Hydrate formation rate and separation effect on the capture of CO2 from binary mixture via forming hydrate with 5 wt% tetra-n-butyl ammonium bromide (TBAB) solution were studied. The results showed that the inductio...Hydrate formation rate and separation effect on the capture of CO2 from binary mixture via forming hydrate with 5 wt% tetra-n-butyl ammonium bromide (TBAB) solution were studied. The results showed that the induction time was 5 min, and the hydrate formation process finished in 1 h at 4.5 ℃ and 4.01 MPa. The hydrate formation rate constant reached the maximum of 1.84× 10^-7 molZ/(s.J) with the feed pressure of 7.30 MPa. The CO2 recovery was about 45 % in the feed pressure range from 4.30 to 7.30 MPa. Under the feed pressure of 4.30 MPa, the maximum separation factor and CO2 concentration in hydrate phase were 7.3 and 38.2 mol%, respectively. The results demonstrated that TBAB accelerated hydrate formation and enriched CO2 in hydrate phase under the gentle condition.展开更多
Semiclathrate hydrates of tetra-n-butyl ammonium bromide (TBAB) offer potential solution for gas storage, transportation, separation of flue gases and CO2 sequestration. Models for phase equilibria for these systems...Semiclathrate hydrates of tetra-n-butyl ammonium bromide (TBAB) offer potential solution for gas storage, transportation, separation of flue gases and CO2 sequestration. Models for phase equilibria for these systems have not yet been developed in open literatures and thus require urgent attention. In this work, the first attempt has been made to model phase equilibria of semiclathrate hydrates of CH4, CO2 and N2 in aqueous solution of TBAB. A thermodynamic model for gas hydrate system as proposed by Chen and Guo has been extended for semiclathrate hydrates of gases in aqueous solution of TBAB. A correlation for the activity of water relating to the system temperature, concentration of TBAB in the system and the nature of guest gas molecule has been proposed. The model results have been validated against available experimental data on phase equilibria of semiclathrate hydrate systems of aqueous TBAB with different gases as guest molecule. The extended Chen and Guo's model is found to be suitable to explain the promotion effect of TBAB for the studied gaseous system such as, methane, carbon dioxide and nitrogen as a guest molecule. Additionally, a correlation for the increase in equilibrium formation temperature (hydrate promotion temperature, ATp) of semiclathrate hydrate system with respect to pure gas hydrate system has been developed and applied to semiclathrate hydrate of TBAB with several gases as guest molecules. The developed correlation is found to predict the promotion effect satisfactorily for the system studied.展开更多
The study of interactions between surfactant and salt in aqueous solutions has attracted significant interest in recent years because of their widespread applications and relatively complex behavior.This work reports ...The study of interactions between surfactant and salt in aqueous solutions has attracted significant interest in recent years because of their widespread applications and relatively complex behavior.This work reports the systematic study of surface phenomenon and self-aggregation behavior of cationic surfactant cetyltrimethyl ammonium bromide(CTAB)with ammonium nitrate(NH_(4)NO_(3))salt.Surface and thermodynamic properties of cationic surfactant CTAB with NH_(4)NO_(3)were investigated at different temperatures using different techniques such as conductometry and surface tensiometery.The surface tension measurement was carried out to find out the critical micelle concentration,free energy of adsorption,free energy of micellization,minimum area per molecule,and surface excess concentration.The study reveals that the process of micellization is spontaneous and exothermic in nature.Conductance measurement was carried out to determine critical micelle concentration,degree of ionization and degree of counter ion binding.Addition of NH_(4)NO_(3)to the surfactant solutions increase the values of degree of ionization and degree of counter ion binding,although it lowers the values of critical micelle concentration showing that the process of micellization is more favorable and spontaneous.The study is very helpful to develop better understanding about interaction between electrolyte and surfactant,which are used in many applications and in different processes(e.g.,pharmaceutical,industrial foaming,drug solubilization,oil recovery,and medium for metal nanoparticle formation).展开更多
Organomontmorillonites (organo-MMT) were synthesized by means of montmorillonites (MMT) modified with a series of 2-methacryloyloxy ethyl alkyl dimethyl ammonium bromide (MAAB) having different alkyl chain lengt...Organomontmorillonites (organo-MMT) were synthesized by means of montmorillonites (MMT) modified with a series of 2-methacryloyloxy ethyl alkyl dimethyl ammonium bromide (MAAB) having different alkyl chain lengths as cationic surfactants through a cationic exchanging reaction, and were characterized by FTIR, TG, elemental analysis, and XRD. The microenvironment of the organic interlayer such as the orientation and arrangement of the alkyl chains of MAAB, as well as the properties of nanocomposite hydrogels, were also investigated. The amount of organic components absorbed on interlayer and the basal spacing of organo-MMT both increase with the increasing of alkyl length of MAAB. When carbon number of alkyl chain is in the region of 8 to 14, the alkyl chains between layers would adopt a disordered gauche conformation; while the carbon number is 16, an ordered all-trans conformation with a vertical orientation would be found together with the disordered gauche conformation according to the results of XRD and FTIR. Due to the difference of microenvironment of organic interlayer, the Young's moduli of the nanocomposite hydrogels increased as the alkyl chains of MAAB became longer.展开更多
The interaction of poly(sodium sulfodecyl methacrylate) (PSSM) with cetyltrimethyl ammonium bromide (CTAB)was studied. It was found that the precipitate formed from PSSM and CTAB will be dissolved by excessive CTAB, r...The interaction of poly(sodium sulfodecyl methacrylate) (PSSM) with cetyltrimethyl ammonium bromide (CTAB)was studied. It was found that the precipitate formed from PSSM and CTAB will be dissolved by excessive CTAB, resultingin the appearance of two maxima of the solution viscosity at the molar ratio (CTAB/-SO_3^-) of≈ 0.68 and≈1.30,respectively. The first one is related closely to the aggregation of polymer chains via CTAB molecules and the second oneshould be ascribed to the formation of the mixed micelles comprising surfactant and the polymer's hydrophobic chains. Theeffect of NaCl on the viscosity, the transmittance of the aqueous solution and the solubility of oil-soluble dye (dimethyl yellow) in the mixed system were also investigated.展开更多
Aromatic ethers were conveniently brominated with quaternary ammonium bromide and iodosylbenzene in glacial acetic acid under mild conditions to give the corresponding monobromo-aromatic ethers in nearly quantitative ...Aromatic ethers were conveniently brominated with quaternary ammonium bromide and iodosylbenzene in glacial acetic acid under mild conditions to give the corresponding monobromo-aromatic ethers in nearly quantitative yields.展开更多
Surfactant-modified natural zeolites(SMNZ)with different coverage types were prepared by loading hexadecyltrimethyl ammonium bromide(HTAB)onto the surface of a natural zeolite.The adsorption behavior of humic acid(HA)...Surfactant-modified natural zeolites(SMNZ)with different coverage types were prepared by loading hexadecyltrimethyl ammonium bromide(HTAB)onto the surface of a natural zeolite.The adsorption behavior of humic acid(HA)on SMNZ was investigated.Results indicate that the adsorbent SMNZ exhibited a higher affinity toward HA than the natural zeolite.HA removal efficiency by SMNZ increased with HTAB loading.Coexisting Ca2+in solution favored HA adsorption onto SMNZ.Adsorption capacity decreased with an increasing solution pH.For typical SMNZ with bilayer HTAB coverage,HA adsorption process is well described by a pseudo-second-order kinetic model.The experimental isotherm data fitted well with the Langmuir model.Calculated maximum HA adsorption capacities for SMNZ with bilayer HTAB coverage at pH 5.5 and 7.5 were 63 and 41 mg·g^(-1),respectively.E2/E3(absorbance at 250 nm to that at 365 nm)and E4/E6(absorbance at 465 nm to that at 665 nm)ratios of the residual HA in solution were lower than that of the original HA solution.This indicates that the HA fractions with high polar functional groups,low molecular weight(MW),and aromaticity had a stronger tendency for adsorption onto SMNZ with bilayer HTAB coverage.Results show that HTABmodified natural zeolite is a promising adsorbent for removal of HA from aqueous solution.展开更多
A new method for indirect determination of cetyl-trimethyl ammonium bromide (CTMAB) with NaCl and NH4SCN by floatation and separation of zinc has been studied. The study shows that Zn(II) can associate with NH4SCN an...A new method for indirect determination of cetyl-trimethyl ammonium bromide (CTMAB) with NaCl and NH4SCN by floatation and separation of zinc has been studied. The study shows that Zn(II) can associate with NH4SCN and CTMAB to form insoluble ternary ion-association complex, and the precipitate can float on the surface of the liquid phase. A good linear relationship is observed between the floatation yield (E%) of Zn(II) and the amount of CTMAB. On the ground, CTMAB can be indirectly determined by determining E% of Zn(II). The results were satisfactory.展开更多
Adsorption experiments were carried out to investigate the sorption behaviors of naphthalene and phenanthrene in six different soils and to determine the effects of temperature, linear alkylbenzene sulfonate (LAS) a...Adsorption experiments were carried out to investigate the sorption behaviors of naphthalene and phenanthrene in six different soils and to determine the effects of temperature, linear alkylbenzene sulfonate (LAS) and cetylrimethyl ammonium bromide (CTAB) on sorption. The results show that for a given sorbent phenanthrene exhibited greater nonlinear and stronger sorption than naphthalene. There was a strong negative correlation for the Koc values with organic carbon content (foc). The increase of temperature was not favorable to sorption. Sorption decreased along with the increasing aqueous LAS concentration from 0 to 1000 mg/L. At low CTAB concentration (〈 100 mg/L), the adsorption increased as CTAB hemimicelles formed on the soil surface. At high concentration, CTAB decreased the adsorption by occupying active hydrophobic adsorption sites and solubilization of naphthalene and phenanthrene.展开更多
he solubilities , refractive indexes of saturated solutions of the quaternary re-ciprocal system Li ̄+ , Br ̄(-) ,I ̄(-)H_(2)O and its boundary ternary system NH_(4)Br-NH_(4)I-H_(2)O at 25℃ have been investigated usi...he solubilities , refractive indexes of saturated solutions of the quaternary re-ciprocal system Li ̄+ , Br ̄(-) ,I ̄(-)H_(2)O and its boundary ternary system NH_(4)Br-NH_(4)I-H_(2)O at 25℃ have been investigated using isothermal method. In the titleternary system which belongs to Roozeboom Ⅳ type, there are two limited solid so-lutions. Entering into the quaternary system, the region of the solid solutions re-duces and disappears with the increase of Li ̄+ , and finally, the quaternary systembecomes a simple system.展开更多
Plasma-induced surface graft copolymerization of acrylic acid on polypropylene non-woven fabric(PP-g-AA)andpolypropylene membrane were reported.The extents of grafting were controlled by the plasma and polymerizationc...Plasma-induced surface graft copolymerization of acrylic acid on polypropylene non-woven fabric(PP-g-AA)andpolypropylene membrane were reported.The extents of grafting were controlled by the plasma and polymerizationcondition.Hexadecyltrimethyl ammonium bromide was then coupled with the carboxyl group of PP-g-AA to obtain apolyion complex(PIC).At last,CF_4 plasma was used to give PICs hydrophobic property.The moisture regain and water-repellency of the processed PICs was investigated.The surfaces were characterized using ATR FT-IR and XPS.The resultindicates that the products have very high ability to adsorb moisture,even better than cotton fiber.At the same time,theproducts show excellent hydrophobic property,which can't be wetted by those reagents whose surface tensions were higherthan 327 mN/m.展开更多
A new catalytic procedure for the chemoselective oxidation of sulfides to sulfoxides was studied.A variety of aliphatic and aromatic sulfides were subjected to sulfoxidation by combining poly(4-vinyl pyridinium nitrat...A new catalytic procedure for the chemoselective oxidation of sulfides to sulfoxides was studied.A variety of aliphatic and aromatic sulfides were subjected to sulfoxidation by combining poly(4-vinyl pyridinium nitrate),silica sulfuric acid(SiO2-OSO3H),and catalytic amounts of ammonium bromide in CH2Cl2 in the presence of a few drops of water at room temperature.Excellent yields were obtained.展开更多
Calcium montmorillonite from Liao-ning was organically intercalated by using cety1 trimethy1 ammonium bromide after it was treated with sodium carbonate. The optimal dosage of intercalating agent was tested. The organ...Calcium montmorillonite from Liao-ning was organically intercalated by using cety1 trimethy1 ammonium bromide after it was treated with sodium carbonate. The optimal dosage of intercalating agent was tested. The organically intercalated montmorillonite composites were characterized by the methods of XRD, FTIR and DTA/TG. The results show that the intercalating effect of the organically intercalated montmorillonite composite is the best when the amount of intercalating agent reached 120% cation exchange capacity (CEC)展开更多
Mesoporous SnO2 was synthesized using cetyltrimethyl ammonium bromide (CTAB) as supermolecule-template by hydrothermal method followed by calcining under different temperature in air. X-ray diffraction analysis (XR...Mesoporous SnO2 was synthesized using cetyltrimethyl ammonium bromide (CTAB) as supermolecule-template by hydrothermal method followed by calcining under different temperature in air. X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM) techniques were used to characterize the structure of mesoporous SnO2. The results indicated that the gas sensors prepared by using mesoporous SnO2 after calcination at 400 ℃ showed quick response and recovery to ethanol at 200 ℃. It was also found that the mesostructure SnO2 with small particle size had higher sensitivity and selectivity to C2HhOH than the SnO2 nanoparticles the particle size of which is 20 nm synthesized by sol-gel method.展开更多
In this study, a new method of synthesis of polyethylene glycol supported potassium tribromide (PEG KBr3) and its application in acylation and bromination reactions are reported. Ammonium persulphate oxidizes I(Br ...In this study, a new method of synthesis of polyethylene glycol supported potassium tribromide (PEG KBr3) and its application in acylation and bromination reactions are reported. Ammonium persulphate oxidizes I(Br to the corresponding tribromide which is entrapped by polyethylene glycol leading to stable PEG KBr3. The reagent is proved to be highly efficient for the acylation of variety of alcohols and bromination of activated aromatic substrates. The method is a mild, one pot reaction and involves no use of toxic reagents.展开更多
Three organo-montmorillonites were prepared using surfactants, and their adsorption behaviors toward sulfamethoxazole(SMX) were investigated. The surfactants used were cetyltrimethyl ammonium bromide(CTMAB), 3-(N...Three organo-montmorillonites were prepared using surfactants, and their adsorption behaviors toward sulfamethoxazole(SMX) were investigated. The surfactants used were cetyltrimethyl ammonium bromide(CTMAB), 3-(N,N-dimethylhexadecylammonio) propane sulfonate(HDAPS) and 1,3-bis(hexadecyldimethylammonio)-propane dibromide(BHDAP). The properties of the organo-montmorillonites were characterized by X-ray diffraction, scanning electron microscopy and N2adsorption–desorption isotherm measurements. Results showed that the interlayer spacing of montmorillonite was increased and the surface area as well as the morphology were changed. Batch adsorption experiments showed that the surfactant loading amount had a great effect on the adsorption of SMX. The adsorption process was p H dependent and the maximum adsorption capacity was obtained at p H 3 for HDAPS-Mt, while CTMAB-Mt and BHDAP-Mt showed a high removal efficiency at 3–11. The adsorption capacity increased with the initial SMX concentration and contact time but decreased with increasing solution ionic strength.Kinetic data were best described by the pseudo second-order model. Equilibrium data were best represented by the Langmuir model, and the Freundlich constant(n) indicated a favorable adsorption process. The maximum adsorption capacity of SMX was 235.29 mg/g for CTMAB-Mt, 155.28 mg/g for HDAPS-Mt and 242.72 mg/g for BHDAP-Mt. Thermodynamic parameters were calculated to evaluate the spontaneity and endothermic or exothermic nature. The adsorption mechanism was found to be dominated by electrostatic interaction,while hydrophobic interaction played a secondary role.展开更多
Organo-fly ash (OFA) was prepared with pretreated fly ash (FA) and hexadecyltrimethyl ammonium bromide (HDTMAB), and the composites composed of OFA and polyaniline were obtained by emulsion polymerization at dif...Organo-fly ash (OFA) was prepared with pretreated fly ash (FA) and hexadecyltrimethyl ammonium bromide (HDTMAB), and the composites composed of OFA and polyaniline were obtained by emulsion polymerization at different OFA weight ratios (2.0 wt%, 5.0 wt%, 10.0 wt%, 15.0 wt% and 20.0 wt%) in the presence of dodecylbenzenesulfonic acid as dopant and emulsifier. A polymerization procedure was supposed. The electrical conductivities of the composites were tested by the four-probe technique. The chemical structure and crystallinity of the composites were confirmed by FT-IR and X-ray diffraction, respectively. Morphologies of FA, OFA and the composites were observed by SEM. The element analysis was performed by energy dispersive spectrometry. The thermal stability of the composites was analyzed by TGA. The results showed that the electrical conductivity of the composites decreased with increasing the feed weight ratio of OFA, and the lowest value was 0.62 S/cm. HDTMAB and PAn were just adsorbed on the surface of FA and OFA, respectively according to the physical adsorption without destroying the crystalline structure of FA or OFA. The surface became smoother after organification of FA by using HDTMAB, and its content on FA surfaces was about 26.9 wt%. The core/shell structure of the composite was observed by SEM analysis. The composites showed a higher thermal stability than pure PAn by introduction of OFA into this polymerization system, the heat stability of PAn was increased by decreasing 31.8 wt% of weight loss after introducing 20 wt% of OFA.展开更多
The performance of Ionic Polymer Metal Composite (IPMC) actuator was significantly enhanced by incorporating surfactant-assisted processable Multi-Walled Carbon Nanotubes (MWCNTs) into a Nation solution. Cationic ...The performance of Ionic Polymer Metal Composite (IPMC) actuator was significantly enhanced by incorporating surfactant-assisted processable Multi-Walled Carbon Nanotubes (MWCNTs) into a Nation solution. Cationic surfactant Cetyl Trimethyl Ammonium Bromide (CTAB) was employed to disperse MWCNTs in the Nation matriX, forming a homogeneous and stable dispersion ofnanotubes. The processing did not involve any strong acid treatment and thus effectively preserved the excellent electronic properties associated with MWCNT. The as-obtained MWCNT/Nafion-IPMC actuator was tested in terms of conductivity, bulk and surface morphology, blocking force and electric current. It was shown that the blocking force and the current of the new IPMC are 2.4 times and 1.67 times higher compared with a pure Nation-based IPMC. Moreover, the MWCNT/IPMC performance is much better than previously reported Nafion-IPMC doped by acid-treated MWCNT. Such significantly improved performance should be attributed to the improvement of electrical property associated with the addition of MWCNTs without acid treatment.展开更多
Facile synthesis of multi-branched gold nanostructures by using the tetrabutyl ammonium bromide (TBAB) as a capping agent is described. The reaction is carried out in a one-step process at mild temperature. Gold nan...Facile synthesis of multi-branched gold nanostructures by using the tetrabutyl ammonium bromide (TBAB) as a capping agent is described. The reaction is carried out in a one-step process at mild temperature. Gold nanostructures with more than six sharp branches ranging from 70 to 130 nm in length are synthesized in high yield. It is proposed that the relative weak adsorption capacity of TBAB leads to the incompletely covered gold surface and the growth of nanoparticles occurs on the uncovered gold surface, and therefore short branches appear consequently. Then positively charged TBAB layers on the gold surfaces prevent the branches from aggregating with each other which stimulates the branch growth. The prepared branched gold nanoparticles show efficient surface-enhanced Raman scattering (SERS) properties. Low temperature (4 ℃) is unfavorable to the formation of multi-branched gold nanostructures, and only thin small irregular plate-like nanoparticles are produced. The addition of SDS in TBAB aqueous solution results in forming SDS micelles at much lower concentration of SDS (0.4 mmol/L) as compared to that in pure water, and short branched gold nanoparticles are obtained in the SDS-TBAB system.展开更多
A novel bromination of α,β-unsaturated carboxylic acids was developed via a decarboxylation by virtue of a direct anodic electro-oxidation.In this method,ammonium bromide was employed as a bromine source and the rea...A novel bromination of α,β-unsaturated carboxylic acids was developed via a decarboxylation by virtue of a direct anodic electro-oxidation.In this method,ammonium bromide was employed as a bromine source and the reaction features transition-metal-free,short time,and no additional supporting electrolyte.展开更多
文摘Hydrate formation rate and separation effect on the capture of CO2 from binary mixture via forming hydrate with 5 wt% tetra-n-butyl ammonium bromide (TBAB) solution were studied. The results showed that the induction time was 5 min, and the hydrate formation process finished in 1 h at 4.5 ℃ and 4.01 MPa. The hydrate formation rate constant reached the maximum of 1.84× 10^-7 molZ/(s.J) with the feed pressure of 7.30 MPa. The CO2 recovery was about 45 % in the feed pressure range from 4.30 to 7.30 MPa. Under the feed pressure of 4.30 MPa, the maximum separation factor and CO2 concentration in hydrate phase were 7.3 and 38.2 mol%, respectively. The results demonstrated that TBAB accelerated hydrate formation and enriched CO2 in hydrate phase under the gentle condition.
基金supported by the the Industrial Consultancy and Sponsored Research (ICSR),Indian Institute of Technology Madras,Chennai (Project Number OEC/10 11/530/NFSC/JITE)the National Institute of Ocean Technology (NIOT),Chennai,India (Project Number OEC/10-11/105/NIOT/JITE)
文摘Semiclathrate hydrates of tetra-n-butyl ammonium bromide (TBAB) offer potential solution for gas storage, transportation, separation of flue gases and CO2 sequestration. Models for phase equilibria for these systems have not yet been developed in open literatures and thus require urgent attention. In this work, the first attempt has been made to model phase equilibria of semiclathrate hydrates of CH4, CO2 and N2 in aqueous solution of TBAB. A thermodynamic model for gas hydrate system as proposed by Chen and Guo has been extended for semiclathrate hydrates of gases in aqueous solution of TBAB. A correlation for the activity of water relating to the system temperature, concentration of TBAB in the system and the nature of guest gas molecule has been proposed. The model results have been validated against available experimental data on phase equilibria of semiclathrate hydrate systems of aqueous TBAB with different gases as guest molecule. The extended Chen and Guo's model is found to be suitable to explain the promotion effect of TBAB for the studied gaseous system such as, methane, carbon dioxide and nitrogen as a guest molecule. Additionally, a correlation for the increase in equilibrium formation temperature (hydrate promotion temperature, ATp) of semiclathrate hydrate system with respect to pure gas hydrate system has been developed and applied to semiclathrate hydrate of TBAB with several gases as guest molecules. The developed correlation is found to predict the promotion effect satisfactorily for the system studied.
文摘The study of interactions between surfactant and salt in aqueous solutions has attracted significant interest in recent years because of their widespread applications and relatively complex behavior.This work reports the systematic study of surface phenomenon and self-aggregation behavior of cationic surfactant cetyltrimethyl ammonium bromide(CTAB)with ammonium nitrate(NH_(4)NO_(3))salt.Surface and thermodynamic properties of cationic surfactant CTAB with NH_(4)NO_(3)were investigated at different temperatures using different techniques such as conductometry and surface tensiometery.The surface tension measurement was carried out to find out the critical micelle concentration,free energy of adsorption,free energy of micellization,minimum area per molecule,and surface excess concentration.The study reveals that the process of micellization is spontaneous and exothermic in nature.Conductance measurement was carried out to determine critical micelle concentration,degree of ionization and degree of counter ion binding.Addition of NH_(4)NO_(3)to the surfactant solutions increase the values of degree of ionization and degree of counter ion binding,although it lowers the values of critical micelle concentration showing that the process of micellization is more favorable and spontaneous.The study is very helpful to develop better understanding about interaction between electrolyte and surfactant,which are used in many applications and in different processes(e.g.,pharmaceutical,industrial foaming,drug solubilization,oil recovery,and medium for metal nanoparticle formation).
文摘Organomontmorillonites (organo-MMT) were synthesized by means of montmorillonites (MMT) modified with a series of 2-methacryloyloxy ethyl alkyl dimethyl ammonium bromide (MAAB) having different alkyl chain lengths as cationic surfactants through a cationic exchanging reaction, and were characterized by FTIR, TG, elemental analysis, and XRD. The microenvironment of the organic interlayer such as the orientation and arrangement of the alkyl chains of MAAB, as well as the properties of nanocomposite hydrogels, were also investigated. The amount of organic components absorbed on interlayer and the basal spacing of organo-MMT both increase with the increasing of alkyl length of MAAB. When carbon number of alkyl chain is in the region of 8 to 14, the alkyl chains between layers would adopt a disordered gauche conformation; while the carbon number is 16, an ordered all-trans conformation with a vertical orientation would be found together with the disordered gauche conformation according to the results of XRD and FTIR. Due to the difference of microenvironment of organic interlayer, the Young's moduli of the nanocomposite hydrogels increased as the alkyl chains of MAAB became longer.
基金This work was supported by the National Natural Science Foundation of China (Contract No: 39870227 & 50173002).
文摘The interaction of poly(sodium sulfodecyl methacrylate) (PSSM) with cetyltrimethyl ammonium bromide (CTAB)was studied. It was found that the precipitate formed from PSSM and CTAB will be dissolved by excessive CTAB, resultingin the appearance of two maxima of the solution viscosity at the molar ratio (CTAB/-SO_3^-) of≈ 0.68 and≈1.30,respectively. The first one is related closely to the aggregation of polymer chains via CTAB molecules and the second oneshould be ascribed to the formation of the mixed micelles comprising surfactant and the polymer's hydrophobic chains. Theeffect of NaCl on the viscosity, the transmittance of the aqueous solution and the solubility of oil-soluble dye (dimethyl yellow) in the mixed system were also investigated.
文摘Aromatic ethers were conveniently brominated with quaternary ammonium bromide and iodosylbenzene in glacial acetic acid under mild conditions to give the corresponding monobromo-aromatic ethers in nearly quantitative yields.
基金This work was supported by the National Major Project of Science and Technology Ministry of China(Grant No.2008ZX07421-002)the National Natural Science Foundation of China(Grant No.50908142)the National Science and Technology Infrastructure Program of China(Grant No.2006BAJ08B02).
文摘Surfactant-modified natural zeolites(SMNZ)with different coverage types were prepared by loading hexadecyltrimethyl ammonium bromide(HTAB)onto the surface of a natural zeolite.The adsorption behavior of humic acid(HA)on SMNZ was investigated.Results indicate that the adsorbent SMNZ exhibited a higher affinity toward HA than the natural zeolite.HA removal efficiency by SMNZ increased with HTAB loading.Coexisting Ca2+in solution favored HA adsorption onto SMNZ.Adsorption capacity decreased with an increasing solution pH.For typical SMNZ with bilayer HTAB coverage,HA adsorption process is well described by a pseudo-second-order kinetic model.The experimental isotherm data fitted well with the Langmuir model.Calculated maximum HA adsorption capacities for SMNZ with bilayer HTAB coverage at pH 5.5 and 7.5 were 63 and 41 mg·g^(-1),respectively.E2/E3(absorbance at 250 nm to that at 365 nm)and E4/E6(absorbance at 465 nm to that at 665 nm)ratios of the residual HA in solution were lower than that of the original HA solution.This indicates that the HA fractions with high polar functional groups,low molecular weight(MW),and aromaticity had a stronger tendency for adsorption onto SMNZ with bilayer HTAB coverage.Results show that HTABmodified natural zeolite is a promising adsorbent for removal of HA from aqueous solution.
文摘A new method for indirect determination of cetyl-trimethyl ammonium bromide (CTMAB) with NaCl and NH4SCN by floatation and separation of zinc has been studied. The study shows that Zn(II) can associate with NH4SCN and CTMAB to form insoluble ternary ion-association complex, and the precipitate can float on the surface of the liquid phase. A good linear relationship is observed between the floatation yield (E%) of Zn(II) and the amount of CTMAB. On the ground, CTMAB can be indirectly determined by determining E% of Zn(II). The results were satisfactory.
基金supported by the National NaturalScience Foundation of China (No. 40372109)the National Basic Research Program (973) of China (No.2004CB418502).
文摘Adsorption experiments were carried out to investigate the sorption behaviors of naphthalene and phenanthrene in six different soils and to determine the effects of temperature, linear alkylbenzene sulfonate (LAS) and cetylrimethyl ammonium bromide (CTAB) on sorption. The results show that for a given sorbent phenanthrene exhibited greater nonlinear and stronger sorption than naphthalene. There was a strong negative correlation for the Koc values with organic carbon content (foc). The increase of temperature was not favorable to sorption. Sorption decreased along with the increasing aqueous LAS concentration from 0 to 1000 mg/L. At low CTAB concentration (〈 100 mg/L), the adsorption increased as CTAB hemimicelles formed on the soil surface. At high concentration, CTAB decreased the adsorption by occupying active hydrophobic adsorption sites and solubilization of naphthalene and phenanthrene.
文摘he solubilities , refractive indexes of saturated solutions of the quaternary re-ciprocal system Li ̄+ , Br ̄(-) ,I ̄(-)H_(2)O and its boundary ternary system NH_(4)Br-NH_(4)I-H_(2)O at 25℃ have been investigated using isothermal method. In the titleternary system which belongs to Roozeboom Ⅳ type, there are two limited solid so-lutions. Entering into the quaternary system, the region of the solid solutions re-duces and disappears with the increase of Li ̄+ , and finally, the quaternary systembecomes a simple system.
文摘Plasma-induced surface graft copolymerization of acrylic acid on polypropylene non-woven fabric(PP-g-AA)andpolypropylene membrane were reported.The extents of grafting were controlled by the plasma and polymerizationcondition.Hexadecyltrimethyl ammonium bromide was then coupled with the carboxyl group of PP-g-AA to obtain apolyion complex(PIC).At last,CF_4 plasma was used to give PICs hydrophobic property.The moisture regain and water-repellency of the processed PICs was investigated.The surfaces were characterized using ATR FT-IR and XPS.The resultindicates that the products have very high ability to adsorb moisture,even better than cotton fiber.At the same time,theproducts show excellent hydrophobic property,which can't be wetted by those reagents whose surface tensions were higherthan 327 mN/m.
基金Supported by the research facilities of Ilam University,Ilam,Iran
文摘A new catalytic procedure for the chemoselective oxidation of sulfides to sulfoxides was studied.A variety of aliphatic and aromatic sulfides were subjected to sulfoxidation by combining poly(4-vinyl pyridinium nitrate),silica sulfuric acid(SiO2-OSO3H),and catalytic amounts of ammonium bromide in CH2Cl2 in the presence of a few drops of water at room temperature.Excellent yields were obtained.
基金Funded by the 11th Five National Science and Technology Supporting 9Key Project "Engineering Research for Nonmetallic Resources Comprehensive Utilization"( 2006BAB12B00) Educational Ministry Scientific and Technological Research Key Project (No. 02052)
文摘Calcium montmorillonite from Liao-ning was organically intercalated by using cety1 trimethy1 ammonium bromide after it was treated with sodium carbonate. The optimal dosage of intercalating agent was tested. The organically intercalated montmorillonite composites were characterized by the methods of XRD, FTIR and DTA/TG. The results show that the intercalating effect of the organically intercalated montmorillonite composite is the best when the amount of intercalating agent reached 120% cation exchange capacity (CEC)
基金Project supported by the Shanghai Leading Academic Discipline Project(Grant No.S30109)the Natural Science Foundation of Shanghai Municipality(Grant No.08ZR1407800)+1 种基金the Research Foundation of State Key Laboratory of Chemical Engineering (ECUST)the Shanghai Key Laboratory of Green Chemistry and Chemical Processes(ECNU)
文摘Mesoporous SnO2 was synthesized using cetyltrimethyl ammonium bromide (CTAB) as supermolecule-template by hydrothermal method followed by calcining under different temperature in air. X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM) techniques were used to characterize the structure of mesoporous SnO2. The results indicated that the gas sensors prepared by using mesoporous SnO2 after calcination at 400 ℃ showed quick response and recovery to ethanol at 200 ℃. It was also found that the mesostructure SnO2 with small particle size had higher sensitivity and selectivity to C2HhOH than the SnO2 nanoparticles the particle size of which is 20 nm synthesized by sol-gel method.
基金the Department of Science and Technology,DST,New Delhi,India,for fnancial assistance received through a SERC fast track project(No.SR/FTP/CS-100/2007)
文摘In this study, a new method of synthesis of polyethylene glycol supported potassium tribromide (PEG KBr3) and its application in acylation and bromination reactions are reported. Ammonium persulphate oxidizes I(Br to the corresponding tribromide which is entrapped by polyethylene glycol leading to stable PEG KBr3. The reagent is proved to be highly efficient for the acylation of variety of alcohols and bromination of activated aromatic substrates. The method is a mild, one pot reaction and involves no use of toxic reagents.
文摘Three organo-montmorillonites were prepared using surfactants, and their adsorption behaviors toward sulfamethoxazole(SMX) were investigated. The surfactants used were cetyltrimethyl ammonium bromide(CTMAB), 3-(N,N-dimethylhexadecylammonio) propane sulfonate(HDAPS) and 1,3-bis(hexadecyldimethylammonio)-propane dibromide(BHDAP). The properties of the organo-montmorillonites were characterized by X-ray diffraction, scanning electron microscopy and N2adsorption–desorption isotherm measurements. Results showed that the interlayer spacing of montmorillonite was increased and the surface area as well as the morphology were changed. Batch adsorption experiments showed that the surfactant loading amount had a great effect on the adsorption of SMX. The adsorption process was p H dependent and the maximum adsorption capacity was obtained at p H 3 for HDAPS-Mt, while CTMAB-Mt and BHDAP-Mt showed a high removal efficiency at 3–11. The adsorption capacity increased with the initial SMX concentration and contact time but decreased with increasing solution ionic strength.Kinetic data were best described by the pseudo second-order model. Equilibrium data were best represented by the Langmuir model, and the Freundlich constant(n) indicated a favorable adsorption process. The maximum adsorption capacity of SMX was 235.29 mg/g for CTMAB-Mt, 155.28 mg/g for HDAPS-Mt and 242.72 mg/g for BHDAP-Mt. Thermodynamic parameters were calculated to evaluate the spontaneity and endothermic or exothermic nature. The adsorption mechanism was found to be dominated by electrostatic interaction,while hydrophobic interaction played a secondary role.
基金supported by the Shaanxi Provincial Education Department(No.09JK528) and Program of Shaanxi Key Subject
文摘Organo-fly ash (OFA) was prepared with pretreated fly ash (FA) and hexadecyltrimethyl ammonium bromide (HDTMAB), and the composites composed of OFA and polyaniline were obtained by emulsion polymerization at different OFA weight ratios (2.0 wt%, 5.0 wt%, 10.0 wt%, 15.0 wt% and 20.0 wt%) in the presence of dodecylbenzenesulfonic acid as dopant and emulsifier. A polymerization procedure was supposed. The electrical conductivities of the composites were tested by the four-probe technique. The chemical structure and crystallinity of the composites were confirmed by FT-IR and X-ray diffraction, respectively. Morphologies of FA, OFA and the composites were observed by SEM. The element analysis was performed by energy dispersive spectrometry. The thermal stability of the composites was analyzed by TGA. The results showed that the electrical conductivity of the composites decreased with increasing the feed weight ratio of OFA, and the lowest value was 0.62 S/cm. HDTMAB and PAn were just adsorbed on the surface of FA and OFA, respectively according to the physical adsorption without destroying the crystalline structure of FA or OFA. The surface became smoother after organification of FA by using HDTMAB, and its content on FA surfaces was about 26.9 wt%. The core/shell structure of the composite was observed by SEM analysis. The composites showed a higher thermal stability than pure PAn by introduction of OFA into this polymerization system, the heat stability of PAn was increased by decreasing 31.8 wt% of weight loss after introducing 20 wt% of OFA.
基金This paper is financially supported by the National Natural Science Foundation of China (51175251 and 61161120323), and the Natural Science Foundation of Jiangsu Province (BK2011734), the Funding for Out- standing Doctoral Dissertation in NUAA (BCXJ 11-06), the Funding of Jiangsu Innovation Program for Graduate Education (CXLXll_0178), and the Fundamental Re- search Funds for the Central Universities. The authors thank Mr. Yajun Xue for his help in SEM measurements, and Mr. Xinyuan Zhu for his help in TEM measurements.
文摘The performance of Ionic Polymer Metal Composite (IPMC) actuator was significantly enhanced by incorporating surfactant-assisted processable Multi-Walled Carbon Nanotubes (MWCNTs) into a Nation solution. Cationic surfactant Cetyl Trimethyl Ammonium Bromide (CTAB) was employed to disperse MWCNTs in the Nation matriX, forming a homogeneous and stable dispersion ofnanotubes. The processing did not involve any strong acid treatment and thus effectively preserved the excellent electronic properties associated with MWCNT. The as-obtained MWCNT/Nafion-IPMC actuator was tested in terms of conductivity, bulk and surface morphology, blocking force and electric current. It was shown that the blocking force and the current of the new IPMC are 2.4 times and 1.67 times higher compared with a pure Nation-based IPMC. Moreover, the MWCNT/IPMC performance is much better than previously reported Nafion-IPMC doped by acid-treated MWCNT. Such significantly improved performance should be attributed to the improvement of electrical property associated with the addition of MWCNTs without acid treatment.
基金Project supported by the National Natural Science Foundation of China (Nos. 50872042, 51003040), Open Research Project (No. KF0802) from State Key Laboratory of Crystal Material (Shandong University) and the Special Fund for Postdoctoral Innovation Program of Shandong Province (No. 200703075).
文摘Facile synthesis of multi-branched gold nanostructures by using the tetrabutyl ammonium bromide (TBAB) as a capping agent is described. The reaction is carried out in a one-step process at mild temperature. Gold nanostructures with more than six sharp branches ranging from 70 to 130 nm in length are synthesized in high yield. It is proposed that the relative weak adsorption capacity of TBAB leads to the incompletely covered gold surface and the growth of nanoparticles occurs on the uncovered gold surface, and therefore short branches appear consequently. Then positively charged TBAB layers on the gold surfaces prevent the branches from aggregating with each other which stimulates the branch growth. The prepared branched gold nanoparticles show efficient surface-enhanced Raman scattering (SERS) properties. Low temperature (4 ℃) is unfavorable to the formation of multi-branched gold nanostructures, and only thin small irregular plate-like nanoparticles are produced. The addition of SDS in TBAB aqueous solution results in forming SDS micelles at much lower concentration of SDS (0.4 mmol/L) as compared to that in pure water, and short branched gold nanoparticles are obtained in the SDS-TBAB system.
基金the National Nature Science Foundation of China(Nos.21472177,21672200,21432009,J1310010)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB20000000)
文摘A novel bromination of α,β-unsaturated carboxylic acids was developed via a decarboxylation by virtue of a direct anodic electro-oxidation.In this method,ammonium bromide was employed as a bromine source and the reaction features transition-metal-free,short time,and no additional supporting electrolyte.