Titanium metal, renowned for its exceptional strength-to-weight ratio, corrosion resistance, and biocompatibility, has become an essential material in a variety of high-end technology fields, including aerospace, medical devices, and chemical processing. Due to these superb properties, titanium plays a critical role in industries that require materials with high performance and durability. However, to fully harness the potential of titanium, it is imperative to focus on its extraction technology, which is pivotal in determining the material's accessibility for various applications ranging from luxury goods to mass-market products. Currently, Kroll process is the dominant method used in the industrial extraction of titanium. Developed in the 1940s, this method involves the reduction of titanium tetrachloride (TiCl₄) using magnesium to yield titanium metal. One of the notable advantages of Kroll process is its well-established nature, supported by decades of development and industrial usage. It demonstrates good reducibility, which means it can effectively convert the titanium tetrachloride into metallic titanium with relatively high yields. Additionally, Kroll process has a substantial production capacity, allowing it to meet the demands of large-scale operations. Despite its advantages, Kroll process possesses significant drawbacks that pose challenges to the titanium industry. One of the most prominent issues is its environmental impact, as the extraction process generates hazardous waste and emits greenhouse gases, contributing to pollution and climate change. Furthermore, the high energy consumption associated with Kroll process leads to increased production costs, which ultimately affects the market price of titanium metal. These economic factors prevent the widespread adoption of titanium in various applications, limiting its potential for broader use. In response to these challenges, researchers and industry professionals are actively exploring alternative methods for titanium extraction. Innovations in extraction technologies aim to lower production costs while maintaining the necessary yield and quality. The focus is not only on producing titanium more efficiently but also on minimizing the environmental impact of the extraction processes. Among the promising alternatives to Kroll process are FFC Cambridge Process and hydrogenation-dehydrogenation methods. FFC Cambridge process, for instance, involves electrochemical reduction and has shown potential for producing titanium with reduced energy inputs and lower environmental footprint. Hydrogenation-dehydrogenation processes offer another innovative approach. In this method, titanium ores are first hydrogenated to form titanium hydride, which is subsequently dehydrogenated to yield titanium metal. This technique is particularly appealing due to its potential for lower energy consumption and simpler processing requirements. The advancements in these and other extraction technologies indicate a significant shift towards more sustainable practices, driven by the growing global emphasis on sustainability and environmentally responsible manufacturing. Moreover, the demand for titanium continues to rise across various sectors, driven by innovations in technology and materials science. In the aerospace industry, for example, titanium is increasingly used in aircraft components to enhance fuel efficiency and reduce weight. In the medical field, titanium implants are favored for their biocompatibility and strength, leading to better patient outcomes. As market demands evolve, the need for more accessible and cost-effective titanium extraction methods becomes increasingly apparent. The collaboration between academia, industry, and research institutions will be pivotal in advancing extraction technologies. By fostering partnerships, sharing knowledge, and pooling resources, stakeholders can accelerate the development and commercialization of new extraction methods. The continuous investment in research and development plays a crucial role in refining these technologies and ensuring their applicability in real-world scenarios. It is clear that the titanium extraction landscape is on the brink of transformation. The intersection of technological innovation, sustainability, and market demand will shape the next generation of titanium extraction methods. A shift toward greener, more energy-efficient processes not only address current environmental concerns but also positions the titanium industry for growth in an increasingly eco-conscious marketplace. Ultimately, the evolution of titanium extraction technologies holds immense promise for the future. By embracing innovative solutions and prioritizing sustainability, the titanium metal industry can thrive while fulfilling the ever-increasing demand for its exceptional properties across a multitude of applications. The journey toward achieving a more sustainable and economically viable titanium extraction process is not just a technical challenge；it is a vital step towards a more sustainable future for industries and society as a whole.

Hydrogen storage technology, as an intermediate link in the manufacture, storage and use of hydrogen energy, has become a bottleneck in the large-scale utilisation of hydrogen energy, and the development of solid-state hydrogen storage materials and systems is expected to be the most effective way to solve this problem. In solid-state hydrogen storage, lightweight hydrogen storage alloys represented by rare earth-magnesium-based metal hydrides are characterised by high hydrogen storage density, fast reaction rate of hydrogen absorption and discharge, and good cyclic stability. Meanwhile, powder alloy compaction can increase the volumetric hydrogen storage density. Therefore, magnesium-rich Mg-Ni-（La, Ce) alloys were determined as the research carriers, and the moulding density and volumetric hydrogen storage density of the powder alloys were improved by moulding pressure. Mg₈₇Ni₁₀（La, Ce）₃ and Mg₉₂Ni₄（La, Ce）₄ alloys pressed plates were prepared at pressures of 760, 1140 and 1520 MPa and their hydrogen storage properties were investigated by using a hydrogen storage property tester (PCT) in order to investigate the effect of molding pressure on the hydrogen storage properties of Mg-Ni-RE alloys. X-ray diffraction (XRD) was used to analyze the longitudinal slices of the alloy after hydrogen absorption, scanning electron microscopy (SEM) was used to study the longitudinal slices of the alloy's pressed slices in terms of macroscopic and microscopic pore structures, and to explore the mechanism of the change in the hydrogen storage properties of the alloy after pressing. The results showed that the higher the forming pressure, the higher the number of cycles to complete the activation of the alloy, in which Mg₈₇Ni₁₀（La, Ce）₃ powder alloy could be activated by four cycles of hydrogen absorption and release, and the maximum forming pressure of 1520 MPa under the piezoelectric sheet alloy needed seven cycles of hydrogen absorption and release in order to complete the activation. Activation of Mg₉₂Ni₄（La, Ce）₄ powdered alloy was completed with two cycles of hydrogen uptake and discharge, whereas four cycles of hydrogen uptake and discharge were required to complete the activation of the pressed sheet alloy at a maximum forming pressure of 1520 MPa. At the initial activation stage, the higher the moulding pressure, the lower the mass hydrogen storage density of the alloy, but the effect of the moulding pressure on the mass hydrogen storage density of the alloy decreased as the number of cycles increased. Among them, Mg₈₇Ni₁₀（La, Ce）₃ had a hydrogen uptake capacity of around 5.20% at different pressures for both the pressed and powdered alloys after the eighth cycle of hydrogen uptake, and Mg₉₂Ni₄（La, Ce）₄ had a hydrogen uptake capacity of around 4.78% for both the powdered and pressed alloys after four cycles of hydrogen uptake. The volumetric hydrogen storage densities of Mg₈₇Ni₁₀（La, Ce）₃ and Mg₉₂Ni₄（La, Ce）₄ alloys reached the maximum values of 115.0 and 99.23 g·L⁻¹, respectively, at a moulding pressure of 1520 MPa, which were more than double the volumetric hydrogen storage densities in the powder state. SEM images showed that after the alloy powder press moulding, the particles were broken and deformed, and the specific surface area and porosity of the materials were reduced, which limited the hydrogen diffusion path and increased the barriers to hydrogen diffusion, and ultimately led to a slowing down of the initial hydrogen storage kinetics of the alloys and a significant decrease in the amount of hydrogen stored, but the effect of the moulding pressure on the alloy's hydrogen uptake kinetics gradually decreased with the increase in the number of cycles. XRD analysis showed that after saturation hydrogen absorption in the press-formed alloy, metal hydride phases were formed from the surface layer to the interior, with no unhydrogenated metal phases remaining.

Given their critical role in permanent magnets for new energy vehicles, wind turbines, communications, and other industries advance, the demand for rare earth metals, such as Pr, and other essential materials is rapidly increasing. Therefore, developing an efficient extraction method for Pr is becoming urgent. The electrolytic reduction methods for rare earths include the ionic liquid method and the high-temperature molten salt method, depending on the electrolyte composition. Ionic liquids offer high electrical conductivity and a broad electrochemical window. However, their complex synthesis, challenging purification, and high cost limit their large-scale industrial application and development. Rare-earth metals are commonly prepared industrially using high-temperature molten salt electrolysis. The chloride system is widely used in laboratory research；however, in industrial production, the chloride system electrolysis of praseodymium faces issues such as low current and electrolysis efficiency, high power consumption, and the generation of chlorine gas. Fluoride molten salts offer better stability and higher current efficiency compared to chloride molten salts. Despite advancements, the electrodeposition kinetics and nucleation mechanisms of rare-earth praseodymium in fluoride molten salt systems remain poorly understood. This study investigated the electrochemical redox behavior and nucleation mechanism of praseodymium (Pr) on an inert tungsten (W) electrode in the LiF-PrF₃ fluoride salt system. The reduced praseodymium was analyzed by using X-ray diffraction (XRD）, scanning electron microscopy (SEM）, energy dispersive spectroscopy (EDS）, and inductively coupled plasma-emission spectroscopy (ICP-AES）. The experiment was conducted in a pit-type furnace using a graphite crucible as the electrolytic cell. A mixture of PrF₃ and LiF in a 9∶1 mass ratio was placed in the crucible, and argon gas was introduced. The mixture was then heated to 1000 ℃ and maintained at this temperature for 1 h with continuous stirring. Following this, the system was connected to an electrochemical workstation to measure cyclic voltammetry and i-t curves. Finally, electrolysis was performed using a direct current supply, with specific electrolysis potential and time settings to prepare praseodymium metal. The electrodeposition behavior of Pr on an inert W electrode in LiF-PrF₃-Pr₆O₁₁ molten salt system was investigated by adding Pr₆O₁₁ to LiF-PrF₃-Pr₆O₁₁ molten salt system, using Pr（Ⅲ) as a representative of the non-variable lanthanide ions：1) The cyclic voltammetry curve displayed two pairs of redox peaks, with one pair for praseodymium emerging around -0.2 V. This indicatedan electrochemical process where solid-phase material formed on a heterogeneous inert electrode, then dissolved into the solution. This pair of signals corresponded to the dissolution and precipitation reactions of Pr（Ⅲ）. The oxidation signal observed around -0.5 V corresponded to Li dissolution, while the reduction signal related to the reduction of Li（Ⅰ）. As the scan rate increased, the reduction peak potentials shifted negatively, while the oxidation peak potentials shifted positively. At scan rates ranging from 0.10 to 0.30 V·s^-1, the oxidation peak potential increased gradually with lgv, indicating that the system didnot exhibit a fully reversible behavior with a zero intercept. The reduction peak potential decreased slowly with lgv within the same scan rate range. This behavior suggested that the praseodymium reduction reaction was quasi-reversible. The average diffusion coefficient of Pr（Ⅲ) in molten LiF-PrF₃-Pr₆O₁₁ with a concentration of 1.8×10⁻⁴ mol·cm⁻³ was 4.667×10⁻⁵~1.414×10⁻⁴ cm²·s⁻¹. 2) The j-t curves of rare earth metal Pr electrodeposited onto W electrodes under varying overpotential pulses aligned with the current transient characteristics of the metal electrodeposition process. Initially, the current decreased rapidly due to bilayer charging, subsequently increased rapidly as nucleation and growth began on the W electrode. As diffusion zones overlap, the current reached a maximum before decaying over time, indicating diffusion-controlled electrodeposition processes. The nucleation rate gradually rose, reflected in larger -j_max values and shorter t_max durations. The dimensionless curves from -0.53 to -0.51 V closely matched the transient nucleation curves, indicating instantaneous nucleation of praseodymium electrodeposition on tungsten electrodes within this range. 3) Overvoltage in the molten salt system supplied the energy needed for the reduction of Pr（Ⅲ) ions to monomers. The deposition rate was influenced by the overvoltage magnitude；a higher overvoltage led to an increased nucleation rate. A 5.08 g sample of praseodymium was obtained after 2 h of constant potential electrolysis at -0.53 V using a direct current power supply. While most peaks correspond to Pr, the presence of Pr₂O₃ peaks suggested oxidation of the praseodymium metal upon exposure to air. The electrolysis efficiency was 87.97%, and the metal sample purity, as determined by ICP, was 98.86%.

Rhenium has high strain hardening index, tensile strength, elastic modulus and hardness, and has no ductile-brittle transition temperature. It is often used in metal-organic chemical vapor deposition (MOCVD) heaters and key components of engines. In order to meet its application in harsh ultra-high temperature service environments such as MOCVD heaters, this paper studied the tensile properties of pure rhenium (PM-Re) prepared by powder metallurgy at room temperature to 2000 ℃. The deformation mechanism of PM-Re was analyzed using scanning electron microscopy (SEM）, electron backscattered diffraction (EBSD）, transmission electron microscopy (TEM）, etc. The results showed that the room temperature tensile strength of PM-Re was 882 MPa. With the increase of temperature, the tensile strength of PM-Re decreased. At 2000 ℃, the tensile strength decreased to 112 MPa. The elongation after fracture of PM-Re at room temperature was 18%. In the temperature range of 1700–2000 ℃, the elongation after fracture was less than 10%. With the increase of temperature, the non-proportional elongation strength (R_p0.2) of PM-Re continuously decreased. At room temperature, R_p0.2 of PM-Re was 171 MPa, and at 1900 and 2000 ℃, it was only 17 and 6 MPa. The room temperature tensile fracture of PM-Re had both intergranular brittle fracture and transgranular fracture. Symmetrical structures along the fracture surface appeared on the grains where transgranular fracture occurred, and dislocation slip traces were found on the fracture surface. At high temperatures, a large number of lamellar structures, dimple-shaped fractures and "river" pattern characteristics appeared in the PM-Re specimens after tensile testing. It was found by EBSD characterization that the original PM-Re sample was composed of equiaxed grains. A large number of twins were produced after the sample was deformed at room temperature. There was a large local orientation difference inside the rhenium grains. The grain boundaries and twin boundaries showed a high local average misorientation (LAM) value. Dislocations were mainly distributed at the grain boundaries and interacted with the twin boundaries. With the increase of temperature, the degree of deformation of PM-Re increased, and the internal point defects and stress concentration areas increased, resulting in a gradual increase in the LAM value of PM-Re. Through the Schmidt factor map, it was found that the average Schmidt factor values of the cylindrical slip system and the conical slip system were the highest at high temperatures, and the non-basal slip system was the main slip system. The twin deformation traces in different directions on the same slip plane and the phenomenon of dislocation aggregation at the twin boundaries after tensile testing at room temperature were found by TEM, indicating that the twin and dislocation interacted, and the twin boundary would become an obstacle to dislocation movement. After tensile testing at 2000 ℃, subgrain boundaries formed by dislocation movement in the PM-Re body. The formation of subgrain boundaries could further hinder the dislocation slip, increase the deformation resistance of the material, and at the same time, the subgrain boundaries could coordinate the deformation between adjacent grains and effectively improve the uniform deformation ability of PM-Re. The above results showed that during the room temperature deformation process of PM-Re, twin deformation and dislocation slip coexisted. Twin deformation could improve the plasticity of rhenium, and dislocation cells and twin boundaries would hinder dislocation movement and thereby increase the work hardening rate of rhenium. The ultra-high temperature deformation process of PM-Re was dominated by dislocation slip, the non-basal slip system was the main slip system, and the basal slip system gradually opened at 2000 ℃.

ZL114A aluminum alloy is an Al-Si-Mg series cast aluminum alloy, renowned for its exceptional casting characteristics, comprehensive performance, and low thermal expansion coefficient. It finds extensive applications in producing intricate structural castings within the aerospace, automotive manufacturing, and construction industries. In recent years, the rapid advancement of China's aerospace industry has led to increasing demands for the service life and reliability of aluminum alloy castings. Currently, ZL114A aluminum alloy castings still face challenges such as low comprehensive performance and short service period, necessitating the urgent development of new technologies or processes to enhance the overall mechanical properties of ZL114A aluminum alloy. However, the utilization of various types of magnetic fields, including constant magnetic fields, pulsed magnetic fields, and alternating magnetic fields, to refine the solidification structure of aluminum alloy has emerged as a key area of research focus. Currently, there is limited literature on the enhanced refinement of microstructure and mechanical properties of ZL114A aluminum alloy through the composite interaction of rare earth elements and a magnetic field. This study proposed a composite treatment technology involving the application of surface pulsed magnetic field and Ce. The solidification process of ZL114A aluminum alloy was systematically investigated under the combined influence of surface pulsed magnetic field and varying Ce content. The effects of surface pulsed magnetic field and Ce compound action on the solidification microstructure, crystal structure, and hardness of ZL114A aluminum alloy were investigated by metallurgical microscopy (OM）, scanning electron microscope (SEM）, X-ray diffraction (XRD）, and Vickers hardness tester. The results showed that when Ce content was 0.15% under the action of the surface pulsed magnetic field, the solidification microstructure of ZL114A aluminum alloy had the best refinement effect, and the average grain size of the solidified structure was 95 μm, compared with the sample without composite treatment and only with 0.3%Ce, the average grain of the solidification microstructure was reduced by 39.5% and 24.4%, respectively. The eutectic Si morphology of ZL114A aluminum alloy had also changed from the original slat-shaped to a fine short rod or spherical shape. Compared with the samples with no composite treatment and only 0.3%Ce, the proportion of eutectic Si area and the average size of length diameter decreased by 20.3%, 34.8%, 9.2% and 26.1%, respectively. Compared with the samples without composite treatment, the comparison of the samples with surface pulsed magnetic field and Ce content of 0.15% promoted the accumulation of Al atoms in <111>, <200> and <220> directions, and hindered the growth of Al atoms in <311> direction, and the comparison of the non-composite samples promoted the accumulation of Si atoms in the <200>, <220> and <422>, and hindered the growth of Si atoms in <111> direction. The surface pulsed magnetic field and the composite effect of Ce were more conducive to the refinement of the solidification microstructure of ZL114A aluminum alloy α-Al grain and eutectic Si morphology, which opened up a new way for the composition design and composite process development of ZL114A aluminum alloy.

With the continuous expansion of the industrial field, the discharge of ammonia nitrogen wastewater is also increasing, which has caused serious damage to the ecological environment. Ammonia nitrogen wastewater is a kind of wastewater containing ammonia nitrogen pollutants, which will not only have toxic effects on aquatic organisms, but also destroy the ecological balance of water bodies. Water is the source of life, and the seriousness of this problem cannot be ignored. At present, the treatment methods of ammonia nitrogen wastewater mainly include chemical method, biological method and physical method. Nevertheless, these traditional methods generally have shortcomings such as long processing cycle, poor separation efficiency and poor recycling performance, which cannot meet the current needs. With the improvement of treatment methods, more and more ammonia nitrogen adsorption materials have been constructed and applied in the field of ammonia nitrogen wastewater treatment. At present, a variety of efficient and feasible adsorption materials have been constructed and applied to the field of ammonia nitrogen wastewater treatment. These materials not only have a high adsorption capacity, but also can be reused and have a long service life. Therefore, it is still a challenge to develop an excellent ammonia nitrogen wastewater adsorption material with a wide range of sources, low cost, friendly to the environment, simple preparation process, large adsorption capacity and strong regeneration performance. These requirements are interrelated and mutually restricted, requiring us to optimize and balance in multiple links such as material design, preparation process and post-treatment. Zeolite is a typical porous adsorption material. It has uniform pore structure, large specific surface area and pore volume, and good hydrothermal stability, and it is a good adsorption material. In addition, fly ash is one of the industrial solid wastes with large displacement and concentration in China. With the development of the power industry, especially the development of coal-burning power plants, the emission of fly ash is increasing year by year. Therefore, the treatment and utilization of fly ash is also one of the hot spots. Fly ash contains many elements such as silicon and aluminum required for the synthesis of zeolite, if the use of fly ash to prepare zeolite, not only can save chemical raw materials, but also low preparation cost and other advantages. In summary, the use of fly ash to prepare zeolite adsorption materials, so that it can be applied to reduce the ammonia nitrogen content in wastewater, is an efficient, cheap and environmentally friendly method, but also provides a new idea for the treatment of fly ash, so that it can achieve the purpose of "waste to treat waste, green chemistry". This paper mainly discussed the feasibility of using fly ash to prepare high efficiency and low-cost ammonia nitrogen wastewater treatment materials. X-type, A-type and series A-X-type fly ash-based zeolites which could treat ammonia nitrogen wastewater were prepared by hydrothermal method. When the temperature was controlled at 80 ℃, the reaction time was 12 h, the solid-liquid ratio was 1∶9, the silica-aluminum ratio was 2.5∶1, and a few crystal seeds were supplemented, the best preparation parameters of purified X-type zeolite could be obtained. At the same time, X-ray powder diffraction (XRD）, thermogravimetric analysis (TG-DSC）, scanning electron microscopy (SEM）, transmission electron microscopy (TEM）, nitrogen adsorption-desorption test (BET）, X-ray energy dispersive spectrometry (EDS) and infrared spectroscopy (FT-IR) were used to characterize purified X-type zeolite. The test results showed that the purified X-type zeolite had more obvious morphology, more prominent shape and better crystal shape. Then, with 50 mg·L⁻¹ ammonium chloride solution as the model pollutant, the adsorption properties of purified X-type zeolite were investigated under different adsorption time, dosage, pH, temperature and initial concentration of ammonium chloride. On this basis, the optimum parameters for adsorption of ammonia nitrogen wastewater by purified X-type zeolite were selected. Finally, the regeneration ability of purified X-type zeolite was investigated and tested. The experimental data showed that the purified X-type zeolite had good stability and regeneration ability while ensuring high adsorption efficiency.

China has abundant molybdenum resources, the majority of which are in the form of molybdenite, which has the highest industrial value. However, the grade and roasting behavior of molybdenum concentrate are different due to different subsequent flotation and pretreatment processes of molybdenum ore mined. To maintain the smooth progress of the reaction, external heat sources are still required for the industrial roasting of molybdenum concentrate. With the wide application of low-grade molybdenum concentrate, it has also brought many problems. It is simple to produce molybdate during the roasting of low-grade molybdenum concentrate, which is challenging to remove, if the temperature is too high or the roasting time is too long. The formed molybdate leads to the decrease of MoO₃ content. Low grade molybdenum concentrate has a high impurity component content, which hinders the concentrate's ability to oxidize. The phenomenon of sintering takes place during the roasting process, leading to a high rate of residual sulfur and MoO₂ in the molybdenum calcine. Therefore, in order to meet the quality of molybdenum calcine, it is necessary to analyze the roasting characteristics and calorific value of various concentrate grades. In this study, five types of molybdenum concentrates processed from different production areas were selected, and the elemental composition and microstructure of the molybdenum concentrates were characterized by inductively coupled plasma (ICP) and scanning eectron microscope (SEM）. The characteristics of oxidation and volatilization in five different grades of molybdenum concentrate during roasting process were studied by simultaneous thermogravimetry-differential scanning calorimetry-mass spectrometry (TG-DTG-DSC-MS）, and the heat release characteristics and linear equations during the roasting process of molybdenum concentrate. Coats-Redfern method was used to calculate the activation energy of different grades of molybdenum concentrate and to determine the limiting step of the reaction in the oxidation/volatilization stage. The results showed that roasting process of molybdenum concentrate was divided into three stages. In the first stage (45~400 ℃）, the moisture and flotation agents in molybdenum concentrate began to volatilize. In the second stage (400~630 ℃）, MoS₂ oxidation to produce MoO₃ and SO₂.In the third stage (630~1000 ℃）, the formed MoO₃ began to undergo significant sublimation and volatilization. While molybdenum was in a different grade during the oxidation stage, this had no bearing on the temperature at which oxidation begins and finishes. The molybdenum grade had a significant effect on the oxidation rate. When the molybdenum grade increased from 48% to 56%, the corresponding maximum oxidation rate increased from 0.065 to 0.095 mg·min⁻¹. When the roasting temperature increased from 600 to 630 ℃, the quality of concentrate with molybdenum grade of 48% increased by 6%. Due to the presence of a large amount of impurity oxides in this grade of molybdenum concentrate, which combined with SO₂ to form sulfates. The calorific value measured by low grade molybdenum concentrate calorimeter was obviously less than the theoretical calorific value. The low-grade molybdenum concentrate contained a significant amount of impurity oxides in addition to the primary MoS₂ phase. The heat released by the impurity oxides during the reaction was 500 J·g⁻¹, which was much smaller than the heat value of MoS₂ oxidation. The calorific value obtained by calorimeter, DSC integration and thermodynamic method was correlated with molybdenum grade. The calorific value equation of molybdenum concentrate calculated by thermodynamics was y=17.74x-0.029, and the fitting degree was R²=0.99. The calorific value equation measured by calorimeter was y=239.36x-7273.91, and the fitting degree was R²=0.91. The calorific value equation y=35.29x-915.05 was obtained by DCS integration, and the fitting degree was R²=0.93. In industrial production, the heat generation during roasting could be effectively predicted based on the grade of molybdenum concentrate.The sublimation/volatilization stage was mainly divided into three parts due to different mechanisms of action：first step (630~720 ℃）was MoO₃sublimate. Second step (721~870 ℃) was MoO₃ melting and volatilizing, and as a result of the eutectic reaction between the formed low melting point molybdate and MoO₃, the melting point of MoO₃ had decreased from the original 795 ℃ to about 750 ℃. At this temperature, MoO₃ melted significantly, which aggravated the volatilization of MoO₃. Third step (871~1000 ℃) was MoO₃ volatilizing and decomposition of unstable molybdate. The activation energy during the oxidation stage of different grade molybdenum concentrates was 120~135 kJ·mol⁻¹, and the control step of the reaction was interfacial chemical reaction. During the sublimation/volatilization stage, the activation energy of molybdenum grade with 51%~56% was 340~360 kJ·mol⁻¹, and the control step of the reaction was nucleation and nucleation growth, while the activation energy of molybdenum grade with 48%~49% was 238~240 kJ·mol⁻¹, and the control step of the reaction was internal diffusion. Different grades of molybdenum concentrate were used together, and the high calorific value of high grade concentrate in the early stage was used reasonably to realize the thorough oxidation reaction of low grade concentrate, so as to inhibit the volatilization and sintering of MoO₃.

The magnetic field-assisted grinding (MFAG) method is a novel ultra-precision surface machining technology. In this paper, a new magnetic abrasive particle with high efficiency and low cost was prepared by the bonding method to improve the uniformity of the iron-based phase and grinding phase for the ultra-precision grinding of 304 stainless steel efficiently. The effects of different component ratios on the abrasive properties of magnetic abrasive particles prepared by the bonding method were investigated. The surface morphology of magnetic abrasive particles and workpieces before and after grinding was observed by ultra-depth three-dimensional microscope and white light interferometer, and the surface quality of workpieces before and after grinding was compared by surface roughness measuring instrument, the excellent proportioning of magnetic abrasive particles by bonding method was finally determined. Two kinds of magnetic abrasive particles were prepared by different processes of bonding method and traditional mechanical mixing method, in addition, the grinding properties were investigated experimentally. The results showed that the initial surface was smoothed after grinding. In addition, the grinding marks were observed, regardless of the mass ratio of iron base phase to grinding phase (3∶1, 4∶1 and 5∶1) used in the grinding process. When the mass ratio of iron base phase to grinding phase was 4∶1, the surface roughness (R_a) decreased from 206 to 49 nm after 9 min grinding, meaning the decrease rate of surface roughness was 76.2% due to the appropriate saturation magnetization. The grinding force was 1.2, 1.6 and 2.4 N, respectively, when the mass ratio of iron base phase to grinding phase was 3∶1, 4∶1 and 5∶1. Once the mass of the iron-base phase was higher, the grinding force increased sharply, resulting in deeper scratches. The mass ratio of the adhesive and curing agent was an important parameter affecting the surface roughness in the MFAG process. The surface roughness decreased first with the increase in additive E-44 epoxy resin, then increased when the mass ratio was more than 40%. It could be observed from the ground abrasive particles that the area of the grinding phase decreased from 80.5% before grinding to 32.6% after grinding with MAP-1 grinding, which was composed of organic silicon resin and curing agent. Due to the addition of E-44 epoxy resin, the toughness of the adhesive was improved, and the impact strength was enhanced. The surface quality of 304 stainless steel was improved after grinding with different ratios of iron matrix to abrasive phase particle size. However, the decreasing trend of surface roughness R_a was not the same. A continuous decrease in surface roughness R_a with increasing of grinding time, but the rate of decline was relatively slow using MAP-d_2-1 (the ratio was 2∶1）. After grinding with MAP-d_3-1 for 9 min, the smoothest surface could be obtained. Subsequently, the surface quality deteriorated, resulting in the fastest decrease rate in surface roughness in the first 3 min using MAP-d_4-1；afterwards, it slowly dropped to its lowest point in the following 6 min. The grinding force was 0.5, 1.6 and 2.0 N, respectively, when the saturation magnetization was 133.3, 149 and 151.9 emu·g⁻¹. During the grinding process, a larger diameter iron powder should be selected first to remove the original defects on the surface of the workpiece. Then, the smaller diameter iron powder should be chosen to achieve lower surface roughness. The influence of different ratios of mixture to binder on surface roughness was finally studied. The lack of binders (the ratio was 10∶0.8) led to a lower bonding strength of the grinding phase, resulting in a few grinding phases participating in the grinding process, leading to lower grinding efficiency. On the contrary, some of the abrasive particles were wrapped entirely by the excessive adhesive (the ratio was 10∶1.2）, reducing the number of cutting edges involved in the grinding process and decreasing grinding efficiency. When the ratio of the mixture to the binder was 10∶1, the surface of the iron substrate was uniformly covered with the grinding phase, which showed excellent grinding effects. To summarize, when the mass ratio of iron base phase to grinding phase was 4∶1, the particle size ratio was 3∶1, the mass ratio of the mixture of iron matrix and grinding phase to binder was 10∶1, and the mass ratio of E-44 epoxy resin, silicone resin to polyamide curing agent was 4∶1∶5, the grinding effect of magnetic abrasive particles was the best. The experimental results showed that the bonding method was superior to the traditional mechanical mixing method regarding grinding efficiency and workpiece surface machining accuracy. After grinding with this magnetic abrasive particle for 9 min, the surface roughness R_a of the workpiece was reduced from the original of 206 nm to 49 nm. The surface quality of the workpiece was improved. The white corundum/ferromagnetic abrasive prepared by the bonding method could achieve high efficiency and high-quality grinding of 304 stainless steel.

Copper (Cu）, as a surface plasmon resonance photocatalyst, drives photochemical reactions in the ultraviolet, visible, and infrared regions with high photocatalytic activity, which is not commonly found in most inorganic semiconductors. To enhance the photocatalytic activity of Cu, polyaniline (PANI) was employed for surface modification. PANI was synthesized by an in-situ polymerization method, utilizing aniline and hydrochloric acid as raw materials in an ice-water bath. Subsequently, PANI-modified Cu nanoparticles (PANI@Cu) were prepared using a solvent-thermal method. PANI@Cu was characterized by X-ray diffraction (XRD）, scanning electron microscopy (SEM）, Fourier transform infrared spectroscopy (FT-IR）, and X-ray photoelectron spectroscopy (XPS) to analyze the composition, morphology, and chemical states. UV-visible near-infrared diffusion reflection spectroscopy (UV-Vis-NIR) and electrochemical impedance spectroscopy (EIS) were measured to support the absorbance, generation, and transfer of the photoinduced charge carriers. The composition analysis of the samples showed that PANI exhibited an amorphous broad peak, while PANI@Cu did not exhibit PANI broad peak, and its diffraction peaks had shifted compared with those of Cu particles. The morphology and particle size of PANI@Cu underwent significant changes after Cu was modified with PANI. The size of PANI@Cu was smaller, and PANI@Cu particles aggregated together to form hemispherical cavities. And the Cu:N bonds were formed after PANI modification on Cu particles. Simultaneously, PANI modification enhanced the light absorbance intensity in the visible and near-infrared regions. Moreover, electron-hole recombination was inhibited, and the transfer of the photoinduced charge carriers was improved. Using methyl orange (MO) to simulate the organic pollutant, the photocatalytic properties of PANI@Cu were studied by photocatalytic degradation of MO solution (30 ml, 20 mg·L^-1）. Photocatalytic degradation experiments indicated that the photocatalytic activity of PANI@Cu catalyst was significantly improved after modifying Cu particles with PANI. When PANI@Cu was used as the photocatalyst, the degradation efficiency of MO reached 94.25% and 91.24% after 60 min under visible illumination and in darkness, respectively. This indicated that the photocatalytic activity increased by approximately 30.0% under both visible illumination and in darkness. After four cycles of photocatalytic degradation, PANI@Cu catalyst still exhibited great photocatalytic activity, and the photocatalytic degradation efficiency of MO solution was 83.30% under visible illumination and 81.13% in darkness, which indicated that PANI@Cu exhibited good photocatalytic stability. Therefore, PANI@Cu catalyst was a round-the-clock photocatalyst. Furthermore, the probable photocatalytic mechanism of PANI@Cuwas discussed. In the photocatalytic system, whether under visible illumination or in darkness, h⁺ and ·O₂⁻ played dominant roles in the photocatalytic decomposing MO, which were strong oxidizing groups and could make organic pollutants degrade. In conclusion, PANI@Cu material prepared possessed excellent photocatalytic properties under illumination and in the dark. PANI modification significantly enhanced the photocatalytic activity of zero-valent Cu particles, which could be attributed to the enhanced charge separation efficiency and increased light absorption intensity in the visible and near-infrared regions. Therefore, PANI@Cu would have some potential applications in the round-the-clock photocatalysis field.

Due to the depletion of fossil fuels and environmental pollution concerns, the urgent need for sustainable energy such as solar, wind, and tidal energy has become critical. However, the renewable energy mentioned above is challenged by instabilities. This has underscored the importance of advancing energy storage technologies that can bridge the gap between availability and demand. Supercapacitors emerge as a promising solution, due to their high-power density, rapid charging and discharging capabilities, substantial energy density, and environmentally friendly attributes. A pivotal factor in the efficacy of supercapacitors is the electrode material. Recent investigations have highlighted metal sulfides for their high theoretical specific capacities and robust stability. Despite this, the practical specific capacities of these materials significantly lag behind their theoretical predictions, which impedes their broader application. To address the problem, the use of pseudo-capacitive materials, such as transition metal compounds, has been explored to boost performance. In this context, a novel electrode material was synthesized via template method. Mushroom stalks were selected as a biological scaffold and melamine as a precursor to synthesize carbon nitride (g-C₃N₄) through a thermal polymerization process. Concurrently, molybdenum disulfide (MoS₂) was synthesized from ammonium molybdate tetrahydrate and thiourea, serving as sources of molybdenum and sulfur, respectively. MoS₂ was then integrated onto g-C₃N₄/C matrix via a hydrothermal method, resulting in the formation of a MoS₂-g-C₃N₄/C three-phase composite. The structural integrity and composition of g-C₃N₄/C were confirmed through X-ray diffraction (XRD）, validating the successful synthesis of the composite. Incorporating mushroom stalks into the synthesis process effectively modulated the grain size of the electrode material, achieving optimal crystallinity at a biomass to carbon nitride precursor mass ratio of 1∶2.5. The electrochemical performance of g-C₃N₄/C composite as a supercapacitor electrode was assessed in a three-electrode configuration using cyclic voltammetry (CV) and constant current charge-discharge tests. These evaluations revealed that the composite with 1∶2.5 ratio delivered superior rate performance and chemical stability, exhibiting a specific capacitance of 104 F·g⁻¹ at a current density of 1 A·g⁻¹. XRD was used to examine the crystal structure, while scanning electron microscopy (SEM) and transmission electron microscopy (TEM) provided insights into the microstructural features. X-ray photoelectron spectroscopy (XPS) was utilized for detailed elemental analysis. Additionally, nitrogen adsorption-desorption isotherms were chosen to assess the pore structure, indicating a heterogenous mix of micro and mesopores that enhanced the electrode's surface area, electron transfer efficiency, contact area with electrolytes, and active site availability. These structural characteristics contributed significantly to the improved electrochemical performance of MoS₂-2.5g-C₃N₄/C composite. CV analysis demonstrated the material's excellent performance and chemical stability. Galvanostatic charge-discharge testing confirmed pronounced pseudocapacitive behavior, with a specific capacitance reaching 220 F·g⁻¹ at a current density of 1 A·g⁻¹. Notably, after 1000 cycles, the material maintained 85.1% of its initial capacitance, underscoring its exceptional cycling stability.