Search

Dichlorophen (Dcp), a harmful environmental pollutant, is broadly utilized in veterinary medications, chemical fertilizers, pesticides, cosmetics, and personal care products. The current work reports a low-cost, simple, and convenient technique to achieve an electrochemical sensor relying on the electropolymerization of poly-L-arginine (PLA) on carboxyl-functionalized graphene oxide (COOH-GO)–modified GCE for the detection of Dcp. The stepwise assembly procedure and electrochemical characteristics of the fabricated sensor were studied by FTIR, FESEM, EIS, and CV. The resulting PLA/COOH-GO-modified electrode showed a well-defined irreversible peak to Dcp with a broad linear range over 0.01–1.5 and 1.5–60 µM with a low detection limit of 3 nM. Finally, the fabricated sensor was successfully utilized for the quantitation of Dcp in spiked river water with satisfying results. This sensor also displayed desirable anti-interference performance and long-term stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • CeO 2 transition layer can disperse Pt species by anchoring action. • Pt/CeO 2 -Ti 4 O 7 REM can evidently promote DCP removal with lower energy consumption. • CeO 2 /Pt orderly load can enhance the interfacial charge transfer efficiency of Ti 4 O 7. • Direct electron transfer reaction drives DCP electrooxidation on Pt/CeO 2 -Ti 4 O 7 REM. • Less containing chlorine products were generated during 1Pt/CeO 2 -Ti 4 O 7 REM treatment. Limited electrooxidation efficiency and high energy consumption restrict the application of Ti 4 O 7 reactive electrochemical membrane (REM). This study aimed to improve the electrooxidation reactivity of Ti 4 O 7 REM through tailoring CeO 2 transition layer into the interface of Ti 4 O 7 loaded with Pt. We found that 1Pt/CeO 2 -Ti 4 O 7 REM (1 wt% Pt) operation in single pass achieved more than 31 times enhancement for dichlorophen (DCP) removal rates compared with pristine Ti 4 O 7 at 0.5 mA cm−2, accompanied by over 98 % energy consumption reduction. Characterization results showed that CeO 2 loaded on Ti 4 O 7 could uniformly disperse Pt clusters by anchoring effect on Pt atoms to exhibit stable and efficient electrooxidation activity. Density functional theory simulations and well-designed experiments elucidated that direct electron transfer (DET) anodic oxidation drove the electrooxidation process of DCP in Pt/CeO 2 -Ti 4 O 7 REM due to the increased charge transfer efficiency, active sites and the adsorption energy for DCP. This differs from the joint action of DET reaction and hydroxyl radicals mediated reaction in pristine Ti 4 O 7 anode. More pronounced charge redistribution and accumulation at DCP-Pt/CeO 2 -Ti 4 O 7 interface especially around Cl atoms facilitated nucleophilic substitution of the hydroxyl group for Cl atoms to realize less containing chlorine intermediate products and greater mineralization rates. These findings provide insights into interface engineering strategies for preparing Ti 4 O 7 REM with excellent reactivity and low energy consumption. [ABSTRACT FROM AUTHOR]

The imprinted polymers were prepared to absorb dichlorophen (DCP) by using mesoporous silica with ordered pores and high specific surface area. Both scanning electron microscopy and transmission electron microscopy results suggested that the mesoporous silica nanosphere pores had a periodic distribution. The imprinted layer of polymers was thin and uniform. The adsorption experiments showed that the adsorption of imprinted polymers was obviously improved due to the presence of mesoporous structure. The maximum adsorption capacity of MSNs@MIPs at 318 K was 91.1 mg/g, and the adsorption process rapidly reached the equilibrium within 40 min. The adsorption isotherm was well fitted by the Freundlich isotherm model, indicating that multimolecular layer adsorption mechanism governs the adsorption of DCP by the polymers. The adsorption of MSNs@MIPs complied with pseudo-second-order kinetic model. Both selective and regenerative experiments demonstrated that MSNs@MIPs can be successfully applied for selective adsorption of DCP.

The metal-organic frameworks (MOFs) nanozyme-mediated paper-based analytical devices (PADs) have shown great potential in portable visual determination of phenolic compounds in the environment. However, most MOF nanozymes suffer from poor dispersibility and block-like structure, which often prompts deposition and results in diminished enzymatic activity, severely hindering their environmental applications. Here, we proposed colorimetric PADs for the visual detection of dichlorophen (Dcp) based on its significant inhibitory effect on the two-dimensional (2D) MOF nanozyme activity. Specifically, we synthesized a 2D Cu TCPP (Fe) (defined as 2D-CTF) MOF nanozyme exhibiting excellent dispersibility and remarkable peroxidase-like (POD-like) activity, which could catalyze the oxidation and subsequent color change of 3,3′,5,5′-tetramethylbenzidine even under neutral conditions. Notably, the POD-like activity of 2D-CTF demonstrated a unique response to Dcp because of the occupation of Fe–N 4 active sites on the 2D-CTF. This property enables the use of 2D-CTF as a highly efficient catalyst to develop colorimetric PADs for naked-eye and portable detection of Dcp. We believe that the proposed colorimetric PADs offer an efficient method for Dcp assay and open fresh avenues for the advancement of colorimetric sensors for analyzing of phenolic toxic substances in real samples. [ABSTRACT FROM AUTHOR]

This study systematically investigated the variable main electrooxidation mechanism of chlorophene (CP) and dichlorophen (DCP) with the change of reaction conditions at Ti 4 O 7 anode operated in batch and reactive electrochemical membrane (REM) modes. Significant degradation of CP and DCP was observed, that is, CP exhibited greater removal efficiency in batch mode at 0.5–3.5 mA cm−2 and REM operation (0.5 mA cm−2) with a permeate flow rate of 0.85 cm min−1 under the same reaction conditions, while DCP exhibited a faster degradation rate with the increase of current density in REM operation. Density functional theory (DFT) simulation and electrochemical performance tests indicated that the electrooxidation efficiency of CP and DCP in batch mode was primarily affected by the mass transfer rates. And the removal efficiency when anodic potentials were less than 1.7 V vs SHE in REM operation was determined by the activation energy for direct electron transfer (DET) reaction, however, the adsorption function of CP and DCP on the Ti 4 O 7 anode became a dominant factor in determining the degradation efficiency with the further increase of anodic potential due to the disappeared activation barrier. In addition, the degradation pathways of CP and DCP were proposed according to intermediate products identification and frontier electron densities (FEDs) calculation, the acute toxicity of CP and DCP were also effectively decreased during both batch and REM operations. [Display omitted] • Evident degradation of CP and DCP was achieved during both batch and REM modes. • Electrooxidation efficiency in batch mode was limited by the mass transfer rates. • DET reaction was the main electrooxidation mechanism at low anodic potential. • Adsorption energy was key factor during REM treatment at higher anodic potential. • REM treatment exhibited more advantages to reduce ecological risks of CP or DCP. [ABSTRACT FROM AUTHOR]

Pesticides, such as dichlorophen (DCP), pose serious threats to the ecosystem and human health. Hence, developing an efficient and sensitive detection method is crucial for environmental monitoring and remediation. In this study, we present a novel composite material comprised of TiO 2 intercalated areca nut husk-derived activated carbon for the ultrasensitive detection of dichlorophen. The activated carbon is derived through a well-established activation process using areca nut husk waste, a sustainable biomass material. The material's irregular structure and large surface area provide abundant adsorption sites for the target analyte, DCP. The integration of TiO 2 nanoparticles further enhances the detection capability due to their exceptional catalytic properties. Upon exposure to DCP, their interaction with the surface of composite material leads to measurable changes in its electrical and chemical properties. Cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques are used to validate the performance of the fabricated electrode. The developed ultrasensitive detection method exhibits remarkable D L (detection limit, 1.01 × 10−8 M) and Q L (quantification limit, 3.36 × 10−8 M) values, hence can be a promising alternative for environmental monitoring, industrial safety, and public health applications. The synergistic effect between activated carbon and TiO 2 nanoparticles ensures a highly sensitive and selective response to DCP. Consequently, this advanced sensor system has great potential for detecting and quantifying dichlorophen concentrations in diverse environmental samples. [Display omitted] • Waste management by utilizing areca nut husk (AC) as the precursor for synthesizing activated carbon. • AC is further modified by intercalating TiO 2 NPs, which enhances the electrochemical performance due to the synergistic effect. • The electrochemical detection of dichlorophen is an irreversible and diffusion-controlled process. • The D L and Q L values were acquired to be 1.01×10-8M and 3.36×10-8M. • Developed sensor can be employed for real-time monitoring of DCP in water and soil samples. [ABSTRACT FROM AUTHOR]

The need for new antibacterial agents is increasingly becoming of great importance as bacterial resistance to current drugs is quickly spreading. Enoyl‐acyl carrier protein reductases (FabI) are important enzymes for fatty acid biosynthesis in bacteria and other micro‐organisms. In this project, we conducted structure‐based virtual screening against the FabI enzyme, and accordingly, 37 compounds were selected for experimental testing. Interestingly, five compounds were able to demonstrate antimicrobial effect with variable inhibition activity against various strains of bacteria and fungi. Minimum inhibitory concentrations of the active compounds were determined and showed to be in low to medium micromolar range. Subsequently, enzyme inhibition assay was carried out for our five antimicrobial hits to confirm their biological target and determine their IC50 values. Three of these tested compounds exhibited inhibition activity for the FabI enzyme where our best hit MN02 had an IC50 value of 7.8 μM. Furthermore, MN02 is a small bisphenolic compound that is predicted to have all required features to firmly bind with the target enzyme. To sum up, hits discovered in this work can act as a good starting point for the future development of new and potent antimicrobial agents. [ABSTRACT FROM AUTHOR]

A core-shell surface-imprinted polymer was successfully synthesized on the surface of silica spheres by precipitation polymerization. The polymers were used to selectively identify dichlorophen in complex environmental system. The physical-chemical properties of the silica sphere molecularly imprinted polymers were analyzed by scanning electron microscopy and transmission electron microscopy scans characterization. The adsorption properties of core-shell polymers were examined by adsorption isotherms, kinetics and selectivity experiments. The Langmuir adsorption isotherm well fitted the adsorption experimental data, and an increase of temperature enhanced the adsorption capacity. The maximum binding capacity of imprinted polymers reached 72.46 mg g-1 at 318 K. Meanwhile, the adsorption data of binding experiments were well-fitting by the pseudo-second-order equation. Compared with nonimprinted polymer, the imprinted polymer not only has specific selectivity towards dichlorophen but also has higher adsorption performance. Moreover, via the regeneration experiments, it has been demonstrated that the MIPs have certain stability to the adsorption for the target, which provides a good reference for the adsorption of dichlorophen by the imprinted polymer in water. [ABSTRACT FROM AUTHOR]

The combined removal of dichlorophen (DDM) by photolysis and laccase-catalysis in aqueous solution under simulated sunlight irradiation was investigated. It was found that DDM could be effectively degraded under simulated sunlight irradiation, which was triggered primarily by singlet/triplet state ( 1 DDM ∗ / 3 DDM ∗ ). The photolysis process of DDM is highly pH-dependent, mainly because of the change in electronic density distribution on the aromatic ring of DDM in its varied ionic speciation under different pH. The significant role of singlet oxygen ( 1 O 2 ) and 3 DDM ∗ in DDM photolysis was verified by experimental measurements and density functional theory (DFT) calculation. The combination of photolysis and laccase-catalysis processes can promote the removal of DDM synergistically. Product identification revealed that photolysis and laccase-catalysis attacked DDM molecule at different moieties. Single aromatic ring products were formed via photo-oxidation of DDM by 1 O 2 . Meanwhile, photolysis can efficiently remove the oxidative coupling products of DDM formed in laccase-catalysis process, which are considered to be potentially high toxic products. In addition, this study also provided first evidence of the laccase inactivation mechanisms induced by simulated sunlight, namely, the destruction of copper catalytic centers and secondary structure. [ABSTRACT FROM AUTHOR]

In this work, a glassy carbon electrode modified with β–cyclodextrins and multi–walled carbon nanotubes (β–CDs/MWCNTs/GCE) was constructed and applied for the square-wave adsorptive stripping voltammetric (SWAdSV) determination of the pesticide dichlorophen ( Dcp ). For the first time, this compound was electrochemically investigated. The voltammetric measurements were conducted in phosphate buffer (PBS) at pH 6.5 as a supporting electrolyte, and SWAdSV technique parameters were optimized. A linear calibration curve in the wide concentration range from 5.0 × 10 −8 mol L −1 to 2.9 × 10 −6 mol L −1 was obtained. Excellent analytical performance in terms of limit of detection (LOD) of 1.4 × 10 −8 mol L −1 was achieved. The utility of the proposed method was verified by the quantitative analysis of Dcp in Pilica River water samples with satisfactory results. The characterization of modified electrodes was conducted by means of atomic force microscopy (AFM), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). Moreover, in this work, the dissociation constants (pK a ) of Dcp using potentiometric pH titration were estimated. The stoichiometry of the Dcp –β–CDs inclusion complex formed in solution was determined by proton nuclear magnetic resonance ( 1 H NMR) spectroscopy, and a binding constant ( β 2 ) was estimated from NMR titration studies. [ABSTRACT FROM AUTHOR]

As active agents in cleaning and disinfecting products, antimicrobials have been widely spread in the environment and have drawn extensive attention as potential threats to the ecological system and human health. In this study, the laccase-catalyzed removal of two emerging antimicrobials, chlorophene (CP) and dichlorophen (DCP), was investigated under simulated environmental conditions. Intrinsic reaction kinetics showed that the removal of CP and DCP followed second-order reaction kinetics, first-order with respect to both the enzyme and the substrate concentration. It was also found that fulvic acid could suppress the transformation of CP and DCP by reversing the oxidation reactions through its action as a scavenger of the free radical intermediates produced from reactions between laccase and the substrates. Several reaction products were identified by a quadrupole time-of-flight mass spectrometer, and detailed reaction pathways were proposed. For both CP and DCP, direct polymerization was the principal pathway, and the coupling patterns were further corroborated based on molecular modeling. The nucleophilic substitution of chlorine by the hydroxyl group was observed, and further oxidation products capable of coupling with each other were also found. Additionally, toxicity evaluation tests using Scenedesmus obliquus confirmed that the toxicity of CP and DCP was effectively eliminated during the reaction processes. [ABSTRACT FROM AUTHOR]

Cytotoxicity of non-polar narcotic chemicals can be predicted by quantitative structure activity relationship (QSAR) models, but the polar narcotic chemicals' actual cytotoxicity exceeds the predicted values by their chemical structures. This discrepancy indicates that the molecular mechanism by which polar narcotic chemicals exert their toxicity is unclear. Taking advantage of Saccharomyces cerevisiae (yeast) functional genome-wide heterozygous essential gene knockout mutants, we here have identified the specific molecular fingerprints of two main chemical structure groups (phenols and anilines) of polar narcotic chemicals (dichlorophen (DCP), 4-chlorophenol (4-CP), 2, 4, 6-trichlorophenol (TCP), 3, 4-dichloroaniline (DCA) and N-methylaniline (NMA)) and one non-polar narcotic chemical 2, 2, 2-trichloroethanol (TCE). Especially, we identify 33, 57, 54, 46, 59 and 53 responsive strains through exposure to TCE, DCP, 4-CP, TCP, DCA and NMA with three test concentrations, respectively, revealing that these polar narcotic chemicals have more responsive strains than the non-polar narcotic chemical. Remarkably, we find that the molecular fingerprints of polar narcotic chemicals in different chemical structure groups are obviously varied, particularly phenols and anilines have their own specific molecular fingerprints. Interestingly, our results demonstrate that the molecular toxicity mechanisms of anilines are associated with DNA replication, but phenols are related with pathway of RNA degradation. Additionally, we find that the two knockout strains (SME1 and DIS3) and the three knockout strains (TSC11, RSP5 and HSF1) can specifically respond to exposure to phenols and anilines, respectively. Thus, they may be served as potential biomarkers to distinguish phenols from anilines. Collectively, our works demonstrate that the functional genomic platform of yeast essential gene mutants can not only act as an effective tool to identify key specific molecular fingerprints for polar narcotic chemicals, but also help to understand the molecular mechanisms of polar narcotic chemicals., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Dichlorophenol (DCP), a commonly used fungicide and insecticide, is widely found in waters and wastewaters. Herein, the degradation of DCP by Ferrate (Fe(VI)) in different matrices was comprehensively investigated. In pure water, a complete removal of DCP was achieved in 300 s at [Fe(VI)]:[DCP] molar ratio of 2:1. The presence of HA (10 mg L−1) inhibited DCP degradation to a certain extent. A total of twenty degradation products were identified by HPLC/MS analysis. Based on these products, reaction pathways including the cleavage of C–C bridge bond, hydroxylation, and radical coupling were proposed. These reaction mechanisms were further rationalized by theoretical calculations. The analyses of Wiberg bond orders and transition state indicated that C 7 –C 8 bond was the most vulnerable site for cleavage, and C 12 site was the most likely site for hydroxyl addition. Mulliken atomic spin densities distribution suggested that self-coupling products was easily generated via C–O–C coupling ways. Finally, the feasibility of applying Fe(VI) to degrade DCP (20 μM) in a municipal wastewater effluent and a lake water was evaluated and verified. The findings in this study are of relevance in designing Fe(VI)-based treatment strategy for chlorine-containing persistent pesticides. [Display omitted] • Dichlorophenol (DCP) was efficiently removed in Fe(VI) oxidation process. • A total of 20 transformation intermediates were identified. • Reaction pathways of DCP mainly involve cleavage of C–C bridge bond, hydroxyl addition, and radical coupling. [ABSTRACT FROM AUTHOR]