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We theoretically identify the ScSeI monolayer as a promising new 2D material for photocatalysis through first-principles calculations. The most notable feature is the significant difference in carrier mobility, with electron mobility in the horizontal direction being 20.66 times higher than hole mobility, minimizing electron–hole recombination. The ScSeI monolayer exhibits a bandgap of 2.51 eV, with the valence band maximum at −6.37 eV and the conduction band minimum at −3.86 eV, meeting the requirements for water splitting. Phosphorus doping lowers the Gibbs free energy by 1.63 eV, enhancing the catalytic activity. The ScSeI monolayer achieves a hydrogen production efficiency of 17%, surpassing the commercial threshold of 10% and shows excellent mechanical, thermal, and dynamic stability, indicating feasibility for experimental synthesis and practical application. Additionally, the monolayer maintains its photocatalytic properties under tensile strain (−6% to 6%) and in aqueous environments, reinforcing its potential as an effective photocatalyst. Based on these findings, we believe the ScSeI monolayer is a highly promising photocatalyst.

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The micro-size flake silver powders were prepared through wet-chemical reduction method by using a micro-jet reactor. Herein ascorbic acid was used as a reducing agent, and sulfuric acid was used as a stabilizer. And the lauric acid was used as a dispersing agent to prevent particles’ agglomeration. The micro-jet reactor collides the two solutions together and uniformly mixes outside the reactor, to avoid the problem of clogging in the microchannel. The effects of dispersant addition and micro-jet flow rate on the morphology, particle size, and other parameters of silver powder is investigated in the present work. Interestingly, the addition of dispersant agent and stabilizer have a significant impact on the morphology and parameter of the silver particles. Under the conditions of micro-jet flow rate of 50 mL·min−1, sulfuric acid addition amount of 2%, and lauric acid addition amount of 0.8% by the weight of silver nitrate, a kind of flake silver powders with 4.40–4.70 μm can be prepared. The volume resistivity of the silver paste prepared from the obtained flake silver powders is in the range of 1.4–1.6 × 10−4Ω·cm−1, which meets the application test requirements of conductive silver paste.

In traditional large-scale industrial applications of solvent extraction, there are some limitations such as low extraction efficiency, emulsification, co-extraction, and potential safety hazards. Recently, the application of microfluidic technology in solvent extraction has been dedicated to avoid the above problems effectively. However, manufacturing microchannels becomes a key problem before the application of such a new technology. In this article, the design and fabrication of a “Y”-shaped microreactor by using a three-dimensional (3D) printer, and its feasibility for extraction and separation, is illustrated. The extraction performance of a “Y”-shaped microreactor was investigated by carrying out the extraction of In3+and Fe3+from a sulfate solution under different experimental conditions. When the residence time was 210 s, the volume fraction of extractant (D2EHPA) was 30%, and the initial pH value of the aqueous solution was 0.7, the extraction rate of In3+and the separation coefficient βIn/Fewere 98.07% and 1593, respectively. Remarkably, the handling capacity of the 3D-printed “Y” microreactor presented in this work with a channel length of 36 mm was superior, whereas the extraction rate of In3+was very close to that of the previously reported microchip with a channel length of 120 mm.

A comparison study about the extraction and separation of Cu2+and Ni2+with Lix984N in a microchannel reactor and separating funnel has been conducted. The results showed that, in the microchannel reactor, the overall volumetric mass transfer coefficient of copper was 20 times that of nickel, whereas in the separating funnel, it was only 2 times that of nickel. In addition, the separation coefficient of copper and nickel in the microchannel reactor was 5 times that of the conventional one. Typically, at initial pH=2.5, contact time 1.95 s, volume fraction of extractant Lix984N 15% and within 1.9 g l−1nickel ion concentration, the extraction rate of copper was higher than 95%, but the nickel was hardly extracted. In comparison, it needed almost 50 s to reach a Cu extraction of 95% in the separation funnel, with more than 5% Ni co-extraction rate. Although the microfluid extraction showed excellent extraction performance, there exists a need to further improve its processing capacity to apply it to industrial production. Furthermore, scaling up the microreactor has become increasingly promising under the fast developing 3D printing technology.

FeF2/carbon composite nanoparticle was prepared by a one-pot thermal reaction using a mixture of ferrous oxalate and PTFE as precursor. FeF2was obtained as the main phase according to the XRD patterns of the samples prepared in the present study. Furthermore, the FeF2particle has a size of 50–100nm. Its electrochemical properties were studied in the 4.2–1.3V region at a current density of 60mAg−1. It exhibited an initial discharge capacity of 503.394mAhg−1and still reserved discharge capacity of about 268.478, 211.34, 193.817 and 183.328mAhg−1at the 2nd, 3rd, 10th, and 20th cycles, respectively.

Microwave-assisted heating technology has become a popular alternative to conventional heating technologies because of its many advantages. However, the matching performance of microwave heating system is of particular concern because it provides an important index of the utilization efficiency of microwave energy. In this work, a new microwave heating system is designed by the theory of optical resonator in first. Then the comprehensive analysis of the mutual coupling of high sensitive geometrical and material parameters were investigated based on this new microwave heating system at 2.45 GHz. It is demonstrated that the thickness of materials dramatically influences microwave energy absorption efficiency and should be carefully considered and perhaps given priority. Moreover, it is shown that matching performance is the best when the titanium concentrates thickness at about 0.075 m.

Tin oxide (SnO 2 ) hollow microspheres with narrow size distribution were prepared by a facile one-pot microwave-assisted spray pyrolysis method. The effect of temperature on microstructural and optical properties was investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), and UV-Vis spectrophotometer (UV-Vis), respectively. The SnO 2 particles obtained at and above 700 °C are tetragonal rutile structure with high purity and smooth surface morphology, which consist of well-interconnected SnO 2 nanocrystallines and the shell thickness was about 26 nm. UV-Vis absorption values were quite low in visible light region and high in ultraviolet region, indicating the possible utilization for optical purpose of the as-prepared SnO 2 . The band gaps were 3.88 and 4.07 eV for SnO 2 synthesized at 700 and 800 °C, respectively. As compared to traditional electrical heating or flame modes, microwave heating introduced here demonstrates a high-efficiency, environmentally benign, and time- and energy-saving technology to synthesize advanced powders. [ABSTRACT FROM AUTHOR]

The present work explores the application of microwave heating for the melting of powdered tin. The morphology and particle size of powdered tin prepared by the centrifugal atomization method were characterized. The tin particles were uniform and spherical in shape, with 90% of the particles in the size range of 38–75 μm. The microwave absorption characteristic of the tin powder was assessed by an estimation of the dielectric properties. Microwave penetration was found to have good volumetric heating on powdered tin. Conduction losses were the main loss mechanisms for powdered tin by microwave heating at temperatures above 150 °C. A 20kW commercial-scale microwave tin-melting unit was designed, developed, and utilized for production. This unit achieved a heating rate that was at least 10 times higher than those of conventional methods, as well as a far shorter melting duration. The results suggest that microwave heating accelerates the heating rate and shortens the melting time. Tin recovery rate was 97.79%, with a slag ratio of only 1.65% and other losses accounting for less than 0.56%. The unit energy consumption was only 0.17 (kW·h)·kg–1—far lower than the energy required by conventional melting methods. Thus, the microwave melting process improved heating efficiency and reduced energy consumption.

Spent CuCl residue produced from zinc hydrometallurgy is a typical toxic and hazardous solid waste as well as a secondary resource owing to its high contents of chlorine and valuable metals (Pb, Cu, Zn). The removal of chlorine from the CuCl residue and recycling of valuable metals are critical issues for the copper slag resource treatment process. In this study, a novel method of microwave sulfation-roasting under an oxygen atmosphere is used to improve the dechlorination process, and various parameters, such as roasting temperature, duration, sulfuric acid concentration, and liquid/solid ratio, are optimized. First, according to thermodynamic calculations, the addition of H2SO4can significantly decrease both the roasting temperature and time needed for microwave oxidation-roasting. The dechlorination experimental results reveal that the dechlorination rate of the CuCl residue is as high as 91.91% under a temperature of 250 °C, holding time of 120 min, sulfuric acid concentration of 70%, and liquid-solid ratio of 1.42. The microstructure, chemical composition, and phase changes of the CuCl residue before and after roasting are characterized using scanning electron microscopy coupled with energy-dispersive spectroscopy, X-ray fluorescence and X-ray diffraction; further, the mass contents of the main elements in the roasting product and tail gas absorption solution are determined by chemical analysis, Evidently, the selective heating property of microwaves produces more holes and cracks in the copper slag, which can provide a new reaction channel for H2SO4and CuCl slag reactions, and almost all CuCl in the copper slag is completely removed by transformation into CuO, CuSO4and Cu2O(SO4). Simultaneously, a large number of gas by-products produced in the dechlorination process, such as SO2and Cl2, can be absorbed by the NaOH solution. Therefore, no pollution is generated in the environment. These findings illustrate that microwave sulfation-roasting is an effective method for promoting the treatment and recycling of CuCl waste residues.

Emerging pollutants, such as sulfonamide antibiotics and pharmaceuticals, have been widely detected in water and soils, posing serious environmental and human health concerns. Thus, it is urgent and necessary to develop a technology for removing them. In this work, a hydrothermal carbonization method was used to prepare the hydrochars (HCs) by pine sawdust with different temperatures. To improve the physicochemical properties of HCs, phosphoric acid (H3PO4) and hydrogen peroxide (H2O2) were used to modify these HCs, and they were referred to as PHCs and HHCs, respectively. The adsorption of sulfamethoxazole (SMX) and carbamazepine (CBZ) by pristine and modified HCs was investigated systematically. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results indicated that the H2O2/H3PO4modification led to the formation of a disordered carbon structure and abundant pores. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy results suggested that carboxyl (-COOH) and hydroxyl (-OH) functional groups of HCs increased after modification, which is the main reason for the higher sorption of SMX and CBZ on H3PO4/H2O2-modified HCs when compared with pristine HCs. In addition, the positive correlation between −COOH/C=O and logKdof these two chemicals also suggested that oxygen-containing functional groups played a crucial role in the sorption of SMX and CBZ. The strong hydrophobic interaction and π–π interaction between CBZ and pristine/modified HCs resulted in its higher adsorption when compared with SMX. The results of this study provide a novel perspective on the investigation of adsorption mechanisms and environmental behaviors for organic contaminants by pristine and modified HCs.

ABSTRACTWater is a kind of strongly microwave absorbing material. However, water is generally believed that it cannot enhance the effect of heat transfer and mass transfer of reactions at high temperature in the microwave field, due to its performance of easy drying. In this work, the intensifying effect of water on the high temperature reactions in the microwave field is proved. Specifically, the effects of different mixing methods of bauxite and alkaline, including wet mix and dry mix, on phase constitution, microstructure and leaching effect of roasting products in microwave heating process are compared. The results show that compared with the dry mixing, the wet mixing method is more benefit for forming NaAlO2and Ca2SiO4. The roasted product of wet mix is looser and more homogeneous, which is more conducive to the subsequent leaching process. The leaching rate of Al2O3is calculated to be 96.68% with wet mix at 800 °C and 92.58% with dry mix at 1000 °C. In addition, the mechanism of intensifying action of water on the high temperature reactions in the microwave field is discussed.

In this work, microwave energy is used for preparing a granular red mud (GRM) adsorbent made of red mud with different binders, such as starch, sodium silicate and cement. The effects of the preparation parameters, such as binder type, binder addition ratio, microwave heating temperature, microwave power and holding time, on the absorption property of GRM are investigated. The BET surface area, strength, pore structure, XRD and SEM of the GRM absorbent are analyzed. The results show that the microwave roasting has a good effect on pore-making of GRM, especially when using organic binder. Both the BET surface area and the strength of GRM obtained by microwave heating are significantly higher than that by conventional heating. The optimum conditions are obtained as follows: 6:100 (w/w) of starch to red mud ratio, microwave roasting with a power of 2.6 kW at 500℃ for holding time of 30 min. The BET surface area, pore volume and average pore diameter of GRM prepared at the optimum conditions are 15.58 m2/g, 0.0337 cm3/g and 3.1693 A0, respectively.

AbstractThis work focuses on the column absorption and regeneration behavior of a granular red mud (GRM) for absorbing methylene blue (MB) in wastewater. By investigating key parameters, such as packing column height of adsorbent, initial concentration of MB, and flow rate, on the adsorption effects of GRM, the results show that the GRM can effectively remove MB from wastewater. The breakthrough time of the absorption process can be as high as 330 min, when 20.5 cm GRM column was used, with initial concentration and flow rate of MB wastewater being 150 mg L−1and 4 mL min−1, respectively. The Thomas model is capable of describing the adsorption kinetics. Finally, for assessing the regeneration ability of the loaded GRM, a series of experiments of eluting the MB-loaded column with dilute nitric acid solution, whose pH value is about 3.0, were conducted. The results showed that the regeneration and re-adsorption effect of the GRM column is good.

This work focuses on the column absorption and regeneration behavior of a granular red mud (GRM) for absorbing methylene blue (MB) in wastewater. By investigating key parameters, such as packing column height of adsorbent, initial concentration of MB, and flow rate, on the adsorption effects of GRM, the results show that the GRM can effectively remove MB from wastewater. The breakthrough time of the absorption process can be as high as 330 min, when 20.5 cm GRM column was used, with initial concentration and flow rate of MB wastewater being 150 mg L−1and 4 mL min−1, respectively. The Thomas model is capable of describing the adsorption kinetics. Finally, for assessing the regeneration ability of the loaded GRM, a series of experiments of eluting the MB-loaded column with dilute nitric acid solution, whose pH value is about 3.0, were conducted. The results showed that the regeneration and re-adsorption effect of the GRM column is good.

A microfluidic solvent extraction method is put forward to solve the problems existing in the conventional solvent extraction of indium, such as large waste of extractant, fire hazards, etc. Experiments were performed in a series of microreactors to separate In3+and Fe3+from sulfate solutions using D2EHPA as the extractant. The effect of main parameters such as different contact times, microchannel sizes, interface to volume ratios and pH values on the indium extraction efficiency was investigated. The results show that the smaller the channel size, the more the beneficial diffusion and mass transfer. Specifically, in a microchannel, with a size of 100 μm × 50 μm × 120 mm, almost 100% extraction efficiency was reached with contact time about 0·5 s. The mean mass transfer rate can be as high as 0·291 g m− 2 s− 1, and the ratio of mean mass transfer rate of In3+to that of Fe3+can be as high as 29·76.

Removal of chlorine (Cl) from the CuCl residue in the process of zinc hydrometallurgy is of great importance to improve the process economics. The current processing methods result in generation of large quantities of polluted discharge necessitating waste treatment systems. The present work attempts to de-chlorinate the CuCl residue through thermal treatment with application of microwave, towards which the effect of the major experimental factors such as roasting temperature, heating duration and particle size of samples on the process has been investigated. And the changes of Gibbs free energy (ΔG) of the dechlorination reactions are calculated which show that: 1) CuCl can react with H2O and air to produce CuO and HCl(g); 2) CuCl can be oxidized by air into CuO and Cl2would be released. The tail gas chromatography, XRD and SEM-EDS analysis results of samples before and after microwave roasting verified the thermodynamics study results. Thus, the process of dechlorination by microwave roasting technology is feasible, and the tail gas can be mainly HCl(g) and air which can be absorbed with water and produce hydrochloride easily.

AbstractThe microreactor has been developed for a wide range of applications because of many advantages, such as high mass transfer efficiency, low energy consumption and the closed and safe system. The application of microreactors in the traditional hydrometallurgy extraction process is expected to overcome difficulties such as co-extraction of impurities, large consumption of extractant and hidden fire risks. In this study, the extraction and separation efficiency of In3+from a complex sulfate solution containing impurities, such as Fe2+and Zn2+, were studied. The microreactor extraction was carried out in a Pyrex microchip, and the organic phase was prepared with the extractant di(2-ethylhexyl) phosphoric acid (D2EHPA) diluted in 260# kerosene. The results showed that with only 0.55 s contact between the organic and aqueous phases, the extraction ratio of In3+can reach 90.80%, while only 0.16% of Fe2+and 0.22% of Zn2+were co-extracted; the average mass transfer speed of In3+was calculated as high as 0.34 g·m-2·s-1. Compared with the traditional mixing settler process, microreactor extraction has advantages of higher extraction ratio of In3+, lower trend of co-extraction of the impurities and emulsification.

AbstractRemoval of chlorine (Cl) from the CuCl residue in the process of zinc hydrometallurgy is of great importance to improve the process economics. The current processing methods result in generation of large quantities of polluted discharge necessitating waste treatment systems. The present work attempts to de-chlorinate the CuCl residue through thermal treatment with the application of microwave energy. Relationship between explanatory and response variables was explored by response surface methodology (RSM) technique searching to optimize the dechlorination efficiency. The effect of three major parameters such as temperature, duration of heating, and particle size of samples were assessed and the optimal process conditions were identified. Analysis of variance (ANOVA) was utilized to identify the suitable model and to eliminate the insignificant model parameters. The optimized process conditions for maximizing the dechlorination efficiency are identified to be a roasting temperature of 426 °C, heating time 125 min, and particle size of samples 0.12 mm. A dechlorination efficiency of 93% could be achieved at the optimal process conditions, and validated through repeat experimental runs at the optimized process conditions. The optimized process samples are characterized utilizing XRD and SEM/EDS to validate the dechlorination efficiency.

Purpose of this paper is to prepare monodispersed plate-shaped silver particles with high density and low radius-thickness ratio through wet-chemical reduction. This shape is suitable for preparing high silver content conductive paste with fine electrical conductivity. In this study, the reactant solutions were added by two parallel pipes to mix the two solutions evenly in the contact area. The sulfuric acid was used as a pH regulator, and polyvinylpyrrolidone (PVP K-30) was used as a capping agent, to control the morphology and particle size distribution of silver particles. The result shows that the combination of sulfuric acid and PVP play an important role on controlling the uniform crystal growth of silver particle. This probably because PVP are adsorbed on the surface of (111) plane to prevent the deposition of silver particles, and the PVP used as dispersant also slow the speed of reducing reaction. This make the flake silver particles grow slowly, and the plate-shaped silver particles with high tap-density and low radius-thickness ratio can be obtained. In addition, the resistivity of conductive silver paste that prepared with the as-synthesized plate-shaped flake silver particle was discussed in detail.