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The objective of this work is to develop a microsomal composite catalytic membrane that exhibits efficient catalytic capabilities and robust stability, thereby addressing the challenge of recycling and reusing powdered photocatalytic materials. Specifically, Bi2MoO6 and WO3 nanoparticles were incorporated onto polyurethane (PU) substrates using a hybrid in situ growth method. By forming Bi2MoO6/WO3 heterojunctions, the photocatalytic activity of the membrane was enhanced without compromising its structural integrity. The flexibility and porosity of PUs play a crucial role in facilitating the adsorption of 2,4-dichlorophenol (DCP) molecules on the membrane's surface, leading to the efficient degradation of contaminants through the cleavage of C–Cl bonds triggered by the migration of electron pairs generated by the photocatalysts. A 5 × 5 cm composite membrane was tested for degradation in 20 mg/L 2,4-DCP solutions with neutral pH, achieving a degradation rate of 78.8% within 120 min. The composite membrane exhibited stability after undergoing six cycles of testing, affirming the effectiveness of its composition. Furthermore, a detailed analysis was conducted on the photocatalytic reaction mechanism of 2,4-DCP on the WO3/Bi2MoO6/PU membrane surface, highlighting the potential of porous composite membranes for wastewater treatment. [ABSTRACT FROM AUTHOR]

This current study explored the effect of pyrite on the treatment of chlorophenolic compounds (CP) by Fenton process with micron-sized zero-valent iron (ZVI) as the catalyst. The experiments were conducted in batch reactors with 100 mg L−1 CP, 0–0.02 M H2O2, and variable pyrite and ZVI doses (0–1 g L−1). Our findings show that while the reactor with 1 g L−1 ZVI as the only catalyst achieved only 10% CP removal efficiency due to rapid ZVI surface passivation and ZVI particle aggregation, the CP removal efficiency increased with increasing pyrite dose and reached 100% within couple of minutes in reactors with 0.8 g L−1 pyrite and 0.2 g L−1 ZVI. The CP removal was mainly driven by the oxidative treatment of CPs with some strong radicals such as hydroxyl radicals (•OH) while the adsorption onto the catalyst surface was only responsible for 10 to 25% of CP removals, depending on the type of CP studied. The positive impact of pyrite on CP removal by the ZVI/H2O2 system could be attributed to the ability of pyrite to (1) create an acidic environment for optimum Fenton process, (2) provide support material for ZVI to minimize ZVI particle agglomeration, and (3) stimulate iron redox cycling for improved surface site generation. Following oxidative Fenton treatment, the degradation intermediate products of CPs, including some aromatic compounds (benzoquinone, hydroquinone, etc.) and organic acids (e.g., acetic acid), became more biodegradable in comparison to their mother compounds. Overall, the treatment systems with a mixture of ZVI and pyrite as catalyst materials could offer a suitable cost-effective technology for the treatment of wastewater containing biologically non- or low-degradable toxic compounds such as chlorophenols. [ABSTRACT FROM AUTHOR]

• CoNi LDH@NF composite membrane was fabricated. • CoNi LDH@NF membrane exhibited excellent activity in PMS activation for 2,4-DCP degradation. • The practical applicability of Coni LDH@NF-PMS system was investigated. • The reactive mechanism of CoNi LDH@NF-PMS system was proposed. In this study, the cobalt-nickel layered double hydroxides (CoNi LDH) were synthesized with a variety of Co/Ni mass ratio, as CoxNiy LDHs. In comparison, Co1Ni3 LDH presented the best peroxymonosulfate (PMS) activation efficiency for 2,4-dichlorophenol removal. Meanwhile, CoNi LDH@Nickel foam (CoNi LDH@NF) composite membrane was constructed for enhancing the stability of catalytic performance. Herein, CoNi LDH@NF-PMS system exerted high degradation efficiency of 99.22% within 90 min for 2,4-DCP when [PMS] 0 = 0.4 g/L, Co1Ni3 LDH@NF = 2 cm × 2 cm (0.2 g/L), reaction temperature = 298 K. For the surface morphology and structure of the catalyst, it was demonstrated that the CoNi LDH@NF composite membrane possessed abundant cavity structure, good specific surface area and sufficient active sites. Importantly, ·OH, SO 4 ·− and 1O 2 played the primary role in the CoNi LDH@NF-PMS system for 2,4-DCP decomposition, which revealed the PMS activation mechanism in CoNi LDH@NF-PMS system. Hence, this study eliminated the stability and adaptability of CoNi LDH@NF composite membrane, proposing a new theoretical basis of PMS heterogeneous catalysts selection. [Display omitted] [ABSTRACT FROM AUTHOR]

Controlled environments are pivotal in all bioconversion processes, influencing the efficacy of biocatalysts. In this study, we designed a batch bioreactor system with a packed immobilization column and a decontamination chamber to enhance phenol and 2,4-dichlorophenol degradation using the hyper-tolerant bacterium Pseudomonas aeruginosa STV1713. When free cells were employed to degrade phenol and 2,4-DCP at a concentration of 1000 mg/L, the cells completely removed the pollutants within 28 h and 66 h, respectively. Simultaneous reductions in chemical oxygen demand and biological oxygen demand were observed (phenol: 30.21 mg/L/h and 16.92 mg/L/h, respectively; 2,4-dichlorophenol: 12.85 mg/L/h and 7.21 mg/L/h, respectively). After assessing the degradation capabilities, the bacterium was immobilized on various matrices (sodium alginate, alginate-chitosan-alginate and polyvinyl alcohol-alginate) to enhance pollutant removal. Hybrid immobilized cells exhibited greater tolerance and degradation capabilities than those immobilized in a single matrix. Among them, polyvinyl alcohol-alginate immobilized cells displayed the highest degradation capacities (up to 2000 mg/L for phenol and 2500 mg/L for 2,4-dichlorophenol). Morphological analysis of the immobilized cells revealed enhanced cell preservation in hybrid matrices. Furthermore, the elucidation of the metabolic pathway through the catechol dioxygenase enzyme assay indicated higher activity of the catechol 1,2-dioxygenase enzyme, suggesting that the bacterium employed an ortho-degradation mechanism for pollutant removal. Additionally, enzyme zymography confirmed the presence of catechol 1,2-dioxygenase, with the molecular weight of the enzyme determined as 245 kDa. [ABSTRACT FROM AUTHOR]

A post-modified covalent organic skeleton (JLNU-305-Fe) for degradation of 2,4-DCP was prepared. This study provides a broad prospect for the practical application of COF materials in the degradation of organic pollutants. [Display omitted] Herein, a novel two-dimensional double-pore covalent organic framework (JLNU-305) was synthesized using N,N,N',N'-tetrakis(4-aminophenyl)-1,4-phenylenediamine (TAPD) and 2,2′-bipyridine-5,5′-dicarboxaldehyde (BPDA). The extended π-π conjugated structure and nitrogen-riched pyridine in JLNU-305 (JLNU = Jilin Normal University) provide abundant binding sites for Fe doping. The obtained JLNU-305-Fe exhibited high and recycled catalytic efficiency for peroxydisulfate (PDS) activation to completely degrade 10 mg/L 2,4-dichlorophenol (2,4-DCP) within 8 min. The JLNU-305-Fe/PDS system showed excellent catalytic activity and cyclic stability. The capture experiments and electron paramagnetic resonance (ESR) analysis indicated that the catalytic behavior of JLNU-305-Fe/PDS is contributed to the synergistic effect between free radicals and non-free radicals. It is the first time to activate PDS for covalent organic frameworks (COFs) being used to degrade 2,4-DCP, which has a great potential for development and practical application in related water environment remediation. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Donghua University (Natural Science Edition) is the property of Journal of Donghua University (Natural Science) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Groundwater environments are complex, and traditional advanced oxidation technologies mainly based on free radicals have limitations such as poor selectivity and low interference resistance, making it difficult to efficiently degrade target pollutants in groundwater. Therefore, we developed a sludge-based biochar-supported FeMg-layered double hydroxide catalyst (BC@FeMg-LDH) for the catalytic degradation of 2, 4-dichlorophenol (2, 4-DCP) using persulfate (PDS) as an oxidant. The removal efficiency of the catalyst exceeded 95%, showing high oxidation activity in a wide pH range while being almost unaffected by reducing substances and ions in the environment. Meanwhile, under neutral conditions, the leaching of metal ions from BC@FeMg-LDH was minimal, thereby eliminating the risk of secondary pollution. According to quenching experiments and electron paramagnetic resonance spectroscopy, the main active species during BC@FeMg-LDH/PDS degradation of 2, 4-DCP is 1O2, indicating a non-radical reaction mechanism dominated by 1O2. Characterization techniques, including X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy, revealed that the carbonyl (C = O) and metal hydroxyl (M-OH) groups on the material surface were the main reactive sites mediating 1O2 generation. The 1O2 generation mechanism during the reaction involved ketone-like activation of carbonyl groups on the biochar surface and complexation of hydroxyl groups on the material surface with PDS, resulting in the formation of O2·− and further generation of 1O2. 1O2 exhibited high selectivity toward electron-rich organic compounds such as 2, 4-DCP and demonstrated strong interference resistance in complex groundwater environments. Therefore, BC@FeMg-LDH holds promising applications for the remediation of organic-contaminated groundwater. [ABSTRACT FROM AUTHOR]

Featured Application: The obtained results can be used in the design and modeling of industrial degradation of 2,4-dichlorophenol when using an enzyme membrane with horseradish peroxidase. Chlorophenol compounds pose a health risk to many organisms due to their toxicity. The present paper presents the estimation of the activation and deactivation energies and the optimum temperatures of 2,4-dichlorophenol degradation by horseradish peroxidase (HRP). The activities of horseradish peroxidase depending on temperature were analyzed. In a mathematical model, describing 2,4-dichlorophenol degradation by HRP was assumed that both the 2,4-dichlorophenol degradation and the deactivation of HRP were first-order reactions by the enzyme concentration. The parameters of the optimum temperatures T o p t , the activation energies E r , and the deactivation energies E d in the process of 2,4-dichlorophenol degradation by HRP immobilized on a modified nanofibrous membrane were determined k d   and   t 1 / 2 were determined for HRP immobilized at temperatures in the range of 25 °C to 75 °C. Likewise, thermodynamic parameters such as the change in the enthalpy ∆ H # , change in entropy ∆ S # , the change in Gibbs free energy ∆ G # for native HPR and the change in the enthalpy ∆ H d # , change in entropy ∆ S d # , and the change in Gibbs free energy ∆ G d # for deactivated HRP were determined at 25 °C. [ABSTRACT FROM AUTHOR]

In this work, the process of decomposition of 2,4-dichlorophenol (2,4-DCP) vapor under the influence of atmospheric pressure DBD in oxygen was studied. The studies were carried out in two modes: with a catalyst (natural vermiculite doped with zirconium) and without it. A number of basic characteristics of the catalyst were assessed. The rates and effective rate constants of sorption processes, as well as decomposition processes in plasma and plasma-catalytic systems, were determined. Based on these data, the energy efficiency of the decomposition process was calculated. The data obtained suggested that the initial stage of decomposition is the reaction of interaction of electrons with pollutant molecules. The catalyst has been shown to speed up the decomposition process, increase energy efficiency and the conversion of 2,4-DCP to CO2 molecules, and prevent the formation of condensed products on the reactor walls. The work estimates the carbon and chlorine balances before and after treatment, which reach a maximum of 99 and 60%, respectively. It was also shown that the catalyst retains its activity for at least 7 h of continuous operation. [ABSTRACT FROM AUTHOR]

Controllable synthesis of micro-flower covalent organic frameworks (MFCOFs) with controllable size, monodisperse, spherical, and beautiful flower shape was realized by using 2,5-diformylfuran (DFF) and p-phenylenediamine (p-PDA) as building blocks at room temperature. High-quality MFCOFs (5 − 7 μm) were synthesized by controlling the kind of solvent, amounts of monomers, catalyst content, and reaction time. The synthesized MFCOFs possessed uniform mesopores deriving from the intrinsic pores of frameworks and wide-distributed pores belonging to the gap between the petals. The MFCOFs-packed solid-phase extraction (SPE) column shows adsorption capacity of about 8.85 mg g−1 for 2,4-dichlorophenol (2,4-DCP). The MFCOF-based SPE combined with the HPLC method was established for the determination of 2,4-DCP in environmental water. The linear range of this method is 20–1000 ng mL−1 (R2 > 0.9994), and limit of detection (S/N = 3) is 10.9 ng mL−1. Spiked recoveries were 94.3–98.5% with relative standard deviations lower than 2.3%. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Industrial units based on chemical processes—the textile and paper industries—are major sources of chlorophenols in the environment, and chlorophenolic compounds persist within the environment for a long time with high toxicity levels. The photo-assisted Fenton's and photocatalysis processes were investigated for the degradation of chlorophenols in the present study. Response surface methodology was employed to get optimised conditions for photocatalysis and photo-Fenton process-governing factors, thus, yielding a profound removal efficiency. Under optimised conditions, with a photocatalyst dose of 0.2 g/L, oxidant concentration of 10.0 mM and pH 5.0, complete removal of 2,4-dichlorophenol (2,4-DCP) was observed in 210 minutes in photocatalytic treatment. In the case of the photo-Fenton process, at an H2O2 dose of 5.0 mM and Fe2+ concentration of 0.5 mM, the organic pollutant was eliminated within 5 minutes of reaction time under acidic conditions (pH 3.0). The RSM model reported the perfect fit of experimental data with the predicted response. Among different isotherm models, the Langmuir isotherm was the best fit. The process followed pseudo-first order rate kinetics among various kinetics models. For the obtained optimised conditions, sonication and solar energy-driven processes were incorporated to study enhanced mineralisation. The solar-assisted Fenton process reported maximum mineralisation (90%) and cost-effective ($0.01/litre for 100 mg/L 2,4-DCP) treatment among different hybrid oxidation processes. The work provides insight into harnessing the naturally available solar energy, reducing the overall treatment cost and opting for a sustainable treatment method. [ABSTRACT FROM AUTHOR]

2,4-Dichlorophenol (2,4-DCP) is difficult to degrade rapidly in the environment due to its stable chemical properties, so it was easy to lead to serious chlorophenol pollution in soil. Consequently, a remediation method which is efficient, safe, and economical is required. In this study, electrokinetic (EK) remediation was used to transfer sodium persulfate (Na2S2O8) into soil to degrade 2,4-DCP, and the effect of several factors (including the addition location of Na2S2O8, applied voltage, and running time) on the remediation efficiency was explored. The concentration of Na2S2O8, residual efficiency of 2,4-DCP and distribution characteristics of pH, and electrical conductivity were analyzed. The results showed that the cathode was the optimal position to add Na2S2O8. Under this condition, Na2S2O8 was uniformly distributed in the whole soil column through electromigration. The optimal removal efficiency of 2,4-DCP in soil by adding Na2S2O8 was approximately 26% when the voltage gradient was 1.0 V/cm and the operating time was 9 days, which was mainly due to the degradation of S2O82−. [ABSTRACT FROM AUTHOR]

To better understand the mechanism and kinetics of peroxynitrite(PS) activation by nano-zerovalent iron(nZVI)a, kinetic model of the degradation process of 2,4-dichlorophenol(2, 4-DCP) was developed based on the Langmuir-Hinshelwood mechanism in conjunction with the main reaction steps in the nZVI/PS system. The kinetic model was fitted and the rate constants were determined using the data of PS, 2,4.DCP concentration variation under different influencing factors(including nZVI dosing, initial PS concentration and initial 2,4-DCP concentration), and the sensitivity analysis of the rate constants yielded that the overall reaction kinetics of 2,4-DCP degradation is composed of the formation of sulfate radicals SO4 by electron transfer reactions within the precursor surface complex and the degradation of 2,4-DCP by hydroxyl radicals OH. [ABSTRACT FROM AUTHOR]

The dechlorination of 2,4-dichlorophenol (2,4-DCP) by a nanoscale Fe/Ni material was investigated at room temperature. 2,4-DCP can be removed more quickly by an Fe/Ni material with 2% Ni. Fe/Ni exhibited excellent adsorption and reduction efficiency toward 2,4-DCP in an aqueous solution over a wide range of pH values. The removal rate of 2,4-DCP exceeded 95% in 60 min in the pH range of 3.0–9.0, and more than 75% was dechlorinated to phenol (CA). The degradation pathway of 2,4-DCP was confirmed based on analysis of the intermediate and end products. A portion of 2,4-DCP was first dechlorinated with a chlorine atom to produce 2-chlorophenol and 4-chlorophenol, and then dechlorination was performed sequentially to form CA. The other portion of 2,4-DCP was dechlorinated to remove two chlorine atoms simultaneously to generate CA. The investigations are essential to the application of iron-based remediation technology. [ABSTRACT FROM AUTHOR]

Phenolic pollutants from industrial and agricultural activities pose a major threat to the world’s potable water supply. The persistent micro-pollutants often find their way into drinking water sources with possible adverse human health implications. In this study, bottled water, tap water, and wastewater treatment plant (WWTP) effluent samples from the Boland region of the Western Cape, South Africa were assessed to determine 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) levels using HPLC/DAD instrumentation. The selected area is known for its vast agricultural ventures and wineries. Evaluation of the human health risk (cancer risk) for the pollutants was conducted using the hazard quotient (HQ). The Ames mutagenicity test was also conducted using the Salmonella typhimurium T98 and T100 strains and the S9 activation enzyme. Trace levels of the phenolics were detected in the samples with a range of 9.32 × 10−7—1.15 × 10−4 mg/L obtained for 4-CP, and 8.80 × 10−7—1.72 × 10−4 mg/L recorded for 2,4-DCP. Both compounds had levels below the limit of 0.01 mg/L prescribed by South African legislation. The assessed HQ for the phenolic concentrations indicates a low level of potential ecological risk and none of the samples had a cancer risk value that exceeded the regulatory limit. The possibility of the analyzed samples causing cancer is unlikely, but non-carcinogenic adverse effects were found. Strong mutagenicity was observed for the T98 strains with a potential ability to cause mutation toward the insertion or deletion of a nucleotide. The T100 bacterial strain showed very slight mutagenicity potential, however, it is unlikely to cause any mutation. The levels of phenolics in the potable water samples may pose a significant threat to human health. Hence, screening persistent organic chemicals in potable water sources and evaluating their potential human health effects is pertinent to prevent associated health challenges.

We developed and optimized an electrocatalytic filtration system to catalytically hydrodechlorinate chlorophenolic compounds. A key part of the system was the cathode, which consisted of a filter constructed with electroactive carbon nanotubes (CNTs) functionalized with atomically precise gold nanoclusters (AuNCs). In the functional membrane electrode, the AuNCs attached to the CNTs functioned as a highly effective hydrodechlorination catalyst. Additionally, the ligands of the AuNCs facilitated the binding of the AuNCs with the CNT and protected the Au core from agglomeration. Atomic H* was the primary reactive species in the system, but direct reduction by cathode electrons also contributed to the elimination of 2,4-dichlorophenol (2,4-DCP) by hydrodechlorination. The generated atomic H* was able to break the C–Cl bond to achieve the rapid hydrodechlorination of 2,4-DCP into phenol, with 91.5% 2,4-DCP removal within 120 min. The AuNC catalysts attached to the CNT exceeded the best catalytic activity of larger nanoparticles (e.g., AuNPs), while the flow-through construction performed better than a standard batch reactor due to the convection-enhanced mass transport. The study provides an environmentally friendly strategy for the elimination of pervasive halogenated organic contaminants using a highly efficient, stable and recyclable system for hydrodechlorination that integrates nanofiltration and electrochemistry. [ABSTRACT FROM AUTHOR]

The abuse of chemicals containing 2,4-dichlorophenol (2,4-DCP) has caused serious pollution to the ecological environment. The chemical properties of 2,4-DCP are stable and difficult to be degraded. 2,4-DCP also have carcinogenic, teratogenic, and mutagenic effects on creatures. Recently, the use of advanced oxidation processes (AOPs) activated by nanoscale zero-valent iron (nZVI) for the degradation of 2,4-DCP has aroused much more attraction. However, the agglomeration and oxidation of nZVI limited its performance. To improve the above defects and enhance nZVI's catalytic performance, nanoscale zero-valent iron (nZVI@BC) was synthesized using ferrous sulfate, sodium borohydride and biochar, and it was characterized by scanning electron microscope (SEM) and other technological means. The effects of catalyst dosage, pH value, and H2O2 concentration on degradation efficiency of 2,4-DCP were investigated using response surface methodology (RSM). The catalytic mechanism of the catalyst in the reaction process was studied. The results of RSM showed that when the catalyst dosage was 0.69 g/L, pH value was 3.34 and H2O2 concentration was 4.56 mM, the predicted degradation rate of 50 mg/L 2,4-DCP was 99.38%. The results of free radical quenching experiments show that nZVI@BC can produce ·OH, O 2 ∙ - , and 1O2 simultaneously, accelerating the degradation of 2,4-DCP. Overall, nZVI@BC is an effective catalyst for the degradation of 2,4-DCP. [ABSTRACT FROM AUTHOR]

Chlorophenol compounds pose a health risk to many organisms due to their toxicity. The present paper presents the estimation of the activation and deactivation energies and the optimum temperatures of 2,4-dichlorophenol degradation by horseradish peroxidase (HRP). The activities of horseradish peroxidase depending on temperature were analyzed. In a mathematical model, describing 2,4-dichlorophenol degradation by HRP was assumed that both the 2,4-dichlorophenol degradation and the deactivation of HRP were first-order reactions by the enzyme concentration. The parameters of the optimum temperatures Topt, the activation energies Er, and the deactivation energies Ed in the process of 2,4-dichlorophenol degradation by HRP immobilized on a modified nanofibrous membrane were determined kd and t1/2 were determined for HRP immobilized at temperatures in the range of 25 °C to 75 °C. Likewise, thermodynamic parameters such as the change in the enthalpy ∆H#, change in entropy ∆S#, the change in Gibbs free energy ∆G# for native HPR and the change in the enthalpy ∆Hd#, change in entropy ∆Sd#, and the change in Gibbs free energy ∆Gd# for deactivated HRP were determined at 25 °C.

Photocatalytic degradation, as an advanced oxidation process (AOPs), offers a great advantage to target persistent organic pollutants (POPs) in water. RSM in the present study which is statistical means for optimizing processes like photocatalysis with minimum laboratory experimentation. RSM has a history of being a potent design experiment tool for creating new processes, modifying their designs, and optimizing their performances. Herein, a highly sought-after, easily preparable, visible-light active, copper bismuth oxide (CuBi2O4) is applied against a toxic emerging contaminant, 2,4-dichlorophenol (2,4-DCP) under an LED light source (viible light λ > 420 nm). A simple coprecipitation method was adopted to synthesize CuBi2O4 and later analyzed with FESEM, EDX, XRD, FTIR, and spectroscopy to determine its intrinsic properties. Principally, the photocatalytic degradation investigations were based on response surface methodology (RSM), which is a commanding tool in the optimization of the processes. The 2,4-DCP concentration (pollutant loading), CuBi2O4 dosage (catalyst dosge), contact time, and pH were the chosen as dependent factors, that were optimized. However, under optimal conditions, the CuBi2O4 nanoparticle showed a remarkable photocatalytic performance of 91.6% at pH = 11.0 with a pollutant concentration of 0.5 mg/L and a catalyst dose of 5 mg/L within 8 h. The obtained RSM model showed a satisfactory correlation between experimental and predicted values of 2,4-DCP removal, with an agreeable probability value (p) of 0.0069 and coefficient of regression (R2) of 0.990. It is therefore anticipated that the study may open up new possibilities for formulating a plan to specifically target these organic pollutants. In addition, CuBi2O4 possessed fair reusability for three-consequent cycles. Hence, the as-synthesized nanoparticles applied for photocatalysis foster a fit-for-purpose and reliable system in the decontamination of 2,4 DCP in environmental samples, and also the study highlights the efficient use of RSM for environmental remediation, particularly in AOP implementation. [ABSTRACT FROM AUTHOR]

Our previous study indicated excellent dechlorination efficiency and phenol conversion rate in the electrocatalytic reduction of 2,4-dichlorophenol (2,4-DCP) with a Pd-MWCNTs/Ni-foam electrode; it is deserved to investigate whether this electrode can efficiently degrade phenol in electro-Fenton oxidation (EFO) process and realize the effective mineralization of 2,4-DCP in aqueous solution. In this work, the sequential electrocatalytic reduction and oxidation of 2,4-DCP were studied after examining phenol degradation in the EFO process. The results showed that the removal efficiency of 0.31 mM phenol could reach 96.76% after 90-min degradation with the rate constant of 0.0367 min−1, and hydroxy radicals (·OH) were the main active species in the EFO process. In the sequential electrocatalytic reduction and oxidation processes, the removal efficiencies of 2,4-DCP, phenol, and total organic carbon (TOC) reached 99.72%, 97.07%, and 61.45%, respectively. The possible degradation mechanism of 2,4-DCP was proposed through monitoring the reaction products, and the stability and reusability of the electrode were also examined. This study suggested that 2,4-DCP in wastewater can be effectively mineralized to realize its efficient degradation through the sequential electrocatalytic reduction and oxidation. [ABSTRACT FROM AUTHOR]

In the current study, polyaniline and polypyrrole with silicon dioxide (PAni:PPy@SiO2) were combined to formulate a new adsorbent, which was examined using XRD, TEM, SEM, FTIR, TGA, and BET, and the adsorption kinetics were investigated by UV–vis spectroscopy. The optical band gap was also evaluated. The electrochemical behavior was investigated using cyclic voltammograms. Moreover, experimental conditions were used to evaluate the 2,4-dichlorophenol (2,4-DCP) adsorption based on the pH, temperature, reaction time, and initial concentration. The analytical isotherm data were determined by Langmuir, Freundlich, Temkin, Sips, and Redlich–Peterson models. For the analysis of the kinetic data, the pseudo-first- and -second-order models and the intraparticle diffusion model were investigated. It was found that this new adsorbent possessed the highest adsorption efficiency after several regeneration cycles. Furthermore, the thermodynamic parameters of adsorption, such as entropy (ΔS), enthalpy (ΔH), and standard Gibbs were measured. These results suggest that the PAni:PPy backbone can generally be better applied for the elimination of 2,4-dichlorophenol by appropriately dispersing it over the surface of suitable SiO2. This search provides a novel way to develop separable, high-performance adsorbents for adsorbing organic contamination from wastewater. [ABSTRACT FROM AUTHOR]

Biotreatment of triclosan is mainly performed in conventional activated sludge systems, which, however, are not capable of completely removing this antibacterial agent. As a consequence, triclosan ends up in surface and groundwater, constituting an environmental threat, due to its toxicity to aquatic life. However, little is known regarding the diversity and mechanism of action of microbiota capable of degrading triclosan. In this work, an immobilized cell bioreactor was setup to treat triclosan-rich wastewater. Bioreactor operation resulted in high triclosan removal efficiency, even greater than 99.5%. Nitrogen assimilation was mainly occurred in immobilized biomass, although nitrification was inhibited. Based on Illumina sequencing, Bradyrhizobiaceae, followed by Ferruginibacter, Thermomonas, Lysobacter and Gordonia, were the dominant genera in the bioreactor, representing 38.40 ± 0.62% of the total reads. However, a broad number of taxa (15 genera), mainly members of Xanthomonadaceae, Bradyrhizobiaceae and Chitinophagaceae, showed relative abundances between 1% and 3%. Liquid Chromatography coupled to Quadrupole Time-Of-Flight Mass Spectrometry (LC-QTOF-MS) resulted in the identification of catabolic routes of triclosan in the immobilized cell bioreactor. Seven intermediates of triclosan were detected, with 2,4-dichlorophenol, 4-chlorocatechol and 2-chlorohydroquinone being the key breakdown products of triclosan. Thus, the immobilized cell bioreactor accommodated a diverse bacterial community capable of degrading triclosan. [ABSTRACT FROM AUTHOR]

Photocatalytic degradation is one of the effective methods to remove various pollutants from domestic and industrial effluents. Several operational parameters can affect the efficiency of photocatalytic degradation. Performing experimental methods to obtain the percentage degradation (%degradation) of pollutants in different operating conditions is costly and time-consuming. For this reason, the use of computational models is very useful to present the %degradation in various operating conditions. In our previous work, Fe3O4/TiO2 nanocomposite containing different amounts of silver nanoparticles (Fe3O4/TiO2/Ag) were synthesized, characterized by various analytical techniques and applied to degradation of 2,4-dichlorophenol (2,4-DCP). In this work, a series of models, including stochastic gradient boosting (SGB), artificial neural network (ANN), adaptive neuro-fuzzy inference system (ANFIS), the improvement of ANFIS with genetic algorithm (GA-ANFIS), and particle swarm optimization (PSO-ANFIS) were developed to estimate the removal percentage of 2,4-DCP. The model inputs comprised of catalyst dosage, radiation time, initial concentration of 2,4-DCP, and various volumes of AgNO3. Evaluating the developed models showed that all models can predict the occurring phenomena with good compatibility, but the PSO-ANFIS and the SGB models gave a high accuracy with the coefficient of determination (R2) of 0.99. Moreover, the relative contributions, and the relevancy factors of input parameters were evaluated. The catalyst dosage and radiation time had the highest (32.6%), and the lowest (16%) relative contributions on the predicting of removal percentage of 2,4-DCP, respectively. [ABSTRACT FROM AUTHOR]

The excessive use of herbicides and fungicides containing 2,4-dichlorophenol (2,4-DCP) has led to serious environmental water pollution; 2,4-DCP is chemically stable and difficult to be degraded effectively by biological and physical methods. And the degradation of 2,4-DCP using advanced oxidation techniques has been a hot topic. Biochar, polyethylene glycol, ferrous sulfate, and sodium borohydride were used to synthesize the heterogeneous catalyst PEGylated nanoscale zero-valent iron supported by biochar (PEG-nZVI@BC). The catalyst was characterized using scanning electron microscope (SEM) and other means to determine its physicochemical properties. Catalytic performance and mechanism of this catalyst with hydrogen peroxide for the oxidation of 2,4-DCP were investigated. The results showed that PEG-nZVI@BC had good dispersibility, stability, and inoxidizability; the degradation efficiency of 50 mg/L 2,4-DCP by PEG-nZVI@BC/H2O2 system 92.94%, 1.68 times higher than that of nZVI/H2O2 system; there are both free radical and non-free radical pathways in PEG-nZVI@BC/H2O2 system; the degradation process of 2,4-DCP includes hydroxylation, dechlorination, and ring-opening. Overall, PEG-nZVI@BC is a promising heterogeneous catalyst for the degradation of 2,4-DCP. [ABSTRACT FROM AUTHOR]

• N/Cu-ZnS nanosphere was synthesized by hydrothermal method for the first time. • More ZnS (111) were exposed by N/Cu co-doping. • The degradation rate constants of 2,4-DCP and TC by N / Cu ZnS were 83.7 and 51 times higher than that of ZnS. • O 2 adsorption on ZnS (111) was enhanced by N/Cu co-doping so that the production of •O 2 − was promoted. • Possible way for the photocatalytic degradation of 2,4-DCP and TC by N/Cu-ZnS was proposed. High-efficiency photocatalysts are of great significance for the application of photocatalytic technology in water treatment. In this study, N/Cu co-doped ZnS nanosphere photocatalyst (N/Cu-ZnS) is synthesized by a hydrothermal method for the first time. After doping, the texture of nanosphere becomes loose, the nanometer diameter is reduced, making the specific surface area of catalyst increased from 34.73 to 101.59 m2/g. The characterization results show that more ZnS (111) crystal planes are exposed by N/Cu co-doping; the calculations of density functional theory show that N/Cu co-doping can increase the catalytic activity of the ZnS (111) crystal plane, enhance the adsorption capacity of (111) crystal plane to O 2 , and promote the generation of •O 2 −. The energy levels of the introduced impurities can be hybridized with the energy levels of S and Zn at the top of valence band and the bottom of conduction band, which makes the band gap narrower, thus enhancing the absorption of visible light. Compared with pure ZnS, the degradation rates of 2,4-dichlorophenol (2,4-DCP) and tetracycline (TC) by N/Cu-ZnS under visible light (>420 nm) are increased by 83.7 and 51 times, respectively. In this research, a promising photocatalyst for photocatalytic degradation of organic pollutants in wastewater is provided. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, a novel adsorbent, activated carbon (PSAC) developed by the activation of pine sawdust's pyrolytic carbon (PSPC), is applied to adsorb 2,4-dichlorophenol (2,4-DCP) and 4-chlorophenol (4-CP). The optimized preparation conditions of PSAC were presented. The results revealed that equilibrium adsorption capacity (qe) of PSAC was notably enhanced up to threefold compared with PSPC. The adsorbents were characterized by a variety of techniques such as SEM, XRD, FT-IR, and elemental analysis. The key factors (such as adsorbent dosage, pH, salt concentration, temperature, and contact time) influencing the adsorption process were also studied. The adsorption quantities of PSAC for 2,4-DCP and 4-CP were 135.7 mg·g−1 and 77.3 mg·g−1, respectively. The equilibrium adsorption of 4-DCP and 4-CP was suitable to be predicted by the Freundlich and Koble-Corrigan models, while kinetic process was better described by the pseudo-second-order kinetic model and Elovich equation. The process was spontaneous. After repeated regeneration of PSAC with ethanol, the adsorption capacity of PSAC was not significantly reduced, indicating that PSAC can be recycled by regeneration after adsorption of 4-CP. This work provides a viable method to use activated carbon as an effective adsorbent for pollutant removal. [ABSTRACT FROM AUTHOR]

Glutathione S-transferases (GSTs) play important roles in many biochemical processes, including the detoxification of xenobiotics, herbicides and pesticides, as well as enhancing stress tolerance in plants. 2,4-Dichlorophenol (2,4-DCP), an extremely toxic chlorophenolic, is a pollutant used as raw material in many industries, including the production of most herbicides and insecticides. This study investigated the response of GST for the phytoremediation of 2,4-DCP in Datura stramonium L., Amaranthus retroflexus L., and Sinapis arvensis L., plants with high phytoremediation potential following 2,4-DCP application. The seedlings grown in a hydroponic system were exposed to various solutions of 2,4-DCP in a concentration range from 75 to 275 ppm for 4 days. The GST activity was evaluated in the seedling roots and leaves. The activities in roots and leaves of D. stramonium increased to 125 ppm but decreased at 150 ppm and its higher doses compared to controls. In A. retroflexus, the GST activity increased to 175 ppm in leaves and 125 ppm in roots but decreased in both in parallel with higher doses of 2,4-DCP. In S. arvensis, on the other hand, all doses of 2,4-DCP decreased GST activity in leaves and roots compared to controls. Our results show that D. stramonium and A. retroflexus respond to 2,4-DCP toxicity with high GST activity, whereas S. arvensis is able tolerate the same toxicity, possibly by a different mechanism. [ABSTRACT FROM AUTHOR]

In this study, a novel thermo-responsive polymer was synthesized with efficient grafting of N-isopropylacrylamide as a thermosensitive polymer onto the graphene oxide surface for the efficient removal of phenol and 2,4-dichlorophenol from aqueous solutions. The synthesized polymer was conjugated with 2-allylphenol. Phenol and 2,4-dichlorophenol were monitored by ultra-performance liquid chromatography system equipped with a photodiode array detector. The nanoadsorbent was characterized by different techniques. The nanoadsorbent revealed high adsorption capacity where the removal percentages of 91 and 99% were found under optimal conditions for phenol and 2,4-dichlorophenol, respectively (for phenol; adsorbent dosage = 0.005 g, pH = 8, temperature= 25 °C, contact time = 60 min; for 2,4-dichlorophenol; adsorbent dosage = 0.005 g, pH = 5, temperature = 25 °C, contact time = 10 min). Adsorption of phenol and 2,4-dichlorophenol onto nanoadsorbent followed pseudo-second-order kinetic and Langmuir isotherm models, respectively. The values of ΔG (average value = − 11.39 kJ mol−1 for phenol and 13.42 kJ mol−1 for 2,4-dichlorophenol), ΔH (− 431.72 J mol−1 for phenol and − 15,721.8 J mol−1 for 2,4-dichlorophenol), and ΔS (35.39 J mol−1 K−1 for phenol and − 7.40 J mol−1 K−1 for 2,4-dichlorophenol) confirmed spontaneous and exothermic adsorption. The reusability study indicated that the adsorbent can be reused in the wastewater treatment application. Thermosensitive nanoadsorbent could be used as a low-cost and efficient sorbent for phenol and 2,4-dichlorophenol removal from wastewater samples. [ABSTRACT FROM AUTHOR]

2,4-Dichlorophenol (2,4-DCP) one of the most common and abundant pollutants, is widely found in various industrial effluents such as resin and plastic products in the petrochemical industry. The apparent effect of this recalcitrance compound on the health and environment is enhancing its efficient degradation before wastewater discharged into the receiving water. Hence, the removal of 2,4-DCP from aqueous solutions using the photocatalytic UV-LED/ZnO process was investigated. In this experimental study, the removal of 2,4-DCP using UV-LED in the presence of ZnO in the bench scale reactor was examined. The effects of operational parameters such as the pH of the solution (3-11), initial concentration of 2,4-DCP (50-200 mg/L), the amount of ZnO dose (0.003-0.025 mol/L) and different ionic strengths were evaluated. The experimental results indicated that different operational parameters influenced the removal of 2,4-DCP. The highest 2,4-DCP removal rate was obtained at pH = 11 by adding 0.006 mol/L ZnO into the solution with an initial concentration of 50 mg/L 2,4-DCP, removing more than 98.2% of 2,4-DCP. When UV-LED and ZnO were used alone, the removal efficiencies were 32.11% and 30.93%, respectively. Also, the maximum chemical oxygen demand removal rate was 64.45% in optimum conditions and ionic strength was reported to be ineffective. The results indicated that combined ZnO and UV-LED processes in optimal conditions could be used as an alternative technology for the treatment of various industrial wastewater containing 2,4-DCP. [ABSTRACT FROM AUTHOR]

In this study, Fe3O4 magnetic nanoparticles (MNPs) were loaded on α-MnO2 nanowires using an improved hydrothermal synthesis method combined with an ultrasonic coprecipitation method, the loading ratio was optimized, the efficiency of the prepared Fe3O4/α-MnO2-activated persulfate (PS) system for the degradation of 2,4-dichlorophenol (2,4-DCP) was investigated, and the effects of PS concentration, Fe3O4/α-MnO2 magnetic nanocomposites (MNCs) dosage, pH value and initial pollutant concentration on the degradation of 2,4-DCP were investigated. The results showed that when the initial concentrations of 2,4-DCP, PS, and Fe3O4/α-MnO2 MNCs were 100 mg/L, 30 mmol/L, and 0.4 g/L, the degradation rate of 2,4-DCP reached 96.3% after 180 min of reaction at 30 °C under a neutral condition, and the fitting results showed that the degradation of 2,4-DCP by the Fe3O4/α-MnO2-activated PS system conformed to quasi-first-order kinetics. The degradation of 2,4-DCP by different Fe3O4/α-MnO2-activated PS systems was compared, and a possible PS activation mechanism was proposed. The Fe3O4/α-MnO2 MNCs exhibited excellent reusability, and by introducing Fe3O4/α-MnO2 MNCs as the PS activator into the advanced oxidation process (AOP) system, the electron transfer of Mn(III/IV) and Fe(III/II) on the surface of MNCs was realized, thus greatly improving the reaction efficiency. [ABSTRACT FROM AUTHOR]

In order to enhance the degradation effect of microorganisms on crude oil in the existence of chlorophenol compounds, oil-degrading bacteria C4 (Alcaligenes faecails), C5 (Bacillus sp.) and 2,4-dichlorophenol (2,4-DCP) degrading bacteria L3 (Bacillus marisflavi), L4 (Bacillus aquimaris) were isolated to construct a highly efficient consortium named (C4C5 + L3L4). When the compound bacteria agent combination by VC4: VC5: VL3: VL4 = 1:2:2:1, the crude oil degradation efficiency of 7 days was stable at 50.63% ~ 55.43% under different conditions. Degradation mechanism was analyzed by FTIR, GC–MS and IC technology and the following conclusions showed that in the system of adding consortium (C4C5 + L3L4), the heavy components were converted into saturated and unsaturated components. The bacterial consortium could first degrade medium and long chain alkanes into short chain hydrocarbons and then further degrade. And the dechlorination efficiency of 2,4-DCP in the degradation system reached 73.83%. The results suggested that the potential applicability and effectiveness of the selected bacteria consortium for the remediation of oil-contaminated water or soil with the existence of chlorophenol compound. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mn(II)-based systems oxidized As(III) via electron-transfer with Mn(III) intermediate. • DCP complexed with Mn(III), and prolonged its lifespan for enhanced As(III) oxidation. • Mn(II) inhibited As(III) adsorption by MnO 2 , while Fe(II) enhanced it due to Fe-(hydr)oxides. • The identified byproducts from DCP degradation revealed As(III) oxidation at MnO 2 surface. Manganese oxides (MnO 2) are widely utilized in arsenic(AsIII)-contaminated groundwater remediation; however, As(III) oxidation is greatly affected by co-occurring substances. This study discusses the oxidation pathways of As(III) oxidation-adsorption in presence of co-solutes (e.g., Mn(II), Fe(II), and 2,4-dichlorophenol (DCP). Mn(II) species competed with As(III) for adsorption and oxidation sites at MnO 2 surface, resulting in a decrease in As(III) removal. As(III) oxidation in Mn(II) and Mn(II)/MnO 2 systems was primarily occurred via electron-transfer with Mn(III) intermediate, however, Mn(III) species were rapidly oxidized into the less reactive oxidant Mn(IV). In the presence of DCP, As(III) oxidation was enhanced due to stabilization of Mn(III) species by complexation with DCP. Fe(II) enhanced the adsorption of Arsenic and DCP by MnO 2 , as Fe-(hydr)oxides formed, creating extra adsorption sites on MnO 2. Three DCP byproducts were also identified by means of LC/MS analysis in the Mn(II)/MnO 2 -DCP system, with reaction As(III) oxidation pathways are proposed. The enhanced As(III) oxidation by Mn(II)/MnO 2 system, in presence of DCP resulted due to a series of chemical reactions with hydroxyl and phenolic radicals generated in system, in addition to electron transfer with DCP-Mn(III) complexes. These results provide new insights into the environmental behavior of As(III) within mixed water systems containing metals (Mn/Fe) and phenolics. [ABSTRACT FROM AUTHOR]

In recent years, the remediation of 2,4-DCP pollution using immobilized microbial technology has attracted increasing attention. Using granular activated carbon (GAC), polyethylene glycol 4000 (PEG-4000), ferrous sulfate, and sodium borohydride as raw materials, granular activated carbon loaded polyethylene glycol modified nano zero-valent iron composite material (PEG-nZVI/GAC) was prepared via a liquid-phase reduction method. Bacillus marisflavi , capable of degrading phenolic compounds, was immobilized on PEG-nZVI/GAC using an adsorption method to prepare immobilization of microorganisms by granular activated carbon loaded polyethylene glycol modified nano zero-valent iron (PEG-nZVI/GAC@ B) for 2,4-DCP removal. Characterization analysis of immobilized microbes was conducted using transmission electron microscopy (TEM) and other methods to determine their physicochemical properties. Response surface methodology (RSM) was employed to optimize the conditions for 2,4-DCP removal, and the performance and mechanism of 2,4-DCP removal by PEG-nZVI/GAC@ B were studied. The results indicate that nanoscale zero-valent iron (nZVI) was uniformly distributed in granular activated carbon, Bacillus marisflavi was successfully loaded onto PEG-nZVI/GAC, PEG-nZVI/GAC@ B had a higher content of oxygen-containing groups on its surface, and exhibits good dispersibility, stability, and reusability. When the immobilized microbial dosage was 270.32 mg/L, the initial concentration of 2,4-DCP was 50.51 mg/L, and pH was 6.58, the predicted removal rate of 2,4-DCP was 96.53 %. Under these conditions, the actual removal rate of 2,4-DCP was 94.68 %. The removal of 2,4-DCP by PEG-nZVI/GAC@ B involved adsorption by granular activated carbon, reductive dechlorination by nanoscale zero-valent iron, and degradation by Bacillus marisflavi. In conclusion, PEG-nZVI/GAC@ B is an excellent immobilized microorganism for the removal of 2,4-DCP. • A novel immobilized microorganism (PEG-nZVI/GAC@ B) was prepared. • Characterization proved the excellent properties of PEG-nZVI/GAC@ B. • Optimization of PEG-nZVI/GAC@ B for 2,4-DCP RSM. The material conservation analysis of 2,4-DCP was carried out. • The mechanism of 2,4-DCP removal by PEG-nZVI/GAC@ B was described. [ABSTRACT FROM AUTHOR]

Herein, a highly effective ɑ-MnO2/Fe3O4 nanocomposite was synthesized employing a hydrothermal process and characterized by scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR), and UV–visible spectroscopy. The ɑ-MnO2/Fe3O4 photocatalyst flaunts two phases: magnetic magnetite (Fe3O4) nanoparticles of 22±5 nm agglomerated on ɑ-MnO2 1-D nanowire of ∼1.5 µm length and 50±10 nm in diameter. The results exhibited ∼100% photocatalytic degradation of 2,4-DCP under UV-visible irradiation within 80 min at pH 9. The photocatalytic experimental values were fitted linearly with first-order reaction exhibiting k = 0.065 min−1, t1/2 = 10.45 min, and R2 = 0.98 for UV-visible light and k = 0.028 min−1, t1/2 = 34 min and R2 = 0.97 for reaction under sunlight. Additionally, the nanocomposite photocatalyst was easily recoverable using an external magnetic field at room temperature with high stability. Therefore, a simple synthesis method, a synergistic effect between ɑ-MnO2 and Fe3O4, an excellent adsorption-induced photocatalytic activity, easy magnetic recovery, and robustness for reusability make the nanocomposite an outstanding material for environmental sustainability and solar energy harvesting.

In the present study, the response surface methodology (RSM) model was used to investigate the photocatalytic performance of silver tungstate (Ag2WO4) in the removal of 2,4-dichlorophenol (2,4-DCP) under natural sunlight. The Ag2WO4 which has nanoflower-like structure was synthesized by a coprecipitation method. The synthesized photocatalyst was characterized for FESEM, TEM, EDX, XRD, FTIR, and UV–Vis spectroscopy. RSM was employed to scrutinize the suitable model to yield a profound pollutant removal rate. The four independent factors such as pollutant concentration, catalyst dosage, pH, and contact time are simulated using RSM. A total of 91% of 2,4-DCP degradation was achieved at a higher catalyst dosage and lower pollutant concentration with a contact duration of 8 h in an alkaline pH condition. The coefficient of regression (R2) and probability value (P) were 0.98 and 0.0472, respectively, which confirmed the ideality of RSM modeling. The study discusses on the possible photocatalytic degradation mechanisms of 2,4-DCP. The results showed a significant dependence of the photocatalytic removal of 2,4-DCP on the functional parameters. [ABSTRACT FROM AUTHOR]

Herein, we report on the development of an effective, environmentally benign and facile method for visible light driven photo-degradation of Rhodamine 6 G and 2,4-dichlorophenol using Zn-5-p-carboxyphenyl-10,15,20-(tris-4-pyridyl)-porphyrin (2) linked to graphitic carbon nitride quantum dots (g-C3N4 QDs) and anchored on TiO2 fibers (represented as 2@g-C3N4 QDs-TiO2 fibers). The results suggest that the porphyrin acts as a photosensitizer, g-C3N4 QDs function as both photosensitizer and electron mediator, whereas the TiO2 fibers supporting matrix is a photocatalyst and a stabilizer. Anchoring 2@g-C3N4 QDs onto TiO2 fibers resulted in enhanced catalytic activity and thermal stability. Singlet oxygen (1O2) was the main reactive species responsible for degradation of Rhodamine 6 G and 2,4-dichlorophenol. The degradation kinetic studies follow pseudo first-order kinetics. The results demonstrate 2@g-C3N4 QDs-TiO2 fibers ternary hybrid catalyst to be a catalyst for visible light driven photo-degradation of refractory organic water pollutants. [ABSTRACT FROM AUTHOR]

The interactions within microbial, chemical and electronic elements in microbial fuel cell (MFC) system can be crucial for its bio-electrochemical activities and overall performance. Therefore, this study explored polynomial models by response surface methodology (RSM) to better understand interactions among anode pH, cathode pH and inoculum size for optimising MFC system for generation of electricity and degradation of 2,4-dichlorophenol. A statistical central composite design by RSM was used to develop the quadratic model designs. The optimised parameters were determined and evaluated by statistical results and the best MFC systematic outcomes in terms of current generation and chlorophenol degradation. Statistical results revealed that the optimum current density of 106 mA/m2 could be achieved at anode pH 7.5, cathode pH 6.3–6.6 and 21–28% for inoculum size. Anode–cathode pHs interaction was found to positively influence the current generation through extracellular electron transfer mechanism. The phenolic degradation was found to have lower response using these three parameter interactions. Only inoculum size-cathode pH interaction appeared to be significant where the optimum predicted phenolic degradation could be attained at pH 7.6 for cathode pH and 29.6% for inoculum size. [ABSTRACT FROM AUTHOR]

A new composite of o-aminobenzene sulfonic acid self-doped polyaniline (SPAN) and multi-walled carbon nanotubes was prepared on a stainless steel wire by electrochemical method as a headspace solid-phase microextraction fiber for gas chromatography. Preparation conditions were investigated, and the resulting composite coating was characterized via scanning electron microscopy, Brunauer–Emmett–Teller (BET) analysis and thermogravimetric analysis. Introduction of MWCNTs and o-aminobenzene sulfonic acid into the composite leads to formation of plenty of microglobules and mesopores and makes BET surface area and thermal decomposition temperature of the composite increase by ~ 340% and ~ 130 ℃, respectively, compared to common polyaniline coating. Extraction conditions were optimized, and chromatographic analysis of 2,4-dichlorophenol was conducted. Extraction efficiency of the new composite coated fiber increases by 320% compared to polyaniline-coated fiber. Relative standard deviations of peak areas are 4.3%, 6.3%, 7.1% (n = 5) for identical fiber, fibers prepared in identical batch and different batches, respectively, exhibiting good repeatability and reproducibility. Detection limit is 1.30 ng L−1 (S/N = 3), and recoveries are in the ranges from 82.3 to 110.2%, from 91.5 to 109.4% and from 94.2 to 113.0% for three different water samples spiked at three levels of 500, 100 and 10 ng mL−1, respectively. [ABSTRACT FROM AUTHOR]

The background value of iron in red soil is superior, primarily absorbed and homogeneously encapsulated in harvested biomass. However, this property on the high-value utilization of bionic iron-encapsulated biomass remains unknown. In this study, special biochar (Fe@BC) was obtained from this kind of biomass by one-step pyrolysis method, which was further used to activate peroxydisulfate (PDS) and degrade 2,4-dichlorophenol (2,4-DCP). The results showed that Fe3O4 was formed and homogeneously embedded in biochar at 500oC. Comparing to catalysts prepared by impregnation pyrolysis (Fe/BC), Fe@BC exhibited excellent degradation performance (90.9%, k = 0.0037 min−1) for 2,4-DCP. According to the free radicals quenching studies, hydroxyl radicals (·OH) and superoxide radicals (·O2−) were the dominant reactive oxygen species (ROS) in Fe@BC/PDS system. Importantly, a PDS adsorption model was established, and the electron transport and PDS activation in the core-shell structure were demonstrated by DFT calculations. Therefore, this study could supply a high-performance catalyst and significant implications for high-value biomass utilization in red soil.

We developed and optimized an electrocatalytic filtration system to catalytically hydrodechlorinate chlorophenolic compounds. A key part of the system was the cathode, which consisted of a filter constructed with electroactive carbon nanotubes (CNTs) functionalized with atomically precise gold nanoclusters (AuNCs). In the functional membrane electrode, the AuNCs attached to the CNTs functioned as a highly effective hydrodechlorination catalyst. Additionally, the ligands of the AuNCs facilitated the binding of the AuNCs with the CNT and protected the Au core from agglomeration. Atomic H* was the primary reactive species in the system, but direct reduction by cathode electrons also contributed to the elimination of 2,4-dichlorophenol (2,4-DCP) by hydrodechlorination. The generated atomic H* was able to break the C–Cl bond to achieve the rapid hydrodechlorination of 2,4-DCP into phenol, with 91.5% 2,4-DCP removal within 120 min. The AuNC catalysts attached to the CNT exceeded the best catalytic activity of larger nanoparticles (e.g., AuNPs), while the flow-through construction performed better than a standard batch reactor due to the convection-enhanced mass transport. The study provides an environmentally friendly strategy for the elimination of pervasive halogenated organic contaminants using a highly efficient, stable and recyclable system for hydrodechlorination that integrates nanofiltration and electrochemistry.

Thin-film nanocomposite (TFN) membranes are the third-generation membranes being explored for nanofiltration applications. Incorporating nanofillers in the dense selective polyamide (PA) layer improves the permeability–selectivity trade-off. The mesoporous cellular foam composite Zn-PDA-MCF-5 was used as a hydrophilic filler in this study to prepare TFN membranes. Incorporating the nanomaterial onto the TFN-2 membrane resulted in a decrease in the water contact angle and suppression of the membrane surface roughness. The pure water permeability of 6.40 LMH bar−1 at the optimal loading ratio of 0.25 wt.% obtained was higher than the TFN-0 (4.20 LMH bar−1). The optimal TFN-2 demonstrated a high rejection of small-sized organics (>95% rejection for 2,4-dichlorophenol over five cycles) and salts—Na2SO4 (≈95%) > MgCl2 (≈88%) > NaCl (86%) through size sieving and Donnan exclusion mechanisms. Furthermore, the flux recovery ratio for TFN-2 increased from 78.9 to 94.2% when challenged with a model protein foulant (bovine serum albumin), indicating improved anti-fouling abilities. Overall, these findings provided a concrete step forward in fabricating TFN membranes that are highly suitable for wastewater treatment and desalination applications.

In the current study, polyaniline and polypyrrole with silicon dioxide (PAni:PPy@SiO2) were combined to formulate a new adsorbent, which was examined using XRD, TEM, SEM, FTIR, TGA, and BET, and the adsorption kinetics were investigated by UV–vis spectroscopy. The optical band gap was also evaluated. The electrochemical behavior was investigated using cyclic voltammograms. Moreover, experimental conditions were used to evaluate the 2,4-dichlorophenol (2,4-DCP) adsorption based on the pH, temperature, reaction time, and initial concentration. The analytical isotherm data were determined by Langmuir, Freundlich, Temkin, Sips, and Redlich–Peterson models. For the analysis of the kinetic data, the pseudo-first- and -second-order models and the intraparticle diffusion model were investigated. It was found that this new adsorbent possessed the highest adsorption efficiency after several regeneration cycles. Furthermore, the thermodynamic parameters of adsorption, such as entropy (ΔS), enthalpy (ΔH), and standard Gibbs were measured. These results suggest that the PAni:PPy backbone can generally be better applied for the elimination of 2,4-dichlorophenol by appropriately dispersing it over the surface of suitable SiO2. This search provides a novel way to develop separable, high-performance adsorbents for adsorbing organic contamination from wastewater.

Attapulgite (ATP) disaggregated by a ball milling–freezing process was used to support Fe/Ni bimetallic nanoparticles (nFe/Ni) to obtain a composite material of D-ATP-nFe/Ni for the dechlorination degradation of 2,4-dichlorophenol (2,4-DCP), thus improving the problem of agglomeration and oxidation passivation of nanoscale zero-valent iron (nFe) in the dechlorination degradation of chlorinated organic compounds. The results show that Fe/Ni nanoparticle clusters were dispersed into single spherical particles by the ball milling–freezing-disaggregated attapulgite, in which the average particle size decreased from 423.94 nm to 54.51 nm, and the specific surface area of D-ATP-nFe /Ni (97.10 m2/g) was 6.9 times greater than that of nFe/Ni (14.15 m2/g). Therefore, the degradation rate of 2,4-DCP increased from 81.9% during ATP-nFe/Ni application to 96.8% during D-ATP-nFe/Ni application within 120 min, and the yield of phenol increased from 57.2% to 86.1%. Meanwhile, the reaction rate Kobs of the degradation of 2,4-DCP by D-ATP-nFe/Ni was 0.0277 min−1, which was higher than that of ATP-nFe/Ni (0.0135 min−1). In the dechlorination process of 2,4-DCP by D-ATP-nFe/Ni, the reaction rate for the direct dechlorination of 2,4-DCP of phenol (k5 = 0.0156 min−1) was much higher than that of 4-chlorophenol (4-CP, k2 = 0.0052 min−1) and 2-chlorophenol (2-CP, k1 = 0.0070 min−1), which suggests that the main dechlorination degradation pathway for the removal of 2,4-DCP by D-ATP-nFe/Ni was directly reduced to phenol by the removal of two chlorine atoms. In the secondary pathway, the removal of one chlorine atom from 2,4-DCP to generate 2-CP or 4-CP as intermediate was the rate controlling step. The final dechlorination product (phenol) was obtained when the dechlorination rate accelerated with the progress of the reaction. This study contributes to the broad topic of organic pollutant treatment by the application of clay minerals. [ABSTRACT FROM AUTHOR]

The current study focuses on utilizing TeO2-deposited ZnO nanotubes fabricated via a solution-free thermo-mechanical method for aquaculture wastewater remediation. The phase, crystallite size, and morphological studies of the fabricated TeO2-deposited ZnO nanotubes were characterized by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD of TeO2-deposited ZnO nanotubes (0.5 wt%, 3 wt%, 5 wt%) exhibited crystallite size of 10–20 nm. FE-SEM shows that TeO2 nanoparticles are uniformly deposited on the surface of ZnO. The photocatalytic studies confirm the higher photocatalytic activity of 3 wt% and 5 wt% TeO2-deposited ZnO (about 90% and 94.5%) and 80% for pristine ZnO towards the photodegradation of 2,4-dichlorophenol in aqueous medium under both UV and sunlight. The antibacterial activity of synthesized samples was investigated against Gram-positive (Bacillus subtilis MTCC 441 strain) and an aquatic fish pathogenic Gram-negative (Aeromonas salmonicida strain MTCC 1522) bacteria applying the disc diffusion method. This assay showed that 5 wt% TeO2-deposited ZnO exhibited excellent antibacterial activity compared to pristine ZnO NPs. Reactive oxygen species (ROS) determination assay confirmed that the 2,4-dichlorophenol degradation by TeO2-deposited ZnO was due to the generation of superoxide radicals. The mechanism of both pollutant degradation and antimicrobial activity is studied in terms of scavenging of produced ROS in the aqueous medium by a scavenger test using histidine and ascorbic acid. The reusability of the TeO2-deposited ZnO nanotubes was also studied, and it showed stability up to three cycles with a negligible loss of efficiency. The synthesized materials could also be applicable for preparation of electrochemical devices to track bacteria. [ABSTRACT FROM AUTHOR]

The narrow band gap and significant separation of photogenerated carriers are essential aspects in practical photocatalytic applications. Nitrogen doping usually narrows the band gap of semiconductor oxides, and it enhances photocatalytic activity. Nitrogen-doped Nb2O5 was prepared by a multiple hydrothermal method. The non-metal element N inside the nanostructure, working as the trapping sites for the holes, which were effectively incorporated into the crystal lattice of Nb2O5 semiconductor oxide, remarkably shorten the band gap (3.1 eV) to enhance the visible light response, effectively reducing the photoinduced electron–hole pair recombination and prolonging carrier lifetime. The multilayer coating structure with a gradient concentration distribution and the type of nitrogen doped is favorable for the migration of photoexcited carriers in the bulk of catalysts. The unique multi-layer coating with the micro-concentration gradient of doped nitrogen provides a fast separation channel and jump steps for the separation of electron–hole pairs. [ABSTRACT FROM AUTHOR]

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• Plasma degradation of 2,4- dichlorophenol micropollutant was investigated. • Degradation process was intensified by introducing eco-friendly oxidants. • A synergistic factor of 1.792 was achieved when 3 mM hydrogen peroxide was added. The detection of micropollutants in surface and groundwater bodies has drawn global concern due to their environmental persistence and risk to human and aquatic life. The dielectric barrier discharge (DBD) plasma reactor was employed to degrade the micropollutant 2,4-dichlorophenol (2,4-DCP). The efficiency of the reactor was investigated, and the plasma degradation process was intensified by introducing three eco-friendly oxidants, sodium percarbonate (SPC), sodium persulfate (SPS), and hydrogen peroxide (HPO), into the reactor. Results indicated that 2,4-DCP removal increased from 62.73 % to 76.37 %, 81.93 %, 100 %, and 90.02 % when 1 mM SPC, 1 mM SPS, 3 mM HPO, and 1 mM SPS + 0.33 mM SPC was added to the wastewater solution, respectively. The synergy between the oxidants and the plasma in the DBD reactor was also explored. The largest synergistic factor (1.792) was achieved when 3 mM HPO was added to the DBD reactor, followed by 0.089 for 1 mM SPC, 0.07 for 1 mM SPS, and 0.041 for 1 mM SPS+0.33 mM SPC. The main active species that catalyzed 2,4-DCP degradation were hydroxyl and sulfate radicals, and introducing the oxidants augmented their production in the solution. The synergy between the DBD+SPS+SPC led to a 58.7 % total organic carbon removal. In conclusion, the 2,4-DCP degradation intermediates and mechanisms were deduced accordingly. The findings reaffirm the effectiveness of the oxidant-coupled DBD reactor in the degradation of micropollutants. [Display omitted] [ABSTRACT FROM AUTHOR]