As part of a better understanding of drying liquids within porous materials, measurements from 293 to 343 K of deionized water surface tension in air as a function of relative humidity are exposed. Experimental work w...As part of a better understanding of drying liquids within porous materials, measurements from 293 to 343 K of deionized water surface tension in air as a function of relative humidity are exposed. Experimental work was carried out using the pendant drop method coupled with image analysis within an adapted instrumented climatic chamber. Results show that surface tension linearly decreases when relative humidity increases. Although the effect of humidity is less compared to that of the temperature and even less compared to a surfactant impact, it must not be neglected and values have to be mentioned when dealing with water evaporation. Modifying surface tension also affects the pendant drop shape. The drying kinetics of the pendant drop volume and its outer shell are connected to this change of shape. Steam in the air can be assimilated to a wetting agent, hence a surfactant, and can be used in an environmental-friendly way to ease the drying stage. Indeed, the challenge is to limit the risk of cracking and damaging pieces during this crucial step in material processing.展开更多
To measure contact angle between CO2 and solid surface, in this study a visual high-pressure vessel has been developed, with a corresponding well-controlled constant temperature system. Pendant drop method is applied ...To measure contact angle between CO2 and solid surface, in this study a visual high-pressure vessel has been developed, with a corresponding well-controlled constant temperature system. Pendant drop method is applied to the investigation of the contact angles of CO2 on a stainless steel surface in its own vapor. The image of the pendant drop is recorded by a camera, and a B-Snake method is used to analyze the contour and the contact angle of the droplet. The experimental results have provided a set of well tested data, which show that CO2 has good infiltration into stainless steel surface and the de- veloped method can be used as a standard testing one for measuring the contact angle between high-pressure liquid and solid surface.展开更多
Piperacillin is a polar organic substance,and can reduce the interfacial tension of oil and water when dissolved in water.In this study,changes in dichloromethane–water interfacial tensions and microdroplet sizes dur...Piperacillin is a polar organic substance,and can reduce the interfacial tension of oil and water when dissolved in water.In this study,changes in dichloromethane–water interfacial tensions and microdroplet sizes during piperacillin synthesis from an aqueous solution of ampicillin and dichloromethane solution of 4-ethyl-2,3-dioxo-1-piperazine carbonyl chloride(EDPC)were observed using a pendent drop technique and a coaxial ring tube system with embedded high-speed camera,respectively.It was found that the rapid N-acylation reaction caused the piperacillin at the interface to synthesize rapidly and diffuse out slowly,resulting in the interfacial tension decreased from 19.5 m N·m-1 to 7.2 m N·m-1 rapidly and then increased slowly as the concentrations of ampicillin and EDPC were 0.05 mol·L-1 and 0.1 mol·L-1.Meanwhile,the increase in the concentration of EDPC increased the peak concentration of piperacillin at the interface,and the addition of ethyl acetate to the ampicillin solution promoted mass transfer and reduced the aggregation of piperacillin effectively.During synthesis,the interfacial tension decreased,leading to a change in droplet sizes in the micro-reaction system.The two-phase reaction was carried out in a coaxial ring tube,with ampicillin and EDPC solutions as continuous and dispersed phases,respectively.The reaction reduced the dripping flow area,and the addition of ethyl acetate to the ampicillin solution slightly affected the division of the flow pattern.Under the same flow conditions,the droplet sizes of the reaction group were smaller than those of the no reaction group.The experimental results demonstrated that the increase of the continuous phase,decrease in the dispersed phase flow rate,or increase in EDPC concentration making droplet sizes smaller,and the addition of ethyl acetate slightly affected droplet sizes.These findings are important for the design and optimization of piperacillin synthesis reactors.展开更多
A pendant drop tensiometry apparatus aided by video-image digitization technology was established, by which static interface or surface tension of some liquids was measured with satisfactory results.In order to study ...A pendant drop tensiometry apparatus aided by video-image digitization technology was established, by which static interface or surface tension of some liquids was measured with satisfactory results.In order to study the effect of emulsifier concentration on emulsion stability, dynamic interfacial tension was measured between toluene and water against concentration of Tween 60(Polyoxyethylene(20) stearyl-sorbitanate). As expected, higher concentration is the Tween 60 solution in toluene injected into the toluene phase, faster falls the interface tension between toluene and water.Furthermore, it reveals interestingly that two steps of diffusion occur in the system, i.e ., at low and high concentration, after the surfactant solution is injected.The characteristic process of dynamic interface tension can be ascribed to diffusion control because of linearity between interface tension and the minus second root of aging time.The discovery is correlated to the fact that much higher concentration of surfactant above its critical micelle concentration is often required when a stable emulsion is planned to prepare.展开更多
文摘As part of a better understanding of drying liquids within porous materials, measurements from 293 to 343 K of deionized water surface tension in air as a function of relative humidity are exposed. Experimental work was carried out using the pendant drop method coupled with image analysis within an adapted instrumented climatic chamber. Results show that surface tension linearly decreases when relative humidity increases. Although the effect of humidity is less compared to that of the temperature and even less compared to a surfactant impact, it must not be neglected and values have to be mentioned when dealing with water evaporation. Modifying surface tension also affects the pendant drop shape. The drying kinetics of the pendant drop volume and its outer shell are connected to this change of shape. Steam in the air can be assimilated to a wetting agent, hence a surfactant, and can be used in an environmental-friendly way to ease the drying stage. Indeed, the challenge is to limit the risk of cracking and damaging pieces during this crucial step in material processing.
基金the Focus of International Science and Technology Cooperation Project of the Ministry of Science and Technology (Grant No. 2003DF000050)――The development of the track detector thermal control system for the International Space Station Alpha Magnetic Spectrometer (AMS)a special preliminary study item of the 973 Program (Grant No. 2006CB708613) the Natural Science Foundation of Guangdong Province (Grant No. 05003274)
文摘To measure contact angle between CO2 and solid surface, in this study a visual high-pressure vessel has been developed, with a corresponding well-controlled constant temperature system. Pendant drop method is applied to the investigation of the contact angles of CO2 on a stainless steel surface in its own vapor. The image of the pendant drop is recorded by a camera, and a B-Snake method is used to analyze the contour and the contact angle of the droplet. The experimental results have provided a set of well tested data, which show that CO2 has good infiltration into stainless steel surface and the de- veloped method can be used as a standard testing one for measuring the contact angle between high-pressure liquid and solid surface.
基金financially supported by the National Key Research and Development Program of China(2019YFA0905100)the National Natural Science Foundation of China(21878169 and 21991102)Tsinghua University Initiative Scientific Research Program(2018Z05JZY010)。
文摘Piperacillin is a polar organic substance,and can reduce the interfacial tension of oil and water when dissolved in water.In this study,changes in dichloromethane–water interfacial tensions and microdroplet sizes during piperacillin synthesis from an aqueous solution of ampicillin and dichloromethane solution of 4-ethyl-2,3-dioxo-1-piperazine carbonyl chloride(EDPC)were observed using a pendent drop technique and a coaxial ring tube system with embedded high-speed camera,respectively.It was found that the rapid N-acylation reaction caused the piperacillin at the interface to synthesize rapidly and diffuse out slowly,resulting in the interfacial tension decreased from 19.5 m N·m-1 to 7.2 m N·m-1 rapidly and then increased slowly as the concentrations of ampicillin and EDPC were 0.05 mol·L-1 and 0.1 mol·L-1.Meanwhile,the increase in the concentration of EDPC increased the peak concentration of piperacillin at the interface,and the addition of ethyl acetate to the ampicillin solution promoted mass transfer and reduced the aggregation of piperacillin effectively.During synthesis,the interfacial tension decreased,leading to a change in droplet sizes in the micro-reaction system.The two-phase reaction was carried out in a coaxial ring tube,with ampicillin and EDPC solutions as continuous and dispersed phases,respectively.The reaction reduced the dripping flow area,and the addition of ethyl acetate to the ampicillin solution slightly affected the division of the flow pattern.Under the same flow conditions,the droplet sizes of the reaction group were smaller than those of the no reaction group.The experimental results demonstrated that the increase of the continuous phase,decrease in the dispersed phase flow rate,or increase in EDPC concentration making droplet sizes smaller,and the addition of ethyl acetate slightly affected droplet sizes.These findings are important for the design and optimization of piperacillin synthesis reactors.
文摘A pendant drop tensiometry apparatus aided by video-image digitization technology was established, by which static interface or surface tension of some liquids was measured with satisfactory results.In order to study the effect of emulsifier concentration on emulsion stability, dynamic interfacial tension was measured between toluene and water against concentration of Tween 60(Polyoxyethylene(20) stearyl-sorbitanate). As expected, higher concentration is the Tween 60 solution in toluene injected into the toluene phase, faster falls the interface tension between toluene and water.Furthermore, it reveals interestingly that two steps of diffusion occur in the system, i.e ., at low and high concentration, after the surfactant solution is injected.The characteristic process of dynamic interface tension can be ascribed to diffusion control because of linearity between interface tension and the minus second root of aging time.The discovery is correlated to the fact that much higher concentration of surfactant above its critical micelle concentration is often required when a stable emulsion is planned to prepare.
