The effects of organic salts on 1,3,5-trioxane synthesis were investigated through batch reaction and continuous production experiments. The organic salts used include sodium methanesulfonate(CH3NaO3S), sodium benze...The effects of organic salts on 1,3,5-trioxane synthesis were investigated through batch reaction and continuous production experiments. The organic salts used include sodium methanesulfonate(CH3NaO3S), sodium benzenesulfonate(C6H5NaO3S), sodium 4-methylbenzenesulfonate(C7H7NaO3S), and sodium 3-nitrobenzene sulfonate(C6H4NNaO5S). It was shown that the effects of organic salts on the yield of 1,3,5-trioxane in reaction solution and distillate follow the order CH3NaO3S /C6H5NaO3S/C7H7NaO3S/C6H4NNaO5S, which is inversely related to the charge density of the anions of the organic salts. In comparison with Cl–-based salts such as magnesium chloride, organic salts have the advantages of less formic acid generation and low corrosion. Studies on water activity revealed that the effect of organic salts on the activity of water was quite small at low concentration of organic salts. UV–visible spectroscopy and vapor–liquid equilibrium experiments were performed to uncover the mechanisms that govern such effects. The results showed that the effect of organic salts on the yield of 1,3,5-trioxane relies primarily on their ability to increase the catalytic activity of sulfuric acid and increase the relative volatilities of 1,3,5-trioxane and water and of 1,3,5-trioxane and oligomers.展开更多
Phase transition behavior and influence of ions on the thermo-sensitive polyamide with polyethylene glycol as the main chain were studied in detail. By measuring the light transmission rates of polymer solutions, the ...Phase transition behavior and influence of ions on the thermo-sensitive polyamide with polyethylene glycol as the main chain were studied in detail. By measuring the light transmission rates of polymer solutions, the change of its lower critical solution temperature (LCST) in the salt solution was investigated. It was found that a reversible phase transition of the polyamide occurred at the LCST and finished in a narrow temperature range. The LCST was associated with species of ions in salt solution. Anions had a great impact on the phase transition performance of the thermo-sensitive polyamide, while the cations had a slight influence on the phase transition. Different anions had different coagulation ability to ‘salt-out' the polyamide. The order was: CO2-3〉SiO2-3〉HPO2-4〉OH-〉Cl-〉HCO3-〉HSOa-〉NO2-〉NO3-.展开更多
The salt effect on the vaporliquid phase equilibrium(VLE)of solvent mixtures is of significant interest in the industrial production of 1,3,5trioxane.Experimental data for the VLE of quinary systems(formaldehyde+1,3,5...The salt effect on the vaporliquid phase equilibrium(VLE)of solvent mixtures is of significant interest in the industrial production of 1,3,5trioxane.Experimental data for the VLE of quinary systems(formaldehyde+1,3,5trioxane+methanol+salt+water)and their ternary subsystems(formaldehyde+salt+water),(1,3,5trioxane+salt+water),and(methanol+salt+water)were systematic measured under atmospheric pressure.The salts considered included KBr,NaNO_(3),and CaCl_(2).The extended UNIFAC model was used to describe the VLE of the saltcontaining reactive mixtures.The model parameters were determined from the experimental VLE data of ternary systems or obtained from the literature,and then were used to predict the VLE of systems(1,3,5trioxane+KBr+water),(methanol+KBr+water),(formaldehyde+KBr+water),and(formaldehyde+1,3,5trioxane+methanol+salt+water)with salt=KBr,NaNO_(3),and CaCl_(2).The predicted results showed good agreements with the measured results.Furthermore,the model was used to uncover the salt effect on the VLE of these multisolvent reactive systems.展开更多
The natural occurrence of methane hydrates in marine sediments has been intensively studied over the past decades, and geochemical charac-teristic of hydrate is one of the most attractive research fields. In this pape...The natural occurrence of methane hydrates in marine sediments has been intensively studied over the past decades, and geochemical charac-teristic of hydrate is one of the most attractive research fields. In this paper, we discussed the geochemical anomaly during hydrate formation in porous media. By doing so, we also investigated the temperature influence on hydrate formation under isobaric condition. It turns out that sub-cooling is an important factor to dominate hydrate formation. Larger subcooling provides more powerful driving force for hydrate formation. During the geochemical anomaly research, six kinds of ions and the total dissolved salt (TDS) were measured before and after the experiment in different porous media. The result is that all kinds of ionic concentration increased after hydrate formation which can be defined as salting out effect mainly affected by gas consumption. But the variation ratio of different ions is not equal. Ca^2+ seems to be the most significantly influenced one, and its variation ratio is up to 80%. Finally, we theoretically made a model to calculate the TDS variation, the result is in good accordance with measured one, especially when gas consumption is large.展开更多
In this paper, the fluorescence spectra of model compounds of light-emitting alternating copolymers. M (TPA-PPV) and M (TPA-PAV) (Scheme 1) were studied and the effect of KNO3 on the interaction between model compound...In this paper, the fluorescence spectra of model compounds of light-emitting alternating copolymers. M (TPA-PPV) and M (TPA-PAV) (Scheme 1) were studied and the effect of KNO3 on the interaction between model compounds and ionic micelle-watts interface was also investigated. It is found that (I) The fluorescence changes of M (TPA-PPV) are related to the state of CTAB and SDS solution. (II)Aggregated state can be formed in M (TPA-PAV) solution at low concentration of CTAB. (III) Higher concentration of KNO3 may affect the interaction between model compounds and ionic micelle-water interface.展开更多
The solubilities of benzene and diphenyl in mixed solvents of t-butyl alcohol(TBA) and water with different salts have been determined at T = 298.15, 303.15, 308.15 and 313.15K. The molar fraction of TBA [x(TBA)] in m...The solubilities of benzene and diphenyl in mixed solvents of t-butyl alcohol(TBA) and water with different salts have been determined at T = 298.15, 303.15, 308.15 and 313.15K. The molar fraction of TBA [x(TBA)] in mixed solvent is 0.045, and the molality of the salts (m_s)in mixed solvents are 0.000, 0.250, 0.500, 0.750 and 1.000 mol/kg, respectively. The standard Gibbsenergies of solution of benzene and diphenyl in the mixed solvents have also been calculated basedon the solubility data. The effects of different salts on the hydrophobic interaction (HI) forbenzene-benzene pair in the systems were discussed.展开更多
The salt effects on molecular orientation at air/liquid methanol interface were investigated by the polarization-dependent sum frequency generation vibrational spectroscopy(SFG-VS). We clarified that the average til...The salt effects on molecular orientation at air/liquid methanol interface were investigated by the polarization-dependent sum frequency generation vibrational spectroscopy(SFG-VS). We clarified that the average tilting angle of the methyl group to be u = 308 58 at the air/pure methanol surface assuming a d-function orientational distribution. Upon the addition of 3 mol/L Na I, the methyl group tilts further away from the surface normal with a new u = 418 38. This orientational change does not explain the enhancement of the SFG-VS intensities when adding Na I, implying the number density of the methanol molecules with a net polar ordering in the surface region also changed with the Na I concentrations. These spectroscopic findings shed new light on the salt effects on the surfaces structures of the polar organic solutions. It was also shown that the accurate determination of the bulk refractive indices and Raman depolarization ratios for different salt concentrations is crucial to quantitatively interpret the SFG-VS data.展开更多
The tide induced groundwater fluctuation and the seawater intrusion have important effects on hydrogeology and ecology of coastal aquifers.Among previous studies,there were few quantitative evaluations of the joint ef...The tide induced groundwater fluctuation and the seawater intrusion have important effects on hydrogeology and ecology of coastal aquifers.Among previous studies,there were few quantitative evaluations of the joint effects of the beach slope and the tide fluctuation on the groundwater dynamics.In this article,a numerical model is built by using the software FEFLOW with consideration of seawater intrusion,tide effects,density dependent flow and beach sloping effects.The simulation results are validated by laboratory experimental data in literature.More numerical scenarios are designed in a practical scale with different beach slopes.Results show that the groundwater fluctuation decays exponentially with the distance to the beach,i.e.,,and our simulation further shows that the beach slope influence can be expressed in the form of a logarithm function.While for the same location,the amplitude increases logarithmically with the beach angle in the form,where and are related with the horizontal distance()in the form of a logarithm function.The beach slope has no influence on the phase lag,although the latter increases regularly with the distance from the sea.The beach slope effect on the seawater intrusion is investigated through the quantitative relationship among the relative intrusion length(),the relative enhancement of the tide induced seawater intrusion()and the beach angle().It is shown that the tide effects on a milder beach is much greater than on a vertical one,and both λ and κ can be expressed in logarithm functions of.The tidal effect on the flow field in the transition zone for a particular mild beach is also studied,with results showing that the tide induced fluctuation of is similar to the groundwater table fluctuation while shows a distinct variation along both directions.展开更多
The equilibrium and dynamic surface tension (DST) of the novel cationic surfactant, 3-(p-nonylphenoxy)-2-hydroxylpropyl trimethyl ammonium bromide, abbreviated as RTAB, were studied. The effect of sodium halide su...The equilibrium and dynamic surface tension (DST) of the novel cationic surfactant, 3-(p-nonylphenoxy)-2-hydroxylpropyl trimethyl ammonium bromide, abbreviated as RTAB, were studied. The effect of sodium halide such as NaCl, NaBr and NaI on the DST behavior of the RTAB solution below its CMC was studied in detail. Due to the preferential adsorption, the effect of hydration and salting out, the ability to reduce the DST values at the same concentration was in the order of NaI〉NaBr〉NaCl. Attributed to its high surface activity, the equilibrium time of the DST of the surfactant solution was insensitive to the ionic strength.展开更多
Pt,H2(g,p0)HCl(mE)|AgCl-AgPt, H2(g, p0)|HCl(mE), EtOH(mN)|AgCl-Ag have been measured at 10 degree intervals from 278.15 to 318.15 K, where EtOH refers to ethanol, mE=0.005-0.1 mol.kg-1, mN=0.4-1.0 mol.kg-1. The saltin...Pt,H2(g,p0)HCl(mE)|AgCl-AgPt, H2(g, p0)|HCl(mE), EtOH(mN)|AgCl-Ag have been measured at 10 degree intervals from 278.15 to 318.15 K, where EtOH refers to ethanol, mE=0.005-0.1 mol.kg-1, mN=0.4-1.0 mol.kg-1. The salting constant kS of EtOH by HCl and the thermodynamic parameters of interaction, fEN(gEN> hEN, sEN] cP,EN)> of EtOH with HCI in water have been evaluated. It has been shown that kS>0, gEN>0,hEN>0, SEN>0 ,and cp,EN<0.The signs of these parameters and the temperature dependence of them have been discussed on the basis of structural interaction and the group additivity models.展开更多
The ultrasonic velocity (U), has been measured for three a-amino acids, namely L-lysine monohydrochloride, L-arginine and L-histidine in solutions (1 mol/L aqueous) of sodium acetate (SA), potassium acetate (PA...The ultrasonic velocity (U), has been measured for three a-amino acids, namely L-lysine monohydrochloride, L-arginine and L-histidine in solutions (1 mol/L aqueous) of sodium acetate (SA), potassium acetate (PA) and calcium acetate (CA) at different temperatures (303.15, 308.15, 313.15, 318.15 and 323.15 K). With the help of these results various ultrasonic derived parameters, viz. isentropic compressibility (Ks), change in isentropic compressibility (△K5), relative change in isentropic compressibility (△Kr), specific acoustic impedance (Z), relative association (RA), and apparent molal compressibility (Фks) have been estimated. The results have been interpreted in the light of intermolecular interactions between solute and solvent.展开更多
基金the National Natural Science Foundation of China (21576285 and 21276271)Science Foundation of China University of Petroleum, Beijing (qzdx-2011-01)
文摘The effects of organic salts on 1,3,5-trioxane synthesis were investigated through batch reaction and continuous production experiments. The organic salts used include sodium methanesulfonate(CH3NaO3S), sodium benzenesulfonate(C6H5NaO3S), sodium 4-methylbenzenesulfonate(C7H7NaO3S), and sodium 3-nitrobenzene sulfonate(C6H4NNaO5S). It was shown that the effects of organic salts on the yield of 1,3,5-trioxane in reaction solution and distillate follow the order CH3NaO3S /C6H5NaO3S/C7H7NaO3S/C6H4NNaO5S, which is inversely related to the charge density of the anions of the organic salts. In comparison with Cl–-based salts such as magnesium chloride, organic salts have the advantages of less formic acid generation and low corrosion. Studies on water activity revealed that the effect of organic salts on the activity of water was quite small at low concentration of organic salts. UV–visible spectroscopy and vapor–liquid equilibrium experiments were performed to uncover the mechanisms that govern such effects. The results showed that the effect of organic salts on the yield of 1,3,5-trioxane relies primarily on their ability to increase the catalytic activity of sulfuric acid and increase the relative volatilities of 1,3,5-trioxane and water and of 1,3,5-trioxane and oligomers.
基金Funded by the Major Special Science and Technology Project of Hainan Province (No.ZDZX20100009)
文摘Phase transition behavior and influence of ions on the thermo-sensitive polyamide with polyethylene glycol as the main chain were studied in detail. By measuring the light transmission rates of polymer solutions, the change of its lower critical solution temperature (LCST) in the salt solution was investigated. It was found that a reversible phase transition of the polyamide occurred at the LCST and finished in a narrow temperature range. The LCST was associated with species of ions in salt solution. Anions had a great impact on the phase transition performance of the thermo-sensitive polyamide, while the cations had a slight influence on the phase transition. Different anions had different coagulation ability to ‘salt-out' the polyamide. The order was: CO2-3〉SiO2-3〉HPO2-4〉OH-〉Cl-〉HCO3-〉HSOa-〉NO2-〉NO3-.
基金The authors gratefully acknowledge financial support from the National Natural Science Foundation of China(grant numbers 22078355,21890763 and 21776300)Petrochemical Research Institute of PetroChina(grant number HX20200668)Scientific Research Project of Ordos Institute of Technology(grant numbers KYYB2019006).
文摘The salt effect on the vaporliquid phase equilibrium(VLE)of solvent mixtures is of significant interest in the industrial production of 1,3,5trioxane.Experimental data for the VLE of quinary systems(formaldehyde+1,3,5trioxane+methanol+salt+water)and their ternary subsystems(formaldehyde+salt+water),(1,3,5trioxane+salt+water),and(methanol+salt+water)were systematic measured under atmospheric pressure.The salts considered included KBr,NaNO_(3),and CaCl_(2).The extended UNIFAC model was used to describe the VLE of the saltcontaining reactive mixtures.The model parameters were determined from the experimental VLE data of ternary systems or obtained from the literature,and then were used to predict the VLE of systems(1,3,5trioxane+KBr+water),(methanol+KBr+water),(formaldehyde+KBr+water),and(formaldehyde+1,3,5trioxane+methanol+salt+water)with salt=KBr,NaNO_(3),and CaCl_(2).The predicted results showed good agreements with the measured results.Furthermore,the model was used to uncover the salt effect on the VLE of these multisolvent reactive systems.
基金Supported by Natural Gas Hydrate in China Sea Exploration and Evaluation Project (G2H200200202)National Basic ResearchProgram of China (973 Program, Grant No. 2009CB219503)
文摘The natural occurrence of methane hydrates in marine sediments has been intensively studied over the past decades, and geochemical charac-teristic of hydrate is one of the most attractive research fields. In this paper, we discussed the geochemical anomaly during hydrate formation in porous media. By doing so, we also investigated the temperature influence on hydrate formation under isobaric condition. It turns out that sub-cooling is an important factor to dominate hydrate formation. Larger subcooling provides more powerful driving force for hydrate formation. During the geochemical anomaly research, six kinds of ions and the total dissolved salt (TDS) were measured before and after the experiment in different porous media. The result is that all kinds of ionic concentration increased after hydrate formation which can be defined as salting out effect mainly affected by gas consumption. But the variation ratio of different ions is not equal. Ca^2+ seems to be the most significantly influenced one, and its variation ratio is up to 80%. Finally, we theoretically made a model to calculate the TDS variation, the result is in good accordance with measured one, especially when gas consumption is large.
基金The authors gratefully thank the NSFC (No. 29992530, 29873060) and CAS for the financial support.
文摘In this paper, the fluorescence spectra of model compounds of light-emitting alternating copolymers. M (TPA-PPV) and M (TPA-PAV) (Scheme 1) were studied and the effect of KNO3 on the interaction between model compounds and ionic micelle-watts interface was also investigated. It is found that (I) The fluorescence changes of M (TPA-PPV) are related to the state of CTAB and SDS solution. (II)Aggregated state can be formed in M (TPA-PAV) solution at low concentration of CTAB. (III) Higher concentration of KNO3 may affect the interaction between model compounds and ionic micelle-water interface.
文摘The solubilities of benzene and diphenyl in mixed solvents of t-butyl alcohol(TBA) and water with different salts have been determined at T = 298.15, 303.15, 308.15 and 313.15K. The molar fraction of TBA [x(TBA)] in mixed solvent is 0.045, and the molality of the salts (m_s)in mixed solvents are 0.000, 0.250, 0.500, 0.750 and 1.000 mol/kg, respectively. The standard Gibbsenergies of solution of benzene and diphenyl in the mixed solvents have also been calculated basedon the solubility data. The effects of different salts on the hydrophobic interaction (HI) forbenzene-benzene pair in the systems were discussed.
基金supported by the National Natural Science Foundation of China (Nos. 21227802, 21303216 and 21473217)
文摘The salt effects on molecular orientation at air/liquid methanol interface were investigated by the polarization-dependent sum frequency generation vibrational spectroscopy(SFG-VS). We clarified that the average tilting angle of the methyl group to be u = 308 58 at the air/pure methanol surface assuming a d-function orientational distribution. Upon the addition of 3 mol/L Na I, the methyl group tilts further away from the surface normal with a new u = 418 38. This orientational change does not explain the enhancement of the SFG-VS intensities when adding Na I, implying the number density of the methanol molecules with a net polar ordering in the surface region also changed with the Na I concentrations. These spectroscopic findings shed new light on the salt effects on the surfaces structures of the polar organic solutions. It was also shown that the accurate determination of the bulk refractive indices and Raman depolarization ratios for different salt concentrations is crucial to quantitatively interpret the SFG-VS data.
基金supported by the Program for New Century Excellent Talents in Universities(Grant No.07-0814)
文摘The tide induced groundwater fluctuation and the seawater intrusion have important effects on hydrogeology and ecology of coastal aquifers.Among previous studies,there were few quantitative evaluations of the joint effects of the beach slope and the tide fluctuation on the groundwater dynamics.In this article,a numerical model is built by using the software FEFLOW with consideration of seawater intrusion,tide effects,density dependent flow and beach sloping effects.The simulation results are validated by laboratory experimental data in literature.More numerical scenarios are designed in a practical scale with different beach slopes.Results show that the groundwater fluctuation decays exponentially with the distance to the beach,i.e.,,and our simulation further shows that the beach slope influence can be expressed in the form of a logarithm function.While for the same location,the amplitude increases logarithmically with the beach angle in the form,where and are related with the horizontal distance()in the form of a logarithm function.The beach slope has no influence on the phase lag,although the latter increases regularly with the distance from the sea.The beach slope effect on the seawater intrusion is investigated through the quantitative relationship among the relative intrusion length(),the relative enhancement of the tide induced seawater intrusion()and the beach angle().It is shown that the tide effects on a milder beach is much greater than on a vertical one,and both λ and κ can be expressed in logarithm functions of.The tidal effect on the flow field in the transition zone for a particular mild beach is also studied,with results showing that the tide induced fluctuation of is similar to the groundwater table fluctuation while shows a distinct variation along both directions.
基金Project supported by the National Natural Science Foundation of China (No. 50472069) and the Ministry of Science and Technology of China (Nos. G2000078104 and 2003CCA02900).
文摘The equilibrium and dynamic surface tension (DST) of the novel cationic surfactant, 3-(p-nonylphenoxy)-2-hydroxylpropyl trimethyl ammonium bromide, abbreviated as RTAB, were studied. The effect of sodium halide such as NaCl, NaBr and NaI on the DST behavior of the RTAB solution below its CMC was studied in detail. Due to the preferential adsorption, the effect of hydration and salting out, the ability to reduce the DST values at the same concentration was in the order of NaI〉NaBr〉NaCl. Attributed to its high surface activity, the equilibrium time of the DST of the surfactant solution was insensitive to the ionic strength.
基金Project supported by the National Natural Science Foundation of China.
文摘Pt,H2(g,p0)HCl(mE)|AgCl-AgPt, H2(g, p0)|HCl(mE), EtOH(mN)|AgCl-Ag have been measured at 10 degree intervals from 278.15 to 318.15 K, where EtOH refers to ethanol, mE=0.005-0.1 mol.kg-1, mN=0.4-1.0 mol.kg-1. The salting constant kS of EtOH by HCl and the thermodynamic parameters of interaction, fEN(gEN> hEN, sEN] cP,EN)> of EtOH with HCI in water have been evaluated. It has been shown that kS>0, gEN>0,hEN>0, SEN>0 ,and cp,EN<0.The signs of these parameters and the temperature dependence of them have been discussed on the basis of structural interaction and the group additivity models.
文摘The ultrasonic velocity (U), has been measured for three a-amino acids, namely L-lysine monohydrochloride, L-arginine and L-histidine in solutions (1 mol/L aqueous) of sodium acetate (SA), potassium acetate (PA) and calcium acetate (CA) at different temperatures (303.15, 308.15, 313.15, 318.15 and 323.15 K). With the help of these results various ultrasonic derived parameters, viz. isentropic compressibility (Ks), change in isentropic compressibility (△K5), relative change in isentropic compressibility (△Kr), specific acoustic impedance (Z), relative association (RA), and apparent molal compressibility (Фks) have been estimated. The results have been interpreted in the light of intermolecular interactions between solute and solvent.