With the intensification of human industrial activities，wastewater discharge from multiple sectors，including chemical manufacturing，pharmaceuticals，textile dyeing，and electroplating，has become a critical challenge requiring urgent resolution in environmental governance.Photocatalytic technology offers an effective approach for removing organic pollutants from water bodies.Bi₂WO₆ is a photocatalyst responsive to visible light（bandgap 2.7 eV），featuring a two-dimensional olivine-type oxide semiconductor structure composed of alternating［Bi₂O₂］²⁺ and ［WO₄］^2- octahedral layers.This material exhibits chemical stability and can degrade organic pollutants under sunlight-driven conditions.However，its overall photocatalytic performance is constrained by limitations such as restricted adsorption capacity and reactive oxygen species generation，high recombination rates of photo-generated carriers，and a narrow visible light response range（λ≤460 nm）.Numerous researchers have addressed these limitations through various modification strategies，including morphological control，defect engineering，elemental doping，heterostructure construction，and metal particle deposition.The several modification methods and mechanisms for Bi₂WO₆ materials were summarized，relevant research progress were systematically organized，and future research directions were proposed to overcome existing limitations.It was aimed to provide theoretical guidance for the design and modification of bismuth-based photocatalytic materials.

Hydrogen energy has become an important strategy for global energy transformation.To achieve large-scale，long-distance，and low-cost hydrogen energy transportation，the use of natural gas pipelines for hydrogen mixed transportation has the feasibility of large-scale application.However，the hydrogen content in hydrogen doped natural gas is usually low，and hydrogen needs to be separated from natural gas before application.Electrochemical hydrogen pump technology is a hydrogen purification and compression technology that uses electricity as the driving force，membrane as the proton conduction and gas barrier medium.It has high selectivity and hydrogen source adaptability，and can simultaneously achieve hydrogen purification and compression.It is an effective way to transport hydrogen and connect with application ends.The common methods for hydrogen separation and purification were compared，and the working principle，main functions，key components，and research progress of electrochemical hydrogen pumps were introduced.The research progress of the core component proton exchange membrane was analyzed，mainly including polymer proton exchange membrane and mixed matrix proton exchange membrane.The prospects and challenges of using electrochemical hydrogen pumps for hydrogen doped natural gas separation were discussed.

Graphite is an important anode material for lithium-ion batteries，but the low initial coulombic efficiency，short cycle life，and poor rate performance of natural graphite limit its application.In order to improve the stability of its graphite structure and electrochemical performance，Al（NO₃）₃·9H₂O was used as the aluminum source with adjusting the pH with ammonia water and uniformly coating a layer of Al（OH）₃ on the surface of graphite by precipitation method，and Al₂O₃ coated graphite anode material was further prepared by heat treatment.Compared with the atomic layer deposition method，this method had the advantages of simple process and low cost，better control of the reaction process and lower energy consumption than the sol gel method.When the Al₂O₃ coating mass was 1.03%，the modified graphite surface was smooth.The Al₂O₃ coating layer could serve as a preformed solid electrolyte interface（SEI），reducing the regeneration of SEI and the consumption of lithium ions during subsequent cycling processes.Electrochemical performance tests showed that the materials exhibited excellent rate performance and cycling stability during charge and discharge processes.Graphite and Al₂O₃ coated graphite anode materials with a modification amount of 1.03% were assembled with lithium sheets to form lithium-ion batteries.After 100 cycles of charge and discharge at a current density of 0.1C（1.0C=372 mA∙h/g），the specific capacities were 212.59 mA∙h/g and 354.37 mA∙h/g，with capacity retention rates of 67.99% and 98.59%，respectively.

The focus of recycling of waste lithium-ion batteries is spent cathode materials.In this paper，Spent LiNi_0.5Co_0.2Mn_0.3O₂（NCM523） was directly generated by a high-temperature solid-phase reaction method，in which the conductive carbon and the polyvinylidene fluoride binder were not removed.The effects of lithium supplementation （x was defined as the mole ratio of NCM523 and LiOH） on the structure and performance of the regenerated NCM523 were investigated by XRD，SEM，CV，EIS，and galvanostatic charging/discharging techniques.As the lithium supplementation increased，the layered structure ordering degree，lithium ion diffusion coefficient，and capacity of the regenerated NCM523 exhibited an initial increase，followed by a subsequent decrease.Concurrently，the redox reaction reversibility，CEI membrane impedance，and charge transfer impedance demonstrated an initial decrease，followed by an increase.The optimal layered structure of the regenerated NCM523 was observed at a lithium replenishment x of 0.75.The regenerated NCM523 exhibited an initial coulombic efficiency of 83.87%，accompanied by a discharge specific capacity of 148.2 mA·h/g at 0.1C.Additionally，it demonstrated an initial capacity of 139.5 mA·h/g at 1.0C，along with a retention rate of 80.18% after 100 cycles.Furthermore，the use of EIS and CV tests demonstrated that the regenerated samples exhibited enhanced structural stability and ionic conductivity.As a comparison，the discarded NCM523 pretreated with calcination to remove conductive carbon and PVDF after regenerating by using high-temperature solid-phase direct regeneration exhibited a first-cycle discharge capacity of 145.0 mA·h/g at 0.1C，with a coulombic efficiency of 79.38%.Its discharge capacity at 1.0C was 123.5 mA·h/g，maintaining 62.29% after 100 cycles.The findings of this study offered novel approaches for the recycling of waste cathode materials.

In the production process of salt lakes，lithium，potassium and other resource elements suffer significant losses during the evaporation and concentration processes in the salt field system.In order to study the distribution pattern of lithium in the salt field system，herein，we took the West Taijinar Salt Lake in Qaidam Basin of qinghai as research subject，and constructed the Computational Fluid Dynamics（CFD） model of the salt field system.Firstly，indoor simulated evaporation experiments were conducted and a CFD model was built to obtain key parameters such as the evaporation rate of brine and the diffusion rate of lithium ions.Then，the CFD model of West Taijinar Salt Lake was constructed to study the variation of lithium elements along different sections in different halogen production stages.Finally，the distribution laws of resource elements in different seasons were studied based on the CFD model，and the differences in the distribution of resource elements in salt pans in summer and winter were pointed out.The on-site sampling analysis results of the salt field indicated that the error in the distribution of lithium elements obtained from CFD simulation was below 2%，demonstrating that the constructed CFD model could accurately predict the distribution of lithium in the salt field system，which provided solod theoretical support for improving the recovery rate of resource elements in the salt field process.

The addition of sulfuric acid in the reverse flotation process of phosphate ore will change the material composition on the surface of calcite and generate CO₂ bubbles，which will affect the adsorption of collector on the surface，and then affect the flotation index.In this paper，the effects of the addition order of sulfuric acid and sodium dodecyl sulfate（SDS） on the flotation separation of calcite and apatite were studied by means of pure mineral flotation test，contact angle test and scanning electron microscopy.The flotation tests of single minerals and mixed minerals showed that the addition of SDS before sulfuric acid had little effect on the flotation of apatite，but it could reduce the inhibitory effect of sulfuric acid on calcite，which was beneficial to the flotation separation of calcite and apatite.In addition，the action time of sulfuric acid under this addition method also had an effect on the flotation of calcite.The shorter the slurry adjustment time of sulfuric acid，the higher the flotation recovery of calcite.The separation effect of calcite and apatite by adding sulfuric acid firstly and then SDS was worse than that of the former.The mechanism study showed that the reason for the good flotation effect of adding SDS firstly and then adding sulfuric acid was that this method could effectively reduce the intensity of the reaction between calcite and acid，increase the retention of bubbles on the surface of calcite，reduce the formation of hydrophilic calcium sulfate on the surface of calcite，and enhance the binding effect of calcite on the generated CO₂ bubbles.This study had certain theoretical significance for the flotation separation of calcite and apatite，and provided some guidance for the comprehensive utilization of phosphate rock resources.

Silica sol has great application prospects in the field of anti-seepage grouting due to its good permeability and injectivity，strong durability，non-toxic and environmental protection.The practical application of single silica sol is limited due to its poor solidification controllability.Adding salt solution/acidity regulator and both can regulate the solidification behavior of silica sol.However，the influences of salt solution and acidity regulator on the composition，viscosity and setting time of silica sol and their mechanisms are still not completely clear.In this paper，calcium chloride solution and acetic acid were selected and added to silica sol respectively or simultaneously to study their effects on the composition，viscosity and setting time of silica sol and elucidate their effects mechanism.At the same time，the strength and permeability coefficient of silica sol/calcium chloride/acetic acid system were investigated.The results showed that calcium chloride could significantly promote the condensation of silica sol，and the viscosity of silica sol was increased rapidly in a short time.After the addition of acetic acid，the viscosity of silica sol was increased slowly and the setting time was longer.When calcium chloride and acetic acid were added at the same time，the viscosity of silica sol experienced a slow increase at first，and then a rapid rise，and the setting time of silica sol could be effectively controlled by controlling the concentration of calcium chloride.After the addition of silica sol/calcium chloride/acetic acid system，the 3 d compressive strength of silica sol solid sand body was greater than 0.39 MPa，and the permeability coefficient of silica sol solid sand body could be maintained in the range of 1×10^-9 cm/s.The results could provide a theoretical basis for the preparation of silica sol grouting materials and their application in the field of grouting.

The by-product fluosilicic acid produced by the wet-process phosphoric acid production contains various impurities such as chlorine.The presence of these impurities not only affects the purity of fluosilicic acid and the quality of subsequent products，but also causes corrosion to the production equipment and pollutes the environment.In this paper，the single-factor method was used to conduct an experimental study on the removal of chlorine from fluosilicic acid solution by ozone oxidation.The effects of ozone flow rate，fluosilicic acid content，reaction time，and reaction temperature on the removal of chloride ions from fluosilicic acid solution by ozone oxidation were analyzed.In order to more accurately determine the parameters for ozone chloride removal，based on the results of the single-factor experiments，three factors that had a significant impact on the chloride removal rate were selected，including reaction time，reaction temperature，and fluosilicic acid content.The Box-Behnken（BBD） method in Design-Expert 13 was used to design a 3-factor 3-level experimental scheme for response surface experiments.The results showed that the optimal conditions for ozone to remove chlorine from fluosilicic acid were：ozone flow rate of 48 g/h，reaction temperature of 45 ℃，reaction time of 4 h，and fluosilicic acid content of 36.00%.Under the best experimental conditions，the chlorine removal rate was 96.85%，and the fluoride loss rate was 3.29%.This study could provide new ideas for removing chlorine from fluosilicic acid.

The direct acid leaching process of low-grade rhodochrosite has problems such as long and complex process flow and large discharge of waste water and residue.In this paper，the low-grade rhodochrosite from Guizhou was used as raw material，and the effects of leaching conditions on the leaching of manganese and the main impurities of calcium，magnesium and iron were investigated by additive-assisted leaching.The phase，morphology and leaching kinetics of manganese before and after leaching were also analyzed.The results were compared with those of the direct acid leaching process.The results revealed that the leaching rate of manganese was 94.36% and the selective leaching rate was 61.57% under the conventional leaching conditions of sulfuric acid concentration of 0.5 mol/L，leaching temperature of 55 ℃，solid-liquid ratio of 0.08 g/mL and reaction time of 120 min.For additive-assisted leaching（solid-liquid vatio of 0.04 g/mL），the leaching rate of manganese was 93.65%，the selective leaching rate was 89.67%.Under such circumstances，gypsum phases were more likely to form in the leaching residue，and calcium was more likely to remain in the residue phase rather than in the solution phase，which was conducive to improving the selective leaching rate of Mn²⁺.The leaching kinetics analysis showed that the leaching of manganese belonged to the diffusion control of the solid product layer，and the activation energy of the conventional leaching reaction was 4.85 kJ/mol，and the activation energy of the additive-assisted leaching reaction was 1.20 kJ/mol.The impurity components could be effectively inhibited at the source the leaching process by additive-assisted leaching，which provided a research basis for the subsequent impurity removal process and the preparation of high-purity manganese products.

During the brine evaporation process，the amount of lithium loss is enormous and the lithium loss rate is usually more than 40% with the evaporation-precipitation method.In this work，the evaporation process of the high calcium brine was studied and the result showed that the reason of lithium loss was entrainment of calcium crystal salt.Therefore，the effects of scrubbing solution which was saturated calcium chloride solution，preconcentrated solution or low lithium brine were further investigated on the washing of calcium crystal salts，and the disposal of the washing liquor was also discussed.It was founded that the effect of calcium crystal salts washing was best with the preconcentrated solution mixing-centrifugal separation-spray washing method.The detailed experimental conditions were as follows：firstly，the preconcentrated solution was used to mix the slurry and spray washing calcium crystal salts.When the slurry liquid-solid ratio（mL/g） was 0.5 and the spray washing ratio（mL/g） was 0.20，the lithium concentration in the washing solution was 6.90 g/L，and the washing solution could be returned to the salt evaporation pond.Subsequently，the fresh water was used for further spray washing.When the washing ratio was 0.03，the lithium recovery rate could be increased by another 10%，the lithium concentration was about 2.66 g/L，the dissolution rate of calcium crystal salts was about 12.56%.Then，the washing solution was recommended to use it for the next stage of washing to further improve the lithium concentration，and finally return to the salt evaporation pond.As a result，the washing rate of lithium reached about 79.12% with the above-mentioned washing calcium crystal salt process，which meant that the overall lithium recovery rate could be significantly improved.

Glauberite gypsum is the leaching tailings produced during the dissolved leaching of calcium glauberite ore.Due to the low purity and high content of insoluble impurities，there are very few application avenues.In response to the above problems，utilizing a crystalline phase transition method，dihydrate calcium sulfate from glauberite gypsum was successfully transformed into large glauberite crystals.These were then separated from smaller insoluble impurities based on particle size differences.Controlled hydration leaching conditions facilitated the conversion of glauberite back into dihydrate gypsum to obtain high-purity dihydrate gypsum.The impact of variables such as sodium sulfate mass concentration，temperature，leaching duration，and liquid-to-solid mass ratio on the size of the glauberite crystals and the yield of CaO were analyzed meticulously.Optimal conditions were identified：sodium sulfate mass concentration of 20%，temperature of 85 ℃，leaching duration of 3.0 h，and liquid-to-solid mass ratio of 6∶1.These conditions resulted in the formation of large-sized glauberite crystals and enabled effective separation of impurities by physical means such as sieving and cyclone，achieving a CaO yield of 79.60% and producing gypsum with a mass fraction of 89% after leaching.

By employing discarded spire snail shells from the Beibu Gulf in Guangxi as raw materials，multi-morphology nano-calcium carbonate（nano-CaCO₃） was successfully synthesized via an ultrasonic-assisted bubble carbonization method.Glycine（Gly） and sodium dodecyl sulfate（SDS） were used as crystal morphology inducers.The synthesized products were characterized using SEM，XRD，FT-IR，Raman spectroscopy，and TG.The results demonstrated that Gly primarily resulted in cubic CaCO₃ particles，while SDS predominantly induced spherical CaCO₃.When both Gly and SDS were combined，the CaCO₃ morphology was mainly spindle-shaped.This study investigated the effects of individual Gly/SDS carbonization systems and the composite carbonization system on the crystal size，morphology，and thermal stability of nano-CaCO₃，proposing a reaction mechanism for Gly/SDS.The analysis indicated that the CaCO₃ in the shells exhibited a wurtzite crystal structure with a purity of 95.46%.Spherical nano-CaCO₃ prepared at a mass concentration of 3.0 mg/mL had the smallest average particle size of 60.80 nm.Both the individual Gly/SDS carbonization system and the composite system produced calcite-type CaCO₃ crystals.The thermal stability of CaCO₃ synthesized under Gly regulation was superior to that of other morphologies.

Ferrochrome slag micropowder and ferrochrome slag aggregate were used to prepare ferrochrome slag ultra-high-performance concrete（FCS-UHPC） by replacing part of the cement and quartz sand，which helped to make up for the lack of natural aggregates and reduce the cost of UHPC as well as the carbon emissions of the production process.In this experiment，FCS-UHPC with different amounts of ferrochrome slag substitution（0~100%） were prepared，and the working performance test，mechanical performance test and shrinkage performance test were also carried out，and its microstructure was analyzed by scanning electron microscope SEM and EDS energy spectroscopy test.The results showed that the ductility of FCS-UHP was decreased with the increase of the replacement rate of ferrochromium slag aggregate.When the replacement rate of ferrochromium slag aggregate was 75%，the mechanical properties of FCS75 were the best in 28 d and its compressive and flexural strengths reached 137.6 MPa and 28.6 MPa.In addition，the concrete had the densest internal microstructure，and there were hydrated products of magnesium in the matrix，which produced magnesium hydroxide（MH） and hydrated magnesium silicate gel （MSH）.Moreover，when the replacement rate of ferrochrome slag aggregate was 100%，the self-shrinkage and drying shrinkage of FCS100 were the lowest，which were 4.13×10^-4 and 1.65×10^-4，respectively，and were reduced by 46.2% and 45.4%，respectively，compared with the baseline group，which indicated that ferrochrome slag aggregate could significantly improve the self-shrinkage and drying shrinkage of UHPC.

Impurity ions are one of the key factors affecting the crystallization and precipitation of fluorine-containing wastewater.In order to investigate the influence of impurity ions（Al³⁺ and Si⁴⁺） on the calcium salt crystallization and precipitation process of fluorine-containing wastewater and improve the treatment effect of fluorine-containing wastewater，the reaction of NaF and CaCl₂ was used to simulate the sedimentation process of fluorine-containing wastewater.Combined with Visual MINTEQ software simulation，XRD characterization，and SEM-EDS testing，the influence of Al³⁺ and Si⁴⁺ on the turbidity of precipitation crystallization，residual fluoride ion concentration，and precipitation product characteristics was systematically studied.The research results indicated that low concentrations of Al³⁺ and Si⁴⁺ had little effect on the precipitation and defluorination of calcium fluoride crystals.When the concentration of Al³⁺ was 200.00 mg/L，impurities such as aluminum hydroxide and cryolite precipitated under alkaline conditions，leading to an increase in reaction turbidity and a decrease in residual fluoride ion concentration with increasing pH.When the concentration of Si⁴⁺ was 200.00 mg/L，the silicon impurities in the crystal precipitation product were mainly quartz and calcium silicate，and the optimal defluorination conditions were n（Ca）/n（F）=2.5，pH=9.At this point，the residual fluoride ion concentration in the solution was 5.62 mg/L.SEM-EDS testing showed that the precipitate products were in the form of block aggregates，and the embedding relationship between calcium fluoride and impurity products was complex，making separation difficult.The research results provided reference for the treatment of complex multi ion fluorine-containing wastewater and the recycling of crystallization products in actual production processes.

There are a large number of potentially active silicate substances in steel slag，and the main component of carbide slag is Ca（OH）₂，which can be used as an alkaline activator to synergistically prepare cementitious materials.However，the strength of carbide slag-steel slag composite cementitious materials is very low and cannot meet the requirements for use.Therefore，the effect of activators such as gypsum admixtures and chemical additives on the properties of carbide slag-steel slag composite cementitious materials was investigated，and the relationship between phase composition and strength development was analyzed by X-ray diffraction（XRD） and Fourier transform infrared spectroscopy（FT-IR）.The results showed that replacing steel slag with carbide slag increased the thixotropy of the freshly mixed slurry and reduced its workability.All three types of gypsum could improve the strength of carbide slag-steel slag composite cementitious materials，with a strength increase of up to 350% at 28 d.However，the activation effect was still weaker than that of chemical additives，and the 28 d strength increase of Na₂SO₄ was 818%.XRD and FT-IR analysis showed that excessive calcium carbide slag did not participate in the reaction and hindered the hydration of steel slag.m（carbide slag）∶m（steel slag） was 5∶95，the Ca（OH）₂ peak of the Na₂SO₄ group became weaker，while the NaOH group still had a higher Ca（OH）₂ peak，indicating that Na₂SO₄ had a better excitation effect on the carbide slag-steel slag composite cementitious material than the NaOH group.This study provided theoretical support for the preparation of carbide slag-steel slag composite cementitious materials and was of great significance for the treatment of bulk solid wastes such as steel slag.

Considering the challenges of traditional homogeneous olefin hydroformylation processes，such as difficult product separation，metal leaching，and the insufficient catalytic activity and selectivity of conventional supported heterogeneous catalysts，a series of nitrogen/phosphorus-doped carbon material in-situ modified Co-based mesoporous silica catalysts（Co/L@SiO₂） were synthesized.The synthesis process involved using Co as the active metal to coordinate with organic nitrogen/phosphorus compounds for preparing catalyst precursors，which were then loaded onto mesoporous silica，followed by high-temperature calcination and reduction.The composition，structure，and morphology of the catalysts were characterized using inductively coupled plasma optical emission spectrometry（ICP-OES），X-ray photoelectron spectroscopy（XPS），transmission electron microscopy（TEM），N₂ physical adsorption，and Raman spectroscopy.The results demonstrated that the Co/Py@SiO₂ catalyst，synthesized with pyridine as the precursor ligand，exhibited a specific surface area of 618.76 m²/g，with uniform mesopores averaging approximately 3.6 nm in size.The catalyst contained 0.92%~0.94% metallic Co，with an average Co particle size of 6.4 nm and almost no agglomeration.Compared with Co@SiO₂，the nitrogen-doped Co/Py@SiO₂ catalyst showed a significant improvement in the selectivity toward n-valeraldehyde in the hydroformylation of mixed C4 hydrocarbons，increasing from 57.3% to 85.2%.The Co/Py@SiO₂ catalyst maintained stable activity and selectivity in fixed-bed continuous evaluation experiments.This study provided a practical approach to improve the reactivity and selectivity of heterogeneous hydroformylation catalysts，showing potential for industrial application.

To explore the mechanism of the synergistic effect of chemical poisoning and high-temperature hydrothermal aging on the NH₃-SCR performance of Cu-SSZ-13 catalysts，various samples were generated by subjecting the catalysts to poisoning and high-temperature treatment on an engine test bench.The physicochemical properties of catalyst coatings at different locations within the monolithic catalyst were investigated by using BET，SEM，NH₃-TPD，and H₂-TPR.The results revealed that K deposition on the fresh catalyst displaced isolated Cu²⁺ and protons on framework Brønsted acid sites，leading to a reduction in the number of active Cu²⁺ ions in the catalyst framework，a decrease in acidity without crystal structure damage，and partial pore blockage.During the high-temperature hydrothermal aging process，the presence of K exacerbated the collapse of the zeolite framework and accelerated the transformation of Cu²⁺ into Cu _x O _y species，which in turn inhibited the recombination of Al（OH）₃，leading to a significant decrease in specific surface area and redox properties.The deNO _x activity of the catalyst was examined by means of a fixed-bed reactor，and it was found that K weakened the activity and undermined the hydrothermal stability of the catalyst.After poisoning，the deNO _x efficiency of CZ at 200 ℃ and 500 ℃ was decreased from 92.84% and 89.38% to 85.64% and 83.22%（KCZ-1），respectively.After aging，the deNO _x efficiency of KCZ-HT1 at 200 ℃ and 500 ℃ was further deteriorated to 74.24% and 76.02%，a decrease of 15.7% and 10.8% compared to the unpolluted aged sample（CZ-HT）.In addition，the deposition of K in the catalyst was decreased along the gas flow direction，and the higher deposition at the front end resulted in poorer stability of the catalyst than at the back end.These findings provided an important basis for optimizing the design of anti-poisoning catalysts.This study clarified the mechanism by which K synergistically deteriorated catalyst activity and high-temperature hydrothermal stability through proton displacement and active site competition，etc，highlighting the sensitivity of D6R site Cu²⁺ to K poisoning and the significant impact on the stability of 8MRs site Cu²⁺ during aging，providing a theoretical basis for the targeted design of anti-poisoning catalysts.