Search

The thermodynamic properties of boron nitride under extreme pressures and temperatures are of great interest and importance for materials science and inertial confinement fusion physics, but they are poorly understood owing to the challenges of performing experiments and realizing ab initio calculations. Here, we report the first shock Hugoniot data on hexagonal boron nitride at pressures of 5–16 Mbar, using hohlraum-driven shock waves at the SGIII-p laser facility in China. Our density functional theory molecular dynamics calculations closely match experimental data, validating the equations of state for modeling the shock response of boron nitride and filling a crucial gap in the knowledge of boron nitride properties in the region of multi-Mbar pressures and eV temperatures. The results presented here provide fundamental insights into boron nitride under the extreme conditions relevant to inertial confinement fusion, hydrogen–boron fusion, and high-energy-density physics. [ABSTRACT FROM AUTHOR]

Compressed leachate is a contaminated liquid containing various organic and inorganic pollutants produced in municipal refuse transfer stations, which pollute soil and groundwater, posing serious risks to the environment and human health. The Environmental Technology Co., Ltd. (Shenzhen, Guangdong Province, South China) treated compressed leachate obtained from a refuse transfer station. The chemical oxygen demand (COD) (641.2 mg/L) of treated compressed leachate did not meet the wastewater quality standards in China for discharge into municipal sewers (COD ≤ 500 mg/L) and the company's design discharge requirements (COD ≤ 400 mg/L). Therefore, their further in-depth treatment is necessary. To this end, waste tobacco leaves were used as the biotemplate herein, and Fe/La-co-doped TiO2 (xFe,yLa)-TTiO2(g) was synthesized using a solvothermal-assisted biotemplating method. The photocatalytic depth treatment of compressed leachate was performed under simulated solar light using the prepared catalysts. After (3Fe,3La)-TTiO2(g) treatment, the COD of the leachate decreased from 641.2 to 280.1 mg/L, and the COD removal rate was 1.2, 1.1, and 1.6 times higher than that of pure Fe-doped, La-doped and non-biological template TiO2, respectively. Characterization confirmed that the biological template endowed the catalyst with a unique morphology and high specific surface area. Its rich activity sites are conducive to enhancing the adsorption capacity of pollutants and providing an ideal place for photocatalytic reactions. Co-doping with iron and lanthanum ions altered the band structure of TiO2 and promoted the interconversion of Fe3+/Fe2+ and La3+/La2+ during photocatalysis. First-principles density functional theory simulations demonstrated that co-doping Fe and La in TiO2 created impurity levels that facilitated the transfer of photogenerated electrons. This study provides a new purification pathway for the depth treatment of compressed leachate. [ABSTRACT FROM AUTHOR]

The wheat scab caused by Fusarium graminearum (F. graminearum) has seriously affected the yield and quality of wheat in China. In this study, gallic acid (GA), a natural polyphenol, was used to synthesize three azole-modified gallic acid derivatives (AGAs1–3). The antifungal activity of GA and its derivatives against F. graminearum was studied through mycelial growth rate experiments and field efficacy experiments. The results of the mycelial growth rate test showed that the EC50 of AGAs–2 was 0.49 mg/mL, and that of AGAs–3 was 0.42 mg/mL. The biological activity of AGAs–3 on F. graminearum is significantly better than that of GA. The results of field efficacy tests showed that AGAs–2 and AGAs–3 significantly reduced the incidence rate and disease index of wheat scab, and the control effect reached 68.86% and 72.11%, respectively. In addition, preliminary investigation was performed on the possible interaction between AGAs–3 and F. graminearum using density functional theory (DFT). These results indicate that compound AGAs–3, because of its characteristic of imidazolium salts, has potential for use as a green and environmentally friendly plant-derived antifungal agent for plant pathogenic fungi. [ABSTRACT FROM AUTHOR]

Myxobacteria are special bacteria with wide adaptability, which are rich sources of structurally diverse natural products with intriguing biological properties. Here, a gram-negative myxobacterium strain s54d21T was isolated from the sediment of a wetland park in China using the Escherichia coli baiting method. Based on 16S rRNA gene sequence and genomic data, the strain was demonstrated to be a novel species of a rare genus Hyalangium, designated Hyalangium ruber sp. nov (type strain s54d21T = GDMCC 1.1945T = JCM 39263T). The subsequent chemical investigation of the strain s54d21T led to the isolation of three rare 3,5,6-trisubstituted 2(1H)-pyrazinones, namely, hyalanones A-C (1-3), together with a known macrolactin A (4). Those new structures and their absolute configurations were unambiguously assigned by extensive analyses of spectroscopic data and density functional theory (DFT) calculations. In biological assays, compound 4 exhibited moderate cytotoxic activities against human cell lines RKO, A549, and NCM460 with IC50 values ranging from 27.21 to 32.14 µM. [ABSTRACT FROM AUTHOR]

In China, most of the high-sulfur iron ores have not been fully developed and utilized due to the lack of breakthrough progress in the research on the sulfur migration and the desulfurization mechanism during the roasting process. This study will focus on revealing the release and fixation mechanisms of sulfur during the roasting process to achieve the transformation of desulfurization from terminal treatment to process control. Experimental results show that as the roasting temperature increases, the release rate of SO2 also increases, reaching the maximum release rate at 900 °C. Simultaneously, it is found that at the same roasting temperature, the release rate and amount of SO2 under the O2/N2 atmosphere is significantly greater than that under the pure N2 and air atmospheres. Meanwhile, X-ray diffraction (XRD) is utilized to explore the phase composition of the roasted product and the sulfur release mechanism. In addition, the adsorption energy, stability and electron transfer of SO2 on the CaO surface are calculated through density functional theory (DFT), and the optimal adsorption active site perpendicular to the O atom (O-top) is also determined. Finally, the sulfur fixing agent CaO is used to study the SO2 fixation mechanism. When the concentration reaches 10%, the sulfur fixation efficiency reaches more than 80%. Therefore, this work will present basic knowledge and systematic guidance for the sulfur migration and release of high-sulfur iron ore under the oxidizing roasting process. [ABSTRACT FROM AUTHOR]

Red mud is a red-coloured, mud-like solid waste discharged from the industrial aluminium production process, which has a high output and is a pollutant. It exhibits a small particle size and a large specific surface area and contains active oxides. In this study, "red mud" and "phosphate" were used as keywords to retrieve research hotspots and progress for the red mud as a phosphate adsorbent in the past 10 y. CiteSpace and VOSviewer visual literature analysis software were used to cluster countries, institutions, authors, and keywords. Related patents showed that research on the phosphate adsorption performance of red mud has considerably increased since 2013 and that China has made a significant contribution. This paper summarises the main chemical composition and modification methods of red mud and collects from literature the relevant mechanism research and data on phosphate adsorption/desorption using red mud as an adsorbent. Summarising data on the microstructure of red mud adsorbent, it is found that there are few reports on red mud as adsorbent based on density functional theory. This study suggests that the problem of the steric hindrance of the red mud adsorbent in the phosphate adsorption process needs further research. [ABSTRACT FROM AUTHOR]

Artemisia divaricate belongs to the Artemisia genus of the family of Compositae, a sort of perennial herb endemic in most regions of China. For the first time, a phytochemical investigation was carried out on the whole plant of Artemisia divaricate, resulting in the identification of 39 sesquiterpenes, with 9 of them being new (1–9). The structures of the new compounds were fully established using extensive analysis of MS and 1D and 2D NMR spectroscopic data and density functional theory (DFT) NMR calculations. Their structures involve germacrane, eudesmane, and bisabolane types. All the new isolates were evaluated for their anti-inflammatory activities in lipopolysaccharide (LPS)-stimulated murine macrophages of RAW 264.7 cells. Compounds 2 and 8 showed a significant inhibition effect on NO production, with IC50 values of 5.35 ± 0.75 and 7.68 ± 0.54 µM, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Clean Coal Technology is the property of Clean Coal Technology 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.)

Iron Chlorin e6 (ICE6), a star plant growth regulator (PGR) with independent intellectual property rights in China, has demonstrated its efficacy through numerous field experiments. We innovatively employed salting-out assisted liquid-liquid extraction (SALLE) with HPLC-UV/Vis to detect ICE6 residues in water, soil, garlic seeds, and sprouts. Using methanol and a C18 column with acetonitrile: 0.1% phosphoric acid mobile phase (55:45, v:v), we achieved a low LOQ of 0.43 to 0.77 μg kg−1. Calibration curves showed strong linearity (R2 > 0.992) within 0.01 to 5.00 mg kg−1. Inter-day and intra-day recoveries (0.05 to 0.50 mg kg−1) demonstrated high sensitivity and accuracy (recoveries: 75.36% to 107.86%; RSD: 1.03% to 8.78%). Additionally, density functional theory (DFT) analysis aligned UV/Vis spectra and indicated ICE6's first-order degradation (2.03 to 4.94 days) under various environmental conditions, mainly driven by abiotic degradation. This study enhances understanding of ICE6's environmental behavior, aids in risk assessment, and guides responsible use in agroecosystems. [Display omitted] • HPLC- UV/Vis coupled to DFT is proposed for PGRs authentication. • Anabiotic degradation was predominant in the degradation of ICE6. • Hydrolysis followed the first-order kinetics. • Increasing the temperature will accelerate hydrolysis. • The validated method was subjected to actual samples. [ABSTRACT FROM AUTHOR]

[Display omitted] The rapid development of nuclear energy and the accelerated consumption of uranium (U(VI)) ores have forced researchers to turn to marine U(VI) harvesting. However, the performance of marine U(VI) harvesting materials was challenged by the combination of ultralow concentrations of U(VI), high concentrations of various interfering ions and biofouling from abundant marine living organisms. Natural abundant hemp fibers (HFs) were adhered by mussel-inspired polydopamine microspheres (HFMPDA) during self-polymerization. Both HFs and PDA are derived from natural products with low-cost and eco-friendly properties to guarantee compatibility with biological marine environments. HFMPDA exhibits an outstanding distribution coefficient of 10.51 ± 0.51 L g−1 for U(VI) and great fouling resistance. The coordination forms between the U(VI) ion and HFMPDA were investigated by density functional theory (DFT), and the antifouling property was simulated by molecular dynamics (MD) calculations. The adsorption capacity of HFMPDA is 128.43 ± 3.26 μg g−1, which is 1.75 and 6.05 times higher than that of HFPDA (only covered by PDA) and V(V), respectively, after immersion for 34 days in the Yellow Sea, China. These polydopamine microspheres adhered to HF will be a photothermal marine U(VI) harvesting material with enhanced selectivity and fouling resistance. [ABSTRACT FROM AUTHOR]

Owing to containing high fraction of organic matter, the tannery sludge seemed to be fit for composting. Actually, it was intensively harmful to the environment, due to containing chromium (Cr). So it might undergo a long time of storage until finding a proper way to dispose it. In the storage period, it would expose the surrounding environment a risk via releasing Cr. In this study, an approach was proposed to minimize the amount of released Cr, and reveal the mechanism on immobilizing Cr. Collagen protein waste (CPW) was adopted to immobilize Cr, and it was evaluated via leaching experiment. The lowest leaching concentration of Cr was 12 mg/L, meeting the limits of related standard in China (GB 5085.3–2007, Tcr < 15 mg/L). Moreover, the compositions and functional groups of the optimum sample (12 mg/L) were also characterized, confirming that the dominant functional groups cross-linking with Cr were hydroxyl (-OH), carboxyl (-COOH), and epoxy (-COC). Importantly, density functional theory (DFT) calculation was also employed, suggesting that Cr was restrained by accepting electrons from O atoms donating by functional groups. [ABSTRACT FROM AUTHOR]

[Display omitted] • A resource utilization approach of field AMD for the formation of LDHs was proposed. • LDHs derived from field AMD possesses a larger removal capacity for Sb compared with other LDHs from chemical reagents. • Sb(V) removal by LDHs was attributed to anion exchange and formation of brandholzite. • The removal mechanism of Sb by LDHs was revealed by DFT calculations. Although acid mine drainage (AMD) has been recognized as a major environmental pollutant, it is also a potential source of valuable metals and sulfate. In this study, a resource utilization approach of field AMD for the formation of iron-based layered double hydroxides (LDHs) with sulfate intercalation was proposed and its capacity for removing antimonate [Sb(V)] was examined. Layered double hydroxides derived from field AMD possesses a more rapid equilibration time (<120 min) and a larger removal capacity (78 mg g−1) for Sb(V) compared with other LDHs from chemical reagents. Following the treatment of field AMD containing 10.7 mg L−1 Sb, a residual Sb concentration of 4.0 μg L−1 was achieved using a dose of 1 g L−1 LDHs, which meets the drinking water standard of 5 μg L−1 recommended by China's Ministry of Health. Leaching tests showed negligible metal(loid)s dissolution in Sb-loaded LDHs over a short period. The interactions between Sb(V) and LDHs include anion exchange and formation of brandholzite, which were further investigated at the electronic scale using density functional theory (DFT) calculations. It is envisaged that this approach for preparing LDHs will provide theoretical support for the remediation and resource recovery of AMD. [ABSTRACT FROM AUTHOR]

Monolayer transition metal dichalcogenides can normally exist in several structural polymorphs with distinct electrical, optical, and catalytic properties. Effective control of the relative stability and transformation of different phases in these materials is thus of critical importance for applications. Using density functional theory calculations, we investigate the effects of low-work-function metal substrates including Ti, Zr, and Hf on the structural, electronic, and catalytic properties of monolayer MoS2 and WS2. The results indicate that such substrates not only convert the energetically stable structure from the 1H phase to the 1T′/1T phase, but also significantly reduce the kinetic barriers of the phase transformation. Furthermore, our calculations also indicate that the 1T′ phase of MoS2 with Zr or Hf substrate is a potential catalyst for the hydrogen evolution reaction. [ABSTRACT FROM AUTHOR]

Steam reforming (SR) is a process for converting transportation fuels into hydrogen-rich gas, which can be fed to SOFCs for on-board power supplies. Herein, we prepare Mg x Ni 1-x O (0.5

Molecular networking strategy-based prioritization of the isolation of the rarely studied soft coral Sinularia tumulosa yielded 14 sesquiterpenes. These isolated constituents consisted of nine different types of carbon frameworks, namely asteriscane, humulane, capillosane, seco-asteriscane, guaiane, dumortane, cadinane, farnesane, and benzofarnesane. Among them, situmulosaols A-C (1, 3 and 4) were previously undescribed ones, whose structures with absolute configurations were established by the combination of extensive spectral data analyses, quantum mechanical-nuclear magnetic resonance and time-dependent density functional theory electronic circular dichroism calculations, the Snatzke's method, and the modified Mosher's method. Notably, situmulosaol C (4) was the second member of capillosane-type sesquiterpenes. The plausible biogenetic relationships of these skeletally different sesquiterpenes were proposed. All sesquiterpenoids were evaluated for their antibacterial, cytotoxic and anti-inflammatory effects. The bioassay results showed compound 14 exhibited significant antibacterial activities against a variety of fish and human pathogenic bacteria with MIC 90 values ranging from 3.6 to 33.8 μg/mL. Moreover, moderate cytotoxic effects against HEL cells for components 13 and 14 and moderate inhibitory effect on lipopolysaccharide-induced inflammatory responses in RAW264.7 cells for substance 13 were also observed., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Dolomite is an important industrial raw material for the production of metal magnesium. However, the calcination of dolomite is a typical pollution-intensive industry and is one of the major contributors to CO 2 emissions in China. The requirements of energy conservation and environmental protection are driving the development of new calcination technologies. Herein, we developed a rapid and environment-friendly strategy for the calcination of dolomite used in subsequent magnesium production through carbothermal reduction, in which the pellets containing dolomite and carbon additive are calcined with in-situ Joule-heating in a vacuum. The effect of input volumetric specific power, heating time, vacuum conditions, carbon additive, and the size of the pellets on the decomposition process has been systematically studied. The dolomite in the pellets can be completely decomposed within tens of seconds. And the kinetic analysis shows that the activation energy of the decomposition of dolomite with the Joule-heating method is 108.4 kJ mol−1, which is much lower than the previous reports. Note that, the novel strategy shows a reduction of calcination time by 70 times, a reduction of energy consumption by 6.22% and a reduction of direct carbon emissions by 56.77% compared to the traditional methods. Combining the results of finite element simulations and density functional theory calculations, we revealed the mechanism of Joule-heating to enhance the decomposition of dolomite. The results show that the Joule-heating method can offer a distinct heating mechanism and deteriorate the structure stability of CaMg(CO 3) 2. • A rapid and environment-friendly method for the calcination of dolomite. • Dolomite can be completely decomposed in tens of seconds with Joule-heating. • Joule-heating can significantly reduce energy consumption and carbon emissions. • The mechanism of Joule-heating to enhance the decomposition of dolomite is analyzed. [ABSTRACT FROM AUTHOR]

At present, coal is still the main source of energy supply in China. However, However, coal dust, due to spontaneous combustion or gas explosion, seriously affects underground safety production and also threatens the occupational health of underground workers. To understand the causes of harm caused by coal from the perspective of its oxidative pyrolysis characteristics, bituminous coal was selected as the experimental coal sample, To further understand the oxidation pyrolysis characteristics of bituminous coal, thermal analysis and density functional theory were applied. By using industrial analysis, particle size analyzer, SEM and FTIR to characterize the experimental bituminous coal. The multi heating rate experiment of bituminous coal was carried out with thermogravimetric analyzer, and the kinetic analysis results displayed the apparent activation energy of oxidation pyrolysis of bituminous coal ranges from 118.57 to 124.96 kJ mol−1. The TG-FTIR experiments found the main gaseous products of the oxidation pyrolysis of bituminous coal were CO and CO 2. The surface electrostatic potential and bond dissociation energy of bituminous coal structure were analyzed by density functional theory. The research results provide important preliminary references for the safe mining of coal mines and the industrial application of bituminous coal. [Display omitted] • TG tests were used to investigate thermal stability and kinetics of bituminous coal. • Gaseous products of bituminous coal were analyzed by EGA technology. • Analyzing the basic characteristics of bituminous coal using characterization methods. • Analyzing bituminous coal bond breaking details through ESP and BDE methods. [ABSTRACT FROM AUTHOR]

Hydrogen produced by electrochemical water splitting depends on the development of highly efficient electrocatalysts. In this study, we report the design and synthesis of a robust hydrogen evolution reaction (HER) electrocatalyst Mo 2 C-Ru@CNBs, which is consisted of heterostructured Mo 2 C-Ru nanoparticles that dispersed on three-dimensional interconnected carbon nanobelts (CNBs). Benefiting from the high intrinsic catalytic activity of Mo 2 C-Ru heterostructure, abundant catalytic active sites and facilitated mass transfer, the Mo 2 C-Ru@CNBs catalyst shows high HER catalytic activity with ultralow overpotentials of 17 and 18 mV at 10 mA cm−2 in acidic and alkaline media, respectively, which are superior to the individual components of Mo 2 C@CNBs and Ru@CNBs catalysts, commercial 20% Pt/C and the recently reported Mo- and Ru-based electrocatalysts. Density functional theory calculations reveal the extensive electronic interaction between Mo 2 C and Ru at the heterointerfaces, leading to well-modulated electronic structure for optimized intrinsic catalytic activity and enhanced electrical conductivity. [Display omitted] In Chinese mythology, the belt-like Chaotic Silk was a magic weapon of Nezha and he defected the fierce dragon with Chaotic Silk in the east China sea. In this TOC image, the Chaotic Silk represents the robust belt-like nanostructured catalyst Mo 2 C-Ru@CNBs and the dragon represents the reaction barriers of HER. We aim to create a vivid visualization image to reveal the high catalytic activity of Mo 2 C-Ru@CNBs for efficient HER electrocatalysis. [ABSTRACT FROM AUTHOR]

To address the drinking safety problems associated with high arsenic(III) (As(III)) and bacteria in underground water, core-shell Fe–Ag@AgCl nanowires were synthesized and exhibited excellent photocatalytic oxidation effects on co-existing As(III) and Escherichia coli (E. coli). With the introduction of Fe, the nanowires that were used 5 times could be easily magnetically collected, and the As(III) oxidation effect of these re-chlorinated nanowires increased from 39% to 60%. E. coli was completely inactivated within 60 min without photoreactivation after 20 min. Extracellular polymeric substances have play a protective role in the disinfection process. Quenching testing results confirmed that, except for the superoxide radical (•O 2 −), the subdominant active species were different for different objects: hole (h VB +) to As(III) and hydroxyl radical (•OH) to E. coli. Therefore the system with co-existing As(III) and E. coli , the inactivation effect of Fe–Ag@AgCl on E. coli decreased remarkably with an increase in As(III) concentration, while the oxidation process of As(III) was not significantly affected by E. coli until E. coli was increased to 108 cfu/mL. The photocatalytic process of co-existing As(III) and E. coli is displayed in a schematic diagram and was tested using desired results obtained from field groundwater in Xiantao City, Hubei Province. The function of Fe in band structures and density of states was analyzed using plane-wave density functional theory. These magnetic nanowires presented excellent photocatalytic ability on co-existing As(III) and E. coli , and provided new insights into drinking water safety in high-arsenic areas. [Display omitted] • Fe–Ag@AgCl exhibited excellent photocatalytic effect on As(III) and E. coli. • O 2 − was the dominant species in the Fe–Ag@AgCl photocatalytic system. • Fe–Ag@AgCl was attempted in groundwater in Xiantao City, Hubei Province, China. • Function of Fe was analyzed using plane-wave DFT and schematic diagram was drawn. [ABSTRACT FROM AUTHOR]

Influence of the surficial physiochemical properties on the adsorption and conversion of SO 2 on calcite {1 0 4}. [Display omitted] • The adsorption of SO 2 can be enhanced by both the surface defects and the adsorbed H 2 O on the calcite {1 0 4}. • Oxidation of SO 2 with O 3 is proposed to occur by an Eley-Rideal mechanism. • For Mn-doped calcite {1 0 4}, SO 2 can be converted to adsorbed SO 3 by O 3. The presence of H 2 O is adverse to the conversion of SO 2. • For CO 3 2– vacancy defected calcite {1 0 4}, with the aid of dissociated H 2 O, SO 2 can be easily converted into sulfate. The role of mineral dust on atmospheric pollutions formation is one of the significant challenges in environmental and atmospheric science. The conversion of atmospheric pollutions on mineral dust depends largely on its surface physiochemical properties. However, the adsorption and conversion of polluting gases on typical mineral dust surface in China are still poorly understood. In this study, the impact of calcite surface defects, oxidizers and adsorbed H 2 O on the adsorption and oxidation process of SO 2 on calcite {1 0 4} surface is systematically studied by density functional theory (DFT) method. The results indicate that the surface defects enhance the adsorption of SO 2 on calcite {1 0 4} surface. Compared with O 2 , O 3 is more beneficial for the oxidation conversion of SO 2 on various calcite {1 0 4} surfaces. For pristine calcite {1 0 4} and Mn-doped calcite {1 0 4}, SO 2 can be converted to adsorbed SO 3 by O 3 , while adsorbed H 2 O inhibits this process. For CO 3 2– vacancy defected calcite {1 0 4} surface, with the aid of dissociated H 2 O, SO 2 can be easily converted to sulfate instead of adsorbed gaseous SO 3. Thus, the evolution of the adsorbed SO 2 on calcite {1 0 4} can be regulated by the surface physiochemical properties and the adsorbed H 2 O. [ABSTRACT FROM AUTHOR]

Cu(II)-EDTA is a highly stable typical metal-organic complex in a wide pH range (3.0–12.0) and it is difficult to deeply purify Cu(II) by conventional precipitation methods. In this study, Fe(III) replacement/diethyldithiocarbamate (DDTC) precipitation combined process is proposed as a promising strategy to achieve the deep purification of Cu(II) from Cu(II)-EDTA acidic wastewater. The underlying mechanism has also been systematically elucidated by chemical equilibriums, experiments, and density functional theory (DFT) calculations, laying a foundation for the development and application. Chemical equilibriums show that Fe(III) replacement favors the stoichiometric release of Cu(II) from Cu(II)-EDTA and the formation of Fe(III)-EDTA complex under acidic conditions. Experimentally, Cu(II) is removed (over 99.99%) and deeply purified (under 0.008 mg/L) under the optimal conditions, which is lower than the most stringent discharge standards of copper ions in electroplating effluent (<0.5 mg/L, China). DFT calculations reveal that DDTC could further precipitate the released free copper ions via the carbon disulfide (–C(=S)–S) chelating group while exhibiting a slight effect on the Fe(III) in Fe(III)-EDTA. Considering these results, the electronic structures of Cu(II) and Fe(III), as well as their interaction with EDTA and DDTC ligands, are discussed to understand the mechanism of Fe(III)/DDTC process. By introducing a low dosage of Fe(III), the DDTC could efficiently purify Cu(II) from the Cu(II)-EDTA acid wastewater and realize the near-zero discharge of metal pollutants in metal-organic complex wastewater. It is believed that the main findings may benefit the water pollution reduction and comprehensive recycling of metal resources. [Display omitted] • Fe(III)/DDTC process is a promising strategy to treat Cu(II)-EDTA wastewater. • Fe(III) can effectively replace the Cu(II) from Cu(II)-EDTA complexes. • The released Cu(II) by Fe(III) replacement can be targetedly precipitated by DDTC. • The underlying mechanism is elucidated based on density functional theory calculations. [ABSTRACT FROM AUTHOR]

The disposal of the Cr containing tannery sludge has become a serious environmental problem in China, which has attracted increasing attention. However, experimental and theoretical research is still needed. We developed a feasible route to synergistic immobilization the Cr in tannery sludge into the spinel-based phases by addition of ZnO and TiO 2. ZnO and Cr3+ can form stable spinel-based phase, and TiO 2 can suppress the formation of Cr6+. The significantly synergistic effect between ZnO and TiO 2 promoted the immobilization of Cr in tannery sludge and reduce the leaching of the chromium in the annealed sludge. The oxidation of Cr3+ to Cr6+ in the presence of alkaline substances has been elucidated by density functional theory, and it is revealed that the electrons from the Cr-d orbit jump to the Ca-d and directly transform into the O 2. [Display omitted] • Chromium element is fixed in the spinel crystal lattice by loading of ZnO. • The Cr3+ oxidation process with the alkaline matter is retarded by ZnO and TiO 2. • The oxidation mechanism of Cr 2 O 3 with CaO is elucidated by computation. [ABSTRACT FROM AUTHOR]

Although there have been a lot of studies on the adsorption of trivalent actinides on clay minerals, the gaps between surface complexation model (SCM) for the description and prediction of macroscopic adsorption and the coordination structures and configurations of the surface complexes are still not completely bridged. Aiming at a multi-scale description of Am(III) adsorption on bentonite, density functional theory (DFT) calculations and surface complexation modeling were carried out. The results showed that the SCM considering cation exchange reactions and the formation of surface complexes, i.e., ≡SSOAm2+, ≡SSOAm(OH)+ and ≡SSOAm(OH) 2 could reproduce all batch experimental data for Am(III) adsorption on Gaomiaozi bentonite, a potential buffer material for China's Beishan high-level radioactive waste repository. The stoichiometric coefficients of 1 in the SCM are deduced, while the surface complexes at the sites of ≡Al(OH) 2 on (010) surface and those of ≡AlO(OH) on (110) surface are bidentate according to DFT calculations. The detailed calculations of electronic structures indicated that both covalent bond and electrostatic interaction account for Am(III) coordinating with the surface hydroxyl groups. In addition, it was found that the structures and energy properties of Am(III) complexes on (010) surface are similar to those on (110) surface. Hydrogen bonds between binding waters of Am(III) and the surface hydroxyl groups are formed in all cases, contributing to additional stability of Am(III) surface complexes. Overall, this study provides an improved understanding of Am(III) adsorption on the edge surfaces of bentonite/montmorillonite. [Display omitted] [ABSTRACT FROM AUTHOR]

The trends and mechanisms of organic carbon changes in coastal delta croplands are not yet clear due to the complexity physicochemical processes in soil. In this study, combing powder x-ray diffraction (XRD), microbial analysis, and density functional theory in quantum mechanics, we proposed a novel mechanism underlying OC accumulation. We investigated changes of three kinds of organic carbon (OC)-dissolved organic carbon (DOC), light fraction organic carbon (LFOC), and heavy fraction organic carbon (HFOC) in the Yellow River Delta croplands. We found that HFOC, dominant in coastal delta cropland soil, formed at different ages and its density increased with increasing reclamation time. Yet, DOC and LFOC had no significant increase or decrease tendency. Moreover, in coastal delta croplands, HFOC accumulation might be a complex progress, including the loss of indigenous OC and the accumulation of newly input OC. Based on these results, we proposed that although root exudative DOC (organic acids) could cause the indigenous OC loss by forming a specific microbial community, it still was a source of HFOC and promoted the OC accumulation. More importantly, based on density functional theory, we verified that these root exudative organic acids could adsorb on SiO 2 together with crystalline Fe oxides (Fe c ) to form aggregates. The finding could explain the phenomenon that the XRD results showed samples were compounds of SiO 2 , Fe c , and OC and the accumulation of HFOC in coastal delta croplands. By revealing a new OC accumulation mechanism in coastal delta croplands, this study provides novel insights into the mechanism of OC dynamics in coastal delta croplands and the global carbon budget., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)