Isothermal titration calorimetry （ITC） was used to study interactions between water vapour and the surface of thermally converted sodium bicarbonate （NaHCO3）. The decarboxyla- tion degree of the samples was varied...Isothermal titration calorimetry （ITC） was used to study interactions between water vapour and the surface of thermally converted sodium bicarbonate （NaHCO3）. The decarboxyla- tion degree of the samples was varied from 3% to 35% and the humidity range was 54-100%. The obtained enthalpy values were all exothermic and showed a positive linear correlation with decarboxylation degrees for each humidity studied. The critical humidity, 75% （RHo）, was determined as the inflection point on a plot of the mean-AH kJ/mole Na2CO3 against RH. Humidities above the critical humidity lead to complete surface dissolution. The water uptake （m） was determined after each calorimetric experiment, complementing the enthalpy data. A mechanism of water vapour interaction with decarboxylated samples, including the formation of trona and Wegscheider＇s salt on the bicarbonate surface is proposed for humidities below RHo.展开更多
Hydrogen cyanide (HCN) was produced by flameless combustion of dried tobacco leaves for investigating the adsorption on Na2CO3, NaHCO3 and proline (HNC4H7COOH). The concentration of HCN could be produced steadily at 0...Hydrogen cyanide (HCN) was produced by flameless combustion of dried tobacco leaves for investigating the adsorption on Na2CO3, NaHCO3 and proline (HNC4H7COOH). The concentration of HCN could be produced steadily at 0.73 mg/dm3. For the given 245 cm3 of smoke with the flow rate of 17.5 cm3/s, the efficiency of adsorption of HCN was improved to 80% by the addition of the optimal amounts of Na2CO3, NaHCO3 and proline (HNC4H7COOH), which were 10, 20, and 30 mg respectively. In the circumstances, the breakthrough concentration was reduced to 0.15 - 0.20 mg/dm3.展开更多
Biodegradable chitosan(CS)films can meet the demand for sustainable development.However,the performance of pure CS membrane still exists a particular gap compared with the traditional film.Inorganic nanomaterials with...Biodegradable chitosan(CS)films can meet the demand for sustainable development.However,the performance of pure CS membrane still exists a particular gap compared with the traditional film.Inorganic nanomaterials with the controllable release are added to improve its physical and chemical properties.Herein,a series of CS/phosphate-stabilized amorphous calcium carbonate(CS/ACCP)and CS/sodium alginate/ACCP(CS/Alginate/ACCP)composite films were prepared by the flow method.The effects of ACCP and Alginate/ACCP nanoparticles on the physical and chemical properties of the composite membrane were investigated.The results showed that the composite nanoparticles could significantly improve CS film’s compactness,hydrophobicity,and mechanical properties and enhance its ultraviolet(UV)blocking ability,water resistance,and water vapor blocking ability.When the number of nanoparticles was 8%,the mechanical properties of the CS composite membrane reached optimum value,and the comprehensive performance was better.In addition,the controlled-release properties of CS composite membranes were also studied,and the antioxidant,antibacterial,biocompatibility,and fresh-keeping effects of the composite membranes were explored.The results indicated that the CS composite membranes had not only excellent bacteriostatic(72%)properties(Escherichia coli)but also presented well fruit preservation(15 days)properties(sugar orange).In particular,the controlled release range of CS composite membrane at 12 h was between 30%and 90%,which provided a theoretical basis for its use as an edible membrane.Therefore,based on ACCP and Alginate/ACCP nanoparticles,CS composite membranes with more excellent application value in the biological field were prepared through further optimization design.展开更多
Thermodynamic simulation was conducted to design a new process of stepwise precipitating NH_(4)VO_(3)and NaHCO_(3)from regulating the CO_(2)carbonation of Na_(3)VO_(4)solution.Firstly,a new V(V)speciation model for th...Thermodynamic simulation was conducted to design a new process of stepwise precipitating NH_(4)VO_(3)and NaHCO_(3)from regulating the CO_(2)carbonation of Na_(3)VO_(4)solution.Firstly,a new V(V)speciation model for the aqueous solution containing vanadate and carbonate is established by using the Bromley-Zemaitis activity coefficient model.Subsequently,thermodynamic equilibrium calculations are conducted to clarify the behavior of vanadium,carbon,sodium,and impurity species in atmospheric or high-pressure carbonation.To ensure the purity and recovery of vanadium products,Na_(3)VO_(4)solution is initially carbonated to the pH of 9.3-9.4,followed by precipitating NH_(4)VO_(3)by adding(NH_(4))_(2)CO_(3).After vanadium precipitation,the solution is deeply carbonated to the final pH of 7.3-7.5 to precipitate NaHCO_(3),and the remaining solution is recycled to dissolve Na_(3)VO_(4)crystals.Finally,verification experiments demonstrate that 99.1%of vanadium and 91.4%of sodium in the solution are recovered in the form of NH_(4)VO_(3)and NaHCO_(3),respectively.展开更多
Capacity and kinetics of COcapture of NaCOwere studied to determine the mechanism for COsequestration under ambient conditions. Bicarbonate formation of NaCOwas examined by a thermogravimetric analysis（TGA） under va...Capacity and kinetics of COcapture of NaCOwere studied to determine the mechanism for COsequestration under ambient conditions. Bicarbonate formation of NaCOwas examined by a thermogravimetric analysis（TGA） under various COand water vapor concentrations and the accompanying structural changes of NaCOwere demonstrated by X-ray diffraction（XRD）. Morphological variations were observed during the reaction of COcapture through scanning electron microscope（SEM）. Structural changes and morphological variations, which occurred during the course of the reaction, were then connected to the kinetic and exothermic properties of the COcapture process from the XRD and SEM measurements. The results showed that the bicarbonate formation of NaCOhas two different pathways.For higher COand HO concentrations, the bicarbonate formation proceeded effectively. However, for lower COand HO concentrations, the reactions were more complicated. The formation of NaCO·HO from NaCOas the first step, followed by the subsequent formation of NaH（CO）, and then the bicarbonate formation proceeds. To understand such fundamental properties in COcapture of NaCOis very important for utilization of NaCOas a sorbent for COcapture.展开更多
Ultra-light carboxylic functionalized multi-walled carbon nanotubes(CNTs-COOH) and Ti3C2 MXene hybrids modified sodium alginate(CNTs/Ti3C2-SA) based composite foams were prepared through ice-templated freeze-drying me...Ultra-light carboxylic functionalized multi-walled carbon nanotubes(CNTs-COOH) and Ti3C2 MXene hybrids modified sodium alginate(CNTs/Ti3C2-SA) based composite foams were prepared through ice-templated freeze-drying method. The microstructure of the synthesized CNTs/Ti3C2 hybrids and CNTs/Ti3C2-SA foams is characterized by the presence of CNTs inserted between MXene layers which prevents their restacking. The resultant CNTs/Ti3C2 hybrids exhibit a unique sandwich-like hierarchical structure. Scanning electron microscopy(SEM) images show that the CNTs/Ti3C2-SA foam exhibits a heterogeneous anisotropic microstructure and CNTs/Ti3C2 hybrids are homogeneously dispersed in the skeleton of the porous foam. In case that the content of the hybrids amounts 40 mg/cm^3, the CNTs/Ti3C2-SA foam possesses excellent electromagnetic(EM) absorption performance with a minimum reflection coefficient(RCmin) as low as-40.0 dB. In case of a sample thickness of 3.95 mm, the RCminreaches-24.4 dB and the effective absorption bandwidth covers the whole X band from 8.2 to 12.4 GHz. A control test shows that, with the same absorbent content, the CNTs/Ti3C2-SA foam exhibits a far better EM performance than that of CNT-free Ti3C2-SA foam.展开更多
文摘Isothermal titration calorimetry （ITC） was used to study interactions between water vapour and the surface of thermally converted sodium bicarbonate （NaHCO3）. The decarboxyla- tion degree of the samples was varied from 3% to 35% and the humidity range was 54-100%. The obtained enthalpy values were all exothermic and showed a positive linear correlation with decarboxylation degrees for each humidity studied. The critical humidity, 75% （RHo）, was determined as the inflection point on a plot of the mean-AH kJ/mole Na2CO3 against RH. Humidities above the critical humidity lead to complete surface dissolution. The water uptake （m） was determined after each calorimetric experiment, complementing the enthalpy data. A mechanism of water vapour interaction with decarboxylated samples, including the formation of trona and Wegscheider＇s salt on the bicarbonate surface is proposed for humidities below RHo.
文摘Hydrogen cyanide (HCN) was produced by flameless combustion of dried tobacco leaves for investigating the adsorption on Na2CO3, NaHCO3 and proline (HNC4H7COOH). The concentration of HCN could be produced steadily at 0.73 mg/dm3. For the given 245 cm3 of smoke with the flow rate of 17.5 cm3/s, the efficiency of adsorption of HCN was improved to 80% by the addition of the optimal amounts of Na2CO3, NaHCO3 and proline (HNC4H7COOH), which were 10, 20, and 30 mg respectively. In the circumstances, the breakthrough concentration was reduced to 0.15 - 0.20 mg/dm3.
基金The work was financially supported by the National Natural Science Foundation of China(31700689)Natural Science Foundation of Shanxi Province(201901D111115)+2 种基金Supported by Transformation of Scientific and Technological Achievements Programs of Higher Education Institutions in Shanxi(2020CG015)Key Technology Research and Development Plan of Jinzhong City in Shanxi(Y201022)Liuwei Zhai Food Research Institute,Taiyuan University of Technology(213020310-J).
文摘Biodegradable chitosan(CS)films can meet the demand for sustainable development.However,the performance of pure CS membrane still exists a particular gap compared with the traditional film.Inorganic nanomaterials with the controllable release are added to improve its physical and chemical properties.Herein,a series of CS/phosphate-stabilized amorphous calcium carbonate(CS/ACCP)and CS/sodium alginate/ACCP(CS/Alginate/ACCP)composite films were prepared by the flow method.The effects of ACCP and Alginate/ACCP nanoparticles on the physical and chemical properties of the composite membrane were investigated.The results showed that the composite nanoparticles could significantly improve CS film’s compactness,hydrophobicity,and mechanical properties and enhance its ultraviolet(UV)blocking ability,water resistance,and water vapor blocking ability.When the number of nanoparticles was 8%,the mechanical properties of the CS composite membrane reached optimum value,and the comprehensive performance was better.In addition,the controlled-release properties of CS composite membranes were also studied,and the antioxidant,antibacterial,biocompatibility,and fresh-keeping effects of the composite membranes were explored.The results indicated that the CS composite membranes had not only excellent bacteriostatic(72%)properties(Escherichia coli)but also presented well fruit preservation(15 days)properties(sugar orange).In particular,the controlled release range of CS composite membrane at 12 h was between 30%and 90%,which provided a theoretical basis for its use as an edible membrane.Therefore,based on ACCP and Alginate/ACCP nanoparticles,CS composite membranes with more excellent application value in the biological field were prepared through further optimization design.
基金the financial supports from the National Natural Science Foundation of China(No.22078343)Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA0430103)the National Key Research and Development Program of China(No.2018YFC1900502)。
文摘Thermodynamic simulation was conducted to design a new process of stepwise precipitating NH_(4)VO_(3)and NaHCO_(3)from regulating the CO_(2)carbonation of Na_(3)VO_(4)solution.Firstly,a new V(V)speciation model for the aqueous solution containing vanadate and carbonate is established by using the Bromley-Zemaitis activity coefficient model.Subsequently,thermodynamic equilibrium calculations are conducted to clarify the behavior of vanadium,carbon,sodium,and impurity species in atmospheric or high-pressure carbonation.To ensure the purity and recovery of vanadium products,Na_(3)VO_(4)solution is initially carbonated to the pH of 9.3-9.4,followed by precipitating NH_(4)VO_(3)by adding(NH_(4))_(2)CO_(3).After vanadium precipitation,the solution is deeply carbonated to the final pH of 7.3-7.5 to precipitate NaHCO_(3),and the remaining solution is recycled to dissolve Na_(3)VO_(4)crystals.Finally,verification experiments demonstrate that 99.1%of vanadium and 91.4%of sodium in the solution are recovered in the form of NH_(4)VO_(3)and NaHCO_(3),respectively.
基金supported by a Grant-in-Aid for Scientific Research(C)(Grant No.15K05583)from the Japan Society for the Promotion of Science
文摘Capacity and kinetics of COcapture of NaCOwere studied to determine the mechanism for COsequestration under ambient conditions. Bicarbonate formation of NaCOwas examined by a thermogravimetric analysis（TGA） under various COand water vapor concentrations and the accompanying structural changes of NaCOwere demonstrated by X-ray diffraction（XRD）. Morphological variations were observed during the reaction of COcapture through scanning electron microscope（SEM）. Structural changes and morphological variations, which occurred during the course of the reaction, were then connected to the kinetic and exothermic properties of the COcapture process from the XRD and SEM measurements. The results showed that the bicarbonate formation of NaCOhas two different pathways.For higher COand HO concentrations, the bicarbonate formation proceeded effectively. However, for lower COand HO concentrations, the reactions were more complicated. The formation of NaCO·HO from NaCOas the first step, followed by the subsequent formation of NaH（CO）, and then the bicarbonate formation proceeds. To understand such fundamental properties in COcapture of NaCOis very important for utilization of NaCOas a sorbent for COcapture.
文摘Ultra-light carboxylic functionalized multi-walled carbon nanotubes(CNTs-COOH) and Ti3C2 MXene hybrids modified sodium alginate(CNTs/Ti3C2-SA) based composite foams were prepared through ice-templated freeze-drying method. The microstructure of the synthesized CNTs/Ti3C2 hybrids and CNTs/Ti3C2-SA foams is characterized by the presence of CNTs inserted between MXene layers which prevents their restacking. The resultant CNTs/Ti3C2 hybrids exhibit a unique sandwich-like hierarchical structure. Scanning electron microscopy(SEM) images show that the CNTs/Ti3C2-SA foam exhibits a heterogeneous anisotropic microstructure and CNTs/Ti3C2 hybrids are homogeneously dispersed in the skeleton of the porous foam. In case that the content of the hybrids amounts 40 mg/cm^3, the CNTs/Ti3C2-SA foam possesses excellent electromagnetic(EM) absorption performance with a minimum reflection coefficient(RCmin) as low as-40.0 dB. In case of a sample thickness of 3.95 mm, the RCminreaches-24.4 dB and the effective absorption bandwidth covers the whole X band from 8.2 to 12.4 GHz. A control test shows that, with the same absorbent content, the CNTs/Ti3C2-SA foam exhibits a far better EM performance than that of CNT-free Ti3C2-SA foam.
