Additive-Free, In Situ Rapid Repair of Vacancies in Fe[Fe(CN)6] Electrodes for Efficient Capacitive Deionization.

Fe[Fe(CN)6] (FeHCF) is considered a promising material for capacitive deionization-desalination of saline wastewater due to its excellent structure. However, additives are usually introduced during the synthesis of FeHCF in order to avoid [Fe(CN)6]3- vacancy defects filled by ligand water, which can result in the appearance of harmful byproducts and additional water treatment costs. In this study, an additive-free in situ vacancy repair strategy is proposed for the rapid synthesis of high-quality FeHCF in a saturated K3Fe(CN)6 solution. During the process of synthesizing FeHCF in solution, a high concentration of [Fe(CN)6]3- is found to facilitate the binding of Fe3+ to [Fe(CN)6]3- and hinder the hydrolysis and coordination reaction of Fe3+. After undergoing repair, FeHCF4 demonstrates an increased capacity and highly reversible electrochemical performance due to the robust structure. When utilized as Faraday cathodes in hybrid capacitive deionization (HCDI) systems, FeHCF4 exhibits a higher salt removal capacity (65.67 mg g-1) and lower energy consumption (0.68 kWh kg-1-NaCl) compared to unrepaired FeHCF1, while still maintaining excellent cycling performance. This environmentally friendly approach of repairing vacancies serves as a source of inspiration for the advancement of high-performance Prussian Blue analogues as capacitive sodium-removing materials.

Facilitating nitrification and biofilm formation of Vibrio sp. by N-acyl-homoserine lactones in high salinity environment.

The N-acyl-homoserine lactones (AHLs)-mediated quorum-sensing (QS) system played a crucial role in regulating biological nitrogen removal and biofilm formation. However, the regulatory role of AHLs on nitrogen removal bacteria in high salinity environment has remained unclear. This study evaluated the roles and release patterns of AHLs in Vibrio sp. LV-Q1 under high salinity condition. Results showed that Vibrio sp. primarily secretes five AHLs, and the AHLs activity is strongly correlated with the bacterial density. Exogenous C10-HSL and 3OC10-HSL were found to significantly enhance ammonium removal, while making a minor contribution to the growth rate. Both the C10-HSL and 3OC10-HSL promoted the biofilm formation of Vibrio sp. with an enhancement of 1.64 and 1.78 times, respectively. The scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM) observations confirmed the biofilm-enhancing effect of AHLs. Further analysis revealed that AHLs significantly improved bacterial self-aggregation and motility, as well as the level of extracellular polymeric substances (EPS). These findings provide significant guidance on construction of nitrification system at high salinity.

Direct Construction of 2D Conductive Metal-Organic Frameworks from a Nonplanar Ligand: In Situ Scholl Reaction and Topological Modulation.

Two-dimensional conductive metal-organic frameworks (2D c-MOFs) are an emerging class of promising porous materials with high crystallinity, tunable structures, and diverse functions. However, the limited topologies and difficulties in synthesizing suitable organic linkers remain a great challenge for 2D c-MOFs synthesis and applications. Herein, two layered 2D c-MOF polymorphs with either a rhombus structure (sql-TBA-MOF) or kagome structure (kgm-TBA-MOF) were directly constructed via in situ Scholl reaction and coordination chemistry from a flexible and nonplanar tetraphenylbenzene-based ligand (8OH-TPB) in a one-pot manner. Interestingly, the kgm-TBA-MOF comprising hexagonal and triangular dual pores exhibit higher conductivities of 1.65 × 10-3 S/cm at 298 K and 3.33 × 10-2 S/cm at 353 K than that of sql-TBA-MOF (4.48 × 10-4 and 2.90 × 10-3 S/cm, respectively). Moreover, the morphology and topology can be modulated via the addition of ammonium hydroxide as modulator. The present work provides a new pathway for design, synthesis, and topological regulation of 2D c-MOFs.

Advances in AHLs-mediated quorum sensing system in wastewater biological nitrogen removal: mechanism, function, and application.

Biological nitrogen removal process is to convert organic nitrogen and ammonia nitrogen into nitrogen via a series of reactions by microorganisms, and is widely used in wastewater treatment for its costless, high-effective, secondary pollution-free characteristics. Quorum sensing (QS) is a communication mode for microorganisms to regulate bacteria's physiological behaviors in response to environmental changes. N-acyl-homoserine lactones (AHLs)-mediated QS system is widespread in nitrogen removal-related functional bacteria and promotes biological nitrogen removal performance by regulating bacteria behavior. Recently, there has been an increasingly investigated AHLs-mediated QS system in wastewater biological nitrogen removal process. Consequently, the AHLs-mediated QS system is considered a promising regulatory strategy in the biological nitrogen removal process. This article reviewed the QS mechanism in various nitrogen removal-related functional bacteria and analyzed its effect on biological nitrogen removal performance. Combined with the application research of the QS system for enhanced biological nitrogen removal, it further put forward some prospects and suggestions which are of practical significance in practical application.

Simultaneous removal characteristics of ammonium and phenol by Alcaligenes faecalis strain WY-01 with the addition of acetate.

In this study, simultaneous removal of ammonium plus phenol could be achieved by Alcaligenes faecalis strain WY-01 with the addition of acetate, although acetate delayed the phenol degradation, probably due to the delayed expression of phenol hydroxylase gene under the presence of acetate. Moreover, the successful expression of key enzyme genes in strain WY-01 provided some evidence to illustrate its metabolic pathways of ammonium and phenol under aerobic conditions. Furthermore, SEM was used to clarify the role of acetate in resisting phenol toxicity, and these results demonstrated that strain WY-01 has the ability to form cell flocs when sodium acetate is used as co-substrate for a high concentration of phenol, and these flocs could protect cells against the toxicity of phenol, further enhancing phenol degradation in a high concentration of phenol. All these will provide further insights into the efficacy of strain WY-01 for treating wastewater cocontaminated by ammonium and phenol.

Nitrate removal performances of a new aerobic denitrifier, Acinetobacter haemolyticus ZYL, isolated from domestic wastewater.

A new aerobic denitrifying bacterium ZYL was isolated from domestic wastewater sludge and identified as Acinetobacter haemolyticus (similarity 99%) by the 16S rDNA sequencing analysis. The strain could use nitrate, nitrite and ammonium as the sole N-source for growth with a final product of N2, demonstrating its good abilities for aerobic denitrification and heterotrophic nitrification. Single-factor experiment results showed that the effective removal of nitrate by strain ZYL occurred with carbon source sodium succinate, C/N 16-24, pH 5-9, temperature 20-40 °C, DO ≥ 4.84 mg/L. Ammonium was preferentially used by strain ZYL with nitrate and ammonium as the mixed nitrogen sources. According to nitrogen utilization, nitrogen balance analysis, enzyme assay and denitrifying gene amplification, nitrate was assimilated directly by the isolate for cell synthesis and also converted into N2 through aerobic denitrification. All these make strain ZYL an ideal choice for treating nitrogen-containing wastewater.

Polymorphism of 2D Imine Covalent Organic Frameworks.

We designed and synthesized A2 B2 type tetraphenyl benzene monomers (p-, m-, and o-TetPB) which have the para-, meta, and ortho-substituted isomeric structures, for the direct construction of isomeric frameworks. Interestingly, both kagome (kgm) and monoclinic square (sql) framework isomers are produced from either p-TetPB (C2h symmetry) or m-TetPB (C2v symmetry) by changing reaction solvents, while their isomeric structures are characterized by X-ray diffraction, computational simulation, microscopy, and sorption isotherm measurements. Only sql frameworks was formed for o-TetPB (C2v symmetry), irrespective of reaction solvents. These results disclose a unique feature in the framework structural formation, that is, the geometry of monomers directs and dominates the lattice growth process while the solvent plays a role in the perturbation of chain growth pattern. The isomeric frameworks exhibit highly selective adsorption of vitamin B12 owing to pore shape and size differences.

Draft Genome Sequence of Thermophilic Bacillus sp. TYF-LIM-B05 Directly Producing Ethanol from Various Carbon Sources Including Lignocellulose.

Bacillus sp. TYF-LIM-B05, which is isolated from spoilage vinegar, is resistant to high temperature, high concentrated alcohol, acid, and salt, and can produce ethanol from mono-, di-, polysaccharide, and complex biomass as the sole carbon source. Thus, this strain is a potential candidate for consolidated bioprocessing (CBP) of fermenting lignocellulose to ethanol in a single step. To provide insight into the key enzymes involved in lignocellulose degradation and ethanol production, a draft genome of TYF-LIM-B05 was developed in this study. The results indicated that 348 genes are related to carbohydrate transport and metabolism according to the clusters of orthologous groups of proteins and annotated 187 CAZy domains from a total of 61 different families. The presence of genes encoding laccases, quinone oxidoreductases/reductases, and aryl-alcohol dehydrogenases further implies that TYF-LIM-B05 has the potential to degrade lignin. Remarkably, this strain has the ability to catalyze the oxidative decarboxylation of pyruvate to acetyl-CoA by pyruvate dehydrogenase complexes. The genomic information provided in this study will help researchers to better understand the mechanisms of the lignocellulose degradation and ethanol production pathway in thermophiles.

The formation mechanism of the initial C-C chain in ethanol synthesis on γ-AlOOH(100).

An in-depth understanding of the reaction mechanism at the molecular level is the key to guide the synthesis of ethanol over the CuZnAl catalyst, which is one of the major challenges for ethanol application in energy. Reported herein is a density functional theory study of ethanol synthesis from mixed methanol and syngas on the γ-AlOOH(100) surface. The possible elementary reactions are unambiguously identified and for the first time we confirm the high reactivity of the γ-AlOOH(100) surface for the initial C-C chain formation via CO insertion into CH3, which has a 62.8 kJ mol-1 (0.65 eV) activation barrier that is significantly lower than the barriers previously reported. And its corresponding reaction energy is -288.2 kJ mol-1 (-2.99 eV). Bader charge analyses indicate that it is advantageous for the nucleophilic attack of CO to the neighboring CH3 on the γ-AlOOH(100) surface. Our calculations show that ethanol synthesis starts with CH3OH dissociation, goes through CH3O dissociation to yield CH3, subsequently, CO inserts into CH3 to form CH3CO, which is further hydrogenated to yield CH3CHO and eventually obtain C2H5OH. And the formation of intermediate CH3 is the rate-determining step of the overall reaction. The results not only provide new mechanistic insights into the role of γ-AlOOH but also may be useful for the rational designing and optimizing of the CuZnAl catalyst for ethanol synthesis.

Mechanistic investigation of methanol-to-olefins conversion catalyzed by H-ZSM-5 zeolite: a DFT study.

CONTEXT: The mechanisms for the formation of the first C - C bond and lower olefins on methanol to olefins (MTO) conversion on H-ZSM-5 had been focused in dispute. In this paper, density functional theory has been used to study the reaction mechanisms of methanol to olefins on ZSM-5. The configurations of reactants, intermediates, products and transition state of the numerous reactions involved in such a process have been optimized, as well as the elementary reactions related to these configurations were determined by the calculation of corresponding activation energy barriers and reaction heats. Here, two different kinds of the mechanisms were proposed for the formation of dimethyl ether (DME), one involving an associative interaction of two methanol molecules with the zeolite Brønsted acid sites and the other occurring via a surface methoxy species and a methanol molecule. A critical intermediate of the methoxy methyl cation was theoretically verified by the reaction of the methoxy species and dimethyl ether. Besides, it was found that the first intermediates containing a C - C bond were 1,2-dimethoxyethane and 2-methoxy-ethanolare, in which the former was formed from methoxy species with dimethyl ether and the latter was formed from methanol by onium ions((CH3)2O+CH2CH2OCH3), respectively. For the whole reaction mechanism, the results in this paper indicated that the ethene formation is more favorable than propylene formation due to the low activation energy barrier for ethene formation (123.49 vs. 162.09 kJ.mol-1). From these calculations, it would be concluded that ethene is the first alkene product that induces the occurrence of the hydrocarbon pool mechanism. METHODS: All the periodic density function theory (DFT) calculations were performed by the Vienna Ab Initio Simulation package (VASP). The interaction between nucleus and valence electron was described using the pseudopotentials found in the projector augmented wave (PAW) method. PBE-D3 was used in the whole DFT calculations and CI-NEB was used to locate transition state.

Design, Synthesis, and Antiviral and Fungicidal Activities of 4-Oxo-4H-quinolin-1-yl Acylhydrazone Derivatives.

To discover novel antiviral agents, based on the high antiviral activity of (4-oxo-4H-quinolin-1-yl)-acetic acid hydrazide (C), a series of 4-oxo-4H-quinoline acylhydrazone derivatives were designed, synthesized, and first evaluated for their antiviral and fungicidal activities. Most acylhydrazone derivatives exhibited moderate to good antiviral activities in vivo. The inactive, curative, and protective activities of compounds 4 (51.2, 47.6, and 46.3%), 11 (49.6, 43.0, and 45.2% at 500 mg/L), and 17 (47.1, 49.2, and 44.1%) were higher than those of ribavirin (39.2, 38.0, and 40.8%) at 500 mg/L. Molecular docking showed that compound 4 exhibited a stronger affinity to TMV coat protein (TMV-CP) than ribavirin, with a binding energy (-6.89 kcal/mol) slightly lower than that of ribavirin (-6.08 kcal/mol). Microscale thermophoresis showed that compound 4 (K d = 0.142 ± 0.060 µM) exhibited a strong binding ability to TMV-CP, superior to that of ribavirin (K d = 0.512 ± 0.257 µM). The results of transmission electron microscopy showed that compound 4 hindered the self-assembly and growth of TMV. The antifungal activities of most compounds were moderate at 50 mg/L, among which compounds 12 and 21 exhibited a 72.1 and 76.5% inhibitory rate against Physalospora piricola, respectively. Meanwhile, compound 16 exhibited a 60% inhibitory rate against Cercospora arachidicola Hori at 50 mg/L.

Research on phthalic acid esters removal and its health risk evaluation by combined process for secondary effluent of wastewater treatment plant.

This paper analyses the treatment effect of the "coagulation-sedimentation-O3-biological sand filtration-GAC" combined process on phthalic acid esters in secondary effluent of municipal wastewater treatment plant and meanwhile evaluate its health risk. The results indicated that when the concentrations of DBP and DiOP in secondary effluent were at range of 0.41 mg/L-0.814 mg/L and 0.23 mg/L-0.36 mg/L, the average total removal rates of DBP and DiOP were 85.10% and 68.11%, and the average concentration of DBP and DiOP in effluent were 0.089 mg/L and 0.091 mg/L, respectively. The quality of the effluent met the requirement of the ornamental scenic environment water in The Quality of Urban Wastewater Recycling and Scenic Environment Water (GB/T 18921-2002), and the health risks of DBP and DiOP in effluent were at range of 1.99 × 10(-12) - 2.15 × 10(-12)/a and 1.48 × 10(-11) - 1.85 × 10(-11)/a, respectively, which is lower than the acceptable maximum risk level: 1.0 × 10(-6).

Theoretical insight into the promotion effect of potassium additive on the water-gas shift reaction over low-coordinated Au catalysts.

CONTEXT: How to elucidate the effect of alkali metal promoters on gold-catalyzed water-gas shift reaction intrinsically remains a challenging, because that the complex synergy effects such as strong metal-support interactions, interfacial effects, and charge transfer of supported metal catalysts makes people difficulty in the understanding the alkali promotion phenomenon in nature. Herein, we report a systematically study of whole water-gas shift reaction mechanism on pure and the K-modified defected-Au(211) (i.e., by removing one surface Au atom from perfect Au(211) and make one model with the Au-Au coordination number is six) by using the microkinetic modeling based on first principles. Our results indicate that the presence of K can increase the adsorption ability of oxygen-containing species via the attractive coulomb interaction, has no significant effect on the adsorption of H species, but inhibits the adsorption of CO due to the steric effect. K promoter stabilizes the water adsorption by ~0.3 eV, which results in one order increasing of whole reaction rate. Interestingly, the strong promotion effect of the K can be assigned to the significant direct space interaction between K and the adsorbate H2O* through the inducted electric field, which can be further confirmed by the posed negative electric field on the unpromoted D-Au(211). Microkinetic modeling results revealed that the carboxyl mechanism is the most likely to occur, redox mechanism is the next one, and the formate mechanism is the least likely to occur. For different kinds of alkali metal additives, the adsorption strength of water molecules gradually weakens from Li to Cs, but Na shows the best promoter behavior at the low temperature. By considering the effect of K contents on the reactivity of water-gas shift reaction, we found that the K with the medium coverage (~0.2~0.3 ML) has the strongest promoting effect. It is expected that the conclusion of this work can be extended to other WGSR catalytic systems like Cu(or Pt). METHODS: All calculations were performed by using the plane-wave based periodic method implemented in Vienna ab initio simulation package (VASP, version 5.4.4), where the ionic cores are described by the projector augmented wave (PAW) method. The exchange and correlation energies were computed using the Perdew, Burke and Ernzerhof functional with the vdw correction (PBE-D3). The transition states (TSs) were searched using the climbing image nudged elastic band (CI-NEB) method. Some electronic structure properties like work function was predicated by the DS-PAW software. Microkinetic simulation was carried out using MKMCXX software.

Effects of Promoter and Calcination Temperatures on the Catalytic Performance of Y Promoted Co/WC-AC for Dry Reforming of Methane.

CH4 -CO2 reforming is a good way to convert two environmentally harmful greenhouse gases into a high value syngas. However, the catalytic activity and stability of the catalysts need to be further improved. In this paper, the effects of promoter Y and calcination temperature on the catalytic activity and stability of Co/WC-AC catalysts were investigated. The catalysts were characterized by BET, XRD, CO2 -TPD, H2 -TPR, XPS, and TG-DSC. XPS and H2 -TPR. The results indicated that the introduction of Y decreased the reduction temperature of Co2 O3 species and facilitated the formation of Co2+ species. Meanwhile, the addition of Y increased the content of lattice oxygen on the catalyst surface, which enhanced the carbon elimination capacity of the catalyst. The TG-DSC results showed that the activity and stability of the catalysts calcined at 550 °C were poor due to the presence of carbon materials with weak carbon interactions on the catalyst support surface. Meanwhile, the catalyst calcined at 700 °C lead to the collapse of the pores due to the high calcination temperature, which eventually led to the decrease of the catalyst stability. It was found that the Co-Y/WC-AC catalysts prepared at the calcination temperature of 600 °C had the best catalytic activity and stability.

Isolation and characterization of a heterotrophic nitrifier from coke plant wastewater.

This study investigated some factors affecting ammonium removal and nitrite accumulation by Alcaligenes faecalis C16, which was isolated from the activated sludge of a coking wastewater treatment plant. Nitrite was produced from ammonium only in the presence of citrate, acetate, meat extract, peptone or ethanol. The highest amount of nitrite was found with citrate as carbon source. A. faecalis C16 could not use glucose, fructose, sucrose and methanol. Under the optimum conditions of initial pH 6.0, C/N 14, 30 °C and 120 rpm, a maximum nitrite accumulation of 28.29 mg/L NO(2)(-)-N was achieved when the organism grew with citrate in four days. Nitrite accumulation increased with the increase of NH(4)(+)-N. Furthermore, A. faecalis C16 was shown to have phenol-degrading capacity during ammonium removal. Metabolism of phenol resulted in acidification of the media, which is not favorable for nitrification, whereas many other carbon sources made the medium more alkaline. However, no inhibitory effect by phenol was observed when phenol and acetate were used as mixed carbon source at different phenol/sodium acetate (P/S) ratios and their pH values were all controlled above 9.2 or P/S ratios below 5:5. These results suggested that A. faecalis C16 has some potential application in industrial wastewater treatment systems.

Oxidative damage induced in Vicia faba by coke plant wastewater.

The present study investigated toxic impacts of coke plant wastewater over a concentration gradient of COD( Cr) 40-640 mg/l on malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in roots and leaves of Vicia faba. MDA levels and SOD activities were significantly increased at all concentrations both in roots and leaves of Vicia faba; CAT and POD activities were significantly enhanced in roots at low concentrations and were significantly decreased at high concentrations (COD(Cr) 320 and 640 mg/l for CAT; COD( Cr) 640 mg/l for POD). In leaves, CAT and POD activities remained enhanced at all concentration and did not show significant difference at COD( Cr) 640 mg/l for CAT and COD(Cr) 40, 640 mg/l for POD. These results suggest that coke plant wastewater can cause oxidative damage in roots and leaves of Vicia faba and root enzymes seemed more sensitive to the wastewater.

Degradation of high concentration starch and biocathode autotrophic denitrification using photo microbial fuel cell.

In the study, a dual-chamber photo MFC was constructed with a photosynthetic bacteria consortium PB-Z and a heterotrophic nitrifier C16 as anode and cathode inoculant, respectively. The electron released from starch degradation in the anode by photosynthetic bacteria was transferred to the cathode, which was utilized by the nitrifying bacteria C16 to realize autotrophic denitrification. Lower resistance was more conducive to the electron transfer and pollutants removal. Comparing with natural light, continuous light greatly promoted starch degradation by the photosynthetic bacteria in the anode and the denitrification by the nitrifying bacteria in the cathode. Under continuous light and external resistance of 500 Ω, high concentration starch was degraded by photosynthetic bacteria PB-Z and the COD removal efficiency reached up to 88.45% within 12 d, and nitrate of 95.8% was removed within 4 d by autotrophic denitrification by heterotrophic nitrifier C16. The study provides some enlightenment and reference for the application of MFC in the field of wastewater treatment.

A new approach for the effective removal of NOx from flue gas by using an integrated system of oxidation-absorption-biological reduction.

A new process of NOx removal from flue gas, using an integrated system of oxidation-absorption-biological reduction (OABR), is introduced. The experimental results show that increasing the NOx oxidation ratio in flue gas can effectively improve the NOx removal efficiency of the OABR system. The NOx removal efficiency could reach 98.8% with 0.02 M NaHCO3 as the chemical absorbent and under the condition of the optimal NOx oxidation ratio of 50%. During stable operation, the OABR system could maintain a high NOx removal efficiency (above 94%) under the following conditions: 1-8 vol% (104-8 × 104 ppmv) O2, 200-800 ppmv NOx, 0.5-1.5 L/min gas flow rate and 100-800 ppmv SO2. The nitrogen equilibrium results showed that about 59% of the nitrogen in the inlet NOx were transformed to N2 through microbial denitrification, 37% of the nitrogen were converted to biological nitrogen for microbial growth, and only 1.1% of the nitrogen remained in the liquid phase. This new approach has an excellent NOx removal performance and great potential for industrial application.

Hollow I-Cu2MoS4 nanocubes coupled with an ether-based electrolyte for highly reversible lithium storage.

Anode materials based on transition metal sulfides suffer from poor electrochemical reversibility, which limits their cycling stability. Herein, we synthesize hollow I-Cu2MoS4 nanocubes composed of ultrathin nanosheets using a solvothermal method with Cu2O nanocubes as sacrificial templates. The presence of a surfactant is a key factor that prevents the structural collapse of the hollow cubic structure of Cu2MoS4 and the formation of nanoplates. An ether-based electrolyte shows better compatibility with the Cu2MoS4 electrode than a carbonate-based electrolyte, which is reflected in high reversible capacity, superior rate performance, and remarkably improved cycling performance. Ex-situ XRD analysis demonstrates a highly reversible electrochemical reaction in the ether-based electrolyte, which enhances the cycling stability.

Correction: Visible-light photocatalytic performance, recovery and degradation mechanism of ternary magnetic Fe3O4/BiOBr/BiOI composite.

[This corrects the article DOI: 10.1039/C9RA04412D.].