This study focuses on using a green reagent scheme of methanesulfonic acid (MSA) and citric acid (CA) to extract valuable metals from the cathodes, aiming to minimize environmental impact during the recycling process....This study focuses on using a green reagent scheme of methanesulfonic acid (MSA) and citric acid (CA) to extract valuable metals from the cathodes, aiming to minimize environmental impact during the recycling process. Leaching studies on LiCoO_(2) identified optimal conditions as follows: 2.4 mol/L MSA, 1.6 mol/L CA, S/L ratio of 80 g/L, leaching temperature of 90oC and leaching time of 6 h. The maximum Co and Li extraction achieved was 92% and 85%, respectively. LiCoO_(2) dissolution in MSA-CA leaching solution is highly impacted by temperature;Avrami equation showed a good fitting for the leaching data. The experimental activation energy of Co and Li was 50.98 kJ/mol and 50.55 kJ/mol, respectively, indicating that it is a chemical reaction-controlled process. Furthermore, cobalt was efficiently recovered from the leachate using oxalic acid, achieving a precipitation efficiency of 99.91% and a high-purity cobalt oxalate product (99.85 wt.%). In the MSA-CA leaching solution, MSA served as a lixiviant, while CA played a key role in reducing Co in LiCoO_(2). The overall organic acid leaching methodology presents an attractive option due to its reduced environmental impact.展开更多
It is still challenging for exploring high-active photocatalysts to efficiently remove levofloxacin(LFX)by activating peroxymonosulfate(PMS).Herein,we constructed a novel Z scheme ZnFe_(2)O_(4)/g-C_(3)N_(4)/CQDs(ZCC)h...It is still challenging for exploring high-active photocatalysts to efficiently remove levofloxacin(LFX)by activating peroxymonosulfate(PMS).Herein,we constructed a novel Z scheme ZnFe_(2)O_(4)/g-C_(3)N_(4)/CQDs(ZCC)heterojunction by anchoring ZnFe_(2)O_(4)on tubular-like g-C_(3)N_(4)induced by CQDs(denoted as CNC)using microwave-assisted thermal methods.The ZCC exhibits the highest photocatalytic activity in activating PMS for LFX degradation,endowing a removal rate~95.3%,which is 4.8 and 7.3 times that of pure ZnFe_(2)O_(4)(19.8%)and g-C_(3)N_(4)(13.1%),separately.The enhanced photocatalytic activity of ZCC can be attributed to the distinctive morphology of CNC,enhanced light response,increased specific surface area and abundant pore structure.Besides,the formed Z scheme heterojunction and CQDs acting as a transmission bridge of the photogenerated charges(e−and h+)can accelerate transfer and inhibit recombination of e−and h+.Radical capture experiments and electron spin resonance(ESR)measurements revealed that SO4•-and O2•-play a predominant role in degradation process of LFX.Liquid chromatography-mass spectrometry(LC-MS)was applied to identify intermediates and propose feasible degradation pathways of LFX.In conclusion,this study presents a promising strategy for regulating the photocatalytic activity of g-C_(3)N_(4)by simultaneously integrating CQDs induction and Z scheme heterojunction construction.展开更多
The breakage and bending of ducts result in a difficulty to cope with ventilation issues in bidirectional excavation tunnels with a long inclined shaft using a single ventilation method based on ducts.To discuss the h...The breakage and bending of ducts result in a difficulty to cope with ventilation issues in bidirectional excavation tunnels with a long inclined shaft using a single ventilation method based on ducts.To discuss the hybrid ventilation system applied in bidirectional excavation tunnels with a long inclined shaft,this study has established a full-scale computational fluid dynamics model based on field tests,the Poly-Hexcore method,and the sliding mesh technique.The distribution of wind speed,temperature field,and CO in the tunnel are taken as indices to compare the ventilation efficiency of three ventilation systems(duct,duct-ventilation shaft,duct–ventilated shaft-axial fan).The results show that the hybrid ventilation scheme based on duct-ventilation shaft–axial fan performs the best among the three ventilation systems.Compared to the duct,the wind speed and cooling rate in the tunnel are enhanced by 7.5%–30.6%and 14.1%–17.7%,respectively,for the duct-vent shaft-axial fan condition,and the volume fractions of CO are reduced by 26.9%–73.9%.This contributes to the effective design of combined ventilation for bidirectional excavation tunnels with an inclined shaft,ultimately improving the air quality within the tunnel.展开更多
The intensifying global energy crisis,coupled with environmental degradation from fossil fuels,highlights that photocatalytic hydrogen evolution technology offers a promising solution due to its efficiency and sustain...The intensifying global energy crisis,coupled with environmental degradation from fossil fuels,highlights that photocatalytic hydrogen evolution technology offers a promising solution due to its efficiency and sustainability.In this study,we synthesized CeO_(2)/Cd_(7.23)Zn_(2.77)S_(10)-DETA(diethylenetriamine is abbreviated as DETA,and subsequently CeO_(2)is referred to as EO,Cd_(7.23)Zn_(2.77)S_(10)-DETA is abbreviated as ZCS,and the composite with EO comprising 30%is abbreviated as EO/ZCS)nanocomposites with S-scheme heterojunctions.Under conditions without external co-catalysts and utilizing only visible light as the excitation source,EO/ZCS nanocomposites exhibited outstanding photocatalytic hydrogen evolution activity and remarkable stability,presenting significant advantages over conventional methods that rely on co-catalysts and ultraviolet light.The photocatalytic hydrogen evolution rate of EO/ZCS nanocomposites reached 4.11 mmol/(g·h),significantly surpassing that of EO(trace)and ZCS(2.78 mmol/(g·h)).This substantial enhancement is attributed to the S-scheme charge transfer mechanism at the heterojunctions in EO/ZCS nanocomposites,which effectively facilitates the efficient separation and transfer of photogenerated electron-hole pairs,thereby substantially enhancing photocatalytic hydrogen evolution activity.Through techniques such as X-ray photoelectron spectroscopy(XPS)and theoretical calculations,we confirmed the formation of S-scheme heterojunctions and elucidated their photocatalytic hydrogen evolution mechanism.The results underscore the potential of EO/ZCS nanocomposites as highly efficient and stable photocatalysts for hydrogen production under environmentally benign conditions.展开更多
文摘This study focuses on using a green reagent scheme of methanesulfonic acid (MSA) and citric acid (CA) to extract valuable metals from the cathodes, aiming to minimize environmental impact during the recycling process. Leaching studies on LiCoO_(2) identified optimal conditions as follows: 2.4 mol/L MSA, 1.6 mol/L CA, S/L ratio of 80 g/L, leaching temperature of 90oC and leaching time of 6 h. The maximum Co and Li extraction achieved was 92% and 85%, respectively. LiCoO_(2) dissolution in MSA-CA leaching solution is highly impacted by temperature;Avrami equation showed a good fitting for the leaching data. The experimental activation energy of Co and Li was 50.98 kJ/mol and 50.55 kJ/mol, respectively, indicating that it is a chemical reaction-controlled process. Furthermore, cobalt was efficiently recovered from the leachate using oxalic acid, achieving a precipitation efficiency of 99.91% and a high-purity cobalt oxalate product (99.85 wt.%). In the MSA-CA leaching solution, MSA served as a lixiviant, while CA played a key role in reducing Co in LiCoO_(2). The overall organic acid leaching methodology presents an attractive option due to its reduced environmental impact.
基金Project(32272823) supported by the National Natural Science Foundation of ChinaProject(145309315) supported by the Research Foundation of Education Bureau of Heilongjiang Province of ChinaProject(YSTSXK202309) supported by the Plant Food Processing Technology Advantages Characteristic Discipline “Science and Technology Research” Special Project in Heilongjiang Province,China。
文摘It is still challenging for exploring high-active photocatalysts to efficiently remove levofloxacin(LFX)by activating peroxymonosulfate(PMS).Herein,we constructed a novel Z scheme ZnFe_(2)O_(4)/g-C_(3)N_(4)/CQDs(ZCC)heterojunction by anchoring ZnFe_(2)O_(4)on tubular-like g-C_(3)N_(4)induced by CQDs(denoted as CNC)using microwave-assisted thermal methods.The ZCC exhibits the highest photocatalytic activity in activating PMS for LFX degradation,endowing a removal rate~95.3%,which is 4.8 and 7.3 times that of pure ZnFe_(2)O_(4)(19.8%)and g-C_(3)N_(4)(13.1%),separately.The enhanced photocatalytic activity of ZCC can be attributed to the distinctive morphology of CNC,enhanced light response,increased specific surface area and abundant pore structure.Besides,the formed Z scheme heterojunction and CQDs acting as a transmission bridge of the photogenerated charges(e−and h+)can accelerate transfer and inhibit recombination of e−and h+.Radical capture experiments and electron spin resonance(ESR)measurements revealed that SO4•-and O2•-play a predominant role in degradation process of LFX.Liquid chromatography-mass spectrometry(LC-MS)was applied to identify intermediates and propose feasible degradation pathways of LFX.In conclusion,this study presents a promising strategy for regulating the photocatalytic activity of g-C_(3)N_(4)by simultaneously integrating CQDs induction and Z scheme heterojunction construction.
基金Project(N2022G031)supported by the Science and Technology Research and Development Program Project of China RailwayProjects(2022-Key-23,2021-Special-01A)supported by the Science and Technology Research and Development Program Project of China Railway Group LimitedProject(52308419)supported by the National Natural Science Foundation of China。
文摘The breakage and bending of ducts result in a difficulty to cope with ventilation issues in bidirectional excavation tunnels with a long inclined shaft using a single ventilation method based on ducts.To discuss the hybrid ventilation system applied in bidirectional excavation tunnels with a long inclined shaft,this study has established a full-scale computational fluid dynamics model based on field tests,the Poly-Hexcore method,and the sliding mesh technique.The distribution of wind speed,temperature field,and CO in the tunnel are taken as indices to compare the ventilation efficiency of three ventilation systems(duct,duct-ventilation shaft,duct–ventilated shaft-axial fan).The results show that the hybrid ventilation scheme based on duct-ventilation shaft–axial fan performs the best among the three ventilation systems.Compared to the duct,the wind speed and cooling rate in the tunnel are enhanced by 7.5%–30.6%and 14.1%–17.7%,respectively,for the duct-vent shaft-axial fan condition,and the volume fractions of CO are reduced by 26.9%–73.9%.This contributes to the effective design of combined ventilation for bidirectional excavation tunnels with an inclined shaft,ultimately improving the air quality within the tunnel.
基金Project(42407636)supported by the National Natural Science Foundation of ChinaProject(2022AH040068)supported by the Major Foundation of the Educational Commission of Anhui Province,China+2 种基金Project(2023AH051861)supported by the Natural Science Research Project for Colleges and Universities in Anhui Province,ChinaProject(SPYJ202201)supported by the Talent Introduction Foundation of Anhui Science and Technology University,ChinaProject(202310879096)supported by the Innovation and Entrepreneurship Training Program for College Students,China。
文摘The intensifying global energy crisis,coupled with environmental degradation from fossil fuels,highlights that photocatalytic hydrogen evolution technology offers a promising solution due to its efficiency and sustainability.In this study,we synthesized CeO_(2)/Cd_(7.23)Zn_(2.77)S_(10)-DETA(diethylenetriamine is abbreviated as DETA,and subsequently CeO_(2)is referred to as EO,Cd_(7.23)Zn_(2.77)S_(10)-DETA is abbreviated as ZCS,and the composite with EO comprising 30%is abbreviated as EO/ZCS)nanocomposites with S-scheme heterojunctions.Under conditions without external co-catalysts and utilizing only visible light as the excitation source,EO/ZCS nanocomposites exhibited outstanding photocatalytic hydrogen evolution activity and remarkable stability,presenting significant advantages over conventional methods that rely on co-catalysts and ultraviolet light.The photocatalytic hydrogen evolution rate of EO/ZCS nanocomposites reached 4.11 mmol/(g·h),significantly surpassing that of EO(trace)and ZCS(2.78 mmol/(g·h)).This substantial enhancement is attributed to the S-scheme charge transfer mechanism at the heterojunctions in EO/ZCS nanocomposites,which effectively facilitates the efficient separation and transfer of photogenerated electron-hole pairs,thereby substantially enhancing photocatalytic hydrogen evolution activity.Through techniques such as X-ray photoelectron spectroscopy(XPS)and theoretical calculations,we confirmed the formation of S-scheme heterojunctions and elucidated their photocatalytic hydrogen evolution mechanism.The results underscore the potential of EO/ZCS nanocomposites as highly efficient and stable photocatalysts for hydrogen production under environmentally benign conditions.
