The thermodynamic properties of the most important NaOH-NaAI(OH)4-H20 system in Bayer process for alumina production were investigated. A theoretical model for calculating the equilibrium constant of gibbsite dissol...The thermodynamic properties of the most important NaOH-NaAI(OH)4-H20 system in Bayer process for alumina production were investigated. A theoretical model for calculating the equilibrium constant of gibbsite dissolved in sodium hydroxide solution was proposed. New Pitzer model parameters and mixing parameters for the system NaOH-NaAI(OH)4-H20 were yielded and tested in the temperature range of 298.15-373.15 K. The results show that the proposed model for calculating the equilibrium constant of gibbsite dissolution is applicable and accurate. The obtained Pitzer model parameters of β(0)(NaAl(OH)4)、β(1)(NaAl(OH)4)和CΦ(NaAl(OH)4),Al(OH)4 for NaAI(OH)4, the binary mixing parameter of θ(OH-Al(OH)4-) with OH-, and the ternary mixing parameter of ψ(Na+OH-Al(OH)4-) for AI(OH)4- with OH- and Na+ are temperature-dependent. The prediction of the equilibrium solubility of gibbsite dissolved in sodium hydroxide solution was feasible in the temperature range of 298.15-373.15 K.展开更多
The use of peat for the removal of nickel from aqueous solutions has been investigated at various pH values by means of static conditions. The present research shows that the ability of Ni to bind to peat increases as...The use of peat for the removal of nickel from aqueous solutions has been investigated at various pH values by means of static conditions. The present research shows that the ability of Ni to bind to peat increases as the pH value increases. The solutions reach adsorption equilibrium rapidly. A reasonable kinetic model, first-order in nickel concentration, has been developed and fitted to the adsorption of nickel (Ⅱ) onto peat. The first-order model provides a good correlation to the experimental data. The characteristic parameters of the Langmuir isotherm were determined at various temperatures. The relationship between kinetics and equilibrium isotherms was established through the forward- and backward-rate-constants, k~ and k2, and the equilibrium constant, K.展开更多
This study investigated the hydrogenation of silicon tetrachloride (SIC14) in microwave plasma. A new launcher of argon (Ar) and hydrogen (Ha) plasma was introduced to produce a non-thermodynamic equilibrium act...This study investigated the hydrogenation of silicon tetrachloride (SIC14) in microwave plasma. A new launcher of argon (Ar) and hydrogen (Ha) plasma was introduced to produce a non-thermodynamic equilibrium activation plasma. The plasma state exhibited a characteristic temperature related to the equilibrium constant, which was termed "Reactive Temperature" in this study. Thus, the hydrogenation of SIC14 in the plasma could easily be handled with high conversion ratio and very high selectivity to trichlorosilane (SiHC13). The effects of SiC14/Ar and H2/Ar ratios on the conversion were also investigated using a mathematical model developed to determine the op- timum experimental parameters. The highest hydrogenation conversion ratio was produced at a H2/SiCl4 molar ratio of 1, with mixtures of SICl4 and H2 to Ar molar ratio of 1.2 to 1.4. In this plasma, the special system pressure and incident power were required for the highest energy efficiency of hydrogenating SIC14, while the optimum system pressure varies from 26.6 to 40 kPa depending on input power, and the optimum feed gas (He and SiCI4) molar en- ergy input was about 350 kJ. mo1-1.展开更多
4-Tert-butyl-2-(α-methylbenzyl) phenol (t-BAMBP) was used in cyclohexane in the extraction of rubidium from brine sources containing lithium. The effect of t-BAMBP concentration and aqueous phase pH on the rubidi...4-Tert-butyl-2-(α-methylbenzyl) phenol (t-BAMBP) was used in cyclohexane in the extraction of rubidium from brine sources containing lithium. The effect of t-BAMBP concentration and aqueous phase pH on the rubidium and lithium extraction equilibrium was studied, t-BAMBP/cyclohexane was efficient and selective for rubidium extraction with optimal operating conditions being pH of 13.0 and initial t-BAMBP concentration of 1.0 mol.L-1. The stoichiometry of the complex of α-BAMBP with rubidium is 4:1. The apparent extraction equilibrium constant of rubidium was calculated by fitting the experimental data.展开更多
A new competitive adsorption isothermal model(CAIM)was developed for the coexistent and competitive binding of heavy metals to the soil surface.This model extended the earlier adsorption isothermal models by consideri...A new competitive adsorption isothermal model(CAIM)was developed for the coexistent and competitive binding of heavy metals to the soil surface.This model extended the earlier adsorption isothermal models by considering more than one kind of ion adsorption on the soil surface.It was compared with the Langmuir model using different conditions, and it was found that CAIM,which was suitable for competitive ion adsorption at the soil solid-liquid surface,had more advantages than the Langmuir model.The new competitive adsorption isothermal model was used to fit the data of heavy metal(Zn and Cd)competitive adsorption by a yellow soil at two temperatures.The results showed that CAIM was appropriate for the competitive adsorption of heavy metals on the soil surface at different temperatures.The fitted parameters of CAIM had explicit physical meaning.The model allowed for the calculation of the standard molar Gibbs free energy change,the standard molar enthalpy change,and the standard molar entropy change of the competitive adsorption of the heavy metals,Zn and Cd,by the yellow soil at two temperatures using the thermodynamic equilibrium constants.展开更多
A new extractant, [N,N-di(2-ethylhexyl)aminolmethylphenylphosphinic acid (DEAPP), was synthesized to de- velop the mutual separation techniques of In(Ⅲ), Ga(Ⅲ) and Zn(Ⅱ). The extraction selectivity for I...A new extractant, [N,N-di(2-ethylhexyl)aminolmethylphenylphosphinic acid (DEAPP), was synthesized to de- velop the mutual separation techniques of In(Ⅲ), Ga(Ⅲ) and Zn(Ⅱ). The extraction selectivity for In(Ⅲ), Ga(Ⅲ) and Zn(Ⅱ) with DEAPP was higher than that of the commercial phosphorus acid extractants such as D2EHPA and PC-88A. The extraction selectivity for metal ions in 1 mob L 1 aqueous ammonium nitrate solution with DEAPP was in the following order: In(Ⅲ) 〉 Ga(Ⅲ) 〉 Zn(Ⅱ). These selective extraction behaviors indicate that the amino moiety of DEAPP plays an important role in the mutual separation of ln(Ⅲ), Ga(Ⅲ) and Zn(ll). The extraction equilibria of In(Ⅲ), Ga(Ⅲ) and Zn(Ⅱ) with DEAPP ( = HR) were expressed by the following reactions: In3+ + 2(HR)2 InR3(HR) + 3H+, Ga3+ + 1.5(HR)2 + N- = GaR2(HR)(NO3) + 2H+, and Zn2+ 4- 2(HR)2 ZnR2 (HR) 2 determined 4- 2H+. The extraction equilibrium constants of In(Ⅲ), Ga(Ⅲ) and Zn(Ⅱ) with DEAPP were to be Kex, M = 1.7 × 104 [dm3.mol 1], 4.17 [(dm3.mol-1)s], and 1.55 × 10 2 [-], respectively.展开更多
The distributions of nicotinic acid (NA) between water and trialkylamine (N235) dissolved in n-octanol was studied. The complexes of N235 and NA were investigated by Fourier transformation infrared spectrometry to ded...The distributions of nicotinic acid (NA) between water and trialkylamine (N235) dissolved in n-octanol was studied. The complexes of N235 and NA were investigated by Fourier transformation infrared spectrometry to deduce the reaction mechanism. It was found that N235/n-octanol was an efficient extractant for extracting nicotinic acid. The favorable operation conditions were equilibrium aqueous pH 4.2 to 5.5 and initial N235 concentration<0.42 mol·L-1 . The reaction processes included the reaction between neutral N235 and neutral NA and the reaction between protonated N235 and anionic NA. Based on the mass action law and some assumptions, an expression for distribution coefficient D was proposed. The apparent extraction equilibrium constants were calculated by fitting the experimental data and the results were satisfactory.展开更多
The utilization of liquid–liquid extraction for the separation of 2-phenylbutyric acid(2-PBA) enantiomers was proposed. Factors affecting the extract process were investigated, including organic solvents, β-cyclod...The utilization of liquid–liquid extraction for the separation of 2-phenylbutyric acid(2-PBA) enantiomers was proposed. Factors affecting the extract process were investigated, including organic solvents, β-cyclodextrin derivatives, cyclodextrin concentration, p H and temperature. A model was proposed to describe the separation process based on the homogeneous phase reaction mechanism. Important parameters of this model were determined experimentally. The physical distribution coefficients for molecular and ionic 2-PBA were0.129 and 7.455, respectively. The equilibrium constants of the complexation reactions were 89.36 and36.78 L·mol^-1 for(+)-and(-)-2-PBA, respectively. The model was verified by experiments and proved to be an excellent means to optimize the separation system. Through modeling prediction and experiment, the best conditions(e.g., pH value of 3.00, extractant concentration of 0.1 mol·L^-1, temperature of 5.0 ℃) were acquired. Under this condition, the maximum enantioselectivity(2.096) was obtained.展开更多
The effects of pulse ultrasound with different pulse parameters on the breakthrough curves of Geniposide on Resin 1300 were studied. The mass transfer model describing the adsorption process was constructed. Adsorptio...The effects of pulse ultrasound with different pulse parameters on the breakthrough curves of Geniposide on Resin 1300 were studied. The mass transfer model describing the adsorption process was constructed. Adsorption capability and the overall mass-transfer coefficient were obtained by fitting the constructed mass-transfer model and the experimental data. The effects of pulse ultrasound on adsorption of Geniposide on Resin1300 in a fixed bed were studied and compared. Amount of Geniposide adsorbed on Resin 1300 in the presence of ultrasound is lower than that in the absence of ultrasound, but the mass-transfer rate with ultrasonic irradiation is higher than that without ultrasound. Furthermore, mass transfer rate is enhanced by pulse modulation. In the conditions studied, the adsorption equilibrium constant decreases with increasing ultrasonic power, while the overall mass-transfer co-efficient increases. With increasing pulse duty ratio, adsorption equilibrium constant decreases initially, reaches a minimum when pulse duty ratio is 0.5, and then increases. On the contrary, the overall mass-transfer coefficient in-creases initially and reaches a maximum when pulse ratio is 0.5, and then decreases. Effects of pulse period on ad-sorption equilibrium and mass transfer rate reached the peak at pulse period of 28.6 ms.展开更多
In this work, the numerical simulation is employed for HL-2A equipment modification project HL-2M. The design of zero field and evolution of plasma configuration in start-up phase and single null divertor equilibrium ...In this work, the numerical simulation is employed for HL-2A equipment modification project HL-2M. The design of zero field and evolution of plasma configuration in start-up phase and single null divertor equilibrium configurations in steady-state phase has been simulated. Results show that new project can satisfy request of design.展开更多
Adsorption of FCC dry gas components, hydrogen(H_2), nitrogen(N_2), methane(CH_4), ethane(C_2H_6) and ethylene(C_2H_4) in zeolite Y was studied by performing the Grant Canonical Monte Carlo(GCMC) simulations at 298K a...Adsorption of FCC dry gas components, hydrogen(H_2), nitrogen(N_2), methane(CH_4), ethane(C_2H_6) and ethylene(C_2H_4) in zeolite Y was studied by performing the Grant Canonical Monte Carlo(GCMC) simulations at 298K and 823K and under a pressure range up to 10 MPa. Simulation results were analyzed using the Langmuir model, which presented fitting of dry gas components adsorption to be suggested as the monolayer adsorption. C_2H_4 presented most single adsorption amount, which reached 7.63 mol/kg at 298K under a pressure of 200kPa. Thermodynamic parameters of the Gibbs free energy change, enthalpy change and entropy change were analyzed based on adsorption equilibrium constant obtained from the GCMC simulations. The results suggested that it was more favorable for C_2H_4 to be adsorbed in zeolite Y. Adsorption molecules were in ordered arrangement in the zeolite, and C_2H_4 exhibited a more orderly arrangement than other components. Additionally, a competition in the adsorption of a mixture of dry gas components was found, and supercages were the priority adsorption space. The competition was favorable to CH_4 and C_2H_6, and the competitive power was affected by temperature.展开更多
The importance of equations of state (EOS) has brought about the proliferation of hundreds of EOS. Nearly all prevailing cubic EOS could be regarded as the results of reforming the original vdW EOS. However, the accur...The importance of equations of state (EOS) has brought about the proliferation of hundreds of EOS. Nearly all prevailing cubic EOS could be regarded as the results of reforming the original vdW EOS. However, the accuracy of the vdW EOS is so low. In view of this, a new general equation is proposed that could be used to value or compare vdW type of EOS, and consequently develop a better vdW type of EOS.展开更多
The solid–liquid extraction process of nylon 6 to eliminate small molecules, i.e., caprolactam(CL), cyclic dimers(CD) and cyclic trimers(CT), is investigated in detail by both batch extraction experiments and numeric...The solid–liquid extraction process of nylon 6 to eliminate small molecules, i.e., caprolactam(CL), cyclic dimers(CD) and cyclic trimers(CT), is investigated in detail by both batch extraction experiments and numerical simulations. In the batch extraction experiments, due to the small molecules attaching to the polymeric surface, the basic physical mechanism shifts from surface diffusion to internal diffusion as the extraction proceeded. The experimental data are well reproduced by a diffusion model consisting of two distinct steps, characterized as surface diffusion and internal diffusion. Furthermore, based on the established mass transfer mechanism and diffusion model of the two distinct steps, the equilibrium constants and internal diffusion coefficients of CL, CD and CT are acquired. An industrial countercurrent extraction tower is further simulated. It is found that the extraction efficiency of CL can be significantly improved by increasing the temperature at the bottom portion of the tower. The elimination of CD, which can be greatly promoted by a high-concentration CL-water solution, is controlled by mass transfer resistance, whereas the removal of CL is mainly affected by the equilibrium.展开更多
Through the long-term plot studies on the precipitation distribution in the evergreen broad-leaved forest ecosystem in Hangzhou for two years, it was indicated that the pattern of precipitation distribution included l...Through the long-term plot studies on the precipitation distribution in the evergreen broad-leaved forest ecosystem in Hangzhou for two years, it was indicated that the pattern of precipitation distribution included larger amounts of penetration water and stemflow and a lower amount of interception water. The results revealed that the main factors to infulence the percentages of penetration and stemflow were the air temperature and the leaf area of the forest. The quantity of seepage through the litter layer was much larger than that through the soil layers which decreased sharply with soil depth. The output of water from the ecosystem by surface runoff and deep infiltration through the soil was much lower, only being 5.20 percent of the rainfall, while the water evapotranspiration loss was as large as more than 90 percent of it. The losses by the soil evaporation and plant evapotranspiration were the largest part of output in this forest ecosystem.展开更多
基金Project (2005CB6237) supported by the National Basic Research Program of China
文摘The thermodynamic properties of the most important NaOH-NaAI(OH)4-H20 system in Bayer process for alumina production were investigated. A theoretical model for calculating the equilibrium constant of gibbsite dissolved in sodium hydroxide solution was proposed. New Pitzer model parameters and mixing parameters for the system NaOH-NaAI(OH)4-H20 were yielded and tested in the temperature range of 298.15-373.15 K. The results show that the proposed model for calculating the equilibrium constant of gibbsite dissolution is applicable and accurate. The obtained Pitzer model parameters of β(0)(NaAl(OH)4)、β(1)(NaAl(OH)4)和CΦ(NaAl(OH)4),Al(OH)4 for NaAI(OH)4, the binary mixing parameter of θ(OH-Al(OH)4-) with OH-, and the ternary mixing parameter of ψ(Na+OH-Al(OH)4-) for AI(OH)4- with OH- and Na+ are temperature-dependent. The prediction of the equilibrium solubility of gibbsite dissolved in sodium hydroxide solution was feasible in the temperature range of 298.15-373.15 K.
基金Projects [2006]331 supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars070712 by the Key Laboratory ofNuclear Resources and Environment,Ministry of Education of China
文摘The use of peat for the removal of nickel from aqueous solutions has been investigated at various pH values by means of static conditions. The present research shows that the ability of Ni to bind to peat increases as the pH value increases. The solutions reach adsorption equilibrium rapidly. A reasonable kinetic model, first-order in nickel concentration, has been developed and fitted to the adsorption of nickel (Ⅱ) onto peat. The first-order model provides a good correlation to the experimental data. The characteristic parameters of the Langmuir isotherm were determined at various temperatures. The relationship between kinetics and equilibrium isotherms was established through the forward- and backward-rate-constants, k~ and k2, and the equilibrium constant, K.
文摘This study investigated the hydrogenation of silicon tetrachloride (SIC14) in microwave plasma. A new launcher of argon (Ar) and hydrogen (Ha) plasma was introduced to produce a non-thermodynamic equilibrium activation plasma. The plasma state exhibited a characteristic temperature related to the equilibrium constant, which was termed "Reactive Temperature" in this study. Thus, the hydrogenation of SIC14 in the plasma could easily be handled with high conversion ratio and very high selectivity to trichlorosilane (SiHC13). The effects of SiC14/Ar and H2/Ar ratios on the conversion were also investigated using a mathematical model developed to determine the op- timum experimental parameters. The highest hydrogenation conversion ratio was produced at a H2/SiCl4 molar ratio of 1, with mixtures of SICl4 and H2 to Ar molar ratio of 1.2 to 1.4. In this plasma, the special system pressure and incident power were required for the highest energy efficiency of hydrogenating SIC14, while the optimum system pressure varies from 26.6 to 40 kPa depending on input power, and the optimum feed gas (He and SiCI4) molar en- ergy input was about 350 kJ. mo1-1.
基金Supported by the research fund for the Doctoral Program of Education Ministry of China(20120002110098)
文摘4-Tert-butyl-2-(α-methylbenzyl) phenol (t-BAMBP) was used in cyclohexane in the extraction of rubidium from brine sources containing lithium. The effect of t-BAMBP concentration and aqueous phase pH on the rubidium and lithium extraction equilibrium was studied, t-BAMBP/cyclohexane was efficient and selective for rubidium extraction with optimal operating conditions being pH of 13.0 and initial t-BAMBP concentration of 1.0 mol.L-1. The stoichiometry of the complex of α-BAMBP with rubidium is 4:1. The apparent extraction equilibrium constant of rubidium was calculated by fitting the experimental data.
基金Project supported by the Program for Changjiang Scholars and Innovative Research Team in University of China(No.IRT0749)
文摘A new competitive adsorption isothermal model(CAIM)was developed for the coexistent and competitive binding of heavy metals to the soil surface.This model extended the earlier adsorption isothermal models by considering more than one kind of ion adsorption on the soil surface.It was compared with the Langmuir model using different conditions, and it was found that CAIM,which was suitable for competitive ion adsorption at the soil solid-liquid surface,had more advantages than the Langmuir model.The new competitive adsorption isothermal model was used to fit the data of heavy metal(Zn and Cd)competitive adsorption by a yellow soil at two temperatures.The results showed that CAIM was appropriate for the competitive adsorption of heavy metals on the soil surface at different temperatures.The fitted parameters of CAIM had explicit physical meaning.The model allowed for the calculation of the standard molar Gibbs free energy change,the standard molar enthalpy change,and the standard molar entropy change of the competitive adsorption of the heavy metals,Zn and Cd,by the yellow soil at two temperatures using the thermodynamic equilibrium constants.
基金supported by The Environment Research and Technology Development Fund (3K133005)
文摘A new extractant, [N,N-di(2-ethylhexyl)aminolmethylphenylphosphinic acid (DEAPP), was synthesized to de- velop the mutual separation techniques of In(Ⅲ), Ga(Ⅲ) and Zn(Ⅱ). The extraction selectivity for In(Ⅲ), Ga(Ⅲ) and Zn(Ⅱ) with DEAPP was higher than that of the commercial phosphorus acid extractants such as D2EHPA and PC-88A. The extraction selectivity for metal ions in 1 mob L 1 aqueous ammonium nitrate solution with DEAPP was in the following order: In(Ⅲ) 〉 Ga(Ⅲ) 〉 Zn(Ⅱ). These selective extraction behaviors indicate that the amino moiety of DEAPP plays an important role in the mutual separation of ln(Ⅲ), Ga(Ⅲ) and Zn(ll). The extraction equilibria of In(Ⅲ), Ga(Ⅲ) and Zn(Ⅱ) with DEAPP ( = HR) were expressed by the following reactions: In3+ + 2(HR)2 InR3(HR) + 3H+, Ga3+ + 1.5(HR)2 + N- = GaR2(HR)(NO3) + 2H+, and Zn2+ 4- 2(HR)2 ZnR2 (HR) 2 determined 4- 2H+. The extraction equilibrium constants of In(Ⅲ), Ga(Ⅲ) and Zn(Ⅱ) with DEAPP were to be Kex, M = 1.7 × 104 [dm3.mol 1], 4.17 [(dm3.mol-1)s], and 1.55 × 10 2 [-], respectively.
基金Supported by the Ministry of Education of Henan Province in China (2011A610004)
文摘The distributions of nicotinic acid (NA) between water and trialkylamine (N235) dissolved in n-octanol was studied. The complexes of N235 and NA were investigated by Fourier transformation infrared spectrometry to deduce the reaction mechanism. It was found that N235/n-octanol was an efficient extractant for extracting nicotinic acid. The favorable operation conditions were equilibrium aqueous pH 4.2 to 5.5 and initial N235 concentration<0.42 mol·L-1 . The reaction processes included the reaction between neutral N235 and neutral NA and the reaction between protonated N235 and anionic NA. Based on the mass action law and some assumptions, an expression for distribution coefficient D was proposed. The apparent extraction equilibrium constants were calculated by fitting the experimental data and the results were satisfactory.
基金Supported by the National Basic Research Program of China(2014CB260407)
文摘The utilization of liquid–liquid extraction for the separation of 2-phenylbutyric acid(2-PBA) enantiomers was proposed. Factors affecting the extract process were investigated, including organic solvents, β-cyclodextrin derivatives, cyclodextrin concentration, p H and temperature. A model was proposed to describe the separation process based on the homogeneous phase reaction mechanism. Important parameters of this model were determined experimentally. The physical distribution coefficients for molecular and ionic 2-PBA were0.129 and 7.455, respectively. The equilibrium constants of the complexation reactions were 89.36 and36.78 L·mol^-1 for(+)-and(-)-2-PBA, respectively. The model was verified by experiments and proved to be an excellent means to optimize the separation system. Through modeling prediction and experiment, the best conditions(e.g., pH value of 3.00, extractant concentration of 0.1 mol·L^-1, temperature of 5.0 ℃) were acquired. Under this condition, the maximum enantioselectivity(2.096) was obtained.
基金Supported by the National lqatural Science Foundation of China (20346003).
文摘The effects of pulse ultrasound with different pulse parameters on the breakthrough curves of Geniposide on Resin 1300 were studied. The mass transfer model describing the adsorption process was constructed. Adsorption capability and the overall mass-transfer coefficient were obtained by fitting the constructed mass-transfer model and the experimental data. The effects of pulse ultrasound on adsorption of Geniposide on Resin1300 in a fixed bed were studied and compared. Amount of Geniposide adsorbed on Resin 1300 in the presence of ultrasound is lower than that in the absence of ultrasound, but the mass-transfer rate with ultrasonic irradiation is higher than that without ultrasound. Furthermore, mass transfer rate is enhanced by pulse modulation. In the conditions studied, the adsorption equilibrium constant decreases with increasing ultrasonic power, while the overall mass-transfer co-efficient increases. With increasing pulse duty ratio, adsorption equilibrium constant decreases initially, reaches a minimum when pulse duty ratio is 0.5, and then increases. On the contrary, the overall mass-transfer coefficient in-creases initially and reaches a maximum when pulse ratio is 0.5, and then decreases. Effects of pulse period on ad-sorption equilibrium and mass transfer rate reached the peak at pulse period of 28.6 ms.
文摘In this work, the numerical simulation is employed for HL-2A equipment modification project HL-2M. The design of zero field and evolution of plasma configuration in start-up phase and single null divertor equilibrium configurations in steady-state phase has been simulated. Results show that new project can satisfy request of design.
基金financial support from the National Natural Science Foundation of China (No. 41302101 and No. 21476263)
文摘Adsorption of FCC dry gas components, hydrogen(H_2), nitrogen(N_2), methane(CH_4), ethane(C_2H_6) and ethylene(C_2H_4) in zeolite Y was studied by performing the Grant Canonical Monte Carlo(GCMC) simulations at 298K and 823K and under a pressure range up to 10 MPa. Simulation results were analyzed using the Langmuir model, which presented fitting of dry gas components adsorption to be suggested as the monolayer adsorption. C_2H_4 presented most single adsorption amount, which reached 7.63 mol/kg at 298K under a pressure of 200kPa. Thermodynamic parameters of the Gibbs free energy change, enthalpy change and entropy change were analyzed based on adsorption equilibrium constant obtained from the GCMC simulations. The results suggested that it was more favorable for C_2H_4 to be adsorbed in zeolite Y. Adsorption molecules were in ordered arrangement in the zeolite, and C_2H_4 exhibited a more orderly arrangement than other components. Additionally, a competition in the adsorption of a mixture of dry gas components was found, and supercages were the priority adsorption space. The competition was favorable to CH_4 and C_2H_6, and the competitive power was affected by temperature.
文摘The importance of equations of state (EOS) has brought about the proliferation of hundreds of EOS. Nearly all prevailing cubic EOS could be regarded as the results of reforming the original vdW EOS. However, the accuracy of the vdW EOS is so low. In view of this, a new general equation is proposed that could be used to value or compare vdW type of EOS, and consequently develop a better vdW type of EOS.
基金Supported by the National Key Research and Development Program of China(2016YFB0302701)the Shanghai Rising-Star Program(16QB140130)the 111 Project(B08021)
文摘The solid–liquid extraction process of nylon 6 to eliminate small molecules, i.e., caprolactam(CL), cyclic dimers(CD) and cyclic trimers(CT), is investigated in detail by both batch extraction experiments and numerical simulations. In the batch extraction experiments, due to the small molecules attaching to the polymeric surface, the basic physical mechanism shifts from surface diffusion to internal diffusion as the extraction proceeded. The experimental data are well reproduced by a diffusion model consisting of two distinct steps, characterized as surface diffusion and internal diffusion. Furthermore, based on the established mass transfer mechanism and diffusion model of the two distinct steps, the equilibrium constants and internal diffusion coefficients of CL, CD and CT are acquired. An industrial countercurrent extraction tower is further simulated. It is found that the extraction efficiency of CL can be significantly improved by increasing the temperature at the bottom portion of the tower. The elimination of CD, which can be greatly promoted by a high-concentration CL-water solution, is controlled by mass transfer resistance, whereas the removal of CL is mainly affected by the equilibrium.
基金Project supported by the Laboratory of Material Cycling in Pedosphere, Institute of Soil Science, Chinese Academy of Sciences.
文摘Through the long-term plot studies on the precipitation distribution in the evergreen broad-leaved forest ecosystem in Hangzhou for two years, it was indicated that the pattern of precipitation distribution included larger amounts of penetration water and stemflow and a lower amount of interception water. The results revealed that the main factors to infulence the percentages of penetration and stemflow were the air temperature and the leaf area of the forest. The quantity of seepage through the litter layer was much larger than that through the soil layers which decreased sharply with soil depth. The output of water from the ecosystem by surface runoff and deep infiltration through the soil was much lower, only being 5.20 percent of the rainfall, while the water evapotranspiration loss was as large as more than 90 percent of it. The losses by the soil evaporation and plant evapotranspiration were the largest part of output in this forest ecosystem.