Co3O4 catalysts prepared with different precipitants（NH3·H2O,KOH,NH4HCO3,K2CO3 and KHCO3）were investigated for the oxidation of formaldehyde（HCHO）.Among these,KHCO3-precipitated Co3O4（KHCO3-Co） was the most...Co3O4 catalysts prepared with different precipitants（NH3·H2O,KOH,NH4HCO3,K2CO3 and KHCO3）were investigated for the oxidation of formaldehyde（HCHO）.Among these,KHCO3-precipitated Co3O4（KHCO3-Co） was the most active low-temperature catalyst,and was able to completely oxidize HCHO at the 100-ppm level to CO2 at 90℃.In situ diffuse reflectance infrared spectroscopy demonstrated that hydroxyl groups on the catalyst surface were regenerated by K~＋ and CO3^（2-）,thus promoting the oxidation of HCHO.Moreover,H2-temperature programmed reduction and X-ray photoelectron spectroscopy showed that employing KHCO3 as the precipitant increased the Co^3＋/Co^2＋molar ratio on the surface of the Co3O4 catalyst,thus further promoting oxidation.Structural characterization revealed that catalysts precipitated with carbonate or bicarbonate reagents exhibited greater specific surface areas and pore volumes.Overall,these data suggest that the high activity observed during the Co3O4 catalyzed oxidation of HCHO can be primarily attributed to the presence of K~＋ and CO3^（2-） on the Co3O4 surface and the favorable Co^3＋/Co^2＋ ratio.展开更多
Producing magnesium hydroxide is the basic way to utilize magnesium resources of natural brines. However, the effect of lithium on properties of product is always neglected. The interaction between ions in magnesium c...Producing magnesium hydroxide is the basic way to utilize magnesium resources of natural brines. However, the effect of lithium on properties of product is always neglected. The interaction between ions in magnesium chloride solution containing lithium was illustrated based on the experimental results, and the effect of lithium on the crystallization of magnesium was clarified. The results of X-ray diffraction（XRD）, scanning election microscope（SEM）, Fourier transform infrared spectroscopy（FTIR）, thermogravimetry analysis（TGA） and laser particle size analysis indicate that the effect of lithium is not obvious on the crystal phase and morphology of the products. But the XRD relative intensity of（001） surface of magnesium hydroxide declines, the specific surface area reduces apparently and the additive mass of lithium affects the heat loss rates of precipitations obviously. Quantum chemical calculations on the interactional systems of Mg（H2O）2＋6 and Li（H2O）＋4 were performed using B3LYP/6-311 G basis set. The results show that when the distance of Mg2＋ and Li＋ is 7-10 , the interaction energy is high and the trend of solvation is strong, which would make hydroxide ions easier to combine with hydrogen ions in ammonia precipitation process. And the absolute value of solvation free energy reduces significantly in MgCl2 solution（1 mol/L） containing lithium ion.展开更多
Ionic liquids as green solvents have shown important application in the extraction and separation of nonferrous metals.The new application perspective,the important fundamental and the applied studies of the extractio...Ionic liquids as green solvents have shown important application in the extraction and separation of nonferrous metals.The new application perspective,the important fundamental and the applied studies of the extraction and separation of nonferrous metals in ionic liquids,including the dissolution and corrosion of metal and metal oxide,hydrometallurgy of chalcopyrite and metallic oxidized ore,and extraction and separation of metal ions,are introduced.展开更多
An inductively coupled plasma mass spectrometry(ICP-MS) method was developed for the determination of Na, Mg, Al,K, Ca, Ti, Cr, Co, Ni, Cu, Ga, As, Mo, Ag, Cd and Pb in MnZn ferrites. The sample was digested by HNO3+H...An inductively coupled plasma mass spectrometry(ICP-MS) method was developed for the determination of Na, Mg, Al,K, Ca, Ti, Cr, Co, Ni, Cu, Ga, As, Mo, Ag, Cd and Pb in MnZn ferrites. The sample was digested by HNO3+HCl with microwave digestion followed by dilution with ultrapure water, then the above 16 impurity elements in the solution were analyzed directly by ICP-MS. The impurity elements were introduced by the helium gas or hydrogen gas into the octopole reaction system(ORS) to eliminate the polyatomic interferences caused by the high salty matrixes. The matrix effect was minimized through matrix matching,and Be, Y and Rh were used as internal standard elements. The working parameters of the instrument were optimized. The results show that the method has good precision and high accuracy. The detection limits for the investigated elements are in the range of0.9-37.5 ng/L, the relative standard deviation of each element is within 1.1%-4.8%, and the recovery of each element is 90%-108%.展开更多
The pure Cr2O3 coated Li4Ti5O12 microspheres were prepared by a facile and cheap solution- based method with basic chromium（III） nitrate solution （pH=ll.9）. And their Li-storage properties were investigated as ano...The pure Cr2O3 coated Li4Ti5O12 microspheres were prepared by a facile and cheap solution- based method with basic chromium（III） nitrate solution （pH=ll.9）. And their Li-storage properties were investigated as anode materials for lithium rechargeable batteries. The pure Cr2O3 works as an adhesive interface to strengthen the connections between Li4Ti5O12 par- ticles, providing more electric conduction channels, and reduce the inter-particle resistance. Moreover, Li2Cr2O3, formed by the lithiation of Cr2O3, can further stabilize LiTTi5O12 with high electric conductivity on the surface of particles. While in the acid chromium solution （pH=3.2） modification, besides Cr2O3, Li2CrO4 and TiO2 phases were also found in the final product. Li2CrO4 is toxic and the presence of TiO2 is not welcome to im- prove the electrochemical performance of Li4Ti5O12 microspheres. The reversible capacity of 1% Cr2O3-coated sample with the basic chromium solution modification was 180 mAh/g at 0.1 C, and 134 mAh/g at 10 C. Moreover, it was even as high as 127 mAh/g at 5 C after 600 cycles. At -20 ℃, its reversible specific capacity was still as high as 118 mAh/g.展开更多
Nanocomposites of zinc/bentonite clay were synthesized for use as an antibacterial material by a quick and simple alkaline ion exchange method. The synthesis of zinc doped bentonite nanocomposite was accomplished by p...Nanocomposites of zinc/bentonite clay were synthesized for use as an antibacterial material by a quick and simple alkaline ion exchange method. The synthesis of zinc doped bentonite nanocomposite was accomplished by placing bentonite in a melting bath of ZnSO4 for 10, 20, 40, 60 and 90 rain. The complexes were characterized by XRD, SEM and DRS. XRD analyses and SEM observations confirmed the diffusion of zinc to the clay surfaces. Antibacterial activity tests against Escherichia coli showed that bentonite did not present any antibacterial properties, but after alkaline ion exchange treatment, inhibition was noted. The highest antibacterial activity was observed with ZnO/bentonite composite alkaline ion exchange for 60 and 90 rain. Interestingly, the leaching test indicated that ZnO/bentonite did not present any risk for drinking water treatment.展开更多
Four acrylamide polymer flocculants, anionic polyacrylamide P（AA-co-AM）, cationic poly- acrylamide P（DMB-co-AM）, nonionic polyacrylamide P（AM）, and hydrophobical polyacry- lamide P（OA-co-AM） have been prepared...Four acrylamide polymer flocculants, anionic polyacrylamide P（AA-co-AM）, cationic poly- acrylamide P（DMB-co-AM）, nonionic polyacrylamide P（AM）, and hydrophobical polyacry- lamide P（OA-co-AM） have been prepared by copolymerizing with acrylic acid, cationic monomer dimethylethyl （acryloxyethyl） ammonium bromide （DMB） and hydrophobical monomer octadecyl acrylate with acrylamide. The interactions between the flocculants with the （012） surface of alumina crystal （A1203） have been simulated by molecular dynamics method. All the polymers can bind tightly with A1203 crystal, the interaction between the O of polymers and A1 of the （012） surface of A1203 is significantly strong. The order of binding energy is as follows： P（DMB-co-AM）〉P（OA-co-AM）〉P（AA-co-AM）〉P（AM）, implying a better flocculation performance of P（DMB-co-AM） than the others. Analy- sis indicates that binding energy is mainly determined by Coulomb interaction. Bonds are found between the O atoms of the polymers and the A1 atoms of A1203. The poly- mers＇ structures deform when they combine with A1203 crystal, but the deformation en- ergies are low and far less than non-bonding energies. Flocculation experiments in sus- pension medium of l%Kaolin show a transmittancy of 90.8% for 6 mg/L P（DMB-co-AM） and 73.0% for P（AM）. The sequence of flocculation performance of four polymers is P（DMB-co-AM）〉P（OA-co-AM）〉P（AA-co-AM）〉P（AM）, which is in excellent agreement with the simulation results of binding energy.展开更多
A simple and rapid method for the determination of polyethylene oxide-type non-ionic surfactants is reported herein. This method is based on the adhesion of calcium/non-ionic surfactant complexes with tetra phenyl por...A simple and rapid method for the determination of polyethylene oxide-type non-ionic surfactants is reported herein. This method is based on the adhesion of calcium/non-ionic surfactant complexes with tetra phenyl porphine sulfonic acid （TPPS） to the wall of reaction vessel upon vigorous shaking. The ion-associate adhering to the inner wall of the vessel was dissolved with water after discarding the solution and spectrophotometrically assayed at 412 nm. From the standard curve for Triton X-100, the order of the sensitivity for different ions was as follows： Ca^2＋〉 K^＋〉 NH4^＋〉 Ba^2＋. The proposed method does not involve extraction of the ion-associated with harmful solvents and can be simply performed by combining a procedure based on hand shaking and the use of a spectrophotometer.展开更多
Polymer-based photoanodes for the water oxidation reaction have recently garnered attention,with carbon nitride standing out due to its numerous advantages.This study focuses on synthesizing crystalline carbon nitride...Polymer-based photoanodes for the water oxidation reaction have recently garnered attention,with carbon nitride standing out due to its numerous advantages.This study focuses on synthesizing crystalline carbon nitride photoanodes,specifically poly(heptazine imide)(PHI),and explores the role of salts in their production.Using a binary molten salt system,optimal photocurrent density of 365μA·cm^(−2)was achieved with a voltage bias of 1.23 V versus the reversible hydrogen electrode under AM 1.5G illumination,this performance is ca.18 times to the pristine PCN photoanode.In this process,NH_(4)SCN facilitates the growth of SnS_(2)seeding layers,while K_(2)CO_(3)enhances film crystallinity.In situ electrochemical analyses show that this salt combination improves photoexcited charge transfer efficiency and minimizes resistance in the SnS_(2)layer.This study clarifies the role of salts in synthesizing the PHI photoanode and provides insights for designing high-crystallinity carbon nitride-based functional films.展开更多
基金supported by the National Natural Science Foundation of China(21577088)~~
文摘Co3O4 catalysts prepared with different precipitants（NH3·H2O,KOH,NH4HCO3,K2CO3 and KHCO3）were investigated for the oxidation of formaldehyde（HCHO）.Among these,KHCO3-precipitated Co3O4（KHCO3-Co） was the most active low-temperature catalyst,and was able to completely oxidize HCHO at the 100-ppm level to CO2 at 90℃.In situ diffuse reflectance infrared spectroscopy demonstrated that hydroxyl groups on the catalyst surface were regenerated by K~＋ and CO3^（2-）,thus promoting the oxidation of HCHO.Moreover,H2-temperature programmed reduction and X-ray photoelectron spectroscopy showed that employing KHCO3 as the precipitant increased the Co^3＋/Co^2＋molar ratio on the surface of the Co3O4 catalyst,thus further promoting oxidation.Structural characterization revealed that catalysts precipitated with carbonate or bicarbonate reagents exhibited greater specific surface areas and pore volumes.Overall,these data suggest that the high activity observed during the Co3O4 catalyzed oxidation of HCHO can be primarily attributed to the presence of K~＋ and CO3^（2-） on the Co3O4 surface and the favorable Co^3＋/Co^2＋ ratio.
基金Projects(51104185,51134007)supported by the National Natural Science Foundation of ChinaProject(2010QZZD003)supported by the Key Project of Central South University of Fundamental Research Funds for the Central Universities of China
文摘Producing magnesium hydroxide is the basic way to utilize magnesium resources of natural brines. However, the effect of lithium on properties of product is always neglected. The interaction between ions in magnesium chloride solution containing lithium was illustrated based on the experimental results, and the effect of lithium on the crystallization of magnesium was clarified. The results of X-ray diffraction（XRD）, scanning election microscope（SEM）, Fourier transform infrared spectroscopy（FTIR）, thermogravimetry analysis（TGA） and laser particle size analysis indicate that the effect of lithium is not obvious on the crystal phase and morphology of the products. But the XRD relative intensity of（001） surface of magnesium hydroxide declines, the specific surface area reduces apparently and the additive mass of lithium affects the heat loss rates of precipitations obviously. Quantum chemical calculations on the interactional systems of Mg（H2O）2＋6 and Li（H2O）＋4 were performed using B3LYP/6-311 G basis set. The results show that when the distance of Mg2＋ and Li＋ is 7-10 , the interaction energy is high and the trend of solvation is strong, which would make hydroxide ions easier to combine with hydrogen ions in ammonia precipitation process. And the absolute value of solvation free energy reduces significantly in MgCl2 solution（1 mol/L） containing lithium ion.
基金Project(50904031) supported by the National Natural Science Foundation of ChinaProject(2008E0049M) supported by the Natural Science Foundation of Yunnan Province,China+1 种基金Project(07Z40082) supported by the Science Foundation of the Education Department of Yunnan Province,ChinaProject(2007-16) supported by the Science Foundation of Kunming University of Science and Technology,China
文摘Ionic liquids as green solvents have shown important application in the extraction and separation of nonferrous metals.The new application perspective,the important fundamental and the applied studies of the extraction and separation of nonferrous metals in ionic liquids,including the dissolution and corrosion of metal and metal oxide,hydrometallurgy of chalcopyrite and metallic oxidized ore,and extraction and separation of metal ions,are introduced.
基金Project(21271187)supported by the National Natural Science Foundation of ChinaProject(cstc2013jcyj A10088)supported by the Chongqing Natural Science Foundation,China+1 种基金Projects(2013FJ3093,2013SK3268)supported by the Science and Technology Project of Hunan Province,ChinaProject(KJZH14217)supported by Achievement Transfer Education in Chongqing,China
文摘An inductively coupled plasma mass spectrometry(ICP-MS) method was developed for the determination of Na, Mg, Al,K, Ca, Ti, Cr, Co, Ni, Cu, Ga, As, Mo, Ag, Cd and Pb in MnZn ferrites. The sample was digested by HNO3+HCl with microwave digestion followed by dilution with ultrapure water, then the above 16 impurity elements in the solution were analyzed directly by ICP-MS. The impurity elements were introduced by the helium gas or hydrogen gas into the octopole reaction system(ORS) to eliminate the polyatomic interferences caused by the high salty matrixes. The matrix effect was minimized through matrix matching,and Be, Y and Rh were used as internal standard elements. The working parameters of the instrument were optimized. The results show that the method has good precision and high accuracy. The detection limits for the investigated elements are in the range of0.9-37.5 ng/L, the relative standard deviation of each element is within 1.1%-4.8%, and the recovery of each element is 90%-108%.
基金This work was supported by the National Natural Science Foundation of China （No.51372060 and No.31501576）.
文摘The pure Cr2O3 coated Li4Ti5O12 microspheres were prepared by a facile and cheap solution- based method with basic chromium（III） nitrate solution （pH=ll.9）. And their Li-storage properties were investigated as anode materials for lithium rechargeable batteries. The pure Cr2O3 works as an adhesive interface to strengthen the connections between Li4Ti5O12 par- ticles, providing more electric conduction channels, and reduce the inter-particle resistance. Moreover, Li2Cr2O3, formed by the lithiation of Cr2O3, can further stabilize LiTTi5O12 with high electric conductivity on the surface of particles. While in the acid chromium solution （pH=3.2） modification, besides Cr2O3, Li2CrO4 and TiO2 phases were also found in the final product. Li2CrO4 is toxic and the presence of TiO2 is not welcome to im- prove the electrochemical performance of Li4Ti5O12 microspheres. The reversible capacity of 1% Cr2O3-coated sample with the basic chromium solution modification was 180 mAh/g at 0.1 C, and 134 mAh/g at 10 C. Moreover, it was even as high as 127 mAh/g at 5 C after 600 cycles. At -20 ℃, its reversible specific capacity was still as high as 118 mAh/g.
文摘Nanocomposites of zinc/bentonite clay were synthesized for use as an antibacterial material by a quick and simple alkaline ion exchange method. The synthesis of zinc doped bentonite nanocomposite was accomplished by placing bentonite in a melting bath of ZnSO4 for 10, 20, 40, 60 and 90 rain. The complexes were characterized by XRD, SEM and DRS. XRD analyses and SEM observations confirmed the diffusion of zinc to the clay surfaces. Antibacterial activity tests against Escherichia coli showed that bentonite did not present any antibacterial properties, but after alkaline ion exchange treatment, inhibition was noted. The highest antibacterial activity was observed with ZnO/bentonite composite alkaline ion exchange for 60 and 90 rain. Interestingly, the leaching test indicated that ZnO/bentonite did not present any risk for drinking water treatment.
文摘Four acrylamide polymer flocculants, anionic polyacrylamide P（AA-co-AM）, cationic poly- acrylamide P（DMB-co-AM）, nonionic polyacrylamide P（AM）, and hydrophobical polyacry- lamide P（OA-co-AM） have been prepared by copolymerizing with acrylic acid, cationic monomer dimethylethyl （acryloxyethyl） ammonium bromide （DMB） and hydrophobical monomer octadecyl acrylate with acrylamide. The interactions between the flocculants with the （012） surface of alumina crystal （A1203） have been simulated by molecular dynamics method. All the polymers can bind tightly with A1203 crystal, the interaction between the O of polymers and A1 of the （012） surface of A1203 is significantly strong. The order of binding energy is as follows： P（DMB-co-AM）〉P（OA-co-AM）〉P（AA-co-AM）〉P（AM）, implying a better flocculation performance of P（DMB-co-AM） than the others. Analy- sis indicates that binding energy is mainly determined by Coulomb interaction. Bonds are found between the O atoms of the polymers and the A1 atoms of A1203. The poly- mers＇ structures deform when they combine with A1203 crystal, but the deformation en- ergies are low and far less than non-bonding energies. Flocculation experiments in sus- pension medium of l%Kaolin show a transmittancy of 90.8% for 6 mg/L P（DMB-co-AM） and 73.0% for P（AM）. The sequence of flocculation performance of four polymers is P（DMB-co-AM）〉P（OA-co-AM）〉P（AA-co-AM）〉P（AM）, which is in excellent agreement with the simulation results of binding energy.
文摘A simple and rapid method for the determination of polyethylene oxide-type non-ionic surfactants is reported herein. This method is based on the adhesion of calcium/non-ionic surfactant complexes with tetra phenyl porphine sulfonic acid （TPPS） to the wall of reaction vessel upon vigorous shaking. The ion-associate adhering to the inner wall of the vessel was dissolved with water after discarding the solution and spectrophotometrically assayed at 412 nm. From the standard curve for Triton X-100, the order of the sensitivity for different ions was as follows： Ca^2＋〉 K^＋〉 NH4^＋〉 Ba^2＋. The proposed method does not involve extraction of the ion-associated with harmful solvents and can be simply performed by combining a procedure based on hand shaking and the use of a spectrophotometer.
文摘Polymer-based photoanodes for the water oxidation reaction have recently garnered attention,with carbon nitride standing out due to its numerous advantages.This study focuses on synthesizing crystalline carbon nitride photoanodes,specifically poly(heptazine imide)(PHI),and explores the role of salts in their production.Using a binary molten salt system,optimal photocurrent density of 365μA·cm^(−2)was achieved with a voltage bias of 1.23 V versus the reversible hydrogen electrode under AM 1.5G illumination,this performance is ca.18 times to the pristine PCN photoanode.In this process,NH_(4)SCN facilitates the growth of SnS_(2)seeding layers,while K_(2)CO_(3)enhances film crystallinity.In situ electrochemical analyses show that this salt combination improves photoexcited charge transfer efficiency and minimizes resistance in the SnS_(2)layer.This study clarifies the role of salts in synthesizing the PHI photoanode and provides insights for designing high-crystallinity carbon nitride-based functional films.
