4-nitrophenol Research Articles

Generation of Reactive Oxygen Species and Degradation of Pollutants in the Fe2+/O2/Tripolyphosphate System: Regulated by the Concentration Ratio of Fe2+ and Tripolyphosphate.

Tripolyphosphate (TPP) has many advantages as a ligand for the optimization of the Fe2+/O2 system in environmental remediation applications. However, the relationship between remediation performance and the Fe2+/TPP ratio in the system has not been previously described. In this study, we report that the degradation mechanism of p-nitrophenol (PNP) in Fe2+/O2 systems is regulated by the Fe2+/TPP ratio under neutral conditions. The results showed that although PNP was effectively degraded at different Fe2+/TPP ratios, the results of specific reactive oxygen species (ROS) scavenging experiments and the determination of PNP degradation products showed that the mechanism of PNP degradation varies with the Fe2+/TPP ratio. When CFe2+ ≥ CTPP, the initially formed O2•- is converted to •OH and the •OH degrades PNP by oxidation. However, when CFe2+ < CTPP, the O2•- persists long enough to degrade PNP by reduction. Density functional theory (DFT) calculations revealed that the main reactive species of Fe2+ in the system include [Fe(TPP)(H2O)3]- and [Fe(TPP)2]4-, whose content in the solution is the key to achieve system regulation. Consequently, by controlling the Fe2+/TPP ratio in the solution, the degradation pathways of PNP can be selected. Our study proposed a new strategy to regulate the oxidation/reduction removal of pollutants by simply varying the Fe2+/TPP ratio of the Fe2+/O2 system.

Treatment of organic wastewater by ozone in a continuous rotating solid foam stirrer tank

The work herein employed a novel rotating solid foam stirrer tank (RSFST) under continuous operation in attempt to intensify ozone-liquid mass transfer rate and possibly enhance treatment of organic wastewater. P-nitrophenol (PNP) and acid red B (ARB) were separately used to simulate phenolic and dye wastewater. Results show that the removal efficiency of PNP and ARB dye increased with increasing rotational speed and gas flow rate but decreased with increasing liquid flow rate and initial wastewater concentration. The highest removal efficiency of PNP and ARB was attained at pH of 11 and 7, respectively. Ozone utilization efficiency increased with increasing stirring speed, liquid flow rate, initial wastewater concentration and pH but decreased with increasing gas flow rate. The treatment efficiency of organic wastewater in the RSFST reactor is superior to that of many other reactors (rotating packed bed and bubble column, etc.). Correlations to predict the removal efficiency of the organics were developed and the deviation between the experimental and predicted values is within 15%, indicating that the correlations can be used to predict the removal efficiency of PNP and ARB by ozone in RSFST. The study provides a scientific reference for development of a new high-efficiency ozone oxidation reactor.

Enhanced photocatalytic performance of NiS/ZnO nanocomposite for the remediation of PNP and RhB dye

A spherical shaped ZnO nanoparticle was combined with a flower like NiS nanoparticle via simple hydrothermal method. The physicochemical properties of the synthesized nanocomposites were observed by using various characterization techniques (HR-XRD, HR-TEM, FE-SEM, EDS, XPS etc.). The photocatalytic performances of the synthesized photocatalysts were monitored by the degradation of p-nitrophenol (PNP) and rhodamine B (RhB) dye under UV-light illumination. The photocatalytic experiment reveals that the synthesized nanocomposites exhibit much higher photocatalytic efficiency than pure ZnO and NiS nanoparticles and removes up to 96% and 93% of PNP & RhB dye respectively via pseudo 1st order kinetics. The observed improvement in the photocatalytic performance of the nanocomposites after the introduction of NiS is mainly due to the separation of useful e-/h+ with strong redox potential at the interface of NiS/ZnO. Moreover, during the photocatalytic experiment we got highest turnover frequency (TOF) for our most efficient nanocomposite (AB-2). The XRD pattern of the used photocatalyst confirms the stability of the nanocomposites. However, the optical band positions and trapping experiment demonstrate that the photocatalytic mechanism proceeds through S-scheme (step scheme). This work gives newer idea to rationalize NiS based hybrid photocatalyts for the removal of pollutants from the environment.

Cytotoxicity and oxidative stress induced by atmospheric mono-nitrophenols in human lung cells

Nitrophenols (NPs) are hazardous pollutants found in various environmental matrices, including ambient fine particulate matter (PM2.5), agricultural residues, rainwater, wildfires, and industrial wastes. This study showed for the first time the effect of three pure nitrophenols and their mixture on human lung cells to provide basic understanding of the NP influence on cell elements and processes. We identified NPs in ambient PM2.5 and secondary organic aerosol (SOA) particles generated from the photooxidation of monocyclic aromatic hydrocarbons in the U.S. EPA smog chamber. We assessed the toxicity of identified NPs and their equimolar mixture in normal bronchial epithelial (BEAS-2B) and alveolar epithelial cancer (A549) lung cell lines. The inhibitory concentration-50 (IC50) values were highest and lowest in BEAS-2B cells treated with 2-nitrophenol (2NP) and 4-nitrophenol (4NP), respectively, at 24 h of exposure. The lactate dehydrogenase (LDH) assay showed that 4NP, the most abundant NP we identified in PM2.5, was the most cytotoxic NP examined in both cell lines. The annexin-V/fluorescein isothiocyanate (FITC) analysis showed that the populations of late apoptotic/necrotic BEAS-2B and A549 cells exposed to 3NP, 4NP, and NP equimolar mixture increased between 24 and 48 h. Cellular reactive oxygen species (ROS) buildup led to cellular death post exposure to 3NP, 4NP and the NP mixtures, while 2NP induced the lowest ROS buildup. An increased mitochondrial ROS signal following NP exposure occurred only in BEAS-2B cells. The tetramethylrhodamine, methyl ester, perchlorate (TMRM) assay showed that exposed cells exhibited collapse of the mitochondrial membrane potential. TMRM signals decreased significantly only in BEAS-2B cells, and most strongly with 4NP exposures. Our results suggest that acute atmospheric exposures to NPs may be toxic at high concentrations, but not at ambient PM2.5 concentrations. Further chronic studies with NP and NP-containing PM2.5 are warranted to assess their contribution to lung pathologies.

Enhanced photocatalytic activity of titanium dioxide-doped graphene aerogel towards p-nitrophenol removal from aqueous solutions

ABSTRACT Titanium dioxide-doped graphene aerogel (TiO2/GA) was synthesized via one-pot the hydrothermal method. The characterisation of the prepared nanocomposite was thoroughly investigated with various modern analysis method. The results revealed a good terms in both of photo–absorption and nanoparticle sizing. The low band-gap energy of 2.61 eV and the larger specific surface area of TiO2/GA are the main differentiators when compared to the pristine materials. The size of TiO2 nanoparticles has been observed to range from 5 to 20 nm, which is necessary to promote a high photocatalytic performance. The photocatalytic performance of TiO2/GA was examined through photodegradation of p-nitrophenol (PNP). The optimization via Box-Behnken model suggested that 99.89% of PNP could be removed at the pH 7, 20 mg photocatalyst dosage, and 1 mL H2O2 volume. With the excellent results obtained, TiO2/GA material has extensive promise in the emoval of phenolic.

Long-acting CoAl2O4 spinel catalyst developed on activated alumina pellets by facile synthesis to activate peroxymonosulfate: Controllable cobalt leaching and environmental adaptability

A novel composite catalyst prepared by fixing cobalt aluminate (CoAl2O4) spinel on formed alumina carrier by impregnation-calcination route is reported, which can be used to efficiently activate peroxymonosulfate (PMS) to degrade p-nitrophenol (PNP). The internal laws of phase composition and preparation conditions are explored in detail, and the results show that the introduction of additional aluminum ions in the preparation process changes the coordination environment and the electronic state of cobalt ions, which leads to the transformation of spinel/inverted spinel in the composition, and further affects the activity and stability of the catalyst. The selected CoAl-Aaps-600 catalyst has high CoAl2O4 content, showing good cycle performance and low cobalt leaching, and has great catalytic degradation performance at different temperatures and a wide pH range. Most notably, a fixed bed reactor packed with 20 g of CoAl-Aaps-600 exhibits excellent capacity to continuously treat 60 L of PNP solution with acceptable PNP removal ratio and low cobalt leaching content. Sulfate radical and singlet oxygen are identified as the main reactive oxygen species produced in CoAl-Aaps-600/PMS system, and the reaction mechanism is reasonably inferred. This work provides a potential application material and process for the treatment of continuous organic wastewater.

Preparation of coal fly ash-based Fenton-like catalyst and its application for the treatment of organic wastewater under microwave assistance

In order to realize the high value-added reuse of coal fly ash (CFA), a reusable CFA catalyst (AFA) for a Fenton-like process conducted under microwave (MW) assistance was prepared by H2SO4 impregnation. The optimal AFA preparation conditions included an impregnation time of 60 min, H2SO4 dosage of 0.5 mol/L, impregnation temperature of 303 K, and solid–liquid ratio of 1 g:5 mL. In addition, several AFA critical parameters such as specific surface area, pore size distribution, particle size distribution, surface morphology, relative content, chemical states of the elements on the AFA surface, mass fractions of various AFA oxides, crystal composition, surface chemical bonds, and coordination structure of Si were determined. The dynamic treatment conditions of organic wastewater were optimised using a continuous wastewater treatment system with MW assistance, and the removal efficiency of p-nitrophenol (PNP) exceeded 90% at a hydraulic retention time of 40 min. The AFA was successfully reused three times while retaining a PNP removal efficiency of 90%. The relationship between the PNP removal rate and the utilised treatment conditions was −d[PNP]dt=0.32⋅[H2O2]0.374⋅[AFA]0.337⋅[H+]0.445⋅[PNP]0.475. Furthermore, the AFA surface played the main role and ·OH was the most reactive oxidative radical. Hence, real coking wastewater can be effectively treated by the AFA-catalysed Fenton-like process under MW assistance.

Biochemical and Molecular Dynamics Study of a Novel GH 43 α-l-Arabinofuranosidase/β-Xylosidase From Caldicellulosiruptor saccharolyticus DSM8903.

The complete hydrolysis of xylan can be facilitated by the coordinated action of xylanase and other de-branching enzymes. Here, a GH43 α-l-arabinofuranosidase/β-xylosidase (CAX43) from Caldicellulosiruptor saccharolyticus was cloned, sequenced, and biochemically investigated. The interaction of the enzyme with various substrates was also studied. With a half-life of 120 h at 70°C, the produced protein performed maximum activity at pH 6.0 and 70°C. The enzyme demonstrated a higher activity (271.062 ± 4.83 U/mg) against para nitrophenol (pNP) α-L-arabinofuranosides. With xylanase (XynA), the enzyme had a higher degree of synergy (2.30) in a molar ratio of 10:10 (nM). The interaction of the enzyme with three substrates, pNP α-L-arabinofuranosides, pNP β-D-xylopyranosides, and sugar beet arabinan, was investigated using protein modeling, molecular docking, and molecular dynamics (MD) simulation. During the simulation time, the root mean square deviation (RMSD) of the enzyme was below 2.5 Å, demonstrating structural stability. Six, five, and seven binding-interacting residues were confirmed against pNP α-L-arabinofuranosides, pNP β-D-xylopyranosides, and arabinan, respectively, in molecular docking experiments. This biochemical and in silico study gives a new window for understanding the GH43 family’s structural stability and substrate recognition, potentially leading to biological insights and rational enzyme engineering for a new generation of enzymes that perform better and have greater biorefinery utilization.

Graphitic-C3N4 quantum dots modified FeOOH for photo-Fenton degradation of organic pollutants

Developing an efficient heterogeneous Fenton-like synergistic photocatalyst is paramount for degrading organic pollutants. Here, based on two types of g-C3N4 quantum dots (CNQDs) with different fluorescence properties, two kinds of composites (CNQDs/ FeOOH) were fabricated by using a facile method. These composites were used as efficient photo-Fenton catalysts for the treatment of organic pollutants. The composites showed enhanced photocatalysis, Fenton, and photo-Fenton in the degradation of tetracycline (TC), p-nitrophenol (PNP), and 2,4-dinitrophenol (2,4-DNP) compared with pure FeOOH. The degradation efficiencies of composites for TC was up to 89% in 2 min, that for PNP was up to 90% in 10 min, and that for 2,4-DNP was up to 90% in 5 min. Finally, the photo-Fenton catalytic mechanism was discussed on the basis of the reactive radical experiments. The results reported herein provide a strategy for degrading organic pollutants efficiently.

Operational Limits of the Bulk Hybrid Liquid Membranes Based on Dispersion Systems.

Liquid membranes usually have three main constructive variants: bulk liquid membranes (BLM), supported liquid membranes (SLM) and emulsion liquid membranes (ELM). Designing hybrid variants is very topical, with the main purpose of increasing the flow of substance through the membrane but also of improving the selectivity. This paper presents the operational limits of some kind of hybrid membrane constituted as a bulk liquid membrane (BLM), but which works by dispersing the aqueous source (SP) and receiving (RP) phases, with the membrane itself being a dispersion of nanoparticles in an organic solvent (NP–OSM). The approached operational parameters were the volume of phases of the hybrid membrane system, the thickness of the liquid membrane, the working temperature, the flow of aqueous phases, the droplet size of the aqueous phases dispersed across the membrane, the nature and concentration of nanoparticles in the membrane, the pH difference between the aqueous phases, the nature of the organic solvent, the salt concentration in the aqueous phases and the nature of transported chemical species. For this study, silver ion (SI) and p-nitrophenol (PNP) were chosen as transportable chemical species, the n-aliphatic alcohols (C6…C12) as membrane organic solvents, 10–undecenoic acid (UDAc) and 10-undecylenic alcohol (UDAl) as carriers and magnetic iron oxides as nanoparticles dispersed in the membrane phase. Under the experimentally established operating conditions, separation efficiencies of over 90% were obtained for both ionic and molecular chemical species (silver ions and p-nitrophenol). The results showed the possibility of increasing the flow of transported chemical species by almost 10 times for the silver ion and approximately 100 times for p-nitrophenol, through the appropriate choice of operational parameters, but they also exposed their limits in relation to the stability of the membrane system.

Remediation of PNP-contaminated groundwater using a modified CaO2/Fe(II) Fenton system: Reactive principles, degradation performance and potential pathways

Calcium peroxide (CP, CaO2), acting as a source of H2O2, was combined with Fe(II) to provide a novel modified Fenton system. The removal of p-nitrophenol (PNP) in groundwater as a model pollutant was investigated using this system while addressing effect of reagents on water quality, mechanism of reactive oxygen species formation, possible degradation pathways, impact of geochemistry and process parameters on the removal efficiency. The dissolved oxygen, oxidation-reduction potential, pH, electrical conductivity and H2O2 concentration in groundwater were all increased significantly due to the addition of CaO2 and Fe(II), especially in the early stage and under acidic conditions. Within 30 min, 96% of an initial 40 mg/L PNP contamination was removed using the optimum conditions, consisting of 250 mg/L CaO2, 50 mg/L Fe(II), an initial pH of 2.6, oscillation frequency of 170 rpm and temperature of 298 K. The batch experiments revealed that the initial pH and the Fe(II) and CaO2 concentrations all decisively affected removal efficiency, while the groundwater dynamics, temperature and illumination conditions had little effect. The presence of hydroxyl radicals (∙OH) and singlet oxygen (1O2) was confirmed by electron paramagnetic resonance spectroscopy. In addition, ∙OH quenching experiments indicated that the former rather than the latter played a major role in PNP removal. The generation of 1O2 in this system was also predicted by classical molecular orbital theory. These findings would provide useful technical support for the remediation of groundwater contamination.

A label-free and modification-free ratiometric electrochemical strategy for enhanced natural enzyme detection using a bare electrode and nanozymes system.

Ratiometric electrochemical assays have been demonstrated to be more sensitive and selective in various sensing events, mainly due to their affordable built-in correction and good self-reference capability. But it is known that complicated modification and labeling operations usually are necessary for the construction of ratiometric electrochemical assays, therefore is a hot and important issue needing consideration carefully. We herein report a new yet simple bare electrode-based ratiometric electrochemical bioassay to achieve sensitive and selective analysis of alkaline phosphatase (ALP), using a liquid phase system that contains CoOOH nanozymes and commercially available indicator substrate. This proposed bioassay works based on the ratiometric change of dual electrochemical signals, arising from an exclusive target ALP-triggered hydrolysis of electrochemical substrate p-nitrophenyl phosphate (PNPP). In this design, the two hydrolyzed products of electrochemically active p-nitrophenol (PNP) and electrochemically inactive phosphate anion (PO43-) are responsible together for the ratiometric electrochemical analysis of ALP. PNP exhibits a straightforward current response toward ALP content; however, PO43- cannot show a direct electrochemical signal thus is rationally designed to offer an alternative response by linking it with the specific CoOOH nanozyme-catalyzed reaction of 3,3',5,5'-tetramethylbenzidine (TMB) and H2O2, in which the nanozyme-catalyzed product oxTMB shows a direct reduction current at the GCE, and significantly decreases with increasing PO43- species due to the good inhibition of PO43- toward CoOOH nanozyme activity. As a result, a ratiometric electrochemical strategy for ALP analysis with a low limit of detection of 0.366 U/L (S/N = 3) was successfully achieved by integrating the above direct and indirect dual electrochemical responses. This developed bioassay can allow the quantitative diagnosis of ALP activity especially with a label-free and modification-free merit, therefore paving the way for simple, convenient, and portable electroanalytical tools in biosensing design and application.

Simultaneous degradation of p-nitrophenol and reduction of Cr(VI) in one step using microwave atmospheric pressure plasma

Different physicochemical properties between Cr(VI) and phenolic compounds pose serious challenges for the effective treatment of co-contamination. This study developed an electrodeless high-flow microwave atmospheric plasma jet for the single-step simultaneous degradation of p-nitrophenol (PNP) and reduction of Cr(VI). Following a 15 min treatment with microwave atmospheric pressure plasma, the removal efficiency of Cr(VI) and PNP reached 97.5% and 93.6%, respectively, whereas that of total organic carbon reached 30.2%. Adding PNP to the solution significantly improved Cr(VI) reduction, whereas PNP degradation increased slightly with Cr(VI). The results indicate that the PNP intermediates significantly affected Cr(VI) reduction. Additionally, long-lived H2O2 and short-lived ·H aided the reduction of Cr(VI) during plasma treatment. The addition of hydroxyl scavengers during treatment implied that ·OH was largely responsible for PNP oxidation. High-performance liquid chromatography–mass spectroscopy (HPLC-MS) revealed that PNP intermediates, including p-nitrocatechol and 5-nitrobenzene-1,2,3-triol, function as Cr(VI) reductants. On the basis of the examined intermediate products, the potential PNP degradation pathway was investigated. The factors that could influence simultaneous dehgradation and reduction, including solution pH, gas velocity, and distance between the plasma outlet and the water surface were researched. Low pH supports Cr(VI) reduction, and the promotion of PNP for Cr(VI) reduction applies to all pH values. The degradation of PNP is insensitive to pH values with or without Cr(VI). The optimal gas velocity for PNP degradation and Cr(VI) reduction was revealed to be 6 L/min. The simultaneous removal of PNP and Cr(VI) benefits from a shorter distance between the plasma outlet and the water's surface.

Catalytic Reduction of Environmental Pollutants with Biopolymer Hydrogel Cross-Linked Gelatin Conjugated Tin-Doped Gadolinium Oxide Nanocomposites.

In the present study, a biopolymer nanocomposite hydrogel based on gelatin and tin-doped gadolinium oxide (Sn-Gd2O3@GH) was prepared for the efficient reduction of water pollutants. The method of Sn-Gd2O3@GH preparation consisted of two steps. A Sn-Gd2O3 nanomaterial was synthesized by a hydrothermal method and mixed with a hot aqueous solution (T > 60 °C) of gelatin polymer, followed by cross-linking. Due to the presence of abundant functional groups on the skeleton of gelatin, such as carboxylic acid (–COOH) and hydroxyl (–OH), it was easily cross-linked with formaldehyde. The structure, morphology, and composition of Sn-Gd2O3@GH were further characterized by the FESEM, XRD, EDX, and FTIR techniques. The FESEM images located the distribution of the Sn-Gd2O3 nanomaterial in a GH matrix of 30.06 nm. The XRD patterns confirmed the cubic crystalline structure of Gd2O3 in a nanocomposite hydrogel, while EDS elucidated the elemental composition of pure Sn-Gd2O3 powder and cross-linked the Sn-Gd2O3@GH samples. The synthesized Sn-Gd2O3@GH nanocomposite was used for the removal of different azo dyes and nitrophenols (NPs). It exhibited an efficient catalytic reduction of Congo red (CR) with a reaction rate of 9.15 × 10−1 min−1 with a strong NaBH4-reducing agent. Moreover, the Sn-Gd2O3@GH could be easily recovered by discharging the reduced (colourless) dye, and it could be reused for a fresh cycle.

Natural Clay Modified with ZnO/TiO2 to Enhance Pollutant Removal from Water

Raw clays, extracted from Bana, west Cameroon, were modified with semiconductors (TiO2 and ZnO) in order to improve their depollution properties with the addition of photocatalytic properties. Cu2+ ions were also added to the clay by ionic exchange to increase the specific surface area. This insertion of Cu was confirmed by ICP-AES. The presence of TiO2 and ZnO was confirmed by the detection of anatase and wurzite, respectively, using X-ray diffraction. The composite clays showed increased specific surface areas. The adsorption property of the raw clays was evaluated on two pollutants, i.e., fluorescein (FL) and p-nitrophenol (PNP). The experiments showed that the raw clays can adsorb FL but are not efficient for PNP. To demonstrate the photocatalytic property given by the added semiconductors, photocatalytic experiments were performed under UVA light on PNP. These experiments showed degradation up to 90% after 8 h of exposure with the best ZnO-modified clay. The proposed treatment of raw clays seems promising to treat pollutants, especially in developing countries.

Silver-capped selenium explored as an electro-catalyst for simultaneous detection of nitro-aromatic drugs in different aqueous samples

Herein, we have fabricated silver (Ag) over selenium (Se) to explore its enriched electrochemical performance towards the simultaneous detection of nitro-aromatic drugs (nitrofurantoin (NFT) and P-nitrophenol (P-NP)). Due to its synergistic effect, Ag/Se modified GCE showed excellent electro-catalytic activity compared to other electrodes. Well-defined and divergent reduction peaks were obtained at −0.49 V (NFT) and −0.85 V (P-NP) with a detection range of 0.9 V at Ag/Se/GCE. It withholds an extensive linear range of 0.1 to 210 µM for NFT and 0.1 to 150 µM for P-NP with a nanomolar level detection limit of 23.87 nM L−1 & 7.82 nM L−1; an appraisable sensitivity of 1.138 µA µM−1 cm−2 & 2.86 µA µM−1 cm−2 for NFT and P-NP, respectively. Interestingly, the electrode possesses a high selectivity in the presence of biomolecules, nitro drugs, and metal ions. Examination of nitro-aromatic drug contamination on water sources shows a massive peril to human life and marine environs due to its adverse hazardous effects. Further, the fabricated Ag/Se-based electrochemical sensor was exposed to various environmental aqueous samples to detect NFT& P-NP which has demonstrated an exquisite recovery results in practical feasibility. Thereby confirms that Ag/Se-based electrochemical sensors have boundless potential for ecological investigations and sensing applications.

Fabrication of Poly(amide-co-ester) Solvent Resistant Nanofiltration Membrane from P-nitrophenol and Trimethyl Chloride via Interfacial Polymerization

P-nitrophenol (PNP), a refractory hazardous substance, has not been efficiently utilized so far. In this paper, PNP is used as a membrane modification material for preparing poly(amide-co-ester) composite nanofiltration membrane. An organic solvent nanofiltration (OSN) membrane was prepared via interfacial polymerization reactionby using PNP and trimethyl chloride (TMC) on a ethylenediamine (EDA) crosslinked polyetherimide substrate. The results of ATR-FTIR and XPS show that interfacial polymerization occurs among with PNP and TMC and the terminal amine groups on the ethylenediamine crosslinked -PEI support forming a poly(amide-co-ester) toplayer. The NF-1PNP membrane maintained stable DMF performance permeance of 2.2 L m−2 h−1 bar−1 and rejection of 98% for Rose Bengal red (RB 1017.64 g mol−1) in 36 h continuous separation process. Furthermore, the average pore diameter of the two membranes including NF-1PNP and NF-1.25PNP, which is 0.40 and 0.36nm, respectively. This study not only provides a good way for the preparation of OSN membrane, but also provides a good demonstration for the comprehensive utilization of PNP and other toxic and harmful pollutants.

Iron carriers promote biofilm formation and p-nitrophenol degradation

Vertical baffled biofilm reactors (VBBR) equipped with Plastic-carriers and Fe-carriers were employed to explore the effect of biofilm carriers on biofilm formation and p-nitrophenol (PNP) degradation. The results showed that Fe-carriers enhanced biofilm formation and PNP degradation. The maximum thickness of biofilm grown on the Fe-carriers was 1.5-fold higher than that on the Plastic-carriers. The Fe-VBBR reached a maximum rate of PNP removal at 13.02 μM L−1 h−1 with less sodium acetate addition (3 mM), while the maximum rate of PNP removal was 11.53 μM L−1 h−1 with more sodium acetate addition (6 mM) in the Plastic-based VBBR. High-throughput sequencing suggested that the Fe-VBBR had a higher biodiversity of the bacterial community in evenness, and the Achromobacter genus and Xanthobacteraceae family were as main PNP degraders. Kyoto Encyclopedia of Genes and Genomes (KEGG) Orthology analysis suggested more abundances of iron uptake genes were expressed to transport iron into the cytoplasm under an iron-limited condition in two VBBRs, and the metabolic pathway of PNP degradation went through 4-nitrocatechol and 1,2,4-benzenetriol. Our results provide a new insight for iron enhancing biofilm formation and PNP degradation.

Design of metalloenzyme mimics based on self-assembled peptides for organophosphorus pesticides detection

Organophosphorus pesticides (OPs) detection has attracted considerable attention because of the extensive application of OPs. In this research, non-toxic and high-performance metalloenzyme mimics of Zn2+-bonding peptides were developed by obtaining inspiration from phosphotriesterase (PTE) and nanofiber formation. Furthermore, based on the electrochemical activity of p-nitrophenol (PNP), the electrochemical sensor of metalloenzyme mimics was developed. By examining the effect of the active sites of peptides and fibril formation on the degradation of OPs, the optimal metalloenzyme mimic was selected. Furthermore, optimal metalloenzyme mimics were combined with NiCo2O4 to develop an electrochemical sensor of OPs. By monitoring square wave voltammetry (SWV) signals of PNP degraded from OPs, the amounts of OPs in actual samples could be determined in 15 min. We discovered that both the active sites of α metal and β metal were required for metalloenzyme mimics; Zn2+ promoted peptide fibrosis and especially acted as a cofactor for degrading OPs. Compared to traditional methods, the electrochemical sensor of metalloenzyme mimics was sensitive, reliable, and non-toxic; furthermore, the detection limit of methyl paraoxon was as low as 0.08 µM. The metalloenzyme mimics will be a promising material for detecting OPs in the food industry and environment fields.

The Environmental Pollutant Bromophenols Interfere With Sulfotransferase That Mediates Endocrine Hormones.

Bromophenols (BPs), known as an important environmental contaminant, can cause endocrine disruption and other chronic toxicity. The study aimed to investigate the potential inhibitory capability of BPs on four human sulfotransferase isoforms (SULT1A1, SULT1A3, SULT1B1 and SULT1E1) and interpret how to interfere with endocrine hormone metabolism. P-nitrophenol(PNP) was utilized as a nonselective probe substrate, and recombinant SULT isoforms were utilized as the enzyme resources. PNP and its metabolite PNP-sulfate were analyzed using a UPLC-UV detecting system. SULT1A1 and SULT1B1 were demonstrated to be the most vulnerable SULT isoforms towards BPs’ inhibition. To determine the inhibition kinetics, 2,4,6-TBP and SULT1A3 were selected as the representative BPs and SULT isoform respectively. The competitive inhibition of 2,4,6-TBP on SULT1A3. The fitting equation was y=90.065x+1466.7, and the inhibition kinetic parameter (Ki) was 16.28 µM. In vitro-in vivo extrapolation (IVIVE) showed that the threshold concentration of 2,4,6-TBP to induce inhibition of SULT1A3 was 1.628 µM. In silico docking, the method utilized indicated that more hydrogen bonds formation contributed to the stronger inhibition of 3,5-DBP than 3-BP. In conclusion, our study gave the full description of the inhibition of BPs towards four SULT isoforms, which may provide a new perspective on the toxicity mechanism of BPs and further explain the interference of BPs on endocrine hormone metabolism.