The adsorption method has the advantages of low cost,high efficiency,and environmental friendliness in treating fluorinated wastewater,and the adsorbent material is the key.This study combines the inherent anion-excha...The adsorption method has the advantages of low cost,high efficiency,and environmental friendliness in treating fluorinated wastewater,and the adsorbent material is the key.This study combines the inherent anion-exchange adsorption properties of layered double hydroxides(LDHs).Self-supported porous adsorbent materials loaded with AFm and AFt were prepared from a composite cementitious system consisting of calcium aluminate cement(CAC)and flue gas desulfurization gypsum(FGDG)by chemical foaming technique.The mineral composition of the adsorbent material was characterized by X-ray diffraction(XRD)and Scanning electron microscopy(SEM).Through the static adsorption experiment,the adsorption effect of the mineral composition of the adsorbent on fluoride ions was deeply analyzed,and the adsorption mechanism was revealed.XRD and SEM showed that the main hydration phases of the composite cementitious system consisting of CAC and FGDG are AFm,AFt,AH_(3),and CaSO_(4)·2H_(2)O.FGDG accelerates the hydration process of CAC and inhibits the transformation of AFt to AFm.The AFt content increased,and the AFm content decreased or even disappeared as the amount of FGDG increased.Static adsorption experiment results showed that AFm and AFt in adsorbent materials could significantly enhance the adsorption of fluoride ions.The adsorption of F^(−)in aqueous solution by PAG tends more towards monolayer adsorption with a theoretical maximum capacity of 108.70 mg/g and is similar to the measured value of 112.77 mg/g.展开更多
The effects of fluoride ions(F^(-)) on the electrochemical behavior and coordination properties of titanium ions(Ti^(n+)) were studied in this work,by combining electrochemical and mathematical analysis as well as spe...The effects of fluoride ions(F^(-)) on the electrochemical behavior and coordination properties of titanium ions(Ti^(n+)) were studied in this work,by combining electrochemical and mathematical analysis as well as spectral techniques.The α was taken as a factor to indicate the molar concentration ratio of F^(-) and Ti^(n+).Cyclic voltammetry(CV),square wave voltammetry(SWV),and open circuit potential method(OCP)were used to study the electrochemical behavior of titanium ions under conditions of various α,and in-situ sampler was used to prepare molten salt samples when α equal to 0.0,1.0,2.0,3.0,4.0,5.0,6.0,and 8.0.And then,samples were analyzed by X-ray photoelectron spectroscopy(XPS) and Raman spectroscopy.The results showed that F^(-) in molten salt can reduce the reduction steps of titanium ions and greatly affects the proportion of valence titanium ions which making the high-valence titanium content increased and more stable.Ti^(2+) cannot be detected in the molten salt when α is higher than 3.0 and finally transferred to titanium ions with higher valence state.Investigation revealed that the mechanism behind those phenomenon is the coordination compounds(TiCl_(j) F_(i)^(m-)) forming.展开更多
The dynamic corrosion behaviors of Ti-6Al-4V alloy in acid artificial saliva containing fluoride ion were traced using electrochemical techniques,optical microscope,scanning electron microscopy,energy dispersive spect...The dynamic corrosion behaviors of Ti-6Al-4V alloy in acid artificial saliva containing fluoride ion were traced using electrochemical techniques,optical microscope,scanning electron microscopy,energy dispersive spectrometer and roughness tester.The experimental results indicate that a negative shift of corrosion potential as well as a continuous decrease in impedance for the alloy exists with increasing immersion time,and the degradation rate of the alloy presents the trend of first increase then decrease following the dissolution of passivation film and the formation of corrosion products.The accumulated fluoride ion on the alloy surface accelerates the fracture of passivation film,and the occurrence and development of corrosion of alloy are mainly located at the sites where the formation and shedding of white particles are composed of fluoride compounds,resulting in the decrease of corrosion resisting property of the alloy.A possible model is proposed to elaborate the dynamic corrosion behavior of the alloy.展开更多
To study a kind of high-efficiency fluoride removal agent based on aluminum salt,through theoretical and experimental research,the influence of different factors(dosage of agent,concentration of fluoride ions,pH,TDS,h...To study a kind of high-efficiency fluoride removal agent based on aluminum salt,through theoretical and experimental research,the influence of different factors(dosage of agent,concentration of fluoride ions,pH,TDS,hardness and alkalinity,etc.)on the removal effect of fluoride ions by fluoride removal agent in industrial wastewater,especially mine water was analyzed.The results show that the fluoride ion removal agent based on aluminum salt could achieve efficient removal of fluoride ions,and the optimal mass ratio of fluoride ion concentration and compound reagent was 1∶130.The concentration of fluoride ions in the water produced after precipitation was≤1 mg/L under the optimal pH condition.As the pH of the solution was 6.5-7.5,the effect of fluoride removal by the agent was the highest.When the pH of the solution was>10.5 or<5,there was no effect of fluoride removal.Under the conditions of optimal pH and reagent dosage,the removal rate of fluoride ions rose with the increase of fluoride ion concentration in wastewater,up to 87.4%.It is also verified that TDS had no obvious effect on fluoride removal,and the smaller the hardness and alkalinity,the better the effect of fluoride removal.展开更多
Novel CaCO_(3)-enhanced Mn-Fe mixed metal oxides(CMFC)were successfully prepared for the first time by a simple-green hydrothermal strategy without any surfactant or template combined with calcination process.These ox...Novel CaCO_(3)-enhanced Mn-Fe mixed metal oxides(CMFC)were successfully prepared for the first time by a simple-green hydrothermal strategy without any surfactant or template combined with calcination process.These oxides were then employed as an adsorbent for adsorptive removal of excess fluoride ions.The adsorbent was characterized by SEM,XPS,XRD,FTIR,and BET analysis techniques.The adsorption property of CMFC toward fluoride ion was analyzed by batch experiments.In fact,CMFC exhibited adsorption capacity of 227.3 mg∙g^(-1)toward fluoride ion.Results showed that ion exchange,electrostatic attraction and chemical adsorption were the main mechanism for the adhesion of large amount of fluoride ion on the CMFC surface,and the high adsorption capacity responded to the low pH of the adsorption system.When the fluoride ion concentration was increased from 20 to 200 mg∙L^(-1),Langmuir model was more in line with experimental results.The change of fluoride ion adsorption with respect to time was accurately described by pseudosecond-order kinetics.After five cycles of use,the adsorbent still maintains a performance of 70.6%of efficiency,compared to the fresh adsorbent.Therefore,this material may act as a potential candidate for adsorbent with broad range of application prospects.展开更多
Neodymium oxyfluoride has received much attention in the fields of anionic solid electrolytes.luminescent,catalytic and magnetic materials because of its structure combined advantages of rareearth cations with F^(-)an...Neodymium oxyfluoride has received much attention in the fields of anionic solid electrolytes.luminescent,catalytic and magnetic materials because of its structure combined advantages of rareearth cations with F^(-)and O_(2)^(-)anions.In this work,neodynium oxyfluoride was synthesized by the reaction between neodymium oxide and four fluoride media with different fluoride ion activities.The synthesis processes in molten LiF-CaF_(2)-NdF_(3),LiF-NdF_(3),NaF-CaF_(2)-NdF_(3)and NaF-KF-NdF_(3)are observed in situ by a confocal scanning laser microscope.The expansion of neodymium oxide particle is observed in the LiF-CaF_(2)-NdF_(3),LiF-NdF_(3),and NaF-KF-NdF_(3)melts,and the growth of needle crystals on neodymium oxide particle is clearly observed in molten NaF-CaF_(2)-NdF_(3).Based on scanning electron microscopy(SEM)-energy dispersive X-ray spectroscopy(EDS)and X-ray diffraction(XRD)analyses of products,neodynium oxyfluoride was successfully synthesized in the four fluoride media.The neodynium oxyfluoride generated in the LiF-CaF_(2)-NdF_(3),LiF-NdF_(3),and NaF-KF-NdF_(3)melts is a tetragonal structure.However,in molten NaF-CaF_(2)-NdF_(3),neodynium oxyfluoride with a rhombohedral structure is formed.It is suggested that the substitution of Na(Ⅰ)and Ca(Ⅱ)for Nd(Ⅲ)can transform NdOF from tetragonal structure to rhombohedral structure.The growth rate of needle crystals generated in molten NaF-CaF_(2)-NdF_(3)was calculated based on the result of a confocal scanning laser microscope,and it is found that the reaction kinetics of crystal formation is zero-order reaction.The effect of fluoride media on the structure and morphology of formed NdOF were evaluated by XRD,X-ray photoelectron spectroscopy(XPS)and SEM.The neodymium oxyfluoride prepared in the fluoride media with high fluoride ion activity has low binding energy of F 1 s.The ratio of adsorbed oxygen to lattice oxygen for neodymium oxyfluoride prepared in molten LiF-NdF_(3)is larger than those in the other three fluoride media,so it can have better catalytic performance.展开更多
Fluoride is widespread in the environment, water, air, vegetation and Earth’s crust which can entre ground and surface water by natural process. Fluoride in minute quantities is essential component for human health a...Fluoride is widespread in the environment, water, air, vegetation and Earth’s crust which can entre ground and surface water by natural process. Fluoride in minute quantities is essential component for human health and help in normal mineralization of bone and formation of dental enamel. The determination of fluoride in some species was performed by using fluoride ion-selective electrode by direct measurement and standard addition method. The concentration of fluoride ion was determined in drinking water (from different place at Kathmandu), toothpaste, various brand of tea and coffees. The range of fluoride concentration in water sample was 0.16 to 0.39 mg/l, tea and coffee samples were 0.011 to 0.084 mg/l and its value of toothpaste was 0.026 to 0.75 mg/l. The concentration of fluoride ion obtain from different sample was compared with the legitimate value given by the world health organization.展开更多
As a monoatomic bridge,fluoride ion can transmit efficient magnetic interaction between lanthanide ions but its effect on tuning the magnetization dynamics has not been well understood.Herein,two monofluoride-bridged ...As a monoatomic bridge,fluoride ion can transmit efficient magnetic interaction between lanthanide ions but its effect on tuning the magnetization dynamics has not been well understood.Herein,two monofluoride-bridged dinuclear dysprosium complexes[Dy_(2)F(bbpen)_(2)(Et OH)_(2)]Br·Et OH(1)and[Dy_(2)F(bbppy)_(2)]Br·2Et OH(2)with Dy-F-Dy angles of~178°and their diamagnetic-ion diluted analogues 1'and 2'were synthesized.Magnetic studies reveal that 1 and 1'barely show any magnetization dynamics,but 2 and 2'exhibit strong magnetization dynamics.Systematical experimental analysis combined with ab initio calculations reveals that the different magnetization dynamics between 1 and 2 mainly originate from the effect of magnetic anisotropy by terminal ligand and bridging group of the chelating ligand,and the fluoride bridge can effectively suppress the quantum tunneling of the magnetization and turn on Orbach process in 2.展开更多
Water fluoride pollution has caused non-negligible harm to the environment and humans,and thus it is crucial to find a suitable treatment technology.In this study,La-Fe@PTA adsorbent was synthesized for the defluorida...Water fluoride pollution has caused non-negligible harm to the environment and humans,and thus it is crucial to find a suitable treatment technology.In this study,La-Fe@PTA adsorbent was synthesized for the defluoridation of mine water.The results showed that the optimum conditions for defluoridation by La-Fe@PTA were p H close to 7.0,the initial F-concentration of 10 mg/L,the dosage of 0.5 g/L and the adsorption time of 240 min.Compared with SO_4^(2-),Cl^(-),NO_(3)^(-),Ca^(2+)and Mg^(2+),CO_(3)^(2-)and HCO_(3)^(-)presented severer inhibition on fluoride uptake by La-Fe@PTA.The adsorption process fits well with the pseudo-second-order kinetic model and Freundlich model,and the maximum adsorption capacity of Langmuir model was 95 mg/g.Fixed-bed adsorption results indicated that fluoride in practical fluorinated mine water could be effectively removed from 3.6 mg/L to less than 1.5 mg/L within130 bed volume(BV)by using 1.5 g La-Fe@PTA.Furthermore,the adsorbent still had good adsorption capacity after regeneration,which confirms the great application potential of La-Fe@PTA as a fluoride ion adsorbent.The mechanism analysis showed that La-Fe@PTA adsorption of fluorine ions is a physicochemical reaction driven by electrostatic attraction and ion exchange.展开更多
It is still a challenge to eliminate efficiently fluoride ion from groundwater,especially to design and synthesis an adsorbent possessing high adsorption capacity,recyclability and wide pH application conditions.Herei...It is still a challenge to eliminate efficiently fluoride ion from groundwater,especially to design and synthesis an adsorbent possessing high adsorption capacity,recyclability and wide pH application conditions.Herein we present millimeter-sized sulfate-type zirconium alginate hydrogel beads with 3D network structure(AHB@Zr-SO^(2−)_(4))that exhibited a maximum adsorption capacity of 101.3 mg/g with wide pH applicability(pH 3−9).This material have~2.5 times higher adsorption capacity than that of pure zirconium alginate hydrogel beads(AHB@Zr)and it was ascribed to ion exchange between SO^(2−)_(4)and F−on the surface of AHB@Zr-SO^(2−)_(4),which was verified via ion chromatography measurement coupled with X-ray photoelectron spectroscopy(XPS)and Fourier Transform Infrared Spectrometer(FTIR Spectrometer)analysis.Density functional theory(DFT)calculations indicated that the ion exchange process between SO^(2−)_(4)and F−in AHB@Zr-SO^(2−)_(4)was energetically favorable than OH^(−)and F^(−)in AHB@Zr.In addition,310 bed volumes(BV)of effluent was realized via column adsorption of groundwater containing fluoride on AHB@Zr-SO^(2−)_(4)and indicated that it is a promising candidate for mitigating the problem of fluoride-containing groundwater.展开更多
The detection of pathogenic bacteria with improved accessibility,reduced analysis time,and increased sensitivity is of great importance for diagnosing the infected disease.Nanozymes have attracted rising attention in ...The detection of pathogenic bacteria with improved accessibility,reduced analysis time,and increased sensitivity is of great importance for diagnosing the infected disease.Nanozymes have attracted rising attention in the bioassay field.Designing a model nanozyme needs the combined merit of sensible nanostructures and a large specific surface area to guarantee exceptional enzyme-mimic activity.Herein,aβ-cyclodextrin modified AuBi aerogel is prepared by a one-pot reduction strategy.The introduction ofβ-cyclodextrin(featured with a hydrophobic cavity and hydrophilic surface)enhances the catalytic activity of AuBi aerogels by engendering host-guest complex and improving dispersity/stability.Based on the specific urea hydrolysis,which could produce NH_(3)to raise pH by urease,the pH up-regulation would inhibit the peroxidase-mimicking performances ofβ-cyclodextrin/AuBi aerogels.Therefore,the sensitive colorimetric detection platform for urease activity could be constructed.Moreover,the sensing platform can detect straightforwardly urease-positive Proteus mirabilis in urine circumstances with a wide detection range and a low limit of detection(LOD)of 4 colony-forming unit(CFU)·mL^(-1).The reproducibility,stability,and specificity of this approach are verified to be satisfactory.Also,as an inhibitor of urease activity,the fluoride ion could be detected by the constructed sensing platform sensitively and specifically.Overall,this work provides a blueprint for designing an ideal nanozyme and paves a new roadway for detecting pathogenic bacteria.展开更多
The cellular structured titanium alloys have attracted significant attention for implants because of their lower Young’s modulus,which is comparable to human bone and has the capability of providing space for bone ti...The cellular structured titanium alloys have attracted significant attention for implants because of their lower Young’s modulus,which is comparable to human bone and has the capability of providing space for bone tissue in-growth.However,there is a gap in the knowledge in regard to the relationship between the pore characteristics and the electrochemical performance of open-cellular structured titanium alloys.In this study,we elucidate the influence of pore characteristics on the electrochemical performance of open-cellular structured Ti-6Al-4V alloys produced by electron beam melting(EBM).Intriguingly,the passive film formed on cellular structured Ti-6Al-4V alloy with a larger pore size was more stable and protective,and the corrosion performance was superior compared to the samples with a smaller pore size in phosphate buffered saline(PBS),mainly because of relatively smaller exposed surface area and unlimited flow of electrolyte.However,in acidic PBS containing fluoride ions,the pore characteristics did not play an important role in the corrosion resistance.It was considered that the protective film breaks down such that the corrosion performance of cellular structured alloys was comparable to each other in this harsh environment.展开更多
基金supported by the National Natural Science Foundation of China(No.52279138)supported by Scientific Research Project of Shanxi Province(2018SF-367).
文摘The adsorption method has the advantages of low cost,high efficiency,and environmental friendliness in treating fluorinated wastewater,and the adsorbent material is the key.This study combines the inherent anion-exchange adsorption properties of layered double hydroxides(LDHs).Self-supported porous adsorbent materials loaded with AFm and AFt were prepared from a composite cementitious system consisting of calcium aluminate cement(CAC)and flue gas desulfurization gypsum(FGDG)by chemical foaming technique.The mineral composition of the adsorbent material was characterized by X-ray diffraction(XRD)and Scanning electron microscopy(SEM).Through the static adsorption experiment,the adsorption effect of the mineral composition of the adsorbent on fluoride ions was deeply analyzed,and the adsorption mechanism was revealed.XRD and SEM showed that the main hydration phases of the composite cementitious system consisting of CAC and FGDG are AFm,AFt,AH_(3),and CaSO_(4)·2H_(2)O.FGDG accelerates the hydration process of CAC and inhibits the transformation of AFt to AFm.The AFt content increased,and the AFm content decreased or even disappeared as the amount of FGDG increased.Static adsorption experiment results showed that AFm and AFt in adsorbent materials could significantly enhance the adsorption of fluoride ions.The adsorption of F^(−)in aqueous solution by PAG tends more towards monolayer adsorption with a theoretical maximum capacity of 108.70 mg/g and is similar to the measured value of 112.77 mg/g.
基金financially supported by the National Natural Science Foundation of China(No.51804277)the State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization,China(No.CNMRCUKF2008)+1 种基金the State Key Laboratory of Special Rare Metal Materials,China(No.SKL2020K004)the Northwest Rare Metal Materials Research Institute,China。
文摘The effects of fluoride ions(F^(-)) on the electrochemical behavior and coordination properties of titanium ions(Ti^(n+)) were studied in this work,by combining electrochemical and mathematical analysis as well as spectral techniques.The α was taken as a factor to indicate the molar concentration ratio of F^(-) and Ti^(n+).Cyclic voltammetry(CV),square wave voltammetry(SWV),and open circuit potential method(OCP)were used to study the electrochemical behavior of titanium ions under conditions of various α,and in-situ sampler was used to prepare molten salt samples when α equal to 0.0,1.0,2.0,3.0,4.0,5.0,6.0,and 8.0.And then,samples were analyzed by X-ray photoelectron spectroscopy(XPS) and Raman spectroscopy.The results showed that F^(-) in molten salt can reduce the reduction steps of titanium ions and greatly affects the proportion of valence titanium ions which making the high-valence titanium content increased and more stable.Ti^(2+) cannot be detected in the molten salt when α is higher than 3.0 and finally transferred to titanium ions with higher valence state.Investigation revealed that the mechanism behind those phenomenon is the coordination compounds(TiCl_(j) F_(i)^(m-)) forming.
基金Funded by the National Natural Science Foundation of China(No.50801057)the Engineering Research Center of Nano-Geo Materials of Ministry of Education,China University of Geosciences(No.NGM2018KF015)。
文摘The dynamic corrosion behaviors of Ti-6Al-4V alloy in acid artificial saliva containing fluoride ion were traced using electrochemical techniques,optical microscope,scanning electron microscopy,energy dispersive spectrometer and roughness tester.The experimental results indicate that a negative shift of corrosion potential as well as a continuous decrease in impedance for the alloy exists with increasing immersion time,and the degradation rate of the alloy presents the trend of first increase then decrease following the dissolution of passivation film and the formation of corrosion products.The accumulated fluoride ion on the alloy surface accelerates the fracture of passivation film,and the occurrence and development of corrosion of alloy are mainly located at the sites where the formation and shedding of white particles are composed of fluoride compounds,resulting in the decrease of corrosion resisting property of the alloy.A possible model is proposed to elaborate the dynamic corrosion behavior of the alloy.
基金Supported by the Science and Technology Achievements Transformation Project of Ordos City—Synthesis and Technology Development of Targeted Agents for the Treatment of Wastewater Containing Fluorine and Silica(2021CG Society2-4)Special Project for Science and Technology Achievements Transformation of Inner Mongolia Autonomous Region—Recycling Project of 15000 m^(3)/d+15000 m^(3)/d Reclaimed Water in Dongsheng District。
文摘To study a kind of high-efficiency fluoride removal agent based on aluminum salt,through theoretical and experimental research,the influence of different factors(dosage of agent,concentration of fluoride ions,pH,TDS,hardness and alkalinity,etc.)on the removal effect of fluoride ions by fluoride removal agent in industrial wastewater,especially mine water was analyzed.The results show that the fluoride ion removal agent based on aluminum salt could achieve efficient removal of fluoride ions,and the optimal mass ratio of fluoride ion concentration and compound reagent was 1∶130.The concentration of fluoride ions in the water produced after precipitation was≤1 mg/L under the optimal pH condition.As the pH of the solution was 6.5-7.5,the effect of fluoride removal by the agent was the highest.When the pH of the solution was>10.5 or<5,there was no effect of fluoride removal.Under the conditions of optimal pH and reagent dosage,the removal rate of fluoride ions rose with the increase of fluoride ion concentration in wastewater,up to 87.4%.It is also verified that TDS had no obvious effect on fluoride removal,and the smaller the hardness and alkalinity,the better the effect of fluoride removal.
基金the Shihezi Science and Technology Plan Project of Eight Division(Grant No.2019GY04)the Double First-Class Counterpart Support University Cooperation Project(Grant No.SHYL-DK201802)the Major Science and Technology Project of Xinjiang Bingtuan(Grant No.2017AA007).
文摘Novel CaCO_(3)-enhanced Mn-Fe mixed metal oxides(CMFC)were successfully prepared for the first time by a simple-green hydrothermal strategy without any surfactant or template combined with calcination process.These oxides were then employed as an adsorbent for adsorptive removal of excess fluoride ions.The adsorbent was characterized by SEM,XPS,XRD,FTIR,and BET analysis techniques.The adsorption property of CMFC toward fluoride ion was analyzed by batch experiments.In fact,CMFC exhibited adsorption capacity of 227.3 mg∙g^(-1)toward fluoride ion.Results showed that ion exchange,electrostatic attraction and chemical adsorption were the main mechanism for the adhesion of large amount of fluoride ion on the CMFC surface,and the high adsorption capacity responded to the low pH of the adsorption system.When the fluoride ion concentration was increased from 20 to 200 mg∙L^(-1),Langmuir model was more in line with experimental results.The change of fluoride ion adsorption with respect to time was accurately described by pseudosecond-order kinetics.After five cycles of use,the adsorbent still maintains a performance of 70.6%of efficiency,compared to the fresh adsorbent.Therefore,this material may act as a potential candidate for adsorbent with broad range of application prospects.
基金Project supported by National Key Research and Development Program of China(2020YFC1909102)Natural Science Foundation of Inner Mongolia(2020BS05033)+1 种基金Inner Mongolia Major Basic Research Open Project(0406091701)Major Projects of Natural Science Foundation of Inner Mongolia of China(2018ZD07)。
文摘Neodymium oxyfluoride has received much attention in the fields of anionic solid electrolytes.luminescent,catalytic and magnetic materials because of its structure combined advantages of rareearth cations with F^(-)and O_(2)^(-)anions.In this work,neodynium oxyfluoride was synthesized by the reaction between neodymium oxide and four fluoride media with different fluoride ion activities.The synthesis processes in molten LiF-CaF_(2)-NdF_(3),LiF-NdF_(3),NaF-CaF_(2)-NdF_(3)and NaF-KF-NdF_(3)are observed in situ by a confocal scanning laser microscope.The expansion of neodymium oxide particle is observed in the LiF-CaF_(2)-NdF_(3),LiF-NdF_(3),and NaF-KF-NdF_(3)melts,and the growth of needle crystals on neodymium oxide particle is clearly observed in molten NaF-CaF_(2)-NdF_(3).Based on scanning electron microscopy(SEM)-energy dispersive X-ray spectroscopy(EDS)and X-ray diffraction(XRD)analyses of products,neodynium oxyfluoride was successfully synthesized in the four fluoride media.The neodynium oxyfluoride generated in the LiF-CaF_(2)-NdF_(3),LiF-NdF_(3),and NaF-KF-NdF_(3)melts is a tetragonal structure.However,in molten NaF-CaF_(2)-NdF_(3),neodynium oxyfluoride with a rhombohedral structure is formed.It is suggested that the substitution of Na(Ⅰ)and Ca(Ⅱ)for Nd(Ⅲ)can transform NdOF from tetragonal structure to rhombohedral structure.The growth rate of needle crystals generated in molten NaF-CaF_(2)-NdF_(3)was calculated based on the result of a confocal scanning laser microscope,and it is found that the reaction kinetics of crystal formation is zero-order reaction.The effect of fluoride media on the structure and morphology of formed NdOF were evaluated by XRD,X-ray photoelectron spectroscopy(XPS)and SEM.The neodymium oxyfluoride prepared in the fluoride media with high fluoride ion activity has low binding energy of F 1 s.The ratio of adsorbed oxygen to lattice oxygen for neodymium oxyfluoride prepared in molten LiF-NdF_(3)is larger than those in the other three fluoride media,so it can have better catalytic performance.
文摘Fluoride is widespread in the environment, water, air, vegetation and Earth’s crust which can entre ground and surface water by natural process. Fluoride in minute quantities is essential component for human health and help in normal mineralization of bone and formation of dental enamel. The determination of fluoride in some species was performed by using fluoride ion-selective electrode by direct measurement and standard addition method. The concentration of fluoride ion was determined in drinking water (from different place at Kathmandu), toothpaste, various brand of tea and coffees. The range of fluoride concentration in water sample was 0.16 to 0.39 mg/l, tea and coffee samples were 0.011 to 0.084 mg/l and its value of toothpaste was 0.026 to 0.75 mg/l. The concentration of fluoride ion obtain from different sample was compared with the legitimate value given by the world health organization.
基金supported by the National Key R&D Program of China(No.2018YFA0306002)the National Natural Science Foundation of China(Nos.21971123 and 21973046)the Natural Science Foundation of Tianjin(No.18JCJQJC47200)。
文摘As a monoatomic bridge,fluoride ion can transmit efficient magnetic interaction between lanthanide ions but its effect on tuning the magnetization dynamics has not been well understood.Herein,two monofluoride-bridged dinuclear dysprosium complexes[Dy_(2)F(bbpen)_(2)(Et OH)_(2)]Br·Et OH(1)and[Dy_(2)F(bbppy)_(2)]Br·2Et OH(2)with Dy-F-Dy angles of~178°and their diamagnetic-ion diluted analogues 1'and 2'were synthesized.Magnetic studies reveal that 1 and 1'barely show any magnetization dynamics,but 2 and 2'exhibit strong magnetization dynamics.Systematical experimental analysis combined with ab initio calculations reveals that the different magnetization dynamics between 1 and 2 mainly originate from the effect of magnetic anisotropy by terminal ligand and bridging group of the chelating ligand,and the fluoride bridge can effectively suppress the quantum tunneling of the magnetization and turn on Orbach process in 2.
基金supported by the National Natural Science Foundation of China(No.51978658)。
文摘Water fluoride pollution has caused non-negligible harm to the environment and humans,and thus it is crucial to find a suitable treatment technology.In this study,La-Fe@PTA adsorbent was synthesized for the defluoridation of mine water.The results showed that the optimum conditions for defluoridation by La-Fe@PTA were p H close to 7.0,the initial F-concentration of 10 mg/L,the dosage of 0.5 g/L and the adsorption time of 240 min.Compared with SO_4^(2-),Cl^(-),NO_(3)^(-),Ca^(2+)and Mg^(2+),CO_(3)^(2-)and HCO_(3)^(-)presented severer inhibition on fluoride uptake by La-Fe@PTA.The adsorption process fits well with the pseudo-second-order kinetic model and Freundlich model,and the maximum adsorption capacity of Langmuir model was 95 mg/g.Fixed-bed adsorption results indicated that fluoride in practical fluorinated mine water could be effectively removed from 3.6 mg/L to less than 1.5 mg/L within130 bed volume(BV)by using 1.5 g La-Fe@PTA.Furthermore,the adsorbent still had good adsorption capacity after regeneration,which confirms the great application potential of La-Fe@PTA as a fluoride ion adsorbent.The mechanism analysis showed that La-Fe@PTA adsorption of fluorine ions is a physicochemical reaction driven by electrostatic attraction and ion exchange.
基金supported by the Natural Science Foundation of Tianjin(No.18JCYBJC17700)the National Natural Science Foundation of China(Nos.21406164,21466035 and 22066022).
文摘It is still a challenge to eliminate efficiently fluoride ion from groundwater,especially to design and synthesis an adsorbent possessing high adsorption capacity,recyclability and wide pH application conditions.Herein we present millimeter-sized sulfate-type zirconium alginate hydrogel beads with 3D network structure(AHB@Zr-SO^(2−)_(4))that exhibited a maximum adsorption capacity of 101.3 mg/g with wide pH applicability(pH 3−9).This material have~2.5 times higher adsorption capacity than that of pure zirconium alginate hydrogel beads(AHB@Zr)and it was ascribed to ion exchange between SO^(2−)_(4)and F−on the surface of AHB@Zr-SO^(2−)_(4),which was verified via ion chromatography measurement coupled with X-ray photoelectron spectroscopy(XPS)and Fourier Transform Infrared Spectrometer(FTIR Spectrometer)analysis.Density functional theory(DFT)calculations indicated that the ion exchange process between SO^(2−)_(4)and F−in AHB@Zr-SO^(2−)_(4)was energetically favorable than OH^(−)and F^(−)in AHB@Zr.In addition,310 bed volumes(BV)of effluent was realized via column adsorption of groundwater containing fluoride on AHB@Zr-SO^(2−)_(4)and indicated that it is a promising candidate for mitigating the problem of fluoride-containing groundwater.
基金This work was financially supported by the Science and Technology Innovation Program of Hunan Province“Huxiang Young Talents Plan”(No.2021RC3106)Hunan Provincial Natural Science Foundation of China(No.2022JJ40360)the Key Research and Development Program of Hunan Province,China(No.2022SK2053)。
文摘The detection of pathogenic bacteria with improved accessibility,reduced analysis time,and increased sensitivity is of great importance for diagnosing the infected disease.Nanozymes have attracted rising attention in the bioassay field.Designing a model nanozyme needs the combined merit of sensible nanostructures and a large specific surface area to guarantee exceptional enzyme-mimic activity.Herein,aβ-cyclodextrin modified AuBi aerogel is prepared by a one-pot reduction strategy.The introduction ofβ-cyclodextrin(featured with a hydrophobic cavity and hydrophilic surface)enhances the catalytic activity of AuBi aerogels by engendering host-guest complex and improving dispersity/stability.Based on the specific urea hydrolysis,which could produce NH_(3)to raise pH by urease,the pH up-regulation would inhibit the peroxidase-mimicking performances ofβ-cyclodextrin/AuBi aerogels.Therefore,the sensitive colorimetric detection platform for urease activity could be constructed.Moreover,the sensing platform can detect straightforwardly urease-positive Proteus mirabilis in urine circumstances with a wide detection range and a low limit of detection(LOD)of 4 colony-forming unit(CFU)·mL^(-1).The reproducibility,stability,and specificity of this approach are verified to be satisfactory.Also,as an inhibitor of urease activity,the fluoride ion could be detected by the constructed sensing platform sensitively and specifically.Overall,this work provides a blueprint for designing an ideal nanozyme and paves a new roadway for detecting pathogenic bacteria.
基金partial support from the National Key Research and Development Program of China(Nos.2017YFC1104902,2016YFC1100502 and 2018YFC1105503)the National Natural Science Foundation of China(Nos.51871220 and 51631007)+3 种基金the Key Research Program of Frontier Sciences,CAS(No.QYZDJ-SSW-JSC031-02)the Natural Science Foundation of Liaoning Province of China(No.2019-MS-327 and 2020-KF-14-01)the State Key Laboratory of Light Alloy Casting Technology for Highend Equipment(No.LACT-007)the Shenyang Talents Program(No.RC200230)。
文摘The cellular structured titanium alloys have attracted significant attention for implants because of their lower Young’s modulus,which is comparable to human bone and has the capability of providing space for bone tissue in-growth.However,there is a gap in the knowledge in regard to the relationship between the pore characteristics and the electrochemical performance of open-cellular structured titanium alloys.In this study,we elucidate the influence of pore characteristics on the electrochemical performance of open-cellular structured Ti-6Al-4V alloys produced by electron beam melting(EBM).Intriguingly,the passive film formed on cellular structured Ti-6Al-4V alloy with a larger pore size was more stable and protective,and the corrosion performance was superior compared to the samples with a smaller pore size in phosphate buffered saline(PBS),mainly because of relatively smaller exposed surface area and unlimited flow of electrolyte.However,in acidic PBS containing fluoride ions,the pore characteristics did not play an important role in the corrosion resistance.It was considered that the protective film breaks down such that the corrosion performance of cellular structured alloys was comparable to each other in this harsh environment.
