Exploring highly efficient catalysts for the oxygen evolution reaction (OER) is essential for water electrolysis. Cost‐effective transition‐metal oxides with reasonable activity are raising ...attention. Recently, OER reactants' and products' differing spin configurations have been thought to cause slow reaction kinetics. Catalysts with magnetically polarized channels could selectively remove electrons with opposite magnetic moment and conserve overall spin during OER, enhancing triplet state oxygen molecule evolution. Herein, antiferromagnetic inverse spinel oxide LiCoVO4 is found to contain d7 Co2+ ions that can be stabilized under active octahedral sites, possessing high spin states S = 3/2 (t2g5eg2). With high spin configuration, each Co2+ ion has an ideal magnetic moment of 3 µB, allowing the edge‐shared Co2+ octahedra in spinel to be magnetically polarized. Density functional theory simulation results show that the layered antiferromagnetic LiCoVO4 studied contains magnetically polarized channels. The average magnetic moment (µave) per transition‐metal atom in the spin conduction channel is around 2.66 µB. Such channels are able to enhance the selective removal of spin‐oriented electrons from the reactants during the OER, which facilitates the accumulation of appropriate magnetic moments for triplet oxygen molecule evolution. In addition, the LiCoVO4 reported has been identified as an oxide catalyst with excellent OER activity.
Antiferromagnetic inverse spinel oxide LiCoVO4 is found to contain spin‐polarized channels. Such channels can enhance selective removal of spin‐oriented electrons from the reactants during the oxygen evolution reaction (OER), which facilitates the accumulation of appropriate magnetic moments for triplet oxygen molecule evolution and conserves the overall spin during the OER.
Antibiotic resistance genes (ARGs) have been considered as emerging contaminants of concern nowadays. There are no special technologies designed to directly remove ARGs in wastewater treatment plants ...(WWTPs). In order to reduce the risk of ARGs, it is vital to understand the efficiency of advanced treatment technologies in removing antibiotic resistance genes in WWTPs. This review highlights the application and efficiency of tertiary treatment technologies on the elimination of ARGs, s, based on an understanding of their occurrence and fate in WWTPs. These technologies include chemical-based processes such as chlorination, ozonation, ultraviolet, and advanced oxidation technology, as well as physical separation processes, biological processes such as constructed wetland and membrane bioreactor, and soil aquifer treatment. The merits, limitations and ameliorative measures of these processes are discussed, with the view to optimizing future treatment strategies and identifying new research directions.
•State of the art of tertiary treatment technologies in potential application of controlling ARGs in WWTPs has been reviewed.•Merits, limitations and an ameliorative measure of each technology have been compared.•The optimal utilization of tertiary treatments has been suggested for future research directions.
Development of efficient, affordable, and sustainable energy storage technologies has become an area of interest due to the worsening environmental issues and rising technological dependence on ...Li‐ion batteries. Na‐ion batteries (NIBs) have been receiving intensive research efforts during the last few years. Owing to their potentially low cost and relatively high energy density, NIBs are promising energy storage devices, especially for stationary applications. A fundamental understanding of electrode properties during electrochemical reactions is important for the development of low cost, high‐energy density, and long shelf life NIBs. This Review aims to summarize and discuss reaction mechanisms of the major types of NIB electrode materials reported. By appreciating how the material works and the fundamental flaws it possesses, it is hoped that this Review will assist readers in coming up with innovative solutions for designing better materials for NIBs.
A fundamental understanding of electrode properties during electrochemical reactions is important for the development of low cost, high‐energy density, and long life Na‐ion batteries. This Review summarizes and discusses reaction mechanisms of the major types of Na‐ion battery electrode materials reported to date.
A 3‐dimensional hydrologic groundwater flow and contaminant transport model was developed to address the feasibility and relevant time‐scales for remediation of a large soil aquifer treatment (SAT) ...site for domestic wastewater. The model accounted for a range of organic pollutant retardation factors and biodegradation kinetics. In order to detect the effect of the most retained and the most refracted/recalcitrant pollutants, it was crucial to model fractions of different properties rather than with average set properties.
Four aquifer remediation scenarios, including two active washing procedures and two involving natural attenuation, were evaluated. The remediation efficiencies, in terms of residual plume size and mass of pollutant washout, were compared to each other and to the current operation scheme. According to the results, remediation mainly via natural attenuation rather than some form of intense pump and treat technology, is feasible, unlike the situation with hazardous waste sites. Enforced washout becomes less efficient with time due to increasing retardation of the residual pollutants. Therefore, pollution containment with natural biodegradation, which removed 95% of the emerging contaminants within 30 to 40 years was found to be the most valuable remediation scheme.
Article Impact Statement: Full remediation of a SAT site, including biodegradation kinetics and retarded organic compounds' influence, modeled.
Despite the technological importance of urea perhydrate (percarbamide) and sodium percarbonate, and the growing technological attention to solid forms of peroxide, fewer than 45 peroxosolvates were ...known by 2000. However, recent advances in X-ray diffractometers more than tripled the number of structurally characterized peroxosolvates over the last 20 years, and even more so, allowed energetic interpretation and gleaning deeper insight into peroxosolvate stability. To date, 134 crystalline peroxosolvates have been structurally resolved providing sufficient insight to justify a first review article on the subject. In the first chapter of the review, a comprehensive analysis of the structural databases is carried out revealing the nature of the co-former in crystalline peroxosolvates. In the majority of cases, the coformers can be classified into three groups: (1) salts of inorganic and carboxylic acids; (2) amino acids, peptides, and related zwitterions; and (3) molecular compounds with a lone electron pair on nitrogen and/or oxygen atoms. The second chapter of the review is devoted to H-bonding in peroxosolvates. The database search and energy statistics revealed the importance of intermolecular hydrogen bonds (H-bonds) which play a structure-directing role in the considered crystals. H
O
always forms two H-bonds as a proton donor, the energy of which is higher than the energy of analogous H-bonds existing in isostructural crystalline hydrates. This phenomenon is due to the higher acidity of H
O
compared to water and the conformational mobility of H
O
. The dihedral angle H-O-O-H varies from 20 to 180° in crystalline peroxosolvates. As a result, infinite H-bonded 1D chain clusters are formed, consisting of H
O
molecules, H
O
and water molecules, and H
O
and halogen anions. H
O
can form up to four H-bonds as a proton acceptor. The third chapter of the review is devoted to energetic computations and in particular density functional theory with periodic boundary conditions. The approaches are considered in detail, allowing one to obtain the H-bond energies in crystals. DFT computations provide deeper insight into the stability of peroxosolvates and explain why percarbamide and sodium percarbonate are stable to H
O
/H
O isomorphic transformations. The review ends with a description of the main modern trends in the synthesis of crystalline peroxosolvates, in particular, the production of peroxosolvates of high-energy compounds and mixed pharmaceutical forms with antiseptic and analgesic effects.
Energy/enthalpy of intermolecular hydrogen bonds (H-bonds) in crystals have been calculated in many papers. Most of the theoretical works used non-periodic models. Their applicability for describing ...intermolecular H-bonds in solids is not obvious since the crystal environment can strongly change H-bond geometry and energy in comparison with non-periodic models. Periodic DFT computations provide a reasonable description of a number of relevant properties of molecular crystals. However, these methods are quite cumbersome and time-consuming compared to non-periodic calculations. Here, we present a fast quantum approach for estimating the energy/enthalpy of intermolecular H-bonds in crystals. It has been tested on a family of crystalline peroxosolvates in which the H∙∙∙O bond set fills evenly (i.e., without significant gaps) the range of H∙∙∙O distances from ~1.5 to ~2.1 Å typical for strong, moderate, and weak H-bonds. Four of these two-component crystals (peroxosolvates of macrocyclic ethers and creatine) were obtained and structurally characterized for the first time. A critical comparison of the approaches for estimating the energy of intermolecular H-bonds in organic crystals is carried out, and various sources of errors are clarified.
A simple and facile one-step method for the synthesis of an organic dye-functionalized polyoxometalate (POM) hybrid with visible-light photo-response was reported. The POM hybrid was fully ...characterized via single crystal XRD, powder XRD, FTIR and elemental analysis. The reaction of the organic dye with inorganic salts gave the dye-functionalized POM (MoBB3), in which the POM cluster was formed in situ. The electronic absorption peak of this hybrid was successfully extended beyond 680 nm. Photoelectrochemical measurement indicated that MoBB3 was photoresponsive under visible-light illumination, suggesting that it is an n-type (electron conductive) semiconducting material. This result might offer a method for the design of novel organic dye-functionalized POMs for photoelectric applications.
Quantitative criteria for selection of tracers for assessment of mixing of wastewater and pristine water are proposed and evaluated for leakage from a wastewater effluent recharge system to nearby ...pristine water wells and the dilution of the effluents in a reclamation well by pristine water from the surrounding aquifer. Two molecular tracers were compared: carbamazepine, an organic drug whose refractory behavior was evaluated on-site, and chloride, a widely used conservative tracer. The mixing ratios and the corresponding uncertainty levels in their calculation were evaluated using actual field data. Uncertainty level analysis illuminates the effects of the analytical errors in the determination of trace micropollutants on one hand and the high level of chloride in the background on the other. Uncertainty level calculations revealed that chloride is a somewhat better tracer for the estimation of the dilution of wastewater by flow from a pristine aquifer, whereas carbamazepine is a much better tracer for the calculation of wastewater contamination of nearby drinking water wells. Surprisingly, we show that even when carbamazepine degrades to a large and unknown extent, it can still be used to estimate accurately the probability that a site is contaminated by a wastewater stream.
PDF
