The effects of temperature, ammonia concentration and ammonium carbonate concentration on the dissolving behavior of ammonium paratungstate were studied in（NH4）2CO3-NH3？H2O-H2O system. The results show that rising ...The effects of temperature, ammonia concentration and ammonium carbonate concentration on the dissolving behavior of ammonium paratungstate were studied in（NH4）2CO3-NH3？H2O-H2O system. The results show that rising temperature, prolonging duration, increasing ammonia concentration and decreasing ammonium carbonate concentration favor dissolving of ammonium paratungstate at temperature below 90 ℃, while the WO3 concentration decreases after a certain time at temperature above 100 ℃. Furthermore, the undissolved tungsten exists in the form of either APT·4 H2O below 90 ℃ or pyrochlore-type tungsten trioxide above 100℃. In dissolving process, the ammonium paratungstate dissolves into paratungstate ions followed by partially converting to tungstate ion, resulting in the coexistence of the both ions. This study may provide a new idea to exploit a novel technique for manufacturing ammonium paratungstate and pyrochlore-type tungsten trioxide.展开更多
The density,viscosity and refractive index of aqueous solutions of tetrabutylammonium hydroxide(TBAOH),piperazine(PZ) and their aqueous blends are determined at several temperatures(303.15 to 333.15 K).All these measu...The density,viscosity and refractive index of aqueous solutions of tetrabutylammonium hydroxide(TBAOH),piperazine(PZ) and their aqueous blends are determined at several temperatures(303.15 to 333.15 K).All these measured physicochemical properties decreases with an increase in temperature.The density data is used to calculate the coefficient of thermal expansion and excess molar volume of all aqueous binary and ternary solutions.The coefficient of thermal expansion increases with increase in temperatures and concentrations.The negativity of excess molar volume for all the aqueous solution decreased with increase in temperature.Each physical property is correlated with temperature by least square method and the corresponding coefficients for each property are presented.The prediction values from correlations for the physical properties are in good agreement with the experimental values.展开更多
This study investigated the influence of temperature on the performance of forward osmosis(FO) under the condition that the feed solution(FS) temperature was diff erent from draw solution(DS) temperature. An FO model ...This study investigated the influence of temperature on the performance of forward osmosis(FO) under the condition that the feed solution(FS) temperature was diff erent from draw solution(DS) temperature. An FO model considering the mass and heat transfer between FS and DS was developed, and the FO experiment with ammonium bicarbonate solution as DS and sodium chloride solution as FS was carried out. The predicted water flux and reverse draw solute flux using the developed model coincided with the experimental fluxes. Increases in the temperature of FS or DS yield corresponding increases in the water flux, reverse draw solute flux, and forward rejection of feed solute. Compared with increasing the FS temperature, increasing the DS temperature has a more significant impact on enhancing FO performance. When the temperature of DS increased from 20 to 40 ℃, the specific reverse solute flux decreased from 0.231 to 0.190 mol/L.展开更多
The effect of initial concentrations on solidification of ammonium chloride water solution is numerically investi- gated in detail.The solidifying process,with the cold wall temperature lower than the eutectic tempera...The effect of initial concentrations on solidification of ammonium chloride water solution is numerically investi- gated in detail.The solidifying process,with the cold wall temperature lower than the eutectic temperature,is assumed to be one-dimensional,and controlled by heat conduction only.The simulation reveals that:(1)The solid-mush interface grows in a linear manner,while the growth rate of the mush-liquid interface decreases in a parabolic manner,with increasing initial concentrations.(2)The temperature field in the whole region has parabolic characteristics,but it shows a linear feature in the solid zone and mushy zone.(3)The concentration always has linear characteristics in the mush.(4)The solid fraction distribution is strongly affected by the ini- tial concentration.The solidification process shows quite different features,especially at small and high initial concentrations.展开更多
基金Project(51274243) supported by the National Natural Science Foundation of China
文摘The effects of temperature, ammonia concentration and ammonium carbonate concentration on the dissolving behavior of ammonium paratungstate were studied in（NH4）2CO3-NH3？H2O-H2O system. The results show that rising temperature, prolonging duration, increasing ammonia concentration and decreasing ammonium carbonate concentration favor dissolving of ammonium paratungstate at temperature below 90 ℃, while the WO3 concentration decreases after a certain time at temperature above 100 ℃. Furthermore, the undissolved tungsten exists in the form of either APT·4 H2O below 90 ℃ or pyrochlore-type tungsten trioxide above 100℃. In dissolving process, the ammonium paratungstate dissolves into paratungstate ions followed by partially converting to tungstate ion, resulting in the coexistence of the both ions. This study may provide a new idea to exploit a novel technique for manufacturing ammonium paratungstate and pyrochlore-type tungsten trioxide.
基金the CO2 Management (MOR) research group of Universiti TeknologiPETRONAS for providing the financial support and facilities
文摘The density,viscosity and refractive index of aqueous solutions of tetrabutylammonium hydroxide(TBAOH),piperazine(PZ) and their aqueous blends are determined at several temperatures(303.15 to 333.15 K).All these measured physicochemical properties decreases with an increase in temperature.The density data is used to calculate the coefficient of thermal expansion and excess molar volume of all aqueous binary and ternary solutions.The coefficient of thermal expansion increases with increase in temperatures and concentrations.The negativity of excess molar volume for all the aqueous solution decreased with increase in temperature.Each physical property is correlated with temperature by least square method and the corresponding coefficients for each property are presented.The prediction values from correlations for the physical properties are in good agreement with the experimental values.
基金supported by The National Key Research and Development Program of China(No.2016YFC0401202)
文摘This study investigated the influence of temperature on the performance of forward osmosis(FO) under the condition that the feed solution(FS) temperature was diff erent from draw solution(DS) temperature. An FO model considering the mass and heat transfer between FS and DS was developed, and the FO experiment with ammonium bicarbonate solution as DS and sodium chloride solution as FS was carried out. The predicted water flux and reverse draw solute flux using the developed model coincided with the experimental fluxes. Increases in the temperature of FS or DS yield corresponding increases in the water flux, reverse draw solute flux, and forward rejection of feed solute. Compared with increasing the FS temperature, increasing the DS temperature has a more significant impact on enhancing FO performance. When the temperature of DS increased from 20 to 40 ℃, the specific reverse solute flux decreased from 0.231 to 0.190 mol/L.
文摘The effect of initial concentrations on solidification of ammonium chloride water solution is numerically investi- gated in detail.The solidifying process,with the cold wall temperature lower than the eutectic temperature,is assumed to be one-dimensional,and controlled by heat conduction only.The simulation reveals that:(1)The solid-mush interface grows in a linear manner,while the growth rate of the mush-liquid interface decreases in a parabolic manner,with increasing initial concentrations.(2)The temperature field in the whole region has parabolic characteristics,but it shows a linear feature in the solid zone and mushy zone.(3)The concentration always has linear characteristics in the mush.(4)The solid fraction distribution is strongly affected by the ini- tial concentration.The solidification process shows quite different features,especially at small and high initial concentrations.
