Search

Copyright of Industrial Water Treatment is the property of CNOOC Tianjin Chemical Research & Design Institute 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.)

Autotrophic denitrification technology has the advantages of no additional carbon source, low sludge yield and low cost. It is one of the promising technologies for deep denitrification of low C/N wastewater under the dual-carbon background. The selection of inorganic electron donor is the key to its wide practical application. According to the principle of denitrification, sulfur autotrophic denitrification is easy to produce acid and sulfate, iron denitrification consumes acid and accumulates nitrite, whereas sulfur-iron coupling autotrophic denitrification can combine the characteristics of both to maintain stable reaction pH and reduce secondary pollution. In this paper, the principle and characteristics of autotrophic denitrification based on sulfur, iron and sulfur-iron as electron donors were analyzed, and the dominant bacteria under different electron donors were introduced. It was hoped to provide reference for improving nitrogen removal efficiency and reducing secondary pollution by sulfur based, iron based and sulfur-iron coupled autotrophic denitrification technologies.

Downsizing the graphdiyne (GDY) network to shape quantum dots (QDs) will provide attractive optical and electronic properties associated with quantum confinement and edge effects. Here, it is demonstrated that quantum confinement and defect introduction allow using GDY in donor–acceptor photocatalytic systems for solar‐to‐hydrogen conversion. The defect‐rich GDY QDs (GDYO‐QDs) exhibit a blue‐to‐green excitation‐dependent photoluminescence behavior, demonstrating their ability to harvest light over a wide energy range. Quantum‐chemical calculations evidenced an increase in the electronic bandgap of GDY upon quantum confinement and defect introduction without the appearance of trap states that can hamper charge transport properties. Such a unique optical behavior of QDs is used in photocatalytic hydrogen generation through the hybridization with TiO2 as a model photocatalyst. Theoretical and experimental results demonstrate that the donor−acceptor system tremendously boosts the photocatalytic performance, reaching 5288 µmol g−1 after 4 h of illumination at a constant rate of 1322 µmol g−1 h−1, using a low volume of a sacrificial electron donor (6% v/v). The QDs act as efficient chromophores harvesting UV and visible light while injecting electrons into the TiO2. This work opens a new area of using GDYO‐QDs as an efficient chromophore in developing donor–acceptor systems for photocatalysis and future photovoltaic devices. [ABSTRACT FROM AUTHOR]

Methanol is a promising feedstock for the bio-based economy as it can be derived from organic waste streams or produced electrochemically from CO2. Acetate production from CO2 in microbial electrosynthesis (MES) has been widely studied, while more valuable compounds such as butyrate are currently attracting attention. In this study, methanol was used as a co-substrate with CO2 to enhance butyrate production in MES. Feeding with CO2 and methanol resulted in the highest butyrate production rates and titres of 0.36 ± 0.01 g L−1 d−1 and 8.6 ± 0.2 g L−1, respectively, outperforming reactors with only CO2 feeding (0.20 ± 0.03 g L−1 d−1 and 5.2 ± 0.1 g L−1, respectively). Methanol acted as electron donor and as carbon source, both of which contributed ca. 50% of the carbon in the products. Eubacterium was the dominant genus with 52.6 ± 2.5% relative abundance. Thus, we demonstrate attractive route for the use of the C1 substrates, CO2 and methanol, to produce mainly butyrate. Key points: • Butyrate was the main product from methanol and CO2in MES • Methanol acted as both carbon and electron source in MES • Eubacterium dominating microbial culture was enriched in MES [ABSTRACT FROM AUTHOR]

Ba-based perovskite oxides rich in oxygen vacancies (OVs) are anticipated to possess robust electron-donating capabilities and other favourable properties, rendering them a promising support for Ru catalysts in NH 3 synthesis. Herein, a glucose-urea deep eutectic solvent calcinating method was developed to synthesize an OV-rich BaTiO 3 (BTO-H) support for Ru catalysts. The BTO-H-supported Ru (Ru/BTO-H) catalyst achieves an impressive NH 3 synthesis rate of 5133 μmol g cat –1 h−1 (256.7 mmol g R u –1 h−1) at 400 °C and 0.1 MPa, surpassing the performance of Ru catalysts supported on OV-poor BTO supports and other supported Ru catalysts. Physical characterizations and kinetic experiments reveal the multifaceted influence of OVs on enhancing the catalytic performance of Ru/BTO-H in NH 3 synthesis. OVs serve as electron donors to Ru catalyst, facilitating the activation and dissociation of N 2. Simultaneously, OVs act as hydrogen acceptors from the Ru surface, mitigating hydrogen poisoning effects. Additionally, OVs stimulate the formation of surface hydrides, not only providing active sites for N 2 activation but also bestowing an electron-donating effect on the supported Ru catalyst. The combined positive effects of OVs establish BTO-H as an outstanding support for Ru catalysts in NH 3 synthesis. • A glucose-urea DES calcinating method was used to synthesize BaTiO 3 (BTO) support. • BTO support had rich oxygen vacancies and large specific surface area (70 m2 g−1). • Oxygen vacancies in BTO support played multiple roles in NH 3 synthesis. • BTO-supported Ru catalyst exhibited an NH 3 synthesis rate of 5133 μmol g-1 cat h−1. [ABSTRACT FROM AUTHOR]

Environmentally persistent free radicals are long-lived pollutants that maintain stability in air, soil, and water. They contribute to the production of reactive oxygen species in environmental media, leading to oxidative stress in biological organisms. This stress can provoke inflammation and damage to biological macromolecules, potentially resulting in cardiopulmonary dysfunction. In this review, we discuss the formation and classification of EPFRs. Typically, EPFRs form through electron transfer from organic compounds to transition metals during thermal processes. In metal-free environments, however, organic compounds can undergo bond cleavage, generating EPFRs under thermal conditions and light exposure. EPFRs are generally categorized into three types: oxygen-centered, carbon-centered, and those containing heteroatoms centered on either oxygen or carbon. We also provide a detailed summary of the fundamental characteristics of EPFRs in different environments such as air, soil, and water. Given their role as electron donors, EPFRs have potential applications in degrading organic pollutants in the environment. The review comprehensively addresses the deleterious impacts of EPFRs on organism health, highlighting risks to metabolic functions and cardiopulmonary health. Furthermore, it underscores the potential involvement of EPFRs as electron donors in atmospheric chemical reactions. The pivotal role of EPFRs in environmental pollutant transformation warrants more studies in future research endeavors. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Water Treatment is the property of CNOOC Tianjin Chemical Research & Design Institute 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.)

Despite the increasing interest in enhancing the electrochemical stability of Al alloys through protective coatings, the role of electron donor agents during coating formation remains poorly understood in terms of morphological control and anticorrosion properties in aqueous environments. In this context, 1H-Benzotriazole (BTA) was utilized as a proof of concept to regulate the in situ reactive integration of V2O5 into the alumina layer via the plasma electrolytic oxidation of a 6061 Al alloy. BTA played a crucial role in chemically incorporating V2O5 into the alumina coating by supplying electrons to VO3− ions, facilitating their reduction. The quantity of BTA added to the electrolyte was found to influence defect morphology and concurrently enhance the chemical incorporation of V2O5. Notably, corrosion measurements revealed that the less porous hybrid film formed with higher corrosion resistance was associated with the utilization of increased concentrations of BTA. These findings highlight the potential of BTA in modifying the structure and improving the ability of alumina coatings to resist corrosion, enabling advanced applications in protecting Al alloys from corrosion. [ABSTRACT FROM AUTHOR]

Background: Ferredoxin 1 (Fd1) is the main electron donor to hydrogenase (HydA) for generating molecular hydrogen (H2) in green microalgae. In order to obtain an increased H2 production, the Fd1 of Chlamydomonas reinhardtii (CrFd1, encoded by crfd1) was therefore overexpressed in Chlorella sp. DT (DT) in this study. Results: The coding region of crfd1 was constructed into the p121-crfd1 plasmid, which was also constructed with a resistance gene to the antibiotic geneticin (G418) as a selection marker. The p121-crfd1 plasmid was transformed into DT cells by electroporation. Observation of the crfd1 gene fragment in the genomic DNA of DT-crfd1 mutants by PCR indicated that the transgene was successfully transformed. Using western blotting, the overexpressed CrFd1 protein, with a molecular weight of about 14 kDa, was found in DT-crfd1 mutants of DT-crfd1-4, DT-crfd1-22, and DT-crfd1-23. Using an in vitro assay, the H2 production of DT-crfd1-4, DT-crfd1-22, and DT-crfd1-23 mutants was about 4.4-, 5.0-, and 3.8-fold higher, respectively, than the DT wild type (DT-WT). Using an in vivo assay, the H2 production of DT-crfd1-4, DT-crfd1-22, and DT-crfd1-23 mutants was about 1.3-, 1.4-, and 1.2-fold higher, respectively, than the DT-WT. Conclusions: The results suggested that heterologous overexpression of CrFd1 could enhance H2 production in DT-crfd1 mutants even though in vitro H2 production of DT-crfd1-22 mutant was up to 5-fold higher than the DT-WT.How to cite: Lin YJ, Chien LF. Hydrogen production in the Chlorella sp. DT mutants carrying heterologous electron donor ferredoxin 1 of Chlamydomonas reinhardtii. Electron J Biotechnol 2024;69. https://doi.org/10.1016/j.ejbt.2024.03.001.

In dye‐sensitized solar cells (DSSCs), flat planar dyes (e. g., highly light‐harvesting porphyrins and corroles) with multiple anchoring groups are known to adopt a horizontal orientation on TiO2 through the multiple binding to TiO2. Due to the strong electronic coupling between the dye and TiO2, fast charge recombination between the oxidized dye and an electron in TiO2 occurs, lowering the power conversion efficiency (η). To overcome this situation, an additional donor moiety can be placed on top of the planar dye on TiO2 to slow down the undesirable charge recombination. Here we report the synthesis and photovoltaic properties of a triarylamine (TAA)‐tethered gold(III) corrole (TAA‐AuCor). The DSSC with TAA‐AuCor using iodine redox shuttle exhibited the highest η‐value among corrole‐based DSSCs, which is much higher than that with the reference AuCor. The transient absorption spectroscopies clearly demonstrated that fast electron transfer from the TAA moiety to the corrole radical cation in TAA‐AuCor competes with the undesirable charge recombination to generate long‐lived charge separated state TAA⋅+‐Cor/TiO2⋅− efficiently. Consequently, the introduction of the TAA moiety enhanced the η‐value remarkably, demonstrating the usefulness of our new concept to manipulate charge‐separated states toward highly efficient DSSCs. [ABSTRACT FROM AUTHOR]

Polythiophene (PTs) is a promising electron donor in organic solar cells (OSCs) due to its simple structure and excellent synthetic scalability. However, the high HOMO (highest occupied molecular orbital) energy level of PTs and the unfavorable active layer morphology limit the performance improvement of PTs-based OSC device. Herein, in order to solve the disadvantage of high HOMO energy level of PTs, a highly planar polymer donor poly(thiazole-ethylene) derivatives(PTzV-T) was designed and synthesized by introducing an ester-functional thiazole-vinyl structure as electronwithdrawing unit into the reported poly(thiophene vinylene) derivative (PTVT-T). The aggregation behavior and energy structure were characterized by ultraviolet-visible (UV-Vis) absorption spectroscopy, electrochemical cyclic voltammetry and two-dimensional grazing incidence wide-angle X-ray scattering. Results show that the polymer PTzV-T has a low HOMO energy level (−5.88 eV) and solid planarity, and shows different preaggregation behaviors and temperature dependence in chloroform, chlorobenzene and o-xylene solvents. The films prepared with these three solvents also show different crystal packing modes and crystallinity [ABSTRACT FROM AUTHOR]

The effects of the influent nitrate (NO3−-N) concentration on reactor performance and microbial communities of anaerobic methane oxidation coupled to denitrification in a membrane biofilm reactor were emphatically investigated after prolonged storage. The system was run for a period of 185 days including the storage period, reactivating process, and stable operation phase. The influent NO3−-N concentrations varied from 10, 20, and 30 mg/L, and the reactor was continuously operated for 135 days. The denitrification rate in the reactor was activated first and then inhibited, with the average value of NO3−-N consumed of 0.42 mg/L·h−1 at influent NO3−-N of 20 mg/L; there was no obvious nitrite and ammonia–nitrogen accumulation in the whole stage. Illumina MiSeq sequencing results showed that increases in NO3−-N loading could improve the microbial abundance in the system. The highest value for variety and the lowest value for the evenness of the microbial community corresponded to the ideal value of 20 mg/L. It speculated that promoting biofilm bacteria (PBB) became the key functional bacterial group after prolonged storage. Besides, the abundance of methane-oxidizing bacteria was significantly increased in synergy with PBB and denitrifiers to achieve reactivating and stable operation of anaerobic methane oxidation coupled to denitrification. [ABSTRACT FROM AUTHOR]

Mariculture wastewater is characterized by low organic carbon to nitrogen ratio (C/N) but high nitrate concentration, which makes it difficult to remove nitrate by the completely heterotrophic denitrification. However, high nitrate discharge poses a threat to the natural environment and human health. Thus, we enriched sulphur-based autotrophic denitrifying (SAD) microbiota and optimized the nitrate removal under different environmental factors and electron donor conditions. The results showed that the dominant genera in the enriched microbiota were previously confirmed autotrophic denitrifiers, Sulfurovum, Thioalkalispira-Sulfurivermis, and Sedimenticola, with a high relative abundance of 41.14%, 21.01%, and 6.17%. Among the environmental factors, pH was the key factor affecting SAD microbiota, and pH 7–9 favoured nitrate removal. However, high pH led to nitrite accumulation (e.g. 10 mg/L at pH = 9), which should be strictly avoided. With regard to electron donors, the optimal concentrations of thiosulphate and nitrate were 50 and 5 mg/L, respectively. The best organic carbon is acetate with an optimal concentration of 10 mg/L. Meanwhile, the initial concentration of thiosulphate was proportional to the nitrate removal rate, while higher concentrations of organic carbon stimulated the heterotrophic denitrification potential of microbiota and thus benefited to dentrification. This study showed that the enriched SAD microbiota was able to achieve efficient nitrate removal under suitable environmental conditions and mixed electron donors and thus presented the potential for application in the treatment of mariculture wastewater. [ABSTRACT FROM AUTHOR]

ABSTRACT In the nitrogen biogeochemical cycle, the reduction of nitrous oxide (N2O) to N2 by N2O reductase, which is encoded by nosZ gene, is the only biological pathway for N2O consumption. In this study, we successfully isolated a strain of denitrifying Paracoccus denitrificans R-1 from sewage treatment plant sludge. This strain has strong N2O reduction capability, and the average N2O reduction rate was 5.10 ± 0.11 × 10−9 µmol·h−1·cell−1 under anaerobic condition in a defined medium. This reduction was accompanied by the stoichiometric consumption of acetate over time when N2O served as the sole electron acceptor and the reduction can yield energy to support microbial growth, suggesting that microbial N2O reduction is related to the energy generation process. Genomic analysis showed that the gene cluster encoding N2O reductase of P. denitrificans R-1 was composed of nosR, nosZ, nosD, nosF, nosY, nosL, and nosZ, which was identified as that in other strains in clade I. Respiratory inhibitors test indicated that the pathway of electron transport for N2O reduction was different from that of the traditional electron transport chain for aerobic respiration. Cu2+, silver nanoparticles, O2, and acidic conditions can strongly inhibit the reduction, whereas NO3- or NH4+ can promote it. These findings suggest that modular N2O reduction of P. denitrificans R-1 is linked to the electron transport and energy conservation, and dissimilatory N2O reduction is a form of microbial anaerobic respiration.IMPORTANCENitrous oxide (N2O) is a potent greenhouse gas and contributor to ozone layer destruction, and atmospheric N2O has increased steadily over the past century due to human activities. The release of N2O from fixed N is almost entirely controlled by microbial N2O reductase activities. Here, we investigated the ability to obtain energy for the growth of Paracoccus denitrificans R-1 by coupling the oxidation of various electron donors to N2O reduction. The modular N2O reduction process of denitrifying microorganism not only can consume N2O produced by itself but also can consume the external N2O generated from biological or abiotic pathways under suitable condition, which should be critical for controlling the release of N2O from ecosystems into the atmosphere.

Experimental investigations and density functional theory (DFT) calculations were carried out to study the comprehensive effect of different 3,5-heptanedioldibenzoate (HDDB) optical isomers as the internal electron donor on the catalytic performance of Ziegler−Natta catalysts. The experimental catalytic activity of HDDB has a positive correlation with the relative content of the mesomer incorporated during catalyst preparation, while the hydrogen response of HDDB displayed a negative correlation with the relative content of the mesomer. In order to apply the DFT calculation results to the macroscopic activity of the catalyst, the content of the active centers of the catalyst was analyzed. Assuming that the content of the active centers is proportional to the internal electron donor content of the catalyst, binary linear regression was carried out, which showed a good linear correlation between experimental activity data and internal electron donor content. Furthermore, the fitted activity of the single active centers aligned well with the calculated activation energies. These results revealed that the catalytic activity of polypropylene (PP) catalysts is dependent on both the active center content and the catalytic activity of an individual active center. Additionally, the lower hydrogen response of HDDB leads to a higher molecular weight of polypropylene obtained from the RS-containing catalyst compared to the SS-containing catalyst. Further study reveals that the hydrogen transfer reactions of 2,4-pentanediol dibenzoate (PDDB)/HDDB are influenced by the orientation of the methyl/ethyl groups in different isomers, which affect the activation energy differences between the hydrogen transfer reaction and the propylene insertion reaction, and finally influence the molecular weight of PP. [ABSTRACT FROM AUTHOR]

Cellobiose dehydrogenase (CDH) catalyzes the oxidation of cello‐oligosaccharides and transfers electrons to oxygen or other electron receptors, such as lytic polysaccharide oxygenases (LPMOs). Cellobiose dehydrogenase has the potential to be used as an electron donor for LPMOs. Therefore, it is important to obtain CDHs under reaction conditions that are compatible with those of cellulases and LPMOs. Here, a CDH gene from Myceliophthora thermophila (MtCDH‐A) was constitutively expressed in Trichoderma reesei, and its ability to donate electrons to the LPMO was validated. MtCDH‐A has an optimal pH of 6.0 and maintains relatively high activity over a wide pH range. The optimal temperature was 60°C, and it remained stable at 50°C for a long time. These enzymatic properties were compatible with the catalytic conditions of fungal LPMOs and cellulases. When MtCDH‐A was used as an electron donor, the synergistic effect of LPMO and cellulase improved the degradation efficiency of phosphoric acid‐swollen cellulose by 141%. This work provides a novel insight into finding a stable electron donor for LPMOs and a new direction for finding more efficient thermostable CDHs in newly identified fungal species. © 2023 Society of Industrial Chemistry and John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR]

Literature review reveals that Persistent Organic Pollutants (POPs), such as polychlorinated biphenyls (PCBs), are electron deficient compounds due to the presence of highly electronegative groups. Hence, they are more amenable to anaerobic biodegradation rather than oxidative metabolism. However, the studies on PCBs bioremediation are more inclined towards aerobic treatment. Besides, the past studies are mainly centered on screening and application of PCB-degrading microorganisms. In our opinion the degradative capacity is already present in the native microflora, and choice of electron donor is of paramount importance for faster reductive metabolism of PCBs. In this study, the use of methanol as electron donor with cow dung as the general microbial inoculum resulted in high specific rate of degradation (0.0542–0.0637 /day) for high-chlorinated biphenyls. The % removal of PCBs ranged between 67.7 and 71.7%. It may be the first study on the application of methanol as a cheap electron donor for PCBs biodegradation without bioaugmentation with specifically selected microorganisms. [ABSTRACT FROM AUTHOR]

The conversion of lignocellulosic biomass to second-generation biofuels through enzymes is achieved at a high cost. Filamentous fungi through a combination of oxidative enzymes can easily disintegrate the glycosidic bonds of cellulose. The combination of cellobiose dehydrogenase (CDH) with lytic polysaccharide monooxygenases (LPMOs) enhances cellulose degradation in many folds. CDH increases cellulose deconstruction via coupling the oxidation of cellobiose to the reductive activation of LPMOs by catalyzing the addition of oxygen to C-H bonds of the glycosidic linkages. Fungal LPMOs show different regio-selectivity (C1 or C4) and result in oxidized products through modifications at reducing as well as nonreducing ends of the respective glucan chain. T. reesei LPMOs have shown great potential for oxidative cleavage of cellobiose at C1 and C4 glucan bonds, therefore, the incorporation of heterologous CDH further increases its potential for biofuel production for industrial purposes at a reduced cost. We introduced CDH of Phanerochaete chrysosporium (PcCDH) in Trichoderma reesei (which originally lacked CDH). We purified CDH through affinity chromatography and analyzed its enzymatic activity, electron-donating ability to LPMO, and the synergistic effect of LPMO and CDH on cellulose deconstruction. The optimum temperature of the recombinant PcCDH was found to be 45 °C and the optimum pH of PcCDH was observed as 4.5. PcCDH has high cello-oligosaccharide kcat, Km, and kcat/Km values. The synergistic effect of LPMO and cellulase significantly improved the degradation efficiency of phosphoric acid swollen cellulose (PASC) when CDH was used as the electron donor. We also found that LPMO undergoes auto-oxidative inactivation, and when PcCDH is used an electron donor has the function of a C1-type LPMO electron donor without additional substrate increments. This work provides novel insights into finding stable electron donors for LPMOs and paves the way forward in discovering efficient CDHs for enhanced cellulose degradation. [ABSTRACT FROM AUTHOR]

Ethylene/1‐hexene copolymerization with two MgCl2‐supported Ziegler‐Natta catalysts containing no internal electron donor or diethylphthalate (DEP) is conducted for different polymerization time. Effects of DEP on active center distribution are studied by fractionating each copolymer sample into boiling n‐heptane soluble (C7‐sol) and insoluble (C7‐ins) fractions, and counting the number of active centers in the copolymer fractions. The main effect of introducing DEP in the catalyst are reduction in the Ti content and significant increase in the proportion of active centers producing C7‐ins fraction. The propagation rate constants of ethylene insertion (kpE) and 1‐hexene insertion (kpH) are respectively estimated by linear fitting/extrapolating the change of apparent propagation rate constants (kpi)a with polymer yield according to a simplified multi‐grain particle model. In both catalysts, kpE in the C7‐ins fraction is 9–12 times larger than that in the C7‐sol fraction, and kpH in the C7‐ins fraction is 3–4 times larger than that in the C7‐sol fraction. The two groups of active centers have distinctly different catalytic properties. Introducing DEP reduced the kpE and kpH values and the extent of diffusion limitation. In summary, addition of electron donor in MgCl2‐supported Z‐N catalyst significantly changed the active center distribution and catalytic properties of its two groups of active centers. [ABSTRACT FROM AUTHOR]

Geobacter grbiciae can grow via coupling oxidation of ethanol to the reduction of various forms of soluble Fe(III) and poorly crystalline Fe(III) oxide, suggesting that G. grbiciae can act as an electron-donor microbe for forming co-cultures through direct interspecies electron transfer (DIET). In this report, potential co-cultures through DIET of G. grbiciae and Methanosarcina barkeri 800, G. sulfurreducens Δhyb, or Methanospirillum hungatei, as electron-acceptor microbes, were examined. Co-cultures of G. grbiciae and G. sulfurreducens Δhyb were performed with ethanol as the sole electron-donor substance and fumarate as the electron-acceptor substance in the presence of granular activated carbon (GAC), magnetite, or polyester felt. The conditions for co-culturing G. grbiciae and M. barkeri 800 (or M. hungatei) were the same as those for G. grbiciae and G. sulfurreducens Δhyb, except fumarate was absent and different cultivation temperatures were used. All co-cultures were anaerobically cultivated. Samples were regularly withdrawn from the co-cultures to monitor methane, fumarate, and succinate via gas or high-performance liquid chromatography. G. grbiciae formed functional co-cultures with M. barkeri 800 in the presence of GAC or magnetite. No co-culture of G. grbiciae with the H2/formate-utilizing methanogen M. hungatei was observed. Additionally, G. grbiciae formed functional co-cultures with H2/formate-un-utilizing G. sulfurreducens Δhyb without the GAC or magnetite supplement. These findings indicate electron transfer between G. grbiciae and M. barkeri 800/G. sulfurreducens Δhyb is via DIET rather than H2/formate, confirming that G. grbiciae acts as an electron-donor microbe. Although the co-cultures of G. grbiciae and M. barkeri 800 syntrophically converted ethanol to methane through DIET, the conversion of propionate or butyrate to methane was not observed. These findings expand the range of microbes that can act as electron donors for interaction with other microbes through DIET. However, propionate and butyrate metabolism through DIET in mixed microbial communities with methane as a product requires further analysis. This study provides a framework for finding new electron-donor microbes. [ABSTRACT FROM AUTHOR]

Geobacter grbiciae can grow via coupling oxidation of ethanol to the reduction of various forms of soluble Fe(III) and poorly crystalline Fe(III) oxide, suggesting that G. grbiciae can act as an electron-donor microbe for forming co-cultures through direct interspecies electron transfer (DIET). In this report, potential co-cultures through DIET of G. grbiciae and Methanosarcina barkeri 800, G. sulfurreducens Δhyb, or Methanospirillum hungatei, as electron-acceptor microbes, were examined. Co-cultures of G. grbiciae and G. sulfurreducens Δhyb were performed with ethanol as the sole electron-donor substance and fumarate as the electron-acceptor substance in the presence of granular activated carbon (GAC), magnetite, or polyester felt. The conditions for co-culturing G. grbiciae and M. barkeri 800 (or M. hungatei) were the same as those for G. grbiciae and G. sulfurreducens Δhyb, except fumarate was absent and different cultivation temperatures were used. All co-cultures were anaerobically cultivated. Samples were regularly withdrawn from the co-cultures to monitor methane, fumarate, and succinate via gas or high-performance liquid chromatography. G. grbiciae formed functional co-cultures with M. barkeri 800 in the presence of GAC or magnetite. No co-culture of G. grbiciae with the H2/formate-utilizing methanogen M. hungatei was observed. Additionally, G. grbiciae formed functional co-cultures with H2/formate-un-utilizing G. sulfurreducens Δhyb without the GAC or magnetite supplement. These findings indicate electron transfer between G. grbiciae and M. barkeri 800/G. sulfurreducens Δhyb is via DIET rather than H2/formate, confirming that G. grbiciae acts as an electron-donor microbe. Although the co-cultures of G. grbiciae and M. barkeri 800 syntrophically converted ethanol to methane through DIET, the conversion of propionate or butyrate to methane was not observed. These findings expand the range of microbes that can act as electron donors for interaction with other microbes through DIET. However, propionate and butyrate metabolism through DIET in mixed microbial communities with methane as a product requires further analysis. This study provides a framework for finding new electron-donor microbes.

A series of 1,8-naphthalimide (NI)-phenothiazine (PTZ) electron donor–acceptor dyads were prepared to study the thermally activated delayed fluorescence (TADF) properties of the dyads, from a point of view of detection of the various transient species. The photophysical properties of the dyads were tuned by changing the electron-donating and the electron-withdrawing capability of the PTZ and NI moieties, respectively, by oxidation of the PTZ unit, or by using different aryl substituents attached to the NI unit. This tuning effect was manifested in the UV–vis absorption and fluorescence emission spectra, e.g., in the change of the charge transfer absorption bands. TADF was observed for the dyads containing the native PTZ unit, and the prompt and delayed fluorescence lifetimes changed with different aryl substituents on the imide part. In polar solvents, no TADF was observed. For the dyads with the PTZ unit oxidized, no TADF was observed as well. Femtosecond transient absorption spectra showed that the charge separation takes ca. 0.6 ps, and admixtures of locally excited (3LE) state and charge separated (1CS/3CS) states formed (in n-hexane). The subsequent charge recombination from the 1CS state takes ca. 7.92 ns. Upon oxidation of the PTZ unit, the beginning of charge separation is at 178 fs and formation of 3LE state takes 4.53 ns. Nanosecond transient absorption (ns-TA) spectra showed that both 3CS and 3LE states were observed for the dyads showing TADF, whereas only 3LE or 3CS states were observed for the systems lacking TADF. This is a rare but unambiguous experimental evidence that the spin–vibronic coupling of 3CS/3LE states is crucial for TADF. Without the mediating effect of the 3LE state, no TADF is resulted, even if the long-lived 3CS state is populated (lifetime τCS ≈ 140 ns). This experimental result confirms the 3CS → 1CS reverse intersystem crossing (rISC) is slow, without coupling with an approximate 3LE state. These studies are useful for an in-depth understanding of the photophysical mechanisms of the TADF emitters, as well as for molecular structure design of new electron donor–acceptor TADF emitters.

Groundwater contamination by trichloroethylene (TCE) presents a pressing environmental challenge with far-reaching consequences. Traditional remediation methods have shown limitations in effectively addressing TCE contamination. This study reviews the limitations of conventional remediation techniques and investigates the application of oxidant-based controlled-release materials, including encapsulated, loaded, and gel-based potassium permanganate since the year 2000. Additionally, it examines reductant controlled-release materials and electron donor-release materials such as tetrabutyl orthosilicate (TBOS) and polyhydroxybutyrate (PHB). The findings suggest that controlled-release materials offer a promising avenue for enhancing TCE degradation and promoting groundwater restoration. This study concludes by highlighting the future research directions and the potential of controlled-release materials in addressing TCE contamination challenges. [ABSTRACT FROM AUTHOR]

In this study, a series of electron donor (–NH2, –NMe2 and –tBu) and electron-withdrawing substituents (–F, –CN and –NO2) were used to tune the nucleophilicity or electrophilicity of a series of square planar Ni2+, Pd2+ and Pt2+ malonate coordination complexes towards a pentafluoroiodobenzene and a pyridine molecule. In addition, Bader's theory of atoms in molecules (AIM), noncovalent interaction plot (NCIplot), molecular electrostatic potential (MEP) surface and natural bond orbital (NBO) analyses at the PBE0-D3/def2-TZVP level of theory were carried out to characterize and discriminate the role of the metal atom in the noncovalent complexes studied herein. We hope that the results reported herein may serve to expand the current knowledge regarding these metals in the fields of crystal engineering and supramolecular chemistry. [ABSTRACT FROM AUTHOR]

Crotonaldehyde is typical inhibitory compound of wastewater discharged in the petrochemical industry. To resolve the inhibition of crotonaldehyde on microorganism, electron donors (cellose, glucose and ethanol) were dosed to accelerate the biodegradation of crotonaldehyde by semi-continuous operation experiments. The results indicated that crotonyl alcohol was the most dominant biodegradable product of crotonaldehyde, and its conversion rates dosing ethanol, glucose and cellose as electron donors (2000 mgCOD/L) were 1.84, 1.46 and 1.21 times higher than that in control test when the initial concentrations of crotonaldehyde was 500 mg/L, respectively. Furthermore, the ethanol as electron donor was superior to cellose and glucose in relieving the inhibition of crotonaldehyde on the processes of acidogenesis, acetogenesis, and methanogenesis duo to the more electron release, faster electron transfer efficiency, less electron competition. Last, the enrichment of electro-active bacteria such as Syntrophobacter , Geobacter and the bacteria associated with reverse β-oxidation pathway (RBO) such as Clostridium_sensu_stricto_12 also proved that higher electron transfer system (ETS) activity was obtained in the reactor dosed ethanol as electron donor. This study suggests that dosing electron donors is an efficient strategy to accelerate the biodegradation of crotonaldehyde, and the results could be referred to pretreat wastewater containing aldehyde pollutants. [ABSTRACT FROM AUTHOR]

In this article, we present the influence of substituents with different electron-donating (ED) powers on the coordination properties of bis(benzoyloxy)dimethylsilane (BDMS) on the MgCl2 support of Ziegler–Natta (ZN) catalysts through molecular simulation of different adsorption adducts. Thermodynamically, the most favourable adsorption structure was found with the diaminoborane substituent in a bridging mode on the (110) crystalline facet, representing a 37.63% increase at PBEh/TZVP in the adsorption strength of the original silyl ester. Generally, the higher the ED strength of the substituent, the higher the exergonicity of donor coordination. All of the new donors except those containing the nitro and formyl groups are preferably chemisorbed on the (110) surface. While the nitro, formyl, vinyl, and hydroxyl substitutions deteriorated the isotacticity of the polymer, a diaminoborane group was predicted to enhance the isotactic index by 306% relative to the original donor. Particularly, nitrophenyl could improve the isotactic index by 69% while its complexation remained in the thermodynamically controlled regime. Overall, the present DFT study demonstrated how a systematic exploration of substituents over a wide range of ED power can help in the design of new Lewis base donors for ZN catalysis. [ABSTRACT FROM AUTHOR]

Despite the increasing interest in enhancing the electrochemical stability of Al alloys through protective coatings, the role of electron donor agents during coating formation remains poorly understood in terms of morphological control and anticorrosion properties in aqueous environments. In this context, 1H-Benzotriazole (BTA) was utilized as a proof of concept to regulate the in situ reactive integration of V2O5 into the alumina layer via the plasma electrolytic oxidation of a 6061 Al alloy. BTA played a crucial role in chemically incorporating V2O5 into the alumina coating by supplying electrons to VO3− ions, facilitating their reduction. The quantity of BTA added to the electrolyte was found to influence defect morphology and concurrently enhance the chemical incorporation of V2O5. Notably, corrosion measurements revealed that the less porous hybrid film formed with higher corrosion resistance was associated with the utilization of increased concentrations of BTA. These findings highlight the potential of BTA in modifying the structure and improving the ability of alumina coatings to resist corrosion, enabling advanced applications in protecting Al alloys from corrosion.

To enhance photoelectrochemical (PEC) performance, additional electron donor/acceptor is generally required to inhibit the electron‐hole recombination. However, the enhancement is limited due to the long‐distance diffusion. Herein a self‐supplying electron strategy is designed for PEC enhancement by coordinating an electron donor 1.4‐diazabicyclo[2.2.2]octane (Dabco) in metal–organic framework (MOF). The intrareticular photoelectron transfer mechanism in mixed‐ligand MOF (m‐MOF) is experimentally revealed and verified by density functional theory calculations. The presence of Dabco efficiently inhibits the electron‐hole recombination due to the self‐supplying electrons and longer electron lifetime in the framework, and thus leads to 23.2‐fold enhancement of photocurrent. As proof of concept, a simple PEC method is constructed with the designed m‐MOF to demonstrate its application in sensitive bioanalysis. This work provides a new avenue for improving the PEC performance of nanomaterials. [ABSTRACT FROM AUTHOR]

[Display omitted] • FBFW was successfully used as an electron donor for refractory ClO 4 - removal. • The average removal rate of ClO 4 - was 217.39 mg/L/d in the CSTR. • Proteobacteria and Dechloromonas contributed positively to the degradation of ClO 4 - Microbial reduction has been considered an effective way to remove perchlorate (ClO 4 -), during which, additional electron donors and carbon sources are required. This work aims to study the potential of fermentation broth of food waste (FBFW) serving as an electron donor for ClO 4 - biodegradation, and further investigates the variance of the microbial community. The results showed that FBFW without anaerobic inoculum at 96 h (F-96) exhibited the highest ClO 4 - removal rate of 127.09 mg/L/d, attributed to higher acetate and lower ammonium contents in the F-96 system. In a 5 L continuous stirred-tank reactor (CSTR), with a 217.39 g/m3·d ClO 4 - loading rate, 100% removal efficiency of ClO 4 - was achieved, indicating that the application of FBFW in the CSTR showed satisfactory performance for ClO 4 - degradation. Moreover, the microbial community analysis revealed that Proteobacteria and Dechloromonas contributed positively to ClO 4 - degradation. Therefore, this study provided a novel approach for the recovery and utilization of food waste, by employing it as a cost-effective electron donor for ClO 4 - biodegradation. [ABSTRACT FROM AUTHOR]

In order to investigate the joint influence of the conformation flexibility and the matching of the energies of the charge-transfer (CT) and the localized triplet excited (3LE) states on the thermally activated delayed fluorescence (TADF) in electron donor–acceptor molecules, a series of compact electron donor–acceptor dyads and a triad were prepared, with naphthalimide (NI) as electron acceptor and phenothiazine (PTZ) as electron donor. The NI and PTZ moieties are either directly connected at the 3-position of NI and the N-position of the PTZ moiety via a C–N single bond, or they are linked through a phenyl group. The tuning of the energy order of the CT and LE states is achieved by oxidation of the PTZ unit into the corresponding sulfoxide, whereas conformation restriction is imposed by introducing ortho-methyl substituents on the phenyl linker, so that the coupling magnitude between the CT and the 3LE states can be controlled. The singlet oxygen quantum yield (ΦΔ) of NI-PTZ is moderate in n-hexane (HEX, ΦΔ = 19%). TADF was observed for the dyads, the biexponential luminescence lifetime are 16.0 ns (99.9%)/14.4 μs (0.1%) for the dyad and 7.2 ns (99.6%)/2.0 μs (0.4%) for the triad. Triplet state was observed in the nanosecond transient absorption spectra with lifetimes in the 4–48 μs range. Computational investigations show that the orthogonal electron donor–acceptor molecular structure is beneficial for TADF. These calculations indicate small energetic difference between the 3LE and 3CT states, which are helpful for interpreting the ns-TA spectra and the origins of TADF in NI-PTZ, which is ultimately due to the small energetic difference between the 3LE and 3CT states. Conversely, NI-PTZ-O, which has a higher CT state and bears a much more stabilized 3LE state, does not show TADF.

Reed is a typical emerged plant in constructed wetlands (CWs). Its litters were used as raw materials for preparing Fe–C ceramic-filler (Fe–C-CF). The physical and chemical properties of Fe–C-CF were studied under different conditions, including the mass ration of Fe to carbon (Fe/C ratio), sintering temperature, and time, to determine the optimum preparing conditions. Meanwhile, the denitrification performance and CO2 emission flux of the surface flow constructed wetland (SFCW) systems were investigated when using Fe–C-CF as the matrix. The optimum preparing conditions for Fe–C-CF were Fe/C ratio of 1:1, sintering temperature and time of 500 °C and 20 min, respectively. The SFCW system with Fe–C-CF obtained a higher total nitrogen (TN), nitrate nitrogen (NO3−-N), and ammonia nitrogen (NH3-N) removal efficiencies than the control SFCW system without Fe–C-CF. Compared with the heterotrophic denitrification process, the SFCW system with Fe–C-CF decreased CO2 emission by 67.9 g m−2 per year. The results of microbial community analysis indicated that addition of Fe–C-CF increased the diversity and abundance of microbial communities in the SFCW systems. The dominant genus of the SFCW system with Fe–C-CF was Bacillus, while Uliginosibacterium was the dominant genus in the system without the filler. [ABSTRACT FROM AUTHOR]

Fe-bearing clay minerals are frequently present in oil reservoirs as potential electron acceptor. Compounds in crude oil may mediate microbial reduction of structural Fe(III) in clay minerals through their roles as electron donor and shuttle. However, there is limited knowledge about these roles and resulting transformation of oil compounds. In this study, bio-reduction of structural Fe(III) in nontronite (NAu-2, Fe-rich smectite) by the dissimilatory iron-reducing bacterium (DIRB) Shewanella putrefaciens CN32 was investigated in the presence of either crude oil or specific fractions of oil. Lactate was added in some experiments as extra electron donor. The fractions of saturates (nC 14 -nC 20 alkanes and nC 8 -nC 14 -alkyl cyclohexanes), aromatics (with two/three benzene rings), and polar compounds (carboxylic acids) of crude oil were adsorbed to NAu-2 surface. Without CN32, crude oil was able to slightly reduce structural Fe(III) in NAu-2. In the presence of CN32, reduction of Fe(III) in NAu-2 was coupled with oxidation of bulk oil and saturated/aromatic fractions. The reduction extent (21.5 ± 0.3%) and rate (0.04 ± 0.00 mM/h) by the saturated oil fraction (nC 17 -nC 30 alkanes and nC 10 -nC 23 -alkyl cyclohexanes as electron donors) were slightly lower than those by bulk oil (22.8 ± 0.4% and 0.05 ± 0.00 mM/h, respectively), but those by the aromatic fraction with two benzene rings were much higher (30.8 ± 0.2% and 0.15 ± 0.00 mM/h, respectively). Fe(III) bio-reduction was coupled with oxidative transformation of oil compounds. Specifically, n -alkanes and alkyl cyclohexanes with shorter carbon chains and aromatic isomers with fewer methyl groups were more easily degraded (i.e., dibenzothiophene series) and/or desorbed (i.e., phenanthrene series) than n -alkanes and alkyl cyclohexanes with longer carbon chains and aromatic isomers with more methyl groups. These hydrocarbons were degraded to oxygen-containing compounds, mainly saturated fatty acids, monocyclic naphthenic acids, and phenols. In the presence of lactate as extra electron donor, the aromatic fraction significantly promoted the Fe(III) bio-reduction extent and rate, suggesting its role as electron shuttle. The oxidative transformation of oil compounds driven by bio-reduction of clay minerals has broad implications for the coupled biogeochemical cycles of carbon and iron in oil reservoirs and organic-rich sedimentary rocks. [ABSTRACT FROM AUTHOR]

Experimental investigations and density functional theory (DFT) calculations were carried out to study the comprehensive effect of different 3,5-heptanedioldibenzoate (HDDB) optical isomers as the internal electron donor on the catalytic performance of Ziegler−Natta catalysts. The experimental catalytic activity of HDDB has a positive correlation with the relative content of the mesomer incorporated during catalyst preparation, while the hydrogen response of HDDB displayed a negative correlation with the relative content of the mesomer. In order to apply the DFT calculation results to the macroscopic activity of the catalyst, the content of the active centers of the catalyst was analyzed. Assuming that the content of the active centers is proportional to the internal electron donor content of the catalyst, binary linear regression was carried out, which showed a good linear correlation between experimental activity data and internal electron donor content. Furthermore, the fitted activity of the single active centers aligned well with the calculated activation energies. These results revealed that the catalytic activity of polypropylene (PP) catalysts is dependent on both the active center content and the catalytic activity of an individual active center. Additionally, the lower hydrogen response of HDDB leads to a higher molecular weight of polypropylene obtained from the RS-containing catalyst compared to the SS-containing catalyst. Further study reveals that the hydrogen transfer reactions of 2,4-pentanediol dibenzoate (PDDB)/HDDB are influenced by the orientation of the methyl/ethyl groups in different isomers, which affect the activation energy differences between the hydrogen transfer reaction and the propylene insertion reaction, and finally influence the molecular weight of PP.

The conversion of lignocellulosic biomass to second-generation biofuels through enzymes is achieved at a high cost. Filamentous fungi through a combination of oxidative enzymes can easily disintegrate the glycosidic bonds of cellulose. The combination of cellobiose dehydrogenase (CDH) with lytic polysaccharide monooxygenases (LPMOs) enhances cellulose degradation in many folds. CDH increases cellulose deconstruction via coupling the oxidation of cellobiose to the reductive activation of LPMOs by catalyzing the addition of oxygen to C-H bonds of the glycosidic linkages. Fungal LPMOs show different regio-selectivity (C1 or C4) and result in oxidized products through modifications at reducing as well as nonreducing ends of the respective glucan chain. T. reesei LPMOs have shown great potential for oxidative cleavage of cellobiose at C1 and C4 glucan bonds, therefore, the incorporation of heterologous CDH further increases its potential for biofuel production for industrial purposes at a reduced cost. We introduced CDH of Phanerochaete chrysosporium (PcCDH) in Trichoderma reesei (which originally lacked CDH). We purified CDH through affinity chromatography and analyzed its enzymatic activity, electron-donating ability to LPMO, and the synergistic effect of LPMO and CDH on cellulose deconstruction. The optimum temperature of the recombinant PcCDH was found to be 45 °C and the optimum pH of PcCDH was observed as 4.5. PcCDH has high cello-oligosaccharide kcat, Km, and kcat/Km values. The synergistic effect of LPMO and cellulase significantly improved the degradation efficiency of phosphoric acid swollen cellulose (PASC) when CDH was used as the electron donor. We also found that LPMO undergoes auto-oxidative inactivation, and when PcCDH is used an electron donor has the function of a C1-type LPMO electron donor without additional substrate increments. This work provides novel insights into finding stable electron donors for LPMOs and paves the way forward in discovering efficient CDHs for enhanced cellulose degradation.

A linear–shaped small organic molecule (E)-4-(5-(3,5-dimethoxy-styryl)thiophen-2-yl)-7-(5″-hexyl-[2,2′:5′,2″-terthiophen]-5-yl)benzo[c][1,2,5]thiadiazole (MBTR) comprising a benzothiadiazole (BTD) acceptor linked with the terminal donors bithiophene and dimethoxy vinylbenzene through a π-bridge thiophene was synthesized and analyzed. The MBTR efficiently tuned the thermal, absorption, and emission characteristics to enhance the molecular packing and aggregation behaviors in the solid state. The obtained optical bandgap of 1.86 eV and low-lying highest occupied molecular orbital (HOMO) level of −5.42 eV efficiently lowered the energy losses in the fabricated devices, thereby achieving enhanced photovoltaic performances. The optimized MBTR:PC71BM (1:2.5 w/w%) fullerene-based devices showed a maximum power conversion efficiency (PCE) of 7.05%, with an open-circuit voltage (VOC) of 0.943 V, short-circuit current density (JSC) of 12.63 mA/cm2, and fill factor (FF) of 59.2%. With the addition of 3% 1,8-diiodooctane (DIO), the PCE improved to 8.76% with a high VOC of 1.02 V, JSC of 13.78 mA/cm2, and FF of 62.3%, which are associated with improved charge transport at the donor/acceptor interfaces owing to the fibrous active layer morphology and favorable phase separation. These results demonstrate that the introduction of suitable donor/acceptor groups in molecular design and device engineering is an effective approach to enhancing the photovoltaic performances of organic solar cells. [ABSTRACT FROM AUTHOR]

Fifteen push-pull dyes comprising the tetracyclic polyaromatic pyrene have been designed and synthesized. The optical properties of the fifteen dyes have been examined in twenty-two solvents of different polarities. Surprisingly, contrarily to what is classically observed for push-pull dyes of D-π-A structures, a negative solvatochromism could be found for numerous dyes. The photoluminescence and thermal properties of the dyes were also examined. Theoretical calculations were carried out to support the experimental results. [ABSTRACT FROM AUTHOR]

Microbial electrosynthesis (MES) is a new technology that uses electrically driven biocatalysts to convert CO 2 into valuable chemicals. However, C2 as the primary product limits the development of MES. To address this issue, ethanol and lactate as additional electron donor (ED) were introduced into MES systems with different inoculants (anaerobic sludge and sediment) for chain elongation. The hybrid EDs in MES with sediment can produce the highest concentrations of butyrate (6.30 g/L) and caproate (1.60 g/L), and the corresponding total electron recovery efficiency reached the maximum value (94.51 ± 1.04%). Hybrid EDs not only provided sufficient reducing force, but also enhanced the gas mass transfer rate by releasing CO 2 from lactate in situ. Metagenomic analysis showed that reverse β-oxidation pathway and fatty acid biosynthesis pathway were the main pathways. This study demonstrated that the addition of ethanol and lactate is promising method for improving the performance of MES. [ABSTRACT FROM AUTHOR]

A novel doubly cyclopentannulated carbazole which is accessible through a successive π‐expansion of di(1‐naphthylamine) is disclosed. The carbazole moiety is generated in the final step through intramolecular oxidative coupling. The π‐expansion of carbazole resulted in strongly altered optoelectronic and electrochemical properties. The solid‐state structure features an interesting packing motif with alternating face‐to‐face π⋅⋅⋅π and edge‐to‐face C−H⋅⋅⋅π interactions. The experimental findings were corroborated by theoretical calculations. [ABSTRACT FROM AUTHOR]

The removal of Cr(VI) from groundwater by zero-valent iron (Fe0) and microorganisms under different nutrients and electron-accepting conditions was investigated using continuously-flowed column reactors with an abiotic Fe0 column as the control. Both abiotic and biotic Fe0 columns were operated at low and relatively high concentrations of organic substrates (sodium acetate and humic acid) and electron acceptors (nitrate and sulfate). Sodium acetate and humic acid were found to be effective substrates for the biotic Fe0 system to remove Cr(VI) since microorganisms were able to gain extra reducing capacity from two nutrients and simultaneously avoid the passivation effect of humic acid on Fe0 by metabolizing it. For nitrate and sulfate, varied influences were observed in the biotic Fe0 system. The former showed apparent inhibition on Cr(VI) removal as it competed with Cr(VI) for electrons, and the inhibition became more severe while nitrate concentrations increased. Differently, highly reactive minerals such as green rusts and iron sulfide could be generated on the biotic Fe0 surface under sulfate-reducing condition. They significantly enhanced Cr(VI) removal by providing more adsorptive and reductive sites. Overall, though the biotic Fe0 column exhibited a longer life-span and higher Cr(VI) removal capacity than the abiotic Fe0 column, the effects of organic substrates and electron acceptors should still be taken into account when applying biotic Fe0 systems for Cr(VI)-contaminated groundwater remediation. [ABSTRACT FROM AUTHOR]

Freshwater rivers are hotspots of N 2 O greenhouse gas emissions. Dissolved organic carbon (DOC) is the dominant electron donor for microbial N 2 O reduction, which can reduce N 2 O emission through enriching high N 2 O affinity denitrifiers or enriching non-denitrifying N 2 O-reducing bacteria (N 2 ORB), but the primary regulatory pathway remains unclear. Here, field study indicated that high DOC concentration in rivers enhanced denitrification rate but reduced N 2 O flux by improving nosZ gene abundance. Then, four N 2 O-fed membrane aeration biofilm reactors inoculated with river sediments from river channel, estuary, adjacent lake, and a mixture were continuously performed for 360 days, including low, high, and mixed DOC stages. During enrichment stages, the (nirS + nirK)/ nosZ ratio showed no significant difference, but the community structure of denitrifiers and N 2 ORB changed significantly (p < 0.05). In addition, N 2 ORB strains isolated from different enrichment stages positioned in different branches of the phylogenetic tree. N 2 ORB strains isolated during high DOC stage showed significant higher maximum N 2 O-reducing capability (V max : 0.6 ± 0.4 ×10−4 pmol h−1 cell−1) and N 2 O affinity (a 0 : 7.8 ± 7.7 ×1 0 −12 L cell−1 h−1) than strains isolated during low (V max : 0.1 ± 0.1 ×10−4 pmol h−1 cell−1, a 0 : 0.7 ± 0.4 ×1 0 −12 L cell−1 h−1) and mixed DOC stages (V max : 0.1 ± 0.1 ×10−4 pmol h−1 cell−1, a 0 : 0.9 ± 0.9 ×1 0 −12 L cell−1 h−1) (p < 0.05). Hence, under high DOC concentration conditions, the primary factor in reducing N 2 O emissions in rivers is the enrichment of complete denitrifiers with high N 2 O affinity, rather than non-denitrifying N 2 ORB. [Display omitted] • Carbon sources didn't change non-denitrifying N 2 O-reducing bacteria abundance. • Carbon sources significantly change the N 2 O-reducing bacterial composition. • High dissolved organic carbon enriched high affinity N 2 O-reducing bacteria. [ABSTRACT FROM AUTHOR]

Groundwater contamination by trichloroethylene (TCE) presents a pressing environmental challenge with far-reaching consequences. Traditional remediation methods have shown limitations in effectively addressing TCE contamination. This study reviews the limitations of conventional remediation techniques and investigates the application of oxidant-based controlled-release materials, including encapsulated, loaded, and gel-based potassium permanganate since the year 2000. Additionally, it examines reductant controlled-release materials and electron donor-release materials such as tetrabutyl orthosilicate (TBOS) and polyhydroxybutyrate (PHB). The findings suggest that controlled-release materials offer a promising avenue for enhancing TCE degradation and promoting groundwater restoration. This study concludes by highlighting the future research directions and the potential of controlled-release materials in addressing TCE contamination challenges.

Two new organic electron-donors derived from carbazole and phenothiazine, 9-Octyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) carbazole-3-carbaldehyde and 10-octyl-7-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenoxazine-3-carbaldehyde, have been synthesized successfully. The process was initiated with multistep reactions, alkylation, formylation, bromination and finally borylation, to give the final products. The successful formation of each structure was confirmed by IR, 1H NMR, 13C NMR, and HRMS. The newly synthesized key electron donors could have promising roles as key intermediates in different synthetic approaches. [ABSTRACT FROM AUTHOR]

A simple homogeneous photoelectrochemical (PEC) sensing platform based on an alkaline phosphatase (ALP)–mediated pesticide assay was established for the sensitive detection of omethoate (OM). The Bi2S3@Bi2Sn2O7 heterojunction was used as a photoactive material to provide stable background photocurrent signals. The inhibition of OM on ALP and PEC determination was carried out in the homogeneous system. In the absence of OM, dephosphorylation of L-ascorbic acid 2-phosphate trisodium salt (AAP) was catalyzed by ALP to produce the enzyme-catalyzed product (L-ascorbic acid, AA). AA, as an electron donor, could capture photogenerated holes on the Bi2S3@Bi2Sn2O7 heterojunction, thus inhibiting the recombination of electron holes to achieve an increase of the photocurrent signal. When the OM was introduced, the enzyme activity of ALP was reduced due to the organophosphorus pesticides (OPs)–based enzyme inhibition, and the AA produced by catalytic hydrolysis was also reduced, thus reducing the photocurrent signal. Compared with the traditional PEC sensor for OPs, this homogeneous PEC sensor avoided immobilization procedures, covalent labeling, separation, and the steric hindrance effect caused by immobilized biomolecules, which achieved high recognition efficiency and caused a reduction in analysis time. Additionally, an ALP-mediated pesticide assay for the determination of OPs with a simplified experimental process further improved the stability and reproducibility of the PEC sensor. The PEC sensor showed high sensitivity to the target OM within a dynamic range of 0.05 ~ 500 ng mL−1, and the detection limit was 0.0146 ng mL−1. Additionally, the PEC biosensing system showed good selectivity and anti-interference ability, and exhibited a satisfactory result in spinach and mustard samples. A homogeneous PEC biosensor based on ALP inhibition strategy was constructed for OM detection in vegetable samples via Bi2S3@Bi2Sn2O7 heterojunction as the photoactive substrate material [ABSTRACT FROM AUTHOR]