Aiming at the problems of high sulfur content and difficult utilization of high sulfur bauxite,the alkaline leaching desulfurization process of high sulfur bauxite was studied.The effects of alkali mass concentration,liquid volume to solid mass ratio,leaching temperature and time on the desulfurization effect were investigated,and the reaction kinetics were analyzed.The results show that under the conditions of base concentration of 180 g/L,liquid volume to solid mass ratio of 8 L/1 kg,leaching temperature of 160 ℃ and leaching time of 5 h,the bauxite sulfur mass fraction after desulphurization is 0.42%.The desulfurization process is controlled by reaction-internal diffusion,and the apparent activation energy is 18.23 kJ/mol.The method can effectively reduce the sulfur content in high sulfur bauxite and is beneficial to the wide utilization of high sulfur bauxite.

Extraction and separation of valuable elements from the positive leaching solution of spent lithium-ion batteries by β-diketone/phosphate extraction system was studied.The optimal conditions for the extraction and separation of cobalt,nickel,manganese,and lithium were determined through equilibrium extraction.The results show that the β-diketone/phosphate extraction system can effectively separate cobalt,nickel,manganese,and lithium from the positive leaching solution of spent lithium-ion batteries by controlling the kinetics.Under optimized conditions,the extraction rate of cobalt,nickel,and manganese can reach 99%,and the yield of lithium can reach more than 95%.The method realizes the separation and recovery of cobalt,nickel,manganese and lithium by a single extraction system,which can provide a new process route for the recovery of waste ternary lithium batteries.

Complex component sandstone-uranium deposits are mainly composed of conglomerate,sandstone and Slate.The uranium minerals are mainly uranite and titanium-uranium ores,including a small amount of pitchblende.The process mineralogy of complex component sandstone uranium ore was studied,and the leaching process was optimized.The results show that most of the uranium in the ore exists in the tetravalent form,and it contains a relatively large amount of calcium,magnesium,aluminium,iron and carbonate.The test results of acid leaching,enhanced leaching and column leaching show that the acid leaching process has a better effect. When 40~50 g/L H₂SO₄ is used as the leaching agent,the slag leaching rate of the acid column leaching is all greater than 90%. Comprehensively considered,it is recommended that the heap leaching process of -10 mm particle size ore be adopted in industrial production,and the mass concentration of the leaching agent H₂SO₄ is preferably 40 g/L.

Extraction of copper from refractory copper oxide ore using a roasting—acid leaching process was investigated.The effects of roasting and leaching conditions on the copper leaching rate were examined. The results show that under the optimal conditions of -200 mesh grinding fineness of 70%,roasting temperature of 850 ℃,roasting time of 1 h,coal addition of 8%,liquid volume to solid mass ratio of 2/1,H₂SO₄ concentration of 15%,leaching temperature of 60 ℃ and leaching time of 3 h,the copper leaching rate can reache 91.03%.The process is demonstrated to be economically efficient for extracting copper from refractory copper oxide ore and is considered to have potential for broader application.

The leaching of silver from failed silver-containing spent catalyst using HNO₃+H₂O₂ system was investigated.The kinetics of the silver leaching process was analyzed using the shrinkage kinematics model of liquid-solid phase reaction.The effects of leaching temperature and nitric acid concentration on the leaching rate of silver were examined.The results show that under the optimal leaching conditions of nitric acid concentration of 1.1 mol/L,leaching temperature of 50 ℃,stirring speed of 300 r/min,n(H₂O₂)∶n(Ag)=1.5∶1,leaching time of 50 min,and liquid volume to solid mass ratio of 4 mL/1 g,the leaching rate of silver can reach 94.18%.The leaching is controlled by the diffusion of the solid film,and the apparent activation energy of the leaching reaction is 15.45 kJ/mol,and the reaction order of hydrogen ion is 1.13.The method can provide reference for the research of efficient resourcing utilization of silver-containing spent catalyst.

To address fiber shrinkage embrittlement and consequent mechanical degradation during surface modification of polyamidoxime (PAO) adsorbents,a "core-shell heterostructure stress transfer" strategy was proposed.A coaxial electrospinning technique was employed to fabricate PS@PAO nanofibers with a polystyrene (PS) flexible core and rigid PAO shell.Microstructural analysis results show that PS@PAO exhibits uniform core-shell architecture (≈200 nm diameter, ≈50 nm thickness) with a specific surface area of 6.22 m²/g,representing a 38% enhancement over pristine PAO fibers. Mechanical testing results demonstrate 13.8% and 30.1% improvements in tensile strength (0.66 MPa) and Young's modulus (34.84 MPa),respectively.Dynamic contact angle measurements show that favorable hydrophilicity with water contact angle decreasing from 30° to 21° within 1 s. When PS@PAO is used to adsorb uranium from seawater with pH of 8.0 and uranium mass concentration of 16 mg/L for 48 h,the adsorption capacity is 34.14 mg/g. Adsorption kinetics analysis results indicate compliance with the pseudo-second-order model,with chelation between uranyl ions ( \mathrm{U} {\mathrm{O}}_2^{2+}) and amidoxime groups identified as the dominant mechanism.Through comprehensive investigation of material architecture,uranium extraction performance,and adsorption mechanisms,this study can provide theoretical foundations and scalable fabrication guidance for developing high-stability marine uranium extraction materials.

The determination of alkyl mercury in water by distillation—purge and trap/gas chromatography-cold atomic fluorescence spectrometry was studied. The detection limit,precision and accuracy of the method were determined,and the factors affecting the effect of distillation and the optimum test conditions were determined.The results show that the detection limit of methymercury is 0.003 1 ng/L and that of ethylmercury is 0.002 8 ng/L.The adding standard recovery rates of both are 99.4%~104%,and the relative standard deviations(RSD) are 1.02%~1.34%. The factors affecting distillation effect are hydrochloric acid and saturated copper sulfate adclition.For 40 mL of pure water,the optimal addition amounts of concentrated hydrochloric acid and saturated copper sulfate are 80 and 200 μL,respectively.When the addition amount of alkylmercury are 4.00,40.0 and 400 pg,the recovery rates are all in line with the quality control requirements. The recovery rate of alkyl mercury adding standard can be significantly improved after distillation treatment in actual lake water.

The removal of uranium bound to organic matter in real uranium-contaminated soil from a certain mining area was studied by using a combined oxidation washing process.The removal effects of uranium by two different new oxidation-washing systems(EDTA-H₂O₂ and SDS-H₂O₂)were compared.The effects of key parameters such as pH,liquid volume to solid mass ratio,oxidant concentration,and washing agent concentration on removal rate of uranium were investigated through single-factor experiments.The process conditions were optimized by response surface methodology,and the optimal conditions were determined.The results show that the removal rate of uranium by the EDTA-H₂O₂ system is 52.8% under the conditions of pH=4,liquid volume to solid mass ratio of 15/1,H₂O₂ concentration of 3%,and EDTA concentration of 100 mmol/L.After optimizing the process conditions by response surface methodology,the removal rate can be increased to 56.3%.The removal rate of uranium by the SDS- H₂O₂ system is 26.8% under the conditions of pH=4,liquid volume to solid mass ratio of 10/1,H₂O₂ concentration of 3%,and SDS concentration of 20 mmol/L.After optimizing the process conditions by response surface methodology,the removal rate can be increased to 29.5%.The removal effects of the two oxidation-washing systems are significantly better than those of single washing agents and single oxidants (EDTA 24.12%,SDS 0.66%,H₂O₂ 13.81%).The process can effectively break the complex of organic matter and uranium,significantly improve the remediation efficiency of real uranium-contaminated soil,and provide a feasible solution for uranium pollution control in mining areas.

Synthesization of mesoporous γ-AlOOH adsorbent via direct aging-ammonium salt substitution combined method in the presence of a desalting agent using metallurgical alumina hydroxide as raw material was investigated,and it was used for the adsorption of Congo red in wastewater.The physical phase and microscopic morphology of mesoporous γ-AlOOH were characterized by XRD,FT-IR,SEM,BET-BJH methods.The results show that the adsorption amount of Congo red by mesoporous γ-AlOOH adsorbent can reach 586.78 mg/g and the removal rate is 97.80% under the conditions of temperature of 25 ℃,adsorbent dosage of 100 mg,Congo red mass concentration of 300 mg/L,adsorption time of 180 min and pH=4.The adsorption process is more consistent with the pseudo-second-order kinetic model and the Langmuir isothermal adsorption model.The saturated adsorption capacity of mesoporous γ-AlOOH on Congo red is 1 965.265 mg/g at room temperature,and the adsorption process is spontaneous,heat absorption and chaotic.The main adsorption mechanism is the formation of hydrogen bonding between the adsorbent and adsorbate.

In view of the problem of secondary environmental pollution caused by acid leaching system for recycling waste lithium cathode materials,a green leaching system for obtaining cobalt carbonate with high efficiency was studied.The cobalt from waste lithium batteries was recovered by ammonia leaching—ion exchange resin method.The results show that under the conditions of ammonia concentration of 5 mol/L,NH₄Cl concentration of 0.7 mol/L,(NH₄)₂SO₃ concentration of 0.5 mol/L,temperature of 140 ℃,liquid volume to solid mass ratio of 20 g/1 L and reaction time of 50 min,the leaching rates of Co,Li and Ni are 88.0%,90.0% and 92.5%,respectively.Under the condition of temperature of 20 ℃ and flow rate of 1 mL/min,150 mL of ammonia leaching solution is selectively adsorbed by 40 g CH-90 resin,and the adsorption capacity of Co is 9.06 mg/g.FT-IR,SEM and XPS characterization results show that cobalt is exchanged with Na⁺ in the functional group of the resin and adsorbed on the resin in the form of [Co(NH₃)_i]²⁺.CoCO₃ products with purity exceeding 97.5% are obtained by using sodium carbonate precipitation to recover cobalt carbonate,after elution,precipitation and impurity removal.