The reduced ability of fatty acids to dissolve and disperse at low temperatures limits their effectiveness in winter applications.In this study,a green and environment-friendly reagent,polyethylene glycol 2000(PEG-200...The reduced ability of fatty acids to dissolve and disperse at low temperatures limits their effectiveness in winter applications.In this study,a green and environment-friendly reagent,polyethylene glycol 2000(PEG-2000),was used to evaluate its effect on the collecting performance of sodium oleate during scheelite flotation at low temperatures.The effect of PEG-2000 on the flotation of scheelite with the collector sodium oleate(NaOL)was studied by flotation tests,surface tension tests,infrared spectral analysis,and zeta potential measurements.Flotation tests showed that adding PEG-2000 can enhance the collecting ability of NaOL on scheelite at low temperature(5℃).The recovery of scheelite with the mixed collector of PEG-200 and NaOL is 4.39%higher than that with NaOL only.The surface tension tests,infrared spectral analysis and zeta potential measurements revealed that PEG-2000 and OL^(−)are co-adsorbed on the scheelite surface at low temperatures.The presence of PEG-2000 promoted the increase of the adsorption concentration of oleate ions(OL^(−))on the scheelite surface.The reason was that PEG-2000 has a shielding effect on the electrostatic repulsion between the OL^(−)groups,which changes the micellar configuration of OL^(−)in the solution system and makes the OL^(−)gather more tightly on the surface of scheelite,leading to the enhancement of its hydrophobicity.This discovery provides a reference for the development of collecting reagents for efficient flotation recovery of scheelite under low temperature environment.展开更多
Gemini quaternary ammonium salt surfactants, butane-a, co-bis（dimethyl dodeculammonium bromide） （BDDA） ethane-a, fl-bis（dimethyl dodeculammonium bromide） （EDDA） were adopted to comparatively study the flotatio...Gemini quaternary ammonium salt surfactants, butane-a, co-bis（dimethyl dodeculammonium bromide） （BDDA） ethane-a, fl-bis（dimethyl dodeculammonium bromide） （EDDA） were adopted to comparatively study the flotation behaviors of kaolinite, pyrophyllite and illite. It was found that three silicate minerals all exhibited good floatability with Gemini cationic surfactants as collectors over a wide pH range, while BDDA showed a stronger collecting power than EDDA. FTIR spectra and zeta potential analysis indicated that the mechanism of adsorption of Gemini collector molecules on three silicate minerals surfaces was almost identical for the electronic attraction and hydrogen bonds effect. The theoretically obtained results of density functional theory （DFT） at B3LYP/6-31G （d） level demonstrated the stronger collecting power of BDDA presented in the floatation test and zeta potential measurement.展开更多
Danckwert’s method was used to determine the specific interfacial area, a, and the individual mass transfer coefficient, kL, during absorption of CO2 in a bubble column with an anionic surfactant in the carbonate-bi...Danckwert’s method was used to determine the specific interfacial area, a, and the individual mass transfer coefficient, kL, during absorption of CO2 in a bubble column with an anionic surfactant in the carbonate-bicarbonate buffer solution and NaAsO2 as catalyst, the presence of which decreases the specific interfacial area and the individual mass transfer coefficient. The specific interfacial area and the individual mass transfer coefficient increase with increasing su- perficial gas velocity. The specific interfacial area decreases whereas the individual mass transfer coefficient increases with increasing temperature. The results of experiments were used to determine the dependence of a, kL, and kLa on the surface tension, the temperature of the absorption phase, and the superficial velocity of the gas. The calculated results from the correlation were found to be within 10% deviation from the actual experimental results.展开更多
β-2CaO＇SiO2 was obtained with analytical grade reagents. Polyethylene glycol （PEG）, sodium polyacrylate （PAAS） and their mixture were used to inhibit the decomposition of β-2CaO·SiO2 in sodium aluminate so...β-2CaO＇SiO2 was obtained with analytical grade reagents. Polyethylene glycol （PEG）, sodium polyacrylate （PAAS） and their mixture were used to inhibit the decomposition of β-2CaO·SiO2 in sodium aluminate solution. The potential of solid-liquid interface and the adsorption mechanism were studied by the methods of Zeta potential measurement and XPS. The results indicate that PEG and PAAS have synergistic effect on the inhibition of secondary reaction. The inhibitory effect is the best when the volume ratio of PAAS to PEG is 1：1 and the total concentration is 12.5 mg/L. PAAS adsorbs on the surface of β-2CaO-SiO2 by the formation of --COOCa coordinate bond, and the negative charge enters into Stem layer, which results in the decrease of particle potential and the obvious change of binding energy of Ca 2p, Si 2p and O Is. PEG only physically adsorbs on the surface ofβ-2CaO·SiO2, and had little effect on particle potential and binding energy of Ca 2p, Si 2p and O Is.展开更多
Modified peanut shell （MPS） was prepared by amination reaction with peanut shell （PS） as the starting material The sorption of Cr（VI） oxyanions on MPS in static and column tests were investigated. In addition, t...Modified peanut shell （MPS） was prepared by amination reaction with peanut shell （PS） as the starting material The sorption of Cr（VI） oxyanions on MPS in static and column tests were investigated. In addition, the sorption isotherm and kinetic models were applied to confirm the sorption capacity and the sorption mechanisms. BET surface area anysis showed the physicochemical characterist!cs of the samples. The results of zeta potential,Fourier transform infrared （FT-IR） and Raman spectra analysis illustrated that chemical adsorption and ion exi change are the potential sorption mechanism. The static sorption test showed that the maximum sorption capacity （qm） of MPS for Cr（VI） increased with temperature, which indicated that the Cr（VI） sorption rocess was endothermic. The saturated sorption capacity of Cr（VI） in the colunm sorption test was 138.34 mg.g-1, which accounted for 93.9% of the qmax at 25 ℃. The regeneration capacity of MPS was evaluated using HC1 solution as an eluent. The high regeneration efficiency （82.6%） validated the dominance of the ion exchange mechanism in the Cr（VI） sorption process with C1ions displacing Cr（VI） oxyanion on MPS. The Langmuir isotherm model showed a higher correlation coefficient than the other adsorption isotherm models. And in the kinetic study, a pseudo-second-order model fit the data best.展开更多
A numerical investigation of the unsteady motion of a deformed drop released freely in another quiescent liquid contaminated by surfactant is presented in this paper. The finite difference method was used to solve num...A numerical investigation of the unsteady motion of a deformed drop released freely in another quiescent liquid contaminated by surfactant is presented in this paper. The finite difference method was used to solve numerically the coupled time-dependent Navier-Stokes and convective-diffusion equations in a body-fitted orthogonal coordinate system. Numerical simulation was conducted on the experimental cases, in which MIBK drops with the size ranging from 1.24 mm to 1.97 mm rose and accelerated freely in pure water and in dilute sodium dodecyl sulphate (SDS) aqueous solution. The applicability of the numerical scheme was validated by the agreement between the simulation results and the experimental data. Both the numerical and experimental results showed that the velocitytime profile exhibited a maximum rising velocity for drops in SDS solutions, which was close to the terminal velocity in pure water, before it dropped down to a steady-state value. The effect of the sorption kinetics of surfactant on the accelerating motion was also evaluated. It is also suggested that introduction of virtual mass force into the formulation improved obviously the precision of numerical simulation of transient drop motion.展开更多
This paper studies the adsorption of diethyl phthalate （DEP,an environmental hormone） on the surface of nanoscale TiO2, effects of pH value of solutions, initial concentrations of DEP and additive surfactant on phot...This paper studies the adsorption of diethyl phthalate （DEP,an environmental hormone） on the surface of nanoscale TiO2, effects of pH value of solutions, initial concentrations of DEP and additive surfactant on photocatalytic degradation and dynamics of DEP. Under ultra violet illumination, the interaction between DEP and surfactants including DBS （sodium dodecylbenzenesulfonate）, CTAB （cetyltrimethylammonium bromide）, and OP-10 （nonylphenol polyoxyethylene ether） was exploited from the perspective of degradation speed calculated by the data of high pressure liquid chromatography （HPLC） and UV-Vis spectra, respectively. Photocatalytic degradation of DEP followed pseudo first-order reaction kinetics. DEP as substrate degraded fast when its initial concentration was 130 mg/L. TiO2 had certain adsorption ability of DEP. TiO2 could adsorb the most DEP at the approximately neutral pH of 6.91. Degradation of DEP was not affected obviously by additives OP-10 and DBS. Degradation rate of DEP was not enhanced greatly in the presence of surfactants, but degradation of DBS was sped up. Degradation rate of DEP was depressed in the presence of additive CTAB. The more CTAB was added, the less DEP was degraded. Degradation rate of CTAB became slow with the increase of initial CTAB concentration. The possible adsorption models among TiO2, DEP and surfactants were given.展开更多
The adsorption state and catalytic properties of pepsin and acidic protease from microorganisms Asp. awamori and Asp. oryzae were studied in solid phase system （in presence of sorsilen, DEAE- and CM-cellulose）. Acco...The adsorption state and catalytic properties of pepsin and acidic protease from microorganisms Asp. awamori and Asp. oryzae were studied in solid phase system （in presence of sorsilen, DEAE- and CM-cellulose）. According to the results, adsorption capacity and catalytic activity of enzymes depend on the physical nature of surface groups of the solid phase. Changing the stability of enzymes in the system with solid phase is observed even the adsorption bond is less stable （in the case of DEAE- and CM-cellulose in acidic media）. Injection to the medium ethanol, surfactants, sodium chloride and changing the temperature of the incubation medium could prevent the negative effects of the solid phases. When sorsilen is used as solid phase, pepsin and acidic protease from Asp. awamori suffer from high surface inactivation. Various surfactants influence adsorption state of enzymes differently. Non-ionic surfactants （Triton X-100） prevent adsorption and restore catalytic properties of enzymes.展开更多
Sorption of carbon tetrachloride （CT） by zero-valent iron （ZVI） is the rate-limiting step in the degradation of CT, so the sorption capacity of ZVl is of great importance. This experiment was aimed at enhancing th...Sorption of carbon tetrachloride （CT） by zero-valent iron （ZVI） is the rate-limiting step in the degradation of CT, so the sorption capacity of ZVl is of great importance. This experiment was aimed at enhancing the sorption of CT by ZVI and the degradation rate of CT by modification of surfactants. This study showed that ZVI modified by cationic surfactants has favorable synergistic effect on the degradation of CT. The CT degradation rate of ZVI modified by cetyl pyridinium bromide （CPB） was higher than that of the unmodified ZVI by 130%, and the CT degradation rate of ZVI modified by cetyl trimethyl ammonium bromide （CTAB） was higher than that of the unmodified ZVI by 81%. This study also showed that the best degradation effect is obtained at the near critical micelle concentrations （CMC） and that high loaded cationic surfactant does not have good synergistic effect on the degradation due to its hydrophilicity and the block in surface reduction sites. Furthermore degradation of CT by ZVI modified by nonionic surfactant has not positive effect on the degradation as the ionic surfactant and the ZVI modified by anionic surfactant has hardly any obvious effects on the degradation.展开更多
基金Project(2023JJ10070)supported by the Hunan Provincial Outstanding Youth Fund,ChinaProjects(51974364,52074355,52304316)supported by the National Natural Science Foundation of China。
文摘The reduced ability of fatty acids to dissolve and disperse at low temperatures limits their effectiveness in winter applications.In this study,a green and environment-friendly reagent,polyethylene glycol 2000(PEG-2000),was used to evaluate its effect on the collecting performance of sodium oleate during scheelite flotation at low temperatures.The effect of PEG-2000 on the flotation of scheelite with the collector sodium oleate(NaOL)was studied by flotation tests,surface tension tests,infrared spectral analysis,and zeta potential measurements.Flotation tests showed that adding PEG-2000 can enhance the collecting ability of NaOL on scheelite at low temperature(5℃).The recovery of scheelite with the mixed collector of PEG-200 and NaOL is 4.39%higher than that with NaOL only.The surface tension tests,infrared spectral analysis and zeta potential measurements revealed that PEG-2000 and OL^(−)are co-adsorbed on the scheelite surface at low temperatures.The presence of PEG-2000 promoted the increase of the adsorption concentration of oleate ions(OL^(−))on the scheelite surface.The reason was that PEG-2000 has a shielding effect on the electrostatic repulsion between the OL^(−)groups,which changes the micellar configuration of OL^(−)in the solution system and makes the OL^(−)gather more tightly on the surface of scheelite,leading to the enhancement of its hydrophobicity.This discovery provides a reference for the development of collecting reagents for efficient flotation recovery of scheelite under low temperature environment.
基金Project(2013AA064102)supported by the High-tech Research and Development Program of ChinaProject(51004114)supported by the National Natural Science Foundation of China+1 种基金Project(2007B52)supported by the Foundation for the Author of National Excellent Doctoral Dissertation of ChinaProject(NCEP-08-0568)supported by the Program for New Century Excellent Talents in Chinese University
文摘Gemini quaternary ammonium salt surfactants, butane-a, co-bis（dimethyl dodeculammonium bromide） （BDDA） ethane-a, fl-bis（dimethyl dodeculammonium bromide） （EDDA） were adopted to comparatively study the flotation behaviors of kaolinite, pyrophyllite and illite. It was found that three silicate minerals all exhibited good floatability with Gemini cationic surfactants as collectors over a wide pH range, while BDDA showed a stronger collecting power than EDDA. FTIR spectra and zeta potential analysis indicated that the mechanism of adsorption of Gemini collector molecules on three silicate minerals surfaces was almost identical for the electronic attraction and hydrogen bonds effect. The theoretically obtained results of density functional theory （DFT） at B3LYP/6-31G （d） level demonstrated the stronger collecting power of BDDA presented in the floatation test and zeta potential measurement.
文摘Danckwert’s method was used to determine the specific interfacial area, a, and the individual mass transfer coefficient, kL, during absorption of CO2 in a bubble column with an anionic surfactant in the carbonate-bicarbonate buffer solution and NaAsO2 as catalyst, the presence of which decreases the specific interfacial area and the individual mass transfer coefficient. The specific interfacial area and the individual mass transfer coefficient increase with increasing su- perficial gas velocity. The specific interfacial area decreases whereas the individual mass transfer coefficient increases with increasing temperature. The results of experiments were used to determine the dependence of a, kL, and kLa on the surface tension, the temperature of the absorption phase, and the superficial velocity of the gas. The calculated results from the correlation were found to be within 10% deviation from the actual experimental results.
文摘β-2CaO＇SiO2 was obtained with analytical grade reagents. Polyethylene glycol （PEG）, sodium polyacrylate （PAAS） and their mixture were used to inhibit the decomposition of β-2CaO·SiO2 in sodium aluminate solution. The potential of solid-liquid interface and the adsorption mechanism were studied by the methods of Zeta potential measurement and XPS. The results indicate that PEG and PAAS have synergistic effect on the inhibition of secondary reaction. The inhibitory effect is the best when the volume ratio of PAAS to PEG is 1：1 and the total concentration is 12.5 mg/L. PAAS adsorbs on the surface of β-2CaO-SiO2 by the formation of --COOCa coordinate bond, and the negative charge enters into Stem layer, which results in the decrease of particle potential and the obvious change of binding energy of Ca 2p, Si 2p and O Is. PEG only physically adsorbs on the surface ofβ-2CaO·SiO2, and had little effect on particle potential and binding energy of Ca 2p, Si 2p and O Is.
基金Supported by the Independent Innovation Foundation of Shandong University(2012TS036)
文摘Modified peanut shell （MPS） was prepared by amination reaction with peanut shell （PS） as the starting material The sorption of Cr（VI） oxyanions on MPS in static and column tests were investigated. In addition, the sorption isotherm and kinetic models were applied to confirm the sorption capacity and the sorption mechanisms. BET surface area anysis showed the physicochemical characterist!cs of the samples. The results of zeta potential,Fourier transform infrared （FT-IR） and Raman spectra analysis illustrated that chemical adsorption and ion exi change are the potential sorption mechanism. The static sorption test showed that the maximum sorption capacity （qm） of MPS for Cr（VI） increased with temperature, which indicated that the Cr（VI） sorption rocess was endothermic. The saturated sorption capacity of Cr（VI） in the colunm sorption test was 138.34 mg.g-1, which accounted for 93.9% of the qmax at 25 ℃. The regeneration capacity of MPS was evaluated using HC1 solution as an eluent. The high regeneration efficiency （82.6%） validated the dominance of the ion exchange mechanism in the Cr（VI） sorption process with C1ions displacing Cr（VI） oxyanion on MPS. The Langmuir isotherm model showed a higher correlation coefficient than the other adsorption isotherm models. And in the kinetic study, a pseudo-second-order model fit the data best.
基金Supported by the National Natural Science Foundation of China(No.20236050)
文摘A numerical investigation of the unsteady motion of a deformed drop released freely in another quiescent liquid contaminated by surfactant is presented in this paper. The finite difference method was used to solve numerically the coupled time-dependent Navier-Stokes and convective-diffusion equations in a body-fitted orthogonal coordinate system. Numerical simulation was conducted on the experimental cases, in which MIBK drops with the size ranging from 1.24 mm to 1.97 mm rose and accelerated freely in pure water and in dilute sodium dodecyl sulphate (SDS) aqueous solution. The applicability of the numerical scheme was validated by the agreement between the simulation results and the experimental data. Both the numerical and experimental results showed that the velocitytime profile exhibited a maximum rising velocity for drops in SDS solutions, which was close to the terminal velocity in pure water, before it dropped down to a steady-state value. The effect of the sorption kinetics of surfactant on the accelerating motion was also evaluated. It is also suggested that introduction of virtual mass force into the formulation improved obviously the precision of numerical simulation of transient drop motion.
基金Supported by Tianjin Natural Science Foundation (No. 033604711) and Science and Technology Foundation of Construction Ministry (No. 03-2-064).
文摘This paper studies the adsorption of diethyl phthalate （DEP,an environmental hormone） on the surface of nanoscale TiO2, effects of pH value of solutions, initial concentrations of DEP and additive surfactant on photocatalytic degradation and dynamics of DEP. Under ultra violet illumination, the interaction between DEP and surfactants including DBS （sodium dodecylbenzenesulfonate）, CTAB （cetyltrimethylammonium bromide）, and OP-10 （nonylphenol polyoxyethylene ether） was exploited from the perspective of degradation speed calculated by the data of high pressure liquid chromatography （HPLC） and UV-Vis spectra, respectively. Photocatalytic degradation of DEP followed pseudo first-order reaction kinetics. DEP as substrate degraded fast when its initial concentration was 130 mg/L. TiO2 had certain adsorption ability of DEP. TiO2 could adsorb the most DEP at the approximately neutral pH of 6.91. Degradation of DEP was not affected obviously by additives OP-10 and DBS. Degradation rate of DEP was not enhanced greatly in the presence of surfactants, but degradation of DBS was sped up. Degradation rate of DEP was depressed in the presence of additive CTAB. The more CTAB was added, the less DEP was degraded. Degradation rate of CTAB became slow with the increase of initial CTAB concentration. The possible adsorption models among TiO2, DEP and surfactants were given.
文摘The adsorption state and catalytic properties of pepsin and acidic protease from microorganisms Asp. awamori and Asp. oryzae were studied in solid phase system （in presence of sorsilen, DEAE- and CM-cellulose）. According to the results, adsorption capacity and catalytic activity of enzymes depend on the physical nature of surface groups of the solid phase. Changing the stability of enzymes in the system with solid phase is observed even the adsorption bond is less stable （in the case of DEAE- and CM-cellulose in acidic media）. Injection to the medium ethanol, surfactants, sodium chloride and changing the temperature of the incubation medium could prevent the negative effects of the solid phases. When sorsilen is used as solid phase, pepsin and acidic protease from Asp. awamori suffer from high surface inactivation. Various surfactants influence adsorption state of enzymes differently. Non-ionic surfactants （Triton X-100） prevent adsorption and restore catalytic properties of enzymes.
基金Project (No. 20030352) supported the Science and TechnologyProgram of Zhejiang Province, China
文摘Sorption of carbon tetrachloride （CT） by zero-valent iron （ZVI） is the rate-limiting step in the degradation of CT, so the sorption capacity of ZVl is of great importance. This experiment was aimed at enhancing the sorption of CT by ZVI and the degradation rate of CT by modification of surfactants. This study showed that ZVI modified by cationic surfactants has favorable synergistic effect on the degradation of CT. The CT degradation rate of ZVI modified by cetyl pyridinium bromide （CPB） was higher than that of the unmodified ZVI by 130%, and the CT degradation rate of ZVI modified by cetyl trimethyl ammonium bromide （CTAB） was higher than that of the unmodified ZVI by 81%. This study also showed that the best degradation effect is obtained at the near critical micelle concentrations （CMC） and that high loaded cationic surfactant does not have good synergistic effect on the degradation due to its hydrophilicity and the block in surface reduction sites. Furthermore degradation of CT by ZVI modified by nonionic surfactant has not positive effect on the degradation as the ionic surfactant and the ZVI modified by anionic surfactant has hardly any obvious effects on the degradation.
