, strong accumulation ability, and high electrocatalytic rate. It was found that the electrochemical oxidation of 4-CP involved the transfer of an electron and a proton. A wide linear range (0.1–50 and 50–500 μM), low detection limit (16.5 nM), high reproducibility, strong stability, and good selectivity were achieved at the Ni-BDC/MWCNTs sensing platform. It also has been successfully used to monitor 4-CP in different river water samples, and got similar results compared to HPLC, which provides promising potential for application in water environment safety monitoring and protection. [Display omitted] • A novel sensor platform for electrochemical monitoring of 4-chlorophenol in water environments was successfully constructed. • The combination of 2D Ni-BDC MOFs and MWCNTs could effectively improve the electrochemical sensing performance. • This sensor would show promising potential for application in water environment safety monitoring and protection. [ABSTRACT FROM AUTHOR]

TiO2 and Fe-doped TiO2 nanoparticles were synthesised by sol-gel method. To determine the properties of nanoparticles, scanning electron microscopy, X-ray diffraction and diffuse reflectance spectroscopy were used. The results of the analysis showed that the synthesised nanoparticles are almost uniform and agglomerated as well as the Fe-TiO2 band gap has decreased from 3.1 to 2.84 and the absorption spectrum has changed towards the visible region. The final concentration of 2,6-dichlorophenol and degradation products were measured with gas chromatography-flame ionisation detector and gas chromatography-mass spectrometry. The maximum efficiency and reaction rate constant of 2,6-dichlorophenol were determined at pH 4 and k0 = 2.11 × 10−2, initial concentration of 2,6-dichlorophenol 20 mg L−1 and k0 = 8.01*10−2, and nanoparticles dosage of 500 mgL−1 and k0 = 5.07*10−2 at 90 min time. The degradation reaction followed the first-order kinetic model. The efficiency of degradation and mineralisation of 2,6-dichlorophenol were in order of sonophotocatalytic > photocatalytic > sonocatalytic. [ABSTRACT FROM AUTHOR]

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The ultrasonic extraction of chlorophenol in textiles was carried out by potassium hydroxide (KOH) solution because of the shortcomings of the existing detection methods for chlorophenol in textiles. A method based on gas chromatography-mass spectrometry (GC-MS) was established for the simultaneous determination of 19 chlorophenols in textiles. Pretreatment conditions of extraction were optimized. Textile samples were ultrasonically extracted with 2.0 mol/L KOH solution in 2.0 h under 70 °. The solution was acetylated by acetic anhydride to produce chlorinated phenol acetate and the target was extracted by hexane liquid/liquid extraction. The results show that the calibration curves are linear between the peak area and the concentration of 19 chlorophenol acetates in the range of 1-40 µg/L, with correlation coefficients greater than 0.995. The limits of detection (LOD) are 0.006-0.025 mg/kg and the limits of quantitation (LOQ) are 0.020-0.082 mg/kg. The average recoveries range from 82.7% to 113.3% at three different spiked levels of 0.05, 0.50 and 1.00 mg/kg, respectively, with relative standard deviation (RSD, n=6) less than 15.0%. The method is simple, rapid and accurate, which is suitable for the determination of various chlorophenols in textiles. [ABSTRACT FROM AUTHOR]

The specification of a particular activated carbon adsorbents for removal of phenol and related derivatives, from dilute aqueous solutions, is still based on lengthy trial and error experimental tests. A predictive model of adsorption of these compounds would considerably reduce the carbon selection time and could also bring new information to support more efficient carbon synthesis. The use of molecular simulation and the methodology of representative pores proved to be adequate for quantitative prediction of phenol adsorption. Here the methodology is being extended to chlorophenols, an important class of phenol-derived pollutants. A set of ortho- and para-chlorophenol isotherms were simulated for different representative pores in order to predict carbon adsorption and determine the most significative pore size. At low concentrations (1 × 10−4 mol/L), the pores of 8.9 and 18.5 Å are the most effective. For concentrations above 3 × 10−4 mol/L, pores in the range of 27.9 Å must be present in the activated carbon. The simulation predicts a step for the 27.9 Å pore that can be correlated with experimental steps in literature. Finally, the adsorption isotherms of chlorophenols for other activated carbons were predicted with the help of the model. [ABSTRACT FROM AUTHOR]

Background: 2,4-Dichlorophenol (2,4-DCP) is a very toxic aromatic compound for humans and the environment and is highly resistant to degradation. Therefore, it is necessary to develop efficient remediation and cost-effective approaches to this pollutant. Microbial enzymes such as laccases can degrade phenols, but limited information is known about immobilized bacterial laccase and their reuse. Methods: Immobilization of marine halophilic Bacillus subtilis AAK cultures via entrapment and adsorption techniques and degradation of different phenolic compounds by immobilized cells were estimated. Partial purification and immobilization of laccase enzymes were carried out. In addition, the biodegradation of 2,4-DCP and others contaminated by wastewater was investigated. Results: Immobilization of cells and partially purified laccase enzymes by adsorption into 3% alginate increased 2,4-DCP biotransformation compared with free cells and free enzymes. In addition, the reuse of both the immobilized culture and laccase enzymes was evaluated. The highest removal of 2,4-DCP from pulp and paper wastewater samples inoculated by immobilized cells and the immobilized enzyme was 90% and 95%, respectively, at 50 h and 52 h of incubation, compared to free cells and free enzyme. Conclusion: The results of this study have revealed the immobilization of a biocatalyst and its laccase enzyme as a promising technique for enhancing the degradation of 2,4-DCP and other toxic phenolic and aromatic compounds. The reuse of the biocatalyst and its laccase enzyme enabled the application of this cost-effective bioremediation strategy. [ABSTRACT FROM AUTHOR]

C 3 N 4 nanotubes modified by hydroxyl groups in situ grafting and halogen ions were prepared by simple hydrothermal treatment strategy with ammonium salt and potassium iodide. The chlorophenols carboxylation efficiency was obviously promoted with the synergistic effect of hydroxyl groups assisted photogenerated holes capture and halogen ions induced surface polarization. [Display omitted] • Carbon nitride nanotubes with hydroxyl groups grafting and halogen ions modification were prepared. • Pollutants chlorophenols and CO 2 were converted to carboxylic acids containing fine chemicals. • Hydroxyl groups induced photogenerated holes capture enhanced the photocatalytic transformation. • Synergistic effect between hydroxyl groups and halogen ions further promoted the photocatalytic performance. • In situ formed CO 2 ·– directly attacked the C Cl bond in p -chlorophenol to achieve the carboxylation. Herein, novel, green and efficient strategy was developed for environmental pollutant chlorophenols and carbon dioxide transformation to carboxylic acids containing fine chemicals over carbon nitride (C 3 N 4) nanotubes based photocatalysis. C 3 N 4 nanotubes structure with hydrothermal treatment method provided the increased active sites, enhanced light absorption capacity and improved charge transfer efficiency. C 3 N 4 nanotubes further modified by hydroxyl groups in situ grafting and halogen ions were prepared by simple hydrothermal treatment strategy with ammonium salt and potassium iodide. Owing to the photogenerated holes capture improvement, hydroxyl groups in situ grafting policy obviously enhanced the chlorophenols and CO 2 transformation. Moreover, the chlorophenols carboxylation efficiency was further promoted with the synergistic effect of hydroxyl groups assisted photogenerated holes capture and halogen ions induced surface polarization. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is a progressively neurodegenerative disease following dopamine neuron loss and motor dysfunction. Selective monoamine oxidase B (MAO-B) inhibitors are regarded as the potential candidates for the treatment of PD. 2-Pyrazoline structure, an important pharmacodynamic parent nucleus of MAO inhibitors, was introduced into the lead compound 2,3-dibromo-4,5-dihydroxylbenzophenone (LM48), thirty-two triphenylpyrazoline ketone chlorophenols were therefore synthesized, and their protective activities against 6-hydroxydopamine damaged SH-SY5Y cells were further evaluated. Seven chlorophenols 9d, 11d, 28d, 29d, 30d, 31d, and 32d exhibited the significant protective activity with the EC50 values in the range of 0.3–1.2 μM, superior to LM48 (EC50 > 20 μM) and Rasagiline (EC50 = 1.1 ± 0.6 μM). Moreover, they could obviously reduce ROS level. Their MAO-A and MAO-B inhibitory activities in vitro were further compared. MAO-A inhibitory activity was not found at 50 μM, but sixteen compounds were discovered showing selective MAO-B inhibitory activity. Of which, compound 6d presented the optimal activity (IC50 = 12.2 ± 2.3 μM). Compared with Rasagiline (an irreversible MAO-B inhibitor), the combination of 6d and MAO-B was reversible displaying the higher selectivity and safety. These findings suggest that triphenylpyrazoline ketone chlorophenols could potentially be promising candidates for the treatment of PD. [ABSTRACT FROM AUTHOR]

• One pot hydrothermal method was used to synthesize the composite between DUT-8(Zn/Ni) MOFs and CeO 2. • The composites show photodegradation efficiency of (86%, 89%) for 2,4-DCP, and (85%, 91%) for 2,6-DCP respectively at optimal conditions (concentration of pollutants-5 mg/L; catalyst dose-0.6 g/L and pH-8). • The practical applicability of the composites as photocatalysts were evaluated by performing mineralisation studies of the industrial effluent from the paper mill industry. • The synthesized photocatalysts show high stability and reusability for over five experimental cycles. A composite DUT-8(Zn/Ni)αCeO 2 photocatalysts were configured using a simple and facile hydrothermal method and characterized using PXRD, SEM, BET, FTIR and Photoluminescence studies to configure their morphological, structural as well spectroscopic characteristics. The as obtained composites demonstrate superior photocatalytic activity for the degradation of dichlorophenols (2, 4 and 2, 6 DCP). The introduction of MOF into the semiconductor oxide proliferate the photocatalytic activity owing to a strong interface between the two that promotes the transfer as well as the separation of photo generated charge carriers. These nanocomposites DUT-8(Zn)@CeO 2 and DUT-8(Ni)@CeO 2 appear highly promising then the individual counterparts as they record the photodegradation efficiency of (86%, 89%) for 2,4-DCP, and (85%, 91%) for 2,6-DCP respectively at optimal conditions (concentration of pollutants-5 mg/L; catalyst dose-0.6 g/L and pH-8). The practical applicability of the nanocomposites was evaluated using mineralization study involving the industrial effluents of the paper mill industry. Notably, the mineralization of chlorophenols (85.3% for 2,4-DCP, and 87% for 2,6-DCP) was observed in case of DUT-8(Zn)@CeO2 and DUT-8(Ni)@CeO2 nanocomposites. Besides, the synthesized photocatalysts show high stability and reusability for over five experimental cycles. [Display omitted] [ABSTRACT FROM AUTHOR]

Ball-milled plastic char supported nano zero-valent iron (nZVI@BMPC) and their application combined with anaerobic sludge for microbial dechlorination of 2,4,6-trichlorophenol (2,4,6-TCP) were investigated. The XRD and FTIR analysis proved composition of zero valent states of iron, and the BET and SEM analysis showed that nZVI was uniformly distributed on the surface of BMPC. Successive addition of 1000 mg/L sodium lactate and nZVI@BMPC enhanced the acclamation of anaerobic sludge and resulted in the degradation of 4-CP within 80 days. The acclimated consortium with nZVI@BMPC completely degraded 2,4,6-TCP into CH 4 and CO 2 , and the key dechlorination route was through 4-CP dechlorinaion and mineralization. The degradation rate of 2,4,6-TCP with nZVI@BMPC was 0.22/d, greater than that without nZVI@BMPC. The dechlorination efficiency was enhanced in the Fe2+/Fe3+ system controlled by nZVI@BMPC and iron-reducing bacteria. Metagenomic analysis result showed that the dominant de-chlorinators were Chloroflexi sp., Desulfovibrio , and Pseudomonas , which could directly degrade 2,4,6-TCP to 4-CP, especially, Chloroflexi bacterium could concurrently be used to mineralize 4-CP. The relative abundance of the functional genes cprA , acoA , acoB , and tfdB increased significantly in the presence of the nZVI@BMPC. This study provides a new strategy can be a good alternative for possible application in groundwater remediation. [Display omitted] • BMPC supported nZVI prepared by chemical reduction method. • Anaerobic sludge acclimated with phenol was used to 4-CP mineralization. • nZVI@BMPC enhanced the anaerobic mineralization efficiency of 4-CP. • 4-CP mineralization was the key stage of 2,4,6-TCP degradation. • nZVI@BMPC improved the collaboration among microorganisms related to dechlorination. [ABSTRACT FROM AUTHOR]

Biological toxicity testing plays an essential role in identifying the possible negative effects induced by substances such as organic pollutants or heavy metals. As an alternative to conventional methods of toxicity detection, paper-based analytical device (PAD) offers advantages in terms of convenience, quick results, environmental friendliness, and cost-effectiveness. However, detecting the toxicity of both organic pollutants and heavy metals is challenging for a PAD. Here, we show the evaluation of biotoxicity testing for chlorophenols (pentachlorophenol, 2,4-dichlorophenol, and 4-chlorophenol) and heavy metals (Cu2+, Zn2+, and Pb2+) by a resazurin-integrated PAD. The results were achieved by observing the colourimetric response of bacteria (Enterococcus faecalis and Escherichia coli) to resazurin reduction on the PAD. The toxicity responses of E. faecalis-PAD and E. coli-PAD to chlorophenols and heavy metals can be read within 10 min and 40 min, respectively. Compared to the traditional growth inhibition experiments for toxicity measuring which takes at least 3 h, the resazurin-integrated PAD can recognize toxicity differences between studied chlorophenols and between studied heavy metals within 40 min.

• Two chlorophenols with particular toxicities were transformed into coumarins (CMs). • CMs were evaluated as multifaceted, and biocompatible therapeutic applicants. • Three studies were conducted on CMs: bioactivity, biosafety, and in silico analysis. • The study suggests that this transforming could lead to biosafe active applicants. In this work, two chlorophenols with particular toxicities were transformed into their 14 corresponding coumarins (CMs). Their chemical structures were confirmed by examining the spectra generated by various spectroscopic instruments. The created CMs were evaluated as influential, multifaceted, and biocompatible therapeutic applicants. This was done through three evaluational studies, which are bioactivity, biosafety, and computer-based druggable analysis. In the first study type, the possibilities of the created CMs to function as antitumor applicants were inspected against six tumor-acquired cellular populations through a MTT-based methodology. Also, the function as an antioxidant was studied using two free radical types, while the antidiabetic function was assessed employing two glucose-regulating enzymes. Moreover, their function as broad-spectrum antimicrobial applicants was evaluated against six infectious aerobic bacteriomers, four anaerobic bacteriomers, and two fungiomers. Concerning the second evaluational study, the biosafety of the created CMs was investigated by following their impact on the regular growth of one normal cellular population and one normal bacterium. In the last study type, the capacity of the created CMs to consider drug applicants was examined using two online platforms. The results of these three study types indicated that the created CMs have good antitumor, antioxidant, and antidiabetic activities with broad-spectrum antimicrobial potential in relation to the applied test settings and references. As antitumor applicants, the created CMs showed an intriguing antitumor impact, with IC 50 values ranging from 13.08 μg/ml to 103.20 μg/ml. With IC 50 values ranging between 62.45 μg/ml and 112.01 μg/ml, these CMs showed considerable neutralizing action towards the free structures under investigation. Given the standard results, the created CMs had a good-to-moderate antidiabetic effect with IC 50 values ranging between 324.46–424.02 μg/ml. In the antimicrobial investigations, the created CMs showed broad-spectrum microbiocidal activity in general and particularly against the test fungiomers. Also, these multifunctional attributes were coupled with outstanding biocompatibility and drug-like properties. The author comes to the conclusion that the transformation of toxic chlorophenols into their CMs modified their effects in a way that served better in therapeutics. Also, this work may open the door to repurposing toxic phenols into biocompatible medicinal applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Chlorophenol compounds have the potential to cause significant environmental and health effects. In this research, response surface methodology (RSM) was utilized to find out the optimum condition for the oxidation of 2-chlorophenol using ultrasound/persulfate treatment technique. Contact time, pH, 2-chlorophenol concentration, persulfate concentration, and ultrasound power are considered as independent variables. The optimization of factors found from the experimental data is conducted by analysis of variance (ANOVA). A quadratic polynomial model is suggested as the best model in terms of statistical significance for 2-chlorophenol removal efficiency prediction. Reaction time = 65 min, pH = 3, 2-chlorophenol concentration = 17 mg/L, persulfate concentration = 120 mg/L, and ultrasound power = 150 W are found as optimum condition under which 2-chlorophenol reduction efficiency is found to be 90.92%. Determination of coefficient (R2) parameter was 0.93. The results demonstrated that the pH (A), reaction time (B), initial 2-chlorophenol concentration (C), persulfate concentration (D), ultrasound power (E), square terms of pH (A2), reaction time (B2), initial 2-chlorophenol concentration (C2), persulfate concentration (D2), ultrasound power (E2), and interaction terms of AB, AC, AD, BD, CD, AE, and DE were found as effective factors. The findings of the biodegradability variation of petrochemical refinery wastewater under ultrasound/persulfate treatment showed a remarkable increase in BOD5/COD ratio (0.14–0.57). It reveals that the process can be employed as a pretreatment step before biological processes to facilitate the biological treatment of the recalcitrant wastewater. [ABSTRACT FROM AUTHOR]

HadA monooxygenase is involved in the initial step of the biodegradation pathway of toxic nitrophenols and halogenated phenols. HadA catalyzes the O2‐dependent denitration of nitrophenols and dehalogenation of halogenated phenols via the hydroquinone pathway. Based on bioinformatics and structural analysis, Arg208 of HadA is located at the proper position for substrate stabilization. This arginine is conserved among hydroquinone pathway‐specific enzymes for toxicant detoxification. In this study, the function of Arg208 in HadA was determined by a single‐point mutation creating HadAArg208 variants. 4‐Nitrophenol was mineralized by HadAArg208 variants that contain side chains as a positive charge and hydrogen‐bond donor, whereas 4‐chlorophenol strictly required a positively charged environment for detoxification. Transient kinetic results indicated that the biodetoxification ability of HadAArg208 variants was diminished due to the slowing down of denitration/dehalogenation. The substrate‐binding mode and affinity energy were evaluated by molecular docking. The findings were consistent with the experimental results indicating that arginine is the most fit for both 4‐nitrophenol and 4‐chlorophenol binding, whereas the active mutants provide a weaker interaction correlated with their denitration/dehalogenation activities. Altogether, Arg208 plays a role in providing proper chemical interactions to the substrate for binding at an appropriate orientation in the active site of hydroquinone pathway‐specific enzymes. In addition, it is proposed to stabilize nitro groups and halide ions that are released in denitration/dehalogenation reactions. This conserved arginine might be the essential feature for related biocatalysts, which could be fundamental knowledge regarding this enzyme family. [ABSTRACT FROM AUTHOR]

Low-molecular-mass iron-reducing compounds (IRCs) were produced by entomopathogenic endophytic fungi Lecanicillium sp. ATA01 in liquid cultures. The extracellular hydrophilic extract contained three IRCs formed by peptides, iron and phenolate structures with molecular masses of 1207, 567 and 550 Da. These compounds were able to chelate and mediate the reduction of Fe+3 to Fe+2 and oxidized recalcitrant lignin-model substrates such as veratryl alcohol (VA), 2,6-dimethoxyphenol (DMP), and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS) with or without hydrogen peroxide. Besides, IRCs can promote the degradation of chlorophenols. The maximal degradation of p-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol was conducted at optimal degradation conditions for IRCs (pH 3.5, iron 100 mM, and H2O2 10 mM). Furthermore, Fenton-like reactions using the synthetic iron chelates DTPA and EDTA and free Fe+2 and Fe+3 were also carried out in order to compare with the reaction mediated by IRCs. The ferric IRCs displayed the ability to enhance the hydroxylation of chlorophenols as a part of a degradation mechanism of the IRC-assisted Fenton reaction. The complexed iron was more efficient than free iron in the Fenton-like reaction, and between them, the fungal chelates were more efficient than the synthetic mill chelates. [ABSTRACT FROM AUTHOR]

Introduction. Whey drinks, fruit nectars, and reconstituted juices are usually based on domestic water. This water may contain various contaminants, which can interact with vitamins in fruit drinks. The research objective was to study the impact of trichloromethane, hydroxybenzene, chlorophenol, trichloroethylene, and ethylene chloride on the state of vitamins in juice products. Study objects and methods. The study featured aqueous fruit and berry concentrates, used in fruit nectar production. The control sample contained water without contaminants, while the test samples involved trichloromethane, trichloroethylene, ethylene chloride, hydroxybenzene, and chlorophenol. Capillary zone electrophoresis made it possible to determine bioactive substances (vitamins) in aqueous fruit and berry concentrates. Molecular absorption spectroscopy in visible spectrum was used to check the color intensity. Gas chromatography helped to analyze the content of contaminants. Results and discussion. The experiment tested vitamin preservation in fruit nectars based on water contaminated with trichloromethane, trichloroethylene, ethylene chloride, hydroxybenzene, and chlorophenol. Trichloromethane did not react with bioactive substances. Trichloroethylene, ethylene chloride, hydroxybenzene, and chlorophenol lowered the content of ascorbic acid, carotene, thiamine, riboflavin, choline, and pyridoxine. Depending on the organic matter, water contamination led to a decrease in carotene by 7–35%, vitamin B1 – by 10–100%, B2 – by 11–100%, B4 – by 8–45%, and B6 – by 8–100 in the finished product. The paper introduces a theoretic substantiation of the interaction between the contaminants and the bioactive substances. Conclusion. Water, contaminated with such organic substances as hydroxybenzene, chlorophenol, trichloroethylene, and ethylene chloride, proved to affect the vitamin preservation in juices, which was illustrated by chemical equations. Therefore, juice production requires preliminary water purification because toxic and cancerogenic substances can decrease the quality and food safety of the finished product.

In the current study, elimination of chlorophenol by the Aspergillus fumigatus was investigated in an airlift inner loop bioreactor (ALBR). The effect of empty bed residence time (EBRT), concentration of peptone and initial chlorophenol concentration on the removal efficiency of chlorophenol was examined. Bioreactor displayed a high elimination rate of 16.59 mg/(L h) at the experimental conditions of 40 h EBRT, 150 mg/L initial chlorophenol concentration, and 0.2 g/L peptone. The removal efficiency was around 50% at 25 h EBRT. The experimental outcomes displayed that chlorophenol and removal efficiency of the bioreactor were higher at the lower concentration of peptone. Also, the Aspergillus fumigatus used chlorophenol as a carbon source, as demonstrated by the growing biomass concentration at fixed peptone concentration. The ALBR restored to the original operation after the transient condition (shutdown, restart, and shock load) and the constant reactor performance was maintained. The biological treatment of chlorophenol is one of the promising treatment techniques as it is relatively less expensive and results in degradation of contaminants. [ABSTRACT FROM AUTHOR]

High surface area microporous activated carbon beads were successfully prepared for removal from aqueous solutions. The polymeric beads were fabricated from sodium alginate (Alg), β-cyclodextrin (β-CD), gelatin (GP) and activated carbon (AC) being used as an efficient 2,4-dichlorophenol (2,4-DCP) removal sorbent. The chemical and morphological analysis of the fabricated beads were investigated using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), while thermal stability was estimated via thermogravimetric analysis (TGA). The main goal of the recent work is to investigate the activated carbon effect on the sorption process. The impact of experimental parameters like original concentration, pH, and adsorption time was explored. The optimum removal of 86.05% was obtained at pH 7. One hour was sufficient for the full saturation of the active sorbent sites, reaching equilibrium. The pseudo second model was the best to describe the adsorption process. Furthermore, it can be seen from the Langmuir equation that the qm for unmodified and modified beads toward 2,4-DCP were 36.48 mg/g and 39.36 mg/g, respectively.

Nitrogen-doped carbon nanotubes (N-CNTs) were synthesized via a hydrothermal method and further modified with magnetic Co0.5Cu0.5Fe2O4 nanoparticles following a one-pot solvothermal method. The characterization data show that the distribution of the magnetic materials and the adsorption characteristics of the CNTs can be tailored as a function of the N doping amount. The N-CNT adsorption isotherms as a function of N content and chlorophenol uptake show that a N doping level of 6% is optimum. After loading the N-CNTs with the magnetic Co0.5Cu0.5Fe2O4 nanoparticles (M-N-CNTs), the resulting materials were easily dispersed in aqueous media with specific surface area reaching 95.64 m2/g. The M-N-CNTs exhibit high affinities toward the adsorption of different chlorophenols following the order: Pentachlorophenol (PCP) > 2,4,6-trichlorophenol (2,4,6-TCP) > 2,4-dichlorophenol (2,4-DCP) > 2,4-dichlorophenoxyacetic acid (2,4-D) > phenol. Additionally, the M-N-CNTs exhibit good microwave absorption performance and can be regenerated by microwave irradiation with high efficiencies (> 90%) maintained with high stabilities. [ABSTRACT FROM AUTHOR]

4-chlorophenol (4-CP) is recognized as a highly toxic organic which can cause damage effects on human life and the aquatic environment. Since conventional wastewater techniques were unable to remove non-biodegradable chlorophenols, advanced oxidation process was investigated to achieve this goal. Amongst them, non-thermal plasma was recently proposed as an alternative and promising technique. However, the energy efficiency of most non-thermal plasma technique is very low as well as the input energy is dissipated in many forms such as heat, UV radiation, electromagnetic waves, etc., that are not totally involved in the pollutant degradation. In this work, quantitative analyses of UV radiation and H2O2 in a moist air gliding arc plasma (glidarc) were performed using potassium ferrioxalate actinometry and peroxytitanyl complex method, respectively. The role of UV light emitted in gliding arc plasma was elucidated by performing parallel experiments: H2O2, glidarc alone, glidarc + H2O2, glidarc + H2O2 + Fe3+ (plasma-Photo-Fenton). The results show that the incorporation of Fenton reagents in 4-CP solution exposed to the plasma enhanced the yields of chemical active species, which were available for efficient removal and mineralization of 4-CP. [ABSTRACT FROM AUTHOR]

The research on developing a purification technology for 2,4-dichlorophenol (2,4-DCP) polluted water with high efficiency and the low energy consumption is crucial for achieving several Sustainable Development Goals (SDGs). In order to achieve these goals, MWCNTs-Pd/Fe nanocomposites were prepared by Fe nanoparticles modified with multi-walled carbon nanotubes (MWCNTs) and palladium (Pd) in the presence of ultrasonic irradiation. The MWCNTs-Pd/Fe nanocomposites were characterized by using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and X-Ray Diffraction (XRD), and others. Characterization results confirmed that the MWCNTs-Pd/Fe was successfully prepared, with the particle size of 80 nm and the specific surface area of 89.5 m2/g confirmed. We studied the reductive dechlorination of 2,4-Dichlorophenol (2,4-DCP) by MWCNTs-Pd/Fe nanocomposites under different conditions, and the optimized experimental results were found when the Pd loading was 0.4 %, the pH was 3, and the temperature was 30 °C. The phenol yield increased from 76.5 % (without ultrasonic irradiation) to 92.3 % (with ultrasonic irradiation) in 300 min and the 2,4-DCP removal rate reached 98.7 % under the optimal conditions. Therefore, ultrasonic irradiation enhanced the performance of MWCNTs-Pd/Fe nanocomposites for 2,4-DCP removal. We also established the degradation mechanism of chlorophenol by analyzing the intermediates, and proposed the degradation kinetics model. The degradation of 2,4-DCP followed the pseudo-first-order kinetics with the rate constant of 0.05988 min−1. Also, this study demonstrated the potential of using ultrasonic irradiation to improve the properties and recovery of MWCNTs-Pd/Fe nanocomposites, contributing to achievement of the Sustainable Development Goals (SDGs), including SDG-3, SDG-6. [ABSTRACT FROM AUTHOR]

Low-molecular-mass iron-reducing compounds (IRCs) were produced by entomopathogenic endophytic fungi Lecanicillium sp. ATA01 in liquid cultures. The extracellular hydrophilic extract contained three IRCs formed by peptides, iron and phenolate structures with molecular masses of 1207, 567 and 550 Da. These compounds were able to chelate and mediate the reduction of Fe+3 to Fe+2 and oxidized recalcitrant lignin-model substrates such as veratryl alcohol (VA), 2,6-dimethoxyphenol (DMP), and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS) with or without hydrogen peroxide. Besides, IRCs can promote the degradation of chlorophenols. The maximal degradation of p-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol was conducted at optimal degradation conditions for IRCs (pH 3.5, iron 100 mM, and H2O2 10 mM). Furthermore, Fenton-like reactions using the synthetic iron chelates DTPA and EDTA and free Fe+2 and Fe+3 were also carried out in order to compare with the reaction mediated by IRCs. The ferric IRCs displayed the ability to enhance the hydroxylation of chlorophenols as a part of a degradation mechanism of the IRC-assisted Fenton reaction. The complexed iron was more efficient than free iron in the Fenton-like reaction, and between them, the fungal chelates were more efficient than the synthetic mill chelates.

Upflow anaerobic sludge blanket (UASB) systems are of specific interest for the treatment of high organic wastewater since they offer the opportunity to recover energy in the form of methane (biogas). The technology is highly suitable for the degradation of biodegradable organics, but its efficiency can be significantly hampered by the presence of toxic pollutants in the water. In this study, the use of electrochemical advanced oxidation (eAOP) coupled to a lab-scale UASB reactor for the degradation of 4-chlorophenol (4-CP) in wastewater was investigated. The eAOP treatment consisted of the electrochemical production of active chlorine at a Ti/RuO 2 –IrO 2 anode with a fixed current density of 25 mA/cm2 in the recycle of the UASB reactor. It was noticed that the total COD removal efficiency decreased from 75.8% when no 4-CP was present in the wastewater to 25.6% and 13.6% after the addition of 100 ppm and 50 ppm 4-CP, respectively. Furthermore, elevated levels of volatile fatty acids and ORP were observed in the effluent of the reactor, indicating process failure. It was postulated that the decrease in COD removal efficiency was due to the release of high amounts of hypochlorite, causing an oxidative environment in the anaerobic reactor. This hypochlorite may have reacted with several components such as ammonia to form other toxic components (e.g., chloramine). • Degradation of 4-chlorophenol in a combined biological/oxidation set-up is studied. • An electrochemical treatment is implemented in the recycle flow of the UASB. • Oxidation is carried out in chloride containing wastewater. • 4-chlorophenol is successfully degraded but excess hypochlorite is detected. • The reactor can suffer from the presence of toxic components. [ABSTRACT FROM AUTHOR]

To effectively address environmental pollution, we synthesized Au‐loaded ZnO nanocomposites and applied for the photocatalytic degradation of 2‐chlorophenol (2‐CP) under visible light irradiation. The as‐prepared nanophotocatalysts delivered much improved photocatalytic degradation activities as compared to the bare ZnO nanoparticles and 32% of the pollutant was degraded with 2AuZnO in 1 hr. These improved photoactivities are attributed to the extended visible light absorption due to the surface plasmon resonance property of the loaded Au nanoparticles. Moreover, Au nanoparticles played important role in charge separation by inducting excited electrons to the conduction band of ZnO photocatalyst and surface catalysis as confirmed from photoluminescence spectra and amount of the generated hydroxyl radicals. The trapping experiments confirmed that positive holes were the major degrading species during the photocatalytic degradation of 2‐CP. This work provides a feasible way to improve the photocatalysis by introducing a proper amount of noble metals over the surface of semiconductor photocatalysts. [ABSTRACT FROM AUTHOR]

A sensitive method termed rapid synergistic cloud point extraction (RS-CPE) combined with partial least squares (PLS) was developed for the extraction and simultaneous determination of trace amounts of phenol and three detrimental chlorophenols (CPs) via a microplate assay (MPA). In this study, n-pentanol was used as a novel synergistic inducer and the linear nonionic surfactant Tergitol 15-S-7 was used as an extractant. The whole process of RS-CPE was accomplished in a few minutes without the need for the time-consuming water- or ice-bath steps used in traditional cloud point extraction. An automated and high-throughput assay using a 96-well plate allowed for the simultaneous processing of multiple samples with low sample volume requirements (approximately 200 µL). However, synchronized determination of several CPs using MPA method was problematic because of spectral interferences. Fortunately, a multivariate calibration method using PLS was applied to circumvent these limitations. Under the optimum conditions, the linear dynamic concentration ranges were from 0.5 to 15 µg/mL for 2-chlorophenol and 0.5 to 20 µg/mL for the other analytes. The detection limit range was from 0.275 to 0.419 µg/mL. The enrichment factor was up to 15.4 fold. The developed methodology was successfully applied to quantitative analysis of phenol and three CPs in water samples with recoveries from 90.0% to 109%. [ABSTRACT FROM AUTHOR]

Chlorophenols (CPs) are known as a class of pollutants posing a great threat to the environment and human health because of their carcinogenesis and teratogenesis, and thus exploring convenient and efficient methods for their detection and identification becomes particularly important. Herein, we report a recyclable colorimetric sensor array according to the oxidase-mimicking catalytic characteristics of Fe 3 O 4 @MnO x for the high-performance quantification and differentiation of typical CPs. The core-shell Fe 3 O 4 @MnO x prepared by growing oxidase-like MnO x nanoflakes on the surface of magnetic Fe 3 O 4 particles via a hydrothermal process can exhibit excellent catalytic activity to trigger the color reaction of CPs and 4-aminoantipyrine with the participation of O 2. By utilizing the Fe 3 O 4 @MnO x -catalyzed color reaction, high-sensitivity quantitative analysis of CPs, taking 2-chlorophenol as a model, was realized, providing a detection limit as low as 0.85 μM. Given different chlorine substitution places and numbers in CPs impact the reaction kinetics diversely, a new nanozyme-based colorimetric sensor array was further constructed for the successful differentiation of various CPs with the help of hierarchical cluster analysis and principal component analysis. Accurate double-blind identification of unknown samples using the proposed sensor array was also demonstrated, indicating its reliability for practical practice. Image 1 • Fe 3 O 4 @MnO x acts as an efficient and recyclable oxidase mimic. • Fe 3 O 4 @MnO x catalyzes the color reaction of CPs and 4-AAP. • A new nanozyme-based colorimetric sensor array is constructed. • Identification and detection of CPs are realized. [ABSTRACT FROM AUTHOR]

Phenolic compounds are mixtures of phenol derivatives which are produced from several industries including biocides, pharmaceuticals and coal production. Phenolics are considered the major contaminants in industrialized wastewater. Therefore, treatment of wastewater polluted by phenolics is mandatory previously to discharge in order to protect the environment. Among the numerous procedures reported for remediation of industrial wastewater from phenolics; adsorption technology was the best method from the effectiveness and economical point of view. In this study, three agricultural wastes produced in huge amounts were evaluated in remediation of wastewater contaminated by 2-chlorophenol. The studied agricultural wastes were water hyacinth, palm leaf, and banana peel. The adsorption process parameters were determined including temperature, pH, amount of adsorbents, concentration of pollutant, and treatment time. The process followed Freundlich adsorption isotherm and pseudo-second-order kinetic model. Boyd model showed that the adsorption mechanism of chlorophenol on the surface of the different adsorbents was occurred via film diffusion mechanism. The obtained adsorption capacities at the equilibrium conditions were 288.1, 290.3, and 388.9 mg/g for water hyacinth, palm leaf, and banana peel, respectively. The spectroscopic evaluation showed the physical interaction between the chlorophenol molecules and the different functional groups on the studied adsorbents. Banana peel showed the highest adsorption efficiency, which was related to the abundance and types of the bioactive compounds in its chemical structure. [ABSTRACT FROM AUTHOR]

The present study compares the effect of using different solvents on the electrochemical properties of the reduced TiO 2 nanotubes (TiO 2 -rNTs) layered Ti/TiO 2 -rNTs/SnO 2 –Sb/PbO 2 anodes. The electrodes are prepared using three different solvent-based precursors: (i) isopropanol, (ii) ethylene glycol and citric acid (Pechini method), and (iii) 2-hydroxyethylammonium acetate (2HEAA) ionic liquid (IL) via the thermal decomposition route. The decomposition mechanism of precursor solutions was explored using the thermogravimetric (TGA) analysis. Further, the physicochemical properties of the electrodes are examined using Field emission Scanning Electron microscopy (FE-SEM), X-ray diffraction spectroscopy (XRD), and X-ray photoelectron emission spectroscopy (XPS). The results revealed that solvents with higher viscosity and slower decomposition rates support better film uniformity and higher stability of the electrode. The TiO 2 -rNTs bottom layer and PbO 2 top layer helped obtain higher film stability, increased working potential window (2.2 V vs. SHE) of the electrode, and the repeatability of the results. The performance of different electrodes based on the precursor solution is found as IL ≫ Pechini > Isopropanol. 4-chlorophenol (4-CP) is used as a model pollutant to test the performance of IL-Ti/TiO 2 -rNTs/SnO 2 –Sb/PbO 2 anode in an anodic oxidation (AO) coupled electro-Fenton (EF) treatment. Further, the reliability of the electrode is evaluated by mineralizing other persistent organic pollutants (POPs) like tetracyclin, phenol, 2-chlorophenol (2-CP), and 2,4-dichlorophenol (2,4-DCP). Under the optimized conditions, the proposed system was able to mineralize the tetracyclin, phenol, 2-CP, 2,4-DCP, and 4-CP up to 78.91, 82.07, 74.96, 78.78, and 69.3 %, respectively. Moreover, the degradation mechanism of chlorophenols is proposed. [Display omitted] • Morphology of electrode depends on the viscosity and decomposition rate of precursor solvent. • 2HEAA IL based precursor presented more stable and uniform coating with minimum preparation time. • Ti/TiO 2 -rNTs/SnO 2 –Sb/PbO 2 non-active anode is used for the EF treatment. • More than 80 % of mineralization of persistent organic pollutants is achieved during 240 min of electrolysis. • Mineralization current efficiency, energy consumption and degradationpathway is discussed. [ABSTRACT FROM AUTHOR]

Chlorophenols are widespread environmental organic pollutants with harmful effects on human beings. Although relationships between chlorophenols and various dysfunctions/diseases have been reported, the contribution of chlorophenols exposure to mortalities is underdetermined. In this cohort study, we included 4 types of urinary chlorophenols, aiming to estimate associations of chlorophenols exposure with all-cause and cause-specific mortalities. Urinary chlorophenols were examined at baseline of National Health and Nutrition Examination Survey (NHANES) 2003–2010, and adjusted for the urinary creatinine level. Associations between chlorophenols and mortalities were estimated using COX regression analyses, results were shown as hazard ratio (HR) and 95% confidence interval (95% CI). By dividing participants into four subgroups based on quartiles of urinary levels of chlorophenols, associations between mortalities and categorical variables of chlorophenols were estimated. Furthermore, the quantile g-computation analysis was used to estimate the joint effects of 4 chlorophenols on mortalities. Among 5817 adults (2863 men), 1034 were deceased during the follow-up. After adjusted for confounders, 2,4,5-trichlorophenol (2,4,5-TCP) was found to be positively associated with both all-cause (HR = 1.46; 95% CI: 1.16, 1.84) and cardiovascular disease (CVD) mortalities (HR = 1.60; 95% CI: 1.00, 2.55). Compared to the subgroup of the lowest level of chlorophenols, participants in subgroups of higher 2,4,5-TCP levels showed higher risk of all-cause mortality (P -value for trend = 0.003). For CVD mortality, HRs in subgroups of higher levels of 2,4-dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP) were statistically significant (P -values for trend were 0.017 for 2,4-DCP and 0.049 for 2,4,6-TCP). The HRs (95% CI) of joint effects of 4 chlorophenols were 1.11 (1.01, 1.21) and 1.32 (1.10, 1.57) for all-cause and CVD-specific mortalities, and 2,4,5-TCP showed the highest weight in joint effects. All of these findings implied that among 4 urinary chlorophenols we included, 2,4,5-TCP might be a sensitive one in associations with mortalities among general populations. [Display omitted] • Urinary 2,4,5-trichlorophenol increased all-cause and cardiovascular mortalities. • Positive joint effects of 4 chlorophenols on associations with mortalities were found. • Urinary 2,4,5-trichlorophenol had the largest weight in the positive joint effects. • Urinary 2,4,5-trichlorophenol could be a sensitive marker related to mortalities. [ABSTRACT FROM AUTHOR]

Stripping crystallization (SC) was introduced in this work to purify p-chlorophenol from the p-chlorophenol-rich liquid mixture and to purify m-chlorophenol from the m-chlorophenol-rich liquid mixture, respectively. Essentially, SC combines melt crystallization and vaporization to produce the solid product and the vapor from a liquid mixture via a series of three-phase transformations at reduced pressures during the cooling process. At the end of the SC, only the solid product remained while the liquid mixture was almost eliminated and the produced vapor was removed. A set of differential equations based on the mass and energy balances were proposed to determine the incremental variations of the amounts of remaining liquid, produced solid and produced vapor during the batch SC process. The experimental yield and product purity of the final product obtained from the batch SC experiments were compared with those predicted by the model.

The reactivity of nanoscale zero-valent iron is limited by surface passivation and particle agglomeration. Here, Ni/Fe bimetallic nanoparticles embedded into graphitized carbon (NiFe@GC) were prepared from Ni/Fe bimetallic complex through a carbothermal reduction treatment. The Ni/Fe nanoparticles were uniformly distributed in the GC matrix with controllable particle sizes, and NiFe@GC exhibited a larger specific surface area than unsupported nanoscale zero-valent iron/nickel (FeNi NPs). The XRD results revealed that Ni/Fe bimetallic nanoparticles embedded into graphitized carbon were protected from oxidization. The NiFe@GC performed excellently in 2,4,6-trichlorophenol (TCP) removal from an aqueous solution. The removal efficiency of TCP for NiFe@GC-50 was more than twice that of FeNi nanoparticles, and the removal efficiency of TCP increased from 78.5% to 94.1% when the Ni/Fe molar ratio increased from 0 to 50%. The removal efficiency of TCP by NiFe@GC-50 can maintain 76.8% after 10 days of aging, much higher than that of FeNi NPs (29.6%). The higher performance of NiFe@GC should be ascribed to the significant synergistic effect of the combination of NiFe bimetallic nanoparticles and GC. In the presence of Ni, atomic H* generated by zero-valent iron corrosion can accelerate TCP removal. The GC coated on the surface of Ni/Fe bimetallic nanoparticles can protect them from oxidation and deactivation.