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Abstract Electrochemical uranium extraction from nuclear wastewater represents an emerging strategy for recycling uranium resources. However, in nuclear fuel production which generates the majority of uranium-containing nuclear wastewater, fluoride ion (F−) co-exists with uranyl (UO2 2+), resulting in the complex species of UO2Fx and thus decreasing extraction efficiency. Herein, we construct Tiδ+-PO4 3− ion pair extraction sites in Ti(OH)PO4 for efficient electrochemical uranium extraction in wastewater from nuclear fuel production. These sites selectively bind with UO2Fx through the combined Ti-F and multiple O-U-O bonds. In the uranium extraction, the uranium species undergo a crystalline transition from U3O7 to K3UO2F5. In real nuclear wastewater, the uranium is electrochemically extracted with a high efficiency of 99.6% and finally purified as uranium oxide powder, corresponding to an extraction capacity of 6829 mg g−1 without saturation. This work paves an efficient way for electrochemical uranium recycling in real wastewater of nuclear production.

Abstract Photo‐assisted uranium reduction from uranium mine wastewater is expected to overcome the competition between impurity ions and U(VI) in the traditional process. Here, B‐TiO2@Co2P‐X S‐scheme heterojunction with metal‐oxygen‐hydrogen (M‐O‐H) is developed insitu modification for photo‐assisted U(VI) (hexavalent uranium) reduction. Relying on the DFT calculation and Hard‐Soft‐Acid‐Base (HSAB) theory, the introduction of metal‐oxygen‐hydrogen (M‐O‐H, hard base) metallic bonds in the B‐TiO2@Co2P‐X is found to enhance the hydrophilicity and the capture capability for uranyl ion (hard acid). Accordingly, B‐TiO2@Co2P‐500 hybrid nanosheets exhibit excellent U(VI) reduction ability (>98%) in the presence of competing ions. By self‐consistent energy band calculations and in‐situ KPFM spectral analysis, the formation of the internal electric field between B‐TiO2 and Co2P at the heterojunction is proven, offering a strong driving force and atomic transportation highway for accelerating the S‐scheme charge carriers directed migration and promoting the photocatalytic reduction of uranium. This work provides a valuable route to explore the functionally modified photocatalyst with high‐efficiency photoelectron separation for U(VI) reduction.

This paper investigates the combustion characteristics and pollutant emission patterns of the mixed combustion of lignite (L) and torrefied pine wood (TPW) under different blending ratios. Isothermal combustion experiments were conducted in a fixed bed reaction system at 800 °C, and pollutant emission concentrations were measured using a flue gas analyzer. Using scanning electron microscopy (SEM) and BET (nitrogen adsorption) experiments, it was found that torrefied pine wood (TPW) has a larger specific surface area and a more developed pore structure, which can facilitate more complete combustion of the sample. The results of the non-isothermal thermogravimetric analysis show that with the TPW blending ratio increase, the entire combustion process advances, and the ignition temperature, maximum peak temperature, and burnout temperature all show a decreasing trend. The kinetic equations of the combustion reaction process of mixed gas were calculated by Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) kinetic equations. The results show that the blending of TPW reduces the activation energy of the combustion reaction of the mixed fuel. When the TPW blending ratio is 80%, the activation energy values of the mixed fuel are the lowest at 111.32 kJ/mol and 104.87 kJ/mol. The abundant alkali metal ions and porous structure in TPW reduce the conversion rates of N and S elements in the fuel to NO and SO2, thus reducing the pollutant emissions from the mixed fuel.

Nuclides pollution and its biological effects are of great concern, especially for bryophytes during their terrestrial adaptation. Understanding PSII activity and electron transport response is vital for comprehending moss abiotic stress reactions. However, little is known about the photosynthetic performance of moss under nuclide treatment. Therefore, this study aimed to evaluate the chlorophyll fluorescence of Racomitrium japonicum L. The moss was subjected to Sr2+ solutions at concentrations of 5, 50, and 500 mg/L to evaluate chlorophyll a fluorescence using the OJIP test. Moderate and high Sr2+ stress led to inner cell membrane dissolution and reduced chlorophyll content, indicating impaired light energy absorption. At 5 mg/L Sr2+, fluorescence kinetics showed increased light energy capture, energy dissipation, and total photosynthetic driving force, thus stimulating transient photosynthetic activity of PSII and improving PSI reduction. Linear electron transfer and PSII stability significantly decreased under moderate and high Sr2+ stress, indicating potential photosynthetic center damage. Cyclic electron transfer (CEF) alleviated photosynthetic stress at 5 mg/L Sr2+. Thus, low Sr2+ levels stimulated CEF, adjusting energy flux and partitioning to protect the photosynthetic apparatus. Nevertheless, significant damage occurred due to inefficient protection under high Sr2+ stress.

Highlights 1. The recyclable high-efficiency Hap@BC was prepared for U(VI) removal. 2. The adsorption capacity for U(VI) of Hap@BC-10% achieved 834.8 mg/g. 3. The U(VI) extraction efficiency reached 99.9% in dynamic adsorption. 4. The interaction mechanism between U(VI) and Hap@BC was clearly expounded.

Abstract Surface chemistry modification represents a promising strategy to tailor the adsorption and activation of reaction intermediates for enhancing activity. Herein, we designed a surface oxygen-injection strategy to tune the electronic structure of SnS2 nanosheets, which showed effectively enhanced electrocatalytic activity and selectivity of CO2 reduction to formate and syngas (CO and H2). The oxygen-injection SnS2 nanosheets exhibit a remarkable Faradaic efficiency of 91.6% for carbonaceous products with a current density of 24.1 mA cm−2 at −0.9 V vs RHE, including 83.2% for formate production and 16.5% for syngas with the CO/H2 ratio of 1:1. By operando X-ray absorption spectroscopy, we unravel the in situ surface oxygen doping into the matrix during reaction, thereby optimizing the Sn local electronic states. Operando synchrotron radiation infrared spectroscopy along with theoretical calculations further reveals that the surface oxygen doping facilitated the CO2 activation and enhanced the affinity for HCOO* species. This result demonstrates the potential strategy of surface oxygen injection for the rational design of advanced catalysts for CO2 electroreduction.

Wheat straw, a typical agricultural solid waste, was employed to clarify the effects of torrefaction on the structural features and combustion reactivity of biomass. Two typical torrefaction temperatures (543 K and 573 K), four atmospheres (argon, 6 vol.% O2, dry flue gas and raw flue gas) were selected. The elemental distribution, compositional variation, surface physicochemical structure and combustion reactivity of each sample were identified using elemental analysis, XPS, N2 adsorption, TGA and FOW methods. Oxidative torrefaction tended to optimize the fuel quality of biomass effectively, and the enhancement of torrefaction severity improved the fuel quality of wheat straw. The O2, CO2 and H2O in flue gas could synergistically enhance the desorption of hydrophilic structures during oxidative torrefaction process, especially at high temperatures. Meanwhile, the variations in microstructure of wheat straw promoted the conversion of N-A into edge nitrogen structures (N-5 and N-6), especially N-5, which is a precursor of HCN. Additionally, mild surface oxidation tended to promote the generation of some new oxygen-containing functionalities with high reactivity on the surface of wheat straw particles after undergoing oxidative torrefaction pretreatment. Due to the removal of hemicellulose and cellulose from wheat straw particles and the generation of new functional groups on the particle surfaces, the ignition temperature of each torrefied sample expressed an increasing tendency, while the Ea clearly decreased. According to the results obtained from this research, it could be concluded that torrefaction conducted in a raw flue gas atmosphere at 573 K would improve the fuel quality and reactivity of wheat straw most significantly.

Developing non-noble-metal heterogeneous catalysts with high efficiency in HCOOH dehydrogenation is significant for the acquisition of hydrogen, but remains a great challenge. Here, the authors modulate oxygen coverage of Ti3C2Tx MXenes to boost the catalytic activity toward HCOOH dehydrogenation.

This paper uses numerical simulation to investigate the effects of diluents on the flame structure and NO generation of H2/CO micromixing flames. The results show that under the same thermal power condition, the diluents reduce the flame temperature and decrease the combustion reaction rate and flame propagation velocity. In addition, the diluents downsize the flame and force it downstream. With an increase in the diluent fraction, these trends are amplified. The NO production decreases due to the diluents, and the NO is lowest when H2O is added. When the diluents are CO2 and H2O, the NO generation is dominated by the reactants’ concentration. This results in the lowest temperature not corresponding to the lowest NO production. The diluents also reduce the sensitivity of the NO production to the temperature, and the CO2 diluent highly weakens the sensitivity.

With the rapid development of the electric vehicle industry in recent years, the use of lithium batteries is growing rapidly. From 2015 to 2040, the production of lithium-ion batteries for electric vehicles could reach 0.33 to 4 million tons. It is predicted that a total of 21 million end-of-life lithium battery packs will be generated between 2015 and 2040. Spent lithium batteries can cause pollution to the soil and seriously threaten the safety and property of people. They contain valuable metals, such as cobalt and lithium, which are nonrenewable resources, and their recycling and treatment have important economic, strategic, and environmental benefits. Estimations show that the weight of spent electric vehicle lithium-ion batteries will reach 500,000 tons in 2020. Methods for safely and effectively recycling lithium batteries to ensure they provide a boost to economic development have been widely investigated. This paper summarizes the recycling technologies for lithium batteries discussed in recent years, such as pyrometallurgy, acid leaching, solvent extraction, electrochemical methods, chlorination technology, ammoniation technology, and combined recycling, and presents some views on the future research direction of lithium batteries.

With the deepening contradiction between energy and environment, the energy industry is transforming from traditional energy to clean energy. Therefore, more and more attention will be paid to high efficiency and low carbon natural gas distributed energy (NGDE). However the continuous improvement of environmental protection requirements will strongly promote the large-scale application flue gas denitriation in project. In this paper, the application possibility of selective catalytic reduction (SCR) denitriation is analyzed and studied, taking a building-type project in NGDE as the research object. Finally, the project has been successfully applied in a small MW NGDE system, and the efficiency of denitriation is over 95%, and the emission value of NOx is 25.4 mg/m3, which meets the emission standard in Beijing. It provides a new solution for denitriation of NGDE projects.

The pressure-induced structural, elastic, vibrational, thermodynamic properties and the hardness of C11N4 polymorphs were investigated by first-principles calculations based on the density functional theory. Our calculations reveal that the g-C11N4 is the most stable structure at ambient pressure among the four C11N4 polymorphs and that α-C11N4 and d-C11N4 are the most energetically preferred structures. The transition from g-C11N4 to α-C11N4 and d-C11N4 with low pressure phases occurs around 3.557 and 9.468 GPa, respectively, and the transition from g-C11N4 to β-C11N4 with high pressure phase occurs around 46.032 GPa. The elastic properties and anisotropic mechanical properties of C11N4 polymorphs are then discussed in detail. Importantly, the hardnesses of C11N4 polymorphs are estimated using a semi-empirical model for the hardness, and the results indicate that α-C11N4, β-C11N4, and d-C11N4 are superhard materials. Finally, the mechanical and thermodynamic properties, including the bulk moduli, heat capacity and the thermal expansion coefficient, of C11N4 polymorphs depending on pressure are predicted. Keywords: Phase transitions, Mechanical property, Hardness, Thermal properties

Carbonate mineralization microbe is a microorganism capable of decomposing the substrate in the metabolic process to produce the carbonate, which then forms calcium carbonate with calcium ions. By taking advantage of this process, contaminative uranium tailings can transform to solid cement, where calcium carbonate plays the role of a binder. In this paper, we have studied the morphology of mineralized crystals by controlling the mineralization time and adding different concentrations of montmorillonite (MMT). At the same time, we also studied the effect of carbonate mineralized cementation uranium tailings by controlling the amount of MMT. The results showed that MMT can regulate the crystal morphology of calcium carbonate. What is more, MMT can balance the acidity and ions in the uranium tailings; it also can reduce the toxicity of uranium ions on microorganisms. In addition, MMT filling in the gap between the uranium tailings made the cement body more stable. When the amount of MMT is 6%, the maximum strength of the cement body reached 2.18 MPa, which increased by 47.66% compared with that the sample without MMT. Therefore, it is reasonable and feasible to use the MMT to regulate the biocalcium carbonate cemented uranium tailings.

Background: The dipeptide-alkylated nitrogen-mustard compound is a new kind of nitrogen-mustard derivative with a strong anti-tumor activity, which can be used as a potential anti-osteosarcoma chemotherapy drug.Objective: 2D- and 3D-QSAR (structure–activity relationship quantification) models were established to predict the anti-tumor activity of dipeptide-alkylated nitrogen-mustard compounds.Method: In this study, a linear model was established using a heuristic method (HM) and a non-linear model was established using the gene expression programming (GEP) algorithm, but there were more limitations in the 2D model, so a 3D-QSAR model was introduced and established through the CoMSIA method. Finally, a series of new dipeptide-alkylated nitrogen-mustard compounds were redesigned using the 3D-QSAR model; docking experiments were carried out on several compounds with the highest activity against tumors.Result: The 2D- and 3D-QSAR models obtained in this experiment were satisfactory. A linear model with six descriptors was obtained in this experiment using the HM through CODESSA software, where the descriptor “Min electroph react index for a C atom” has the greatest effect on the compound activity; a reliable non-linear model was obtained using the GEP algorithm model (the best model was generated in the 89th generation cycle, with a correlation coefficient of 0.95 and 0.87 for the training and test set, respectively, and a mean error of 0.02 and 0.06, respectively). Finally, 200 new compounds were designed by combining the contour plots of the CoMSIA model with each other, together with the descriptors in the 2D-QSAR, among which compound I1.10 had a high anti-tumor and docking ability.Conclusion: Through the model established in this study, the factors influencing the anti-tumor activity of dipeptide-alkylated nitrogen-thaliana compounds were revealed, providing direction and guidance for the further design of efficient chemotherapy drugs against osteosarcoma.

This study was inspired by the unique multi-scale and multi-level ‘brick-and-mortar’ (B&M) structure of nacre layers. We prepared the B&M, environmentally-friendly graphene oxide-carrageenan (GO-Car) nanocomposite films using the following steps. A natural polyhydroxy polymer, carrageenan, was absorbed on the surface of monolayer GO nanosheets through hydrogen-bond interactions. Following this, a GO-Car hybridized film was produced through a natural drying process. We conducted structural characterization in addition to analyzing mechanical properties and cytotoxicity of the films. Scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses showed that the nanocomposite films had a similar morphology and structure to nacre. Furthermore, the results from Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Thermogravimetric (TG/DTG) were used to explain the GO-Car interaction. Analysis from static mechanical testers showed that GO-Car had enhanced Young’s modulus, maximum tensile strength and breaking elongation compared to pure GO. The GO-Car nanocomposite films, containing 5% wt. of Car, was able to reach a tensile strength of 117 MPa. The biocompatibility was demonstrated using a RAW264.7 cell test, with no significant alteration found in cellular morphology and cytotoxicity. The preparation process for GO-Car films is simple and requires little time, with GO-Car films also having favorable biocompatibility and mechanical properties. These advantages make GO-Car nanocomposite films promising materials in replacing traditional petroleum-based plastics and tissue engineering-oriented support materials. [ABSTRACT FROM AUTHOR]

Robust, high-strength and environmentally friendly antibacterial composite films were prepared by simply blending konjac glucomannan (KGM) and silver nanowires (Ag NWs) in an aqueous system. The samples were then characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), thermal gravimetric analysis, mechanical property tests, Fourier transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy (XPS) and antimicrobial tests. The results showed that there was a high ratio of Ag NWs uniformly distributed in the composite films, which was vital for mechanical reinforcement and stable antibacterial properties. The enhanced thermal stability and mechanical intensity increased, while the elongation at break was reduced with an increase in the amount of Ag NWs found in the composite films. When the percentage of Ag NWs in the composite films reached 5%, the tensile strength was 148.21 MPa, Young’s modulus was 13.79 GPa and the ultimate strain was 25.28%. Antibacterial tests showed that the KGM films had no antibacterial effect. After the addition of Ag NWs, the composite films had an obvious inhibitory effect on bacteria, with the uniform dispersion of Ag NWs promoting the antibacterial effect to a certain degree. These results indicated that these composite films would have a potential application in the fields of environmentally friendly packaging or medicine. [ABSTRACT FROM AUTHOR]

With the development of nuclear energy, the removal/recovery of radionuclides has attracted increasing attention. Here, an ultra-light, super-elastic, konjac glucomannan/graphene oxide composite aerogel (KGCA) as a high performance adsorbent for radionuclide removal/recovery was fabricated by a three-step process of freeze-casting, freeze-drying, and carbonization. The as-prepared bionic structured KGCA showed ultralow density, high specific surface area, desirable super-elasticity, and abundant oxygen-containing functional groups. Batch adsorption results demonstrated the maximum adsorption capacity of uranium (U(VI)) on KGCA is as high as 513.4 mg g−1, far exceeding other biomass carbon aerogels. Furthermore, KGCA showed good radiation stability, selective adsorption of U(VI), and high recycling performance. The KGCA also showed good adsorption properties even under simulated seawater or high salt concentration. Thus, these ultra-light and super-elastic biomass-derived composite aerogels could have a wide range of applications for nuclear wastewater treatment in the future. [ABSTRACT FROM AUTHOR]

Carbon nanotube (CNT)-based materials have attracted tremendous interest for their high performance in oil separation. However, the preparation of CNT based materials always require harmful and expensive chemicals. Here, a biological assembly route was applied to assemble CNTs onto a fungal hyphae (FH) to produce FH/CNTs composites, followed by pyrolysis to obtain a hydrophobic CNT based aerogel for oil separation, which is a more environmentally friendly process. The as-prepared FH/CNTs-800 aerogel (pyrolyzed at 800 °C) showed hydrophobicity with a water contact angle of 143° and high specific surface area (1041.2 m2 g−1). The oil absorption results showed that the as-prepared FH/CNTs aerogels could absorb a wide range of oils with high absorption capacities ranging from 48 to 138 times their own weight. Furthermore, the oil-loaded aerogel was recycled through burning with little reduction in the oil absorption capacity. In addition, FH/CNTs-800 provided a high specific capacitance of 232 F g−1 at 1 A g−1 and maintained a capacity retention of 70.62% at 20 A g−1. Therefore, this study offers a simple, low-cost and environmentally friendly bioassembly route for large-scale assembly of CNTs into macroscopic 3D hydrophobic aerogels for highly efficient water-oil separation. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) MoS2 coated CoS2-nitrogen doped graphene (NG) (CoS2@MoS2-NG) hybrid has been synthesized by a one step hydrothermal method as supercapacitor (SC) electrode material for the first time. Such a composite consists of NG embedded with stacked CoS2@MoS2 sheets. With a 3D skeleton, it prevents the agglomeration of CoS2@MoS2 nanoparticles, resulting in sound conductivity, rich porous structures and a large surface area. The results indicate that CoS2@MoS2-NG has higher specific capacitance (198 F g−1 at 1 A g−1), better rate performance (with about 56.57% from 1 to 16 A g−1) and an improved cycle stability (with about 96.97% after 1000 cycles). It is an ideal candidate for SC electrode materials. [ABSTRACT FROM AUTHOR]

Coal fly aerogel (CFAA), as a low-cost, recyclable and highly efficient U(VI) adsorbent, was successfully prepared. Notably, the removal rate for U(VI) of CFAA was up to 94.5% (Co = 10 mg L-1, m/V = 1.0 g L-1, T = 2981<, t = 24 h and pH = 3.0), which was much higher than previous studies. Meanwhile, the maximum removal capacity of U(VI) on CFAA was 110.73 mg g-1 (m/V = 1.0 g L-1, T = 298 K, t = 24 h and pH = 3.0), which was nearly twice as much as untreated coal fly ash. Notable, the removal rate of U(VI) by CFAA was more than 80% after five cycles, indicating that CFAA was a recyclable adsorbent. In addition, Pseudo-second-order and Langmuir model were more suitable to describe the adsorption behavior on the surface of CFAA, meaning that the rate limiting step might be chemical sorption or chemisorption involving valency forces through sharing or exchange of electrons between sorbent and sorbate. The conclusions of SEM, FTLow-IR, XRD as well as XPS further illustrated that adsorption behavior for U(VI) of CFAA was mainly depended on the groups on the surface of CFAA, such as OH-, SiO- and AIO-. In conclusion, CFAA could be considered as an excellent candidate for the capture of U(VI) from wastewater. [ABSTRACT FROM AUTHOR]