Extraction of theanine from waste liquid of tea polyphenol production was studied in aqueous surfactanttwo-phase system （ASTP） with cationic surfactant （CTAB） and anionic surfactant （SDS）. Results indicate that ...Extraction of theanine from waste liquid of tea polyphenol production was studied in aqueous surfactanttwo-phase system （ASTP） with cationic surfactant （CTAB） and anionic surfactant （SDS）. Results indicate that the region of ASTP is narrow and there is only a two-phase region of cationic surfactant. The increase in concentrations of NaBr and Na2SO4 are beneficial to the formation of ASTP. Theanine concentration in the bottom phase increases with increasing concentration of theanine, whereas the Partition coefficient and extraction rate only change a littlewhen the concentration of theanine is above 0.2 g.L-＇. With the increase of SDS concentration, the phase ratio and the partition coefficient decrease, while the extraction efficiency of theanine increases and the concentration of theanine changes a little in the range from 2.4/7.5 to 2.8/7.2 for SDS/CTAB ratio. The temperature has a notable ef- fect on the concentration of theanine in the bottom phase, partition coefficient and extraction rate of theanine. The increase of waste liquid decreases the phase ratio, increases the concentration and extraction rate of theanine in the bottom ohase, since the orotein and the saccharide enter the bottom nhase with theanine.展开更多
The adsorption of aqueous cadmium ions(Cd(Ⅱ)) have been investigated for modified activated carbon(AC-T)with oxygen-containing functional groups.The oxygen-containing groups of AC-T play an important role in Cd(Ⅱ) i...The adsorption of aqueous cadmium ions(Cd(Ⅱ)) have been investigated for modified activated carbon(AC-T)with oxygen-containing functional groups.The oxygen-containing groups of AC-T play an important role in Cd(Ⅱ) ion adsorption onto AC-T.The modified activated carbon is characterized by scanning electron microscopy,Fourier transform infrared spectroscopy(FT-IR) and X-ray photoelectron spectroscopy(XPS).The results of batch experiments indicate that the maximal adsorption could be achieved over the broad pH range of 4.5 to 6.5.Adsorption isotherms and kinetic study suggest that the sorption of Cd(Ⅱ) onto AC-T produces monolayer coverage and that adsorption is controlled by chemical adsorption.And the adsorbent has a good reusability.According to the FT-IR and XPS analyses,electrostatic attraction and cation exchange between Cd(Ⅱ) and oxygen-containing functional groups on AC-T are dominant mechanisms for Cd(Ⅱ) adsorption.展开更多
This paper studies the reaction between alkaline metal ions Li＋, Na＋ and K＋ and ASR （alkali-silica reaction） reactive aggregates to determine whether Li＋ can substitute Na＋ and K＋ that are unified in cement pa...This paper studies the reaction between alkaline metal ions Li＋, Na＋ and K＋ and ASR （alkali-silica reaction） reactive aggregates to determine whether Li＋ can substitute Na＋ and K＋ that are unified in cement paste. Reactive aggregates use meta-sandstone from eastern Taiwan and Pyrex glass. Non-reactive aggregates use siliceous sand. The results show that the dissolved amount of SiO2 is lower when the reactive aggregates are immersed in an 80 ℃1 N LiOH＇H20 solution than in NaOH and KOH solutions. The reduced amounts of OH and Li＋ in the solution are also higher than those in the NaOH and KOH solutions. These results reveal that reactive SiO2 can react with LiOH to form a reactant with low water solubility. When the powder of the cement paste is immersed in an 80 ℃ 1 N LiOH-H2O solution, the amounts of free Na＋ and K＋ in the solution are higher than those in water. The increased amount increases with the duration of immersion. The amount of Li＋ in the solution also decreases with the duration of immersion. These results reveal that Li＋ can substitute Na＋ and K＋ that are unified in cement paste, which indicates that ASR can be prevented with the existence of Li＋.展开更多
The conventional collector for diaspore mineral is oleic acid （OLA）, which is highly insoluble and must be used in high dosage in bauxite flotation. Firstly flotation experiments with every reagent （sodium oleate, ...The conventional collector for diaspore mineral is oleic acid （OLA）, which is highly insoluble and must be used in high dosage in bauxite flotation. Firstly flotation experiments with every reagent （sodium oleate, tween-20）were carried out and it was shown that sodium oleate was an effective diaspore collector, whereas nonionic surfactant tween-20 showed little collectivity. Then experiments were carried out with sodium oleate as the main collector with the addition of tween-20 to study the influences of potentiator on diaspore flotation. It could be seen from the experiments that potentiator had a marked influence on the recovery of diaspore, which was raised by more than 12 % and that addition sequence also affected the flotation behavior. It gave the best results with the reagents mixed thoroughly before added and the best ratio of collector oleic acid and potentiator tween-20 slLood at 10： 1. From the calculation of the ingredients in the sodium oleate solution, at the pH 9, sodium oleate acted with surface of the mineral with the acid-soap polymer [ HOL ~ OL- ]. Zeta potential test showed that the potentiator promoted the absorption of collector on the mineral surface, which lowered zeta potential. As could be seen from surface tension experiments, the addition of potentiator tween-20 lowered the CMC （ critical micelle concentration） value of oleic acid solution, which was equivalent to raise the power of the agents. By the adsorptive capability tests, with the addition of tween-20, the adsorption of oleic acid on diaspore got more.展开更多
The goal of this research was to determine the impact of nonionic surfactants on drag reduction effect in water and metal oxide nanofluid. Two nonionic surfactants （Rokacet 07 and Rokanol KT） and copper（II） oxide ...The goal of this research was to determine the impact of nonionic surfactants on drag reduction effect in water and metal oxide nanofluid. Two nonionic surfactants （Rokacet 07 and Rokanol KT） and copper（II） oxide wa- ter-based nanofluid were examined. Friction factors in a 4 mm diameter pipe for the Reynolds number between 8000 and 50000 were determined. Results showed that addition of nonionic surfactants caused the decrease of fric- tion factor in water and nanofluid. The drag reduction effect was similar in both cases. Presence of nanoparticles in the system has no great influence on drag reduction effect.展开更多
Microemulsions of both O/W and W/O types were formulated by using Brij76, Brij97 and Tween80 as nonionic surfactant and propanol or butanol as cosurfactant with isopropyl myristate oil and water. Low concentrations of...Microemulsions of both O/W and W/O types were formulated by using Brij76, Brij97 and Tween80 as nonionic surfactant and propanol or butanol as cosurfactant with isopropyl myristate oil and water. Low concentrations of sodium salts of hexanoic, decanoic, palmitic and stearic acids were added to the prepared microemulsions to assess their ability to enhance microemulsion stability. Solubilization capacity of microemulsions was estimated and compared with their conductivities at the same water content. Solubilization capacity for YweenS0-containing microemulsions was found to be lower than that of Brij containing microemulsions. Different effects of the ionic surfactants at the maximum solubilization capacity were observed in both O/W and W/O microemulsions. Microemulsion conductivity results showed that different ionic surfactants exerted minor and comparable effects regardless to the implemented nonionic surfactant. Analysis of solubilization conductivity revealed that the presence of ionic surfactant can improve microemulsion solubilization capacity and provided that optimum physicochemical properties for both surfactants are fulfilled. These properties have direct impact at the goodness of the interracial film.展开更多
Molecular dynamics simulations have been performed to investigate the structural properties of hydroxyl-substituted alkyl benzenesulfonate monolayers formed at the water/vapor and water/decane interfaces.We report a d...Molecular dynamics simulations have been performed to investigate the structural properties of hydroxyl-substituted alkyl benzenesulfonate monolayers formed at the water/vapor and water/decane interfaces.We report a detailed study of the interfacial properties-liquid density profile,hydrogen bond structure,surfactant aggregate structure and order parameter-of the novel anionic surfactant,sodium 2-hydroxy-3-decyl-5-octylbenzenesulfonate(C10C8OHphSO3Na).Simulation results show that:with increasing number of surfactant molecules,the average number of intramolecular hydrogen bonds per surfactant molecule in the monolayer decreases,but the structures forming the intramolecular hydrogen bonds still play a dominant role;the hydrophobic part of the alkyl tail chain,especially the decyl substituent on the third carbon atom in the benzene ring,becomes straighter,and more ordered towards the external interface at higher surfactant coverage;two-dimensional radial distribution functions can describe the characteristic of surfactant aggregate structures and highlight the decane phase effect on the orientation of the hydrophobic part of the surfactant;the surfactant molecules readily form long-range hydrogen bonded structures.Our results are an important complement to experimental studies.We used the all-atom model by employing the GROMACS and ffAMBER programs in the simulations,which provides a new way to simulate the interfacial behavior of alkyl benzenesulfonate surfactants.展开更多
In order to develop turbulent drag-reducing technology by using an environmentally friendly additive in a water-transporting system,the drag reducing characteristics in a non-ionic surfactant(Oleyldimethylamineoxide,O...In order to develop turbulent drag-reducing technology by using an environmentally friendly additive in a water-transporting system,the drag reducing characteristics in a non-ionic surfactant(Oleyldimethylamineoxide,ODMAO) dilute aqueous solution flowing in a circular pipe of 5 mm diameter have been experimentally investigated with an air-driven fluid resistance test device.The rheological characteristics of the solution have also been examined by a rheometer with a cone-plate flow cell.The results show that the ODMAO solutions are drag-reducing when concentration is 400 ppm or higher,that the critical Reynolds number corresponding to the maximum drag reduction rate increases with both concentration and temperature,and that the maximum drag reduction rate can reach up to 70% in the straight pipe.At low shear rates,the shear viscosity of ODMAO solutions with a relatively high drag-reduction behaves similarly to Newtonian fluids;at above a certain critical shear rate,it is firstly shear-thickening,then shear-thinning.Such shear-rate-dependent characteristics of the shear viscosity are attributed to the different transitions of micellar network structure induced by different shear rates.Relaxation of shear stress after removing an applied constant shear rate at which the solution is in the SIS(shear-induced structure) state is found to be well expressed by a 2-step Maxwell model with a tail relaxation time much shorter than that for a drag-reducing cationic surfactant,which indicates that for the ODMAO solution,a viscoelasticity as strong as a drag-reducing cationic surfactant is not needed to realize turbulent drag-reduction.展开更多
基金Supported by the Fundamental Research Funds for the Central Universities(JUSRP11205)
文摘Extraction of theanine from waste liquid of tea polyphenol production was studied in aqueous surfactanttwo-phase system （ASTP） with cationic surfactant （CTAB） and anionic surfactant （SDS）. Results indicate that the region of ASTP is narrow and there is only a two-phase region of cationic surfactant. The increase in concentrations of NaBr and Na2SO4 are beneficial to the formation of ASTP. Theanine concentration in the bottom phase increases with increasing concentration of theanine, whereas the Partition coefficient and extraction rate only change a littlewhen the concentration of theanine is above 0.2 g.L-＇. With the increase of SDS concentration, the phase ratio and the partition coefficient decrease, while the extraction efficiency of theanine increases and the concentration of theanine changes a little in the range from 2.4/7.5 to 2.8/7.2 for SDS/CTAB ratio. The temperature has a notable ef- fect on the concentration of theanine in the bottom phase, partition coefficient and extraction rate of theanine. The increase of waste liquid decreases the phase ratio, increases the concentration and extraction rate of theanine in the bottom ohase, since the orotein and the saccharide enter the bottom nhase with theanine.
基金Supported by the Fundamental Research Funds for the Central Universities(TD2013-2,2012LYB33)the National Natural Science Foundation of China(51278053,21373032)grant-in-aid from Kochi University of Technology and China Scholarship Council
文摘The adsorption of aqueous cadmium ions(Cd(Ⅱ)) have been investigated for modified activated carbon(AC-T)with oxygen-containing functional groups.The oxygen-containing groups of AC-T play an important role in Cd(Ⅱ) ion adsorption onto AC-T.The modified activated carbon is characterized by scanning electron microscopy,Fourier transform infrared spectroscopy(FT-IR) and X-ray photoelectron spectroscopy(XPS).The results of batch experiments indicate that the maximal adsorption could be achieved over the broad pH range of 4.5 to 6.5.Adsorption isotherms and kinetic study suggest that the sorption of Cd(Ⅱ) onto AC-T produces monolayer coverage and that adsorption is controlled by chemical adsorption.And the adsorbent has a good reusability.According to the FT-IR and XPS analyses,electrostatic attraction and cation exchange between Cd(Ⅱ) and oxygen-containing functional groups on AC-T are dominant mechanisms for Cd(Ⅱ) adsorption.
文摘This paper studies the reaction between alkaline metal ions Li＋, Na＋ and K＋ and ASR （alkali-silica reaction） reactive aggregates to determine whether Li＋ can substitute Na＋ and K＋ that are unified in cement paste. Reactive aggregates use meta-sandstone from eastern Taiwan and Pyrex glass. Non-reactive aggregates use siliceous sand. The results show that the dissolved amount of SiO2 is lower when the reactive aggregates are immersed in an 80 ℃1 N LiOH＇H20 solution than in NaOH and KOH solutions. The reduced amounts of OH and Li＋ in the solution are also higher than those in the NaOH and KOH solutions. These results reveal that reactive SiO2 can react with LiOH to form a reactant with low water solubility. When the powder of the cement paste is immersed in an 80 ℃ 1 N LiOH-H2O solution, the amounts of free Na＋ and K＋ in the solution are higher than those in water. The increased amount increases with the duration of immersion. The amount of Li＋ in the solution also decreases with the duration of immersion. These results reveal that Li＋ can substitute Na＋ and K＋ that are unified in cement paste, which indicates that ASR can be prevented with the existence of Li＋.
基金National Key Fundamental Research and Development Program(No.2005cbc237601)
文摘The conventional collector for diaspore mineral is oleic acid （OLA）, which is highly insoluble and must be used in high dosage in bauxite flotation. Firstly flotation experiments with every reagent （sodium oleate, tween-20）were carried out and it was shown that sodium oleate was an effective diaspore collector, whereas nonionic surfactant tween-20 showed little collectivity. Then experiments were carried out with sodium oleate as the main collector with the addition of tween-20 to study the influences of potentiator on diaspore flotation. It could be seen from the experiments that potentiator had a marked influence on the recovery of diaspore, which was raised by more than 12 % and that addition sequence also affected the flotation behavior. It gave the best results with the reagents mixed thoroughly before added and the best ratio of collector oleic acid and potentiator tween-20 slLood at 10： 1. From the calculation of the ingredients in the sodium oleate solution, at the pH 9, sodium oleate acted with surface of the mineral with the acid-soap polymer [ HOL ~ OL- ]. Zeta potential test showed that the potentiator promoted the absorption of collector on the mineral surface, which lowered zeta potential. As could be seen from surface tension experiments, the addition of potentiator tween-20 lowered the CMC （ critical micelle concentration） value of oleic acid solution, which was equivalent to raise the power of the agents. By the adsorptive capability tests, with the addition of tween-20, the adsorption of oleic acid on diaspore got more.
基金Supported by the State Committee for Scientific Research(Poland)(NN209764040)Michal Drzazga received the Scholarship under the Project DoktoRIS-Scholarship Program for Innovative Silesia Co-financed by the European Union under the European Social Fund
文摘The goal of this research was to determine the impact of nonionic surfactants on drag reduction effect in water and metal oxide nanofluid. Two nonionic surfactants （Rokacet 07 and Rokanol KT） and copper（II） oxide wa- ter-based nanofluid were examined. Friction factors in a 4 mm diameter pipe for the Reynolds number between 8000 and 50000 were determined. Results showed that addition of nonionic surfactants caused the decrease of fric- tion factor in water and nanofluid. The drag reduction effect was similar in both cases. Presence of nanoparticles in the system has no great influence on drag reduction effect.
文摘Microemulsions of both O/W and W/O types were formulated by using Brij76, Brij97 and Tween80 as nonionic surfactant and propanol or butanol as cosurfactant with isopropyl myristate oil and water. Low concentrations of sodium salts of hexanoic, decanoic, palmitic and stearic acids were added to the prepared microemulsions to assess their ability to enhance microemulsion stability. Solubilization capacity of microemulsions was estimated and compared with their conductivities at the same water content. Solubilization capacity for YweenS0-containing microemulsions was found to be lower than that of Brij containing microemulsions. Different effects of the ionic surfactants at the maximum solubilization capacity were observed in both O/W and W/O microemulsions. Microemulsion conductivity results showed that different ionic surfactants exerted minor and comparable effects regardless to the implemented nonionic surfactant. Analysis of solubilization conductivity revealed that the presence of ionic surfactant can improve microemulsion solubilization capacity and provided that optimum physicochemical properties for both surfactants are fulfilled. These properties have direct impact at the goodness of the interracial film.
基金supported by the National Natural Science Foundation of China (21003143)
文摘Molecular dynamics simulations have been performed to investigate the structural properties of hydroxyl-substituted alkyl benzenesulfonate monolayers formed at the water/vapor and water/decane interfaces.We report a detailed study of the interfacial properties-liquid density profile,hydrogen bond structure,surfactant aggregate structure and order parameter-of the novel anionic surfactant,sodium 2-hydroxy-3-decyl-5-octylbenzenesulfonate(C10C8OHphSO3Na).Simulation results show that:with increasing number of surfactant molecules,the average number of intramolecular hydrogen bonds per surfactant molecule in the monolayer decreases,but the structures forming the intramolecular hydrogen bonds still play a dominant role;the hydrophobic part of the alkyl tail chain,especially the decyl substituent on the third carbon atom in the benzene ring,becomes straighter,and more ordered towards the external interface at higher surfactant coverage;two-dimensional radial distribution functions can describe the characteristic of surfactant aggregate structures and highlight the decane phase effect on the orientation of the hydrophobic part of the surfactant;the surfactant molecules readily form long-range hydrogen bonded structures.Our results are an important complement to experimental studies.We used the all-atom model by employing the GROMACS and ffAMBER programs in the simulations,which provides a new way to simulate the interfacial behavior of alkyl benzenesulfonate surfactants.
基金supported by the Center of Natural Science and Technology of Japan
文摘In order to develop turbulent drag-reducing technology by using an environmentally friendly additive in a water-transporting system,the drag reducing characteristics in a non-ionic surfactant(Oleyldimethylamineoxide,ODMAO) dilute aqueous solution flowing in a circular pipe of 5 mm diameter have been experimentally investigated with an air-driven fluid resistance test device.The rheological characteristics of the solution have also been examined by a rheometer with a cone-plate flow cell.The results show that the ODMAO solutions are drag-reducing when concentration is 400 ppm or higher,that the critical Reynolds number corresponding to the maximum drag reduction rate increases with both concentration and temperature,and that the maximum drag reduction rate can reach up to 70% in the straight pipe.At low shear rates,the shear viscosity of ODMAO solutions with a relatively high drag-reduction behaves similarly to Newtonian fluids;at above a certain critical shear rate,it is firstly shear-thickening,then shear-thinning.Such shear-rate-dependent characteristics of the shear viscosity are attributed to the different transitions of micellar network structure induced by different shear rates.Relaxation of shear stress after removing an applied constant shear rate at which the solution is in the SIS(shear-induced structure) state is found to be well expressed by a 2-step Maxwell model with a tail relaxation time much shorter than that for a drag-reducing cationic surfactant,which indicates that for the ODMAO solution,a viscoelasticity as strong as a drag-reducing cationic surfactant is not needed to realize turbulent drag-reduction.
