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Two-dimensional single-atom catalysts (2D SACs) have been widely studied on the nitrogen reduction reaction (NRR). The characteristics of 2D catalysts imply that both sides of the monolayer can be catalytic sites and adsorb electrolyte ions or molecules from solutions. Overstrong adsorption of electrolyte ions or molecules on both sides of the catalyst site will poison the catalyst, while the adsorbate on one side of the catalytic site will modify the activity and selectivity of the other side for NRR. Discovering the influence of adsorption of electrolyte ions or molecules as a functional ligand on catalyst performance on the NRR is crucial to improve NRR efficiency. Here, we report this work using the density functional theory (DFT) method to investigate adsorption of electrolyte ions or molecules as a functional ligand. Among all of the studied 18 functional ligands and 3 transition metals (TMs), the results showed that Ru&F, Ru&COOH, and Mo&H2O combinations were screened as electrocatalysis systems with high activity and selectivity. Particularly, the Mo&H2O combination possesses the highest activity with a low ΔGMAX of 0.44 eV through the distal pathway. The superior catalytic performance of the Mo&H2O combination is mainly attributed to the electron donation from the metal d orbital. Furthermore, the functional ligands can occupy the active sites and block the competing vigorous hydrogen evolution reaction. Our findings offer an effective and practical strategy to design the combination of the catalyst and electrolyte to improve electrocatalytic NRR efficiency.

This research reveals biochemical and genetic changes for enhanced lipid production in Desmodesmus sp. mutated using atmospheric and room temperature plasma. Three lipid-rich mutant strains were selected by the special screening method, decided by the specific growth rate, relative fluorescence and the combination. There were no significant differences in genetic stability under 3-generation cultivation (p > 0.05). The highest lipid production and biomass increased by >100% and >15% compared to original strain, respectively. The activities of lipid enzymes, including acetyl-CoA carboxylase and diacylglycerol acyltransferases, responded to similar trends with lipid accumulation. Functional genes classification of mutant strains showed a great ratio in genetic information process (33.51%) and metabolism pathway (28.74%). More than 80% genes were not significant in lipid-related metabolisms and total 27 significant genes were analyzed, signifying similar genetic changes in mutant strains. Finally the establishing simplified diagram explained high lipid accumulation based on typical enzymes for fatty acid synthesis by upregulated genes, ACACA, fabF, fabG, ACSL, as well as triacylglycerol synthesis by upregulated genes, glpk, GPAT1_2, plsC, PDAT, dgat 1 and MGAT2. Lipid-rich strains performed a positive effect on lipid accumulation. These relative regulated genes and analysis might provide the control points for high lipid production in energy consumption.

Owing to the high expenses and numerous potential avenues for formula research in ceramic production, obtaining cost-effective and high-quality ceramic formulas for high-performance ceramics poses significant challenges. To address this issue, a flux formula optimization procedure is proposed to develop the predictive ceramic formula P18, which allows precise control of the Al/Si ratio and is compatible with standard manufacturing processes. This cost-effective method enables the visual examination of ceramics’ physical, mechanical and thermodynamic properties. It is found that sintering temperature plays a crucial role in phase and microstructure evolution by classical phenomenological kinetic theory. Moreover, the sintered sample P18 exhibits remarkable mechanical performance, with a strength of 96.82 ± 2.0 MPa and fracture toughness of 1.89 ± 0.02 MPa·m1/2. These outstanding properties can be attributed to the reinforcing effects of multiple phases, such as high-strength corundum and in situ mullite whiskers. The mechanical mechanisms of the resulting ceramic tiles include particle reinforcement, microcrack deflection, intergranular and transgranular fracture, and in situ mullite whisker bridge pull-out, which collectively contribute to increase energy consumption per unit length, thus reducing the risk of brittle fractures.

Designing atomically dispersed metal catalysts for the nitrogen reduction reaction (NRR) is an effective approach to achieve better energy conversion efficiencies. In this study, we designed a series of single molybdenum (Mo) atom-anchored porous two-dimensional Mo porphyrin (2D Mo-Pp) monolayers modified by B, C, O, P and S as efficient NRR catalysts to improve the catalytic performance. We introduced two key parameters, θ (pz orbital filling of heteroatoms) and φ (Bader charge of central Mo atoms). It shows that θ and φ play important roles in nitrogen absorption by analyzing the regression models. In particular, the theoretical results suggested that the 2D Mo-Pp monolayer modified by B has an ultralow limiting potential of 0.35 V and can suppress the hydrogen evolution reaction, making the 2D Mo-Pp monolayer modified by B a promising NRR electrocatalyst with high efficiency and selectivity. This work provides insights into the rational design of the elaborate structure of single-atom catalysts with tunable electrocatalytic activities.

QSAR modeling could be a promising tool for guiding the development of novel and cost-effective environmental technologies. As an example, it could be widely used to analyze the degradation rules of organic pollutants in various decomposition methods. However, a lack of systematic research on a particular removal method is significant in revealing the decomposition rule of pollutants more accurately and guiding industrial applications. In this study, six coagulation systems (MnO

Lattice strain, either tensile or compressive, can fine-tune the electronic structure of surfaces via altering the distances between surface atoms, thereby modifying the catalytic activity of catalysts. Numerous examples of strain engineering have been applied to various electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), but strain-optimized 2D carbon-based single-atom electrocatalysts for catalyzing the overall water splitting reaction have received little attention. Here, we applied the lattice strain of Co,N co-decorated graphyne (Co@N1-GY) to directly optimize its catalytic activity for the overall water splitting reaction based on first-principles calculations. Our calculations suggest that compressive strain and tensile strain lead to less stability of Co@N1-GY and the distances between C and Co atoms increase linearly with the strain changing from compressive to tensile, thus linearly upshifting the p-band center of C atoms and the d-band center of Co atoms. In addition, biaxial strain has more remarkable effects on these properties than uniaxial strain. From compressive to tensile strain, the chemisorption of electrochemically generated intermediates in both HER and OER becomes weaker and weaker. A tensile strain of 0.5% on Co@N1-GY gives an ideal HER performance, while the OER reaches the minimum overpotential of 0.33 V under the biaxial tensile strain of 3%.

Iron-impregnated biochar-activated urea-hydrogen peroxide (FB-activated UHP) is a potential in-situ technology for simultaneously reducing soil sulfonamide antibiotic contaminants and improving soil fertility. To better understand the degradation of sulfonamide antibiotics by FB-activated UHP, a two-dimensional quantitative structure-activity relationship (2D-QSAR) model based on quantum chemical parameters and a three-dimensional QSAR (3D-QSAR) model based on molecular force field were developed to investigate the factors influencing the removal efficiencies (Re%). The optimal 2D-QSAR model was Re%= 0.858-8.930 E-5 E

Sodium-glucose cotransporter-2 (SGLT2) inhibitors represent novel hypoglycemic drugs for the treatment of adult diabetes that have shown considerable potential for cardioprotection and renoprotection. This new drug can inhibit SGLT2 at the proximal tubule, increase glucosuria and natriuresis, and thus decreases the serum glucose level and blood pressure. Furthermore, the tubuloglomerular feedback (TGF) activated by the natriuresis can decrease glomerular hyperfiltration, acknowledged as the main foundation of renoprotection. Several studies have confirmed the protective effects of SGLT2 inhibitors on the kidneys of adult diabetic patients and those with non-diabetic nephropathy; however, limited researches are seen in pediatric patients. In this review, we have summarized the mechanisms of action of SGLT2 inhibitors, the current experiences in adults, results of exploratory studies in children, and adverse events & obstacles of pediatric use. We further explore the potential and possible future research direction of SGLT2 inhibitors in pediatric diseases. This article is protected by copyright. All rights reserved.

Two-dimensional single-atom catalysts (2D SACs) have been widely studied on the nitrogen reduction reaction (NRR). The characteristics of 2D catalysts imply that both sides of the monolayer can be catalytic sites and adsorb electrolyte ions or molecules from solutions. Overstrong adsorption of electrolyte ions or molecules on both sides of the catalyst site will poison the catalyst, while the adsorbate on one side of the catalytic site will modify the activity and selectivity of the other side for NRR. Discovering the influence of adsorption of electrolyte ions or molecules as a functional ligand on catalyst performance on the NRR is crucial to improve NRR efficiency. Here, we report this work using the density functional theory (DFT) method to investigate adsorption of electrolyte ions or molecules as a functional ligand. Among all of the studied 18 functional ligands and 3 transition metals (TMs), the results showed that RuF, RuCOOH, and MoH

Artificial ammonia (NH3) synthesis from molecular nitrogen (N2) in aqueous solutions under mild conditions is one of the most attractive and challenging processes in chemistry. In this work, by mea...

Developing highly active and non-precious-metal single-atom catalysts (SAC) for electrochemical water splitting is of great significance to the development of renewable energy technology in future. Herein, 10 first-row transition-metal (TM, from Sc to Zn) single atoms anchored on a graphyne (GY) nanosheet (TM@GY) as electrocatalysts for water splitting are explored through computational screening approach. It is found that the single atoms prefer to tightly bind at the acetylenic-ring center of GY. Meanwhile, these TM@GY catalysts show metallic properties or reduced band gap, favoring electron transfer during the electrochemical processes. Moreover, both Co@GY and Mn@GY catalysts present good catalytic performance for hydrogen evolution reaction (HER) with both the acetylenic C and TM atoms being highly active sites. However, only the Co@GY catalyst shows good oxygen evolution reaction (OER) activity with an overpotential of 0.55 V. Thus, Co@GY could serve as a potential bifunctional electrocatalyst for water splitting. Besides, the d-band center of TM atoms on TM@GY can be turned through controlling TM atoms with different d-electron number and be used to predict the OER performance. This work highlights that GY doped with single non-precious-metals can be considered for designing high-active and low-cost bifunctional electrocatalysts for practical electrochemical reactions.

Catalytic supercritical water oxidation (CSCWO) has sprung up as a promising technique to eliminate refractory aromatic compounds, which are difficult to be removed by conventional wastewater treatment processes. Decompositions and degradation mechanisms of 18 aromatic compounds, including benzene, phenol, bisphenol A (BPA) etc., were investigated using CSCWO in this study. It was found that TOC removal efficiencies of the aromatic compounds were significantly enhanced, when CSCWO temperatures raised from 325 to 525 °C and reaction time prolonged from 0.5 to 6 min, with the addition of Cu(NO3)2. The correlationships among TOC degradation rates (kTOC), temperature at TOC removal rate of 90% (T90) and 19 molecular descriptors were studied. The results indicated that BOn and q(H)x could greatly impact the degradation behaviors. Fukui indices based density functional theory (DFT) method was applied to reveal the conceivable degradation pathway of BPA during CSCWO process.

Atomic transition metal–nitrogen in carbon (TMNC), as single-atom catalysts employing in electrochemical hydrogen evolution reaction (HER), has recently sparked broad research interests, but the effects of the edge-site N/C atoms neighboring TMNC moieties on catalytic HER performance are less investigated. Herein, by employing first-principles computations, we have established a series of TMN1C (TM = Cu, Mo, and Pt) nanoarchitectures as electrocatalysts for HER. It is found that the MoN1C is the best catalyst for HER with the calculated Gibbs free energy of hydrogen adsorption ( Δ G H* ) of 0.038 eV. We further construct various N/C edge-sites around the Mo atom on the MoN1C catalyst, which endow tunable structures and selective exposure of interior active sites. These N/C edge-sites alter the charge density distribution of catalytic active sites and affect the distortion of the TMN1C catalysts as well as the structures of intermediate hydrogen adsorption. Their catalytic activities are further enhanced. The work is suggestive of a new approach for the edge-site engineering of geometric and electronic structures of TMNC to optimize their catalytic activities.

The high-efficient electrochemical hydrogen evolution reaction (HER) is a promising pathway to provide clean energy. An electrocatalyst was computer-aided designed with Mo isolated single atoms (Mo-ISA) supported on heteroatom S, N-codoped carbon having excellent HER performance. Here, by performing comprehensive density functional theory (DFT) computations, we investigated the influence of the N dopent concentration and the sites of S atom doping on the HER performance. Our computed results demonstrate that the Mo-ISA/N1C and Mo-ISA/S6N1C catalysts possess good stability and high HER reactivity. Moreover, the interactions between hydrogen and the Mo atoms could be controlled by the N dopent concentration on carbon support, and the Mo-ISA/N1C catalyst showed best HER reactivity. In particular, the S atom was introduced into Mo-ISA/N1C at the S6 site showing an enhanced HER performance due to the competitive effect of the S-induced tensile strain and charge transfer. Our DFT computations open up new opportunities for application of S, N-codoped Mo-based high-efficient catalysts for HER.

Supercritical water oxidation (SCWO) has sprung up as a green and high-effective treatment to eliminate refractory aromatic compounds, which are difficult to be removed by conventional wastewater treatment processes. Decompositions and degradation mechanisms of 14 organophosphate flame retardants (OPFRs) were investigated using SCWO in this study. It was found that TOC removal efficiencies of the OPFRs were significantly enhanced, when SCWO temperatures raised from 623 to 823 K and reaction time prolonged from 1 to 6 min. The aryl and chloro OPFRs achieved higher TOC degradation rates (kTOC) than the alkyl ones. The correlationship between kTOC and 18 molecular descriptors of 14 OPFRs were studied. The results implied that F(0)x and q(C)x could greatly impact the degradation behaviors. Moreover, Fukui indices based density functional theory method was successfully applied to predict the conceivable degradation pathways of OPFRs, which proposing .OH attack at molecular bond level.

Developing low-cost, high adsorption capacity, and recyclable mercury sorbents is an important step for control of mercury in coal-fired flue gas. However, few sorbents meet all the requirements. Herein, we explore the adsorption behavior and oxidation mechanisms of mercury on 2D Ti2CO2 (MXenes) monolayer and defective Ti2CO2 monolayer with an Ov (Ov-Ti2CO2) through first-principles computations based on density functional theory (DFT). Our calculation results show that Hg0 adsorption on Ti2CO2 and Ov-Ti2CO2 monolayers are mainly physisorption and chemisorption mechanisms, respectively. Moreover, the presence of a single oxygen vacancy on Ti2CO2 monolayer can improve the interaction between the mercury and Ov-Ti2CO2 monolayer, thereby enhancing the adsorption energy of mercury by 66 kJ/mol. Hg0 has a strong interaction with Ti atom on Ov-Ti2CO2 monolayer by the atomic orbital hybridization and overlap. The adsorption of HgO molecule on Ti2CO2 and Ov-Ti2CO2 monolayers are chemisorption processes. Furthermore, electron density difference analysis indicates that the remarkable charge accumulation across the interface is closely related to the strong interaction between HgO molecule and Ti2CO2 or Ov-Ti2CO2 monolayers. The three-step reaction processes (Hg0 → Hg(ads) → HgO(ads) → HgO) are taken place on Ti2CO2 and Ov-Ti2CO2 monolayers, resulting in the formation of gaseous HgO molecule. The energy barrier for the Hg0 oxidation reaction step on Ov-Ti2CO2 monolayer (54.85 kJ/mol) is about half of that on Ti2CO2 monolayer (104.73 kJ/mol). The desorption steps of the resultant HgO molecule from Ti2CO2 and Ov-Ti2CO2 monolayers are the rate-determining steps, which need external energies of about 119.3 and 183.2 kJ/mol, respectively.

Aiming at the problem of ease of falling into local optimum and low solution quality when solving optimization problems, this paper proposes an adaptive hybrid cuckoo search (AHCS) algorithm. AHCS improves the Levy flight method and population evolution strategy of the cuckoo search (CS) algorithm, and introduces a mutation operation operator. Inspired by the idea of position update of particle swarm optimization (PSO) algorithm, this paper introduces the inertia weight $w$ in the Levy flight method of CS algorithm, and gives the new dynamic adjustment methods of parameters $\alpha $ and $\beta $ respectively. In order to enhance the local search ability and optimization speed of the algorithm, this paper introduces the mutation operation operator, and presents a new evolution strategy of the hybrid cuckoo search algorithm. In addition, in order to verify the performance of AHCS, 30 benchmark functions and CEC 2017 optimization problems were selected. The calculation results of the 30 benchmark functions and CEC 2017 optimization problems show that compared with other algorithms, the number of winning cases of $t$ -test values and the Friedman average ranking for AHCS are significantly better than other algorithms. Finally, AHCS and various intelligent optimization methods in the literature are used to optimize the structural parameters of the reducer and the cantilever beam. The optimization results show that the quality of AHCS solution is significantly better than other algorithms.

Aiming at the problem of slow convergence speed and ease of falling into local optimum when solving high dimensional problems, this paper proposes an improved chicken swarm optimization algorithm. The improved chicken swarm optimization includes four aspects, namely, cock position update mode, hen position update mode, chick position update mode, and population update strategy, so it is abbreviated as ICSO-RHC. On the basis of algorithm improvement, the influence of the number of retained elite individuals and control parameters on the convergence speed of the algorithm is discussed. The calculation results of the test function show that when the number of elite individuals in the population is 1, and the control parameters is a random number uniformly distributed between [0, 1], the algorithm has a faster convergence speed. In addition, in order to verify the performance of ICSO-RHC, 30 test functions and CEC 2005 benchmark functions were selected. The calculation results of these test functions show that the success rate of ICSO-RHC is significantly higher than other algorithms, both for low-dimensional and high-dimensional optimization problems. The average iteration number and average running time are significantly lower than other algorithms. Finally, ICSO-RHC and other improved algorithms in the literature are used to optimize the parameters of four practical engineering problems. The optimization results show that the statistical results obtained by ICSO-RHC are significantly better than other algorithms. The calculation results of the test functions and the actual engineering problems show that the performance of ICSO-RHC proposed in this paper is significantly better than other algorithms.

Designing atomically dispersed metal catalysts for the nitrogen reduction reaction (NRR) is an effective approach to achieve better energy conversion efficiencies. In this study, we designed a series of single molybdenum (Mo) atom-anchored porous two-dimensional Mo porphyrin (2D Mo-Pp) monolayers modified by B, C, O, P and S as efficient NRR catalysts to improve the catalytic performance. We introduced two key parameters, θ (pz orbital filling of heteroatoms) and φ (Bader charge of central Mo atoms). It shows that θ and φ play important roles in nitrogen absorption by analyzing the regression models. In particular, the theoretical results suggested that the 2D Mo-Pp monolayer modified by B has an ultralow limiting potential of 0.35 V and can suppress the hydrogen evolution reaction, making the 2D Mo-Pp monolayer modified by B a promising NRR electrocatalyst with high efficiency and selectivity. This work provides insights into the rational design of the elaborate structure of single-atom catalysts with tunable electrocatalytic activities.

Electrochemical reduction is a promising technology to treat polluted water contaminated by nitrate and nitrite ions under mild conditions. NO is an important intermediate species and determines selectivity toward different product and rate of whole reaction. However, the most studied NOER electrocatalysts are noble pure metal, which face problems of low utilization and high cost. Herein, by means of density functional theory computations, catalytic performance of 2D TM-Pc sheets (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, Ru) as NOER catalysts were systematically evaluated. Among all the studied 2D TM-Pc sheets, our results revealed 2D Co-Pc sheet was identified as the best NOER catalyst, for a proper NO absorption energy and its relatively low limiting potential. The final reduction product of NOER is either NH3 at low coverages with energy input of 0.58 eV or N2O at high coverages with no energy barrier. Moreover, 2D Co-Pc sheet can efficiently suppress the competing HER. This study could not only provide a new approach for electrochemical denitrification to resolve environmental pollution but also be useful for valuable ammonia production.

Background: Pancreatic cancer(PC) is seriously harmful to human health, and the pathogenesis is not clear. The present study aimed to explore the functional role of syncytin-1 in PC.Methods: Syncytin-1 and miR-31 expression was analyzed by qRT-PCR and Western blot analysis in both human PC cell lines and tissuse. The prognostic significance of syncytin-1 was investigated using the immunohistochemistry(IHC) and Kaplan-Meier survival. The CCK-8 assay and transwell assays were used to determine the role of syncytin-1 and miR-31 in cell proliferation, migration and invasion. Luciferase reporter assays was used to identify possible miRNA targets in tumorigenesis.Results: The results showed that the syncytin-1 level was significantly decreased in PC cell lines and tissues than normal(P P P P Conclusion: We verified that syncytin-1 can inhibit proliferation and invasion of PC cell lines by targeting miR-31.

Developing an in-situ soil remediation technology for simultaneous catalytic degradation of contaminants and nitrogen supplementation is of great importance but remains challenging. Herein, MgFe-LDH engineered biochar (MB) was successfully synthesized by using a simple co-precipitation method. The as-prepared materials were used as catalysts for the first time to activate urea-hydrogen peroxide (UHP) to degrade antibiotic sulfamethoxazole (SMX) and provide nitrogen. The enhanced degradation efficiency of SMX (91%) were mainly attributed to •OH and 1O2-mediated oxidation. Pot experiments showed MB/UHP significantly decreased the SMX concentration from 6.47 to 2.10 mg kg-1 and simultaneously increased NH4+-N and NO3--N concentration. The optimal quantitative-structure-activity-relationship model for 19 antibiotics suggested the dipole moment, energy of the highest occupied molecular orbital, and bond order were the intrinsic influencing factors. This study not only provides a green remediation technology but also offers a theoretical basis for estimating the removal rate of unexplored antibiotics.

Reducers play a particularly important role in mechanical transmission field, and even a slight reduction in the material consumption would bring considerable economic and social benefits. With the goal of the minimum volume of consumables, a general mathematical model for the widely used single-stage cylindrical gear reducer (SSCGR), is established. When some real and discrete parameters are selected as the design variables, the SSCGR problem becomes a mixed-discrete SSCGR problem. To minimize the mixed-discrete SSCGR problem and make discrete design variables always satisfy discrete constraints, an improved mixed-coded hybrid firefly algorithm (IMCHFA) is proposed. The proposed approach uses new mixed-coded method to encode the position structure, and uses sorting group selection to select paired fireflies for position update, then uses combinatorial mutation to accelerate convergence of the algorithm. Meanwhile, the rounding technique is adopted to make the position structure meet the coding rules. 28 modified CEC 2017 mixed-discrete problems and two practical mixed-discrete engineering optimization problems are tested by the IMCHFA and other improved algorithms. The results show that the solution quality of IMCHFA is significantly better than other improved algorithms examined in this study. Finally, the proposed IMCHFA is applied to optimize the mixed-discrete SSCGR problem. Compared to the solution quality of other improved algorithms examined in this study, the proposed IMCHFA can obtain more efficient and economic solutions.

The early internal leakage fault characteristics in hydraulic cylinder are very weak and vulnerable to environmental noise, which makes the early internal leakage fault detection very difficult. In comparison with internal leakage detection by the pressure signal, internal leakage by Acoustic emission (AE) signal has higher sensitivity and accuracy. So this paper adapts the algorithms combining complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and auto regressive (AR) spectrum. Comparing with the mean value of first intrinsic mode function (IMF1) instantaneous amplitude based on EEMD, The experimental results verify the proposed algorithms based on CEEMDAN distinguish different internal leakage levels obviously and has better performance.

Supercritical water oxidation (SCWO), in which hazardous wastes are removed from water at high temperature and pressure, is an effective method for wastewater treatment. To gain a better understanding of the removal rules for nitrogenous organics in SCWO, a Quantitative-Structure-Activity-Relationship (QSAR) approach was applied to establish the relationship between quantum chemical parameters and removal behaviors. In this study, 41 nitrogenous organics were used to study the removal behaviors, including the reaction rate constants of total nitrogen ( k TN ) and the temperature at which the total nitrogen removal efficiency is 50% ( T TN 50 ). QSAR models were subsequently developed and evaluated. The two optimal models for k TN and T TN 50 were stable, robust and accurate, with the associated statistical indices of R2 = 0.725 and 0.951, q2 = 0.568 and 0.931, Q ext 2 = 0.847 and 0.987, respectively. The two optimal models both contained f ( - ) n , E gap , q N and BO x , but varied in the correlation between these four parameters and dependent variables. A three factors theory was thus proposed based on the two optimal models: the selectivity of active site, the transfer of electrons, and the breaking of chemical bond. These two models not only offer theoretical methods for predicting k TN and T TN 50 , but also have predictive power for the removal behaviors of other nitrogenous organics in SCWO, reducing the need for further experiments.

The ozonation process is an effective method for removing hazardous wastes in water. To better characterize and understand the factors influencing the reaction rate constants of organic compounds during the ozonation process, a quantitative-structure–activity-relationship (QSAR) model was developed using the principal component analysis and multiple linear regression (PCA-MLR) method. In principal component analysis, five of the seven components were found to mechanistically and statistically affect the reaction rate constants. Component 1 was represented by the number of oxygen atoms ( n O ) and minimum value of bond order ( BO n ), component 2 was represented by the energy of the highest occupied molecular orbital ( E HOMO ), and component 3 and 4 were dominated by the largest change in the charge of each atom during nucleophilic attack ( f ( + ) x ) and the energy of the lowest unoccupied molecular orbital ( E LUMO ), respectively. The temperature ( T ) was the most important factor for component 7. The optimal model was l n k O 3 = 4.102 + 0.007 T - 3.419 BO n + 1.765 f ( + ) x + 5.698 E LUMO - 4.016 E HOMO - 0.241 n O , with the following evaluation index values: squared correlation coefficient ( R 2 ) = 0.916, internal validation ( q 2 ) = 0.895 and external validation ( Q ext 2 ) = 0.962. Based on these evaluation indices, Y-randomization validation and the definition of the applicability domain, the optimal model was stable, robust and predictive. We anticipate that our work will provide a credible theoretical foundation for estimating the reaction rate constants for degradation of high-molecular weight organic compounds during ozonation over a temperature range from 25 to 60 °C.

Supercritical water oxidation (SCWO) has sprung up as a promising technique to eliminate refractory compounds, which are difficult to be removed by conventional wastewater treatment processes. However, data is still sparse on SCWO of a series of N-containing compounds, such as TN removal, N-containing species distribution and molecular characteristics. In this work, decomposition of 44 nitrogen-containing compounds was investigated under temperature of 350–550 °C, resulted in total nitrogen (TN) removal from 55 to 94%. The N-containing products were primary N2, nitrate and ammonium. The primary products were NO3− and NH4+ from nitro- and amino-group compounds, respectively. As for diazo and N-heterocyclic ones, NO3− and NH4+ were the main nitrogen containing products, respectively. Interestingly, in terms of aniline and its derivatives, the amount of N2 followed the order: aniline > N-methylaniline (N-MA) > N,N-dimethylaniline (N,N-DMA). These experimental results were in agreement with the results of Fukui function. The correlationship between the temperature at TN removal rate of 50% (TN50) and 17 molecular characteristics has been calculated, which resulted EHOMO and Fukui indices could largely influence temperature behavior of TN removal.

In order to have a better prediction for the degradation reaction rate constant of organic compounds in Fenton process at different temperatures. A partial least squares (PLS) model was established based on 116 lgk values for 24 organic compounds and quantum chemical parameters, some basic information of molecules as well as the temperature of reaction system. The optimal model was demonstrated as stable, robust and had good predictive ability, with the associate statistical indices of adjusted squared correlation coefficient was 0.722, internal validation was 0.652, external validation was 0.512, cumulative cross-validation coefficient was 0.635, the criterions indicated the developed model could be used to estimate the reaction rate of organic compounds in Fenton process at different temperature. The model contains three components, the most significant descriptors explaining the reaction rate are T and 1/T for component 1, the maximum charge in a carbon atom and minimum charge for nucleophilic attack for component 2, the charge in a hydrogen atom, maximum charge for hydroxyl radical attack and minimum value of bond order for component 3. The applicability domain (APD) of the proposed model was calculated by the Euclidean distances. The results of APD showed that the predictions by the derived PLS model were reliable. The proposed model not only offer a method to predict the reaction rates, but also give some insights of the mechanism for the degradation of organic compounds in Fenton process at different temperatures.

Supercritical water oxidation (SCWO) of 2-, 3- and 4-nitroaniline (NA) was investigated under residence time of 1–6 min, pressure of 18–26 MPa, temperature of 350–500 °C, with initial concentration of 1 mM and 300% excess oxygen. Among these operating conditions, temperature and residence time played a more significant role in decomposing TOC and TN than pressure. Moreover, the products of N-containing species were mainly N2, ammonia and nitrate. When temperature, pressure and retention time enhanced, the yields of NO3− and org-N were reduced, the amount of N2 was increasing, the proportion of NH4+, however, presented a general trend from rise to decline in general. The experiment of aniline/nitrobenzene indicated that TN removal behavior between amino and nitro groups would prefer to happen in the molecule rather than between the molecules, therefore, the smaller interval between the amino and nitro group was the more easily to interreact. This might explain the reason why TN removal efficiency was in an order that 2-NA > 3-NA > 4-NA. The NH4+/NO3− experiment result demonstrated that ammonia and nitrate did convert into N2 during SCWO, however, the formation of N2 was little without auxiliary fuel. Density functional theory (DFT) method was used to calculate the molecular structures of 2-, 3- and 4-NA to further explore reaction mechanism, which verified that amino group was more easily to be attacked than nitro group. Based on these results, the conceivable reaction pathways of 2-, 3- and 4-NA were proposed, which contained three parts, namely denitrification, ring-open and mineralization.