Extraction of silica from fly ash to produce mesoporous silica materials is one of the most important utilization approaches.Mesoporous silica could not be synthesized on a large-scale by conventional sol-gel method.I...Extraction of silica from fly ash to produce mesoporous silica materials is one of the most important utilization approaches.Mesoporous silica could not be synthesized on a large-scale by conventional sol-gel method.In this paper,facile preparation of mesoporous silica with controllable pore structure from fly ash by the template-free process via two steps of mineral phase transformation and selective acid etching was proposed.The influence of crystalline structure and acid etching degree on structure of as-synthesized mesoporous silica materials was revealed,as well as mechanism of crystalline structure transformation and pore structure formation.The results show that mullite and quartz could be transformed into acid-soluble kaliophilite when fly ash reacted with K_(2)CO_(3)at temperature of 800-1100℃.The hexagonal kaliophilite would be transformed into orthorhombic KAlSiO_(4)-O1 phase when the temperature is controlled at 1100℃.Mesoporous silica with specific surface area of 475.93 m^(2)/g and 642.57 m^(2)/g could be synthesized from activated fly ash with kaliophilite and KAlSiO_(4)-O1 phase crystalline structure.By controlling the degree of acid etching,mesoporous silica materials with different pore structures can be obtained.This paper provides a cost-effective and large-scale process for the preparation of mesoporous silica materials with controllable pore structure from solid waste fly ash.展开更多
Antimony(Sb)in natural water has long-term effects on both the ecological environment and human health.Iron mineral phase transformation(IMPT)is a prominent process for removing Sb(V)from natural water.However,the imp...Antimony(Sb)in natural water has long-term effects on both the ecological environment and human health.Iron mineral phase transformation(IMPT)is a prominent process for removing Sb(V)from natural water.However,the importance of IMPT in eliminating Sb remains uncertain.This study examined the various Sb–Fe binding mechanisms found in different IMPT pathways in natural water,shedding light on the underlying mechanisms.The study revealed that the presence of goethite(Goe),hematite(Hem),and magnetite(Mag)significantly affected the concentration of Sb(V)in natural water.Elevated pH levels facilitated higher Fe content in iron solids but impeded the process of removing Sb(V).To further our understanding,polluted natural water samples were collected from various locations surrounding Sb smelter sites.Results confirmed that converting ferrihydrite(Fhy)to Goe significantly reduced Sb levels(<5μg/L)in natural water.The emergence of secondary iron phases resulted in greater electrostatic attraction and stabilized surface complexes,which was the most likely cause of the decline of Sb concentration in natural water.The comprehensive findings offer new insights into the factors governing IMPT as well as the Sb(V)behavior control.展开更多
基金supported by the National Natural Science Foundation of China(grant Nos.U21A20321 and 21908138)Shanxi Province Central Government Guided Local Science and Technology Development Fund Project(grant No.YDZJSX2022A004)Shanxi Province Scientific and Technological Innovation Project of Colleges and Universities(grant No.2020L0009).
文摘Extraction of silica from fly ash to produce mesoporous silica materials is one of the most important utilization approaches.Mesoporous silica could not be synthesized on a large-scale by conventional sol-gel method.In this paper,facile preparation of mesoporous silica with controllable pore structure from fly ash by the template-free process via two steps of mineral phase transformation and selective acid etching was proposed.The influence of crystalline structure and acid etching degree on structure of as-synthesized mesoporous silica materials was revealed,as well as mechanism of crystalline structure transformation and pore structure formation.The results show that mullite and quartz could be transformed into acid-soluble kaliophilite when fly ash reacted with K_(2)CO_(3)at temperature of 800-1100℃.The hexagonal kaliophilite would be transformed into orthorhombic KAlSiO_(4)-O1 phase when the temperature is controlled at 1100℃.Mesoporous silica with specific surface area of 475.93 m^(2)/g and 642.57 m^(2)/g could be synthesized from activated fly ash with kaliophilite and KAlSiO_(4)-O1 phase crystalline structure.By controlling the degree of acid etching,mesoporous silica materials with different pore structures can be obtained.This paper provides a cost-effective and large-scale process for the preparation of mesoporous silica materials with controllable pore structure from solid waste fly ash.
基金financially supported by the National Key R&D Program of China(No.2022YFC3900200)Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52121004)+3 种基金Major program Natural Science Foundation of Hunan Province of China(No.2021JC0001)National Natural Science Foundation of China(No.22276218)key projects of Science and Technology of Hunan Province(No.2020SK2006)Science and Technology Innovation Program of Hunan Province(No.2021RC3013).
文摘Antimony(Sb)in natural water has long-term effects on both the ecological environment and human health.Iron mineral phase transformation(IMPT)is a prominent process for removing Sb(V)from natural water.However,the importance of IMPT in eliminating Sb remains uncertain.This study examined the various Sb–Fe binding mechanisms found in different IMPT pathways in natural water,shedding light on the underlying mechanisms.The study revealed that the presence of goethite(Goe),hematite(Hem),and magnetite(Mag)significantly affected the concentration of Sb(V)in natural water.Elevated pH levels facilitated higher Fe content in iron solids but impeded the process of removing Sb(V).To further our understanding,polluted natural water samples were collected from various locations surrounding Sb smelter sites.Results confirmed that converting ferrihydrite(Fhy)to Goe significantly reduced Sb levels(<5μg/L)in natural water.The emergence of secondary iron phases resulted in greater electrostatic attraction and stabilized surface complexes,which was the most likely cause of the decline of Sb concentration in natural water.The comprehensive findings offer new insights into the factors governing IMPT as well as the Sb(V)behavior control.
