镓-2,4-二甲氧基苯基荧光酮-CTMAB体系的分光光度研究

在 p H 7— 9的 NH4Cl- NH3 · H2 O缓冲体系中 ,镓与显色剂 2 ,4 -二甲氧基苯基荧光酮及十六烷基三甲基溴化铵 (CTMAB)形成多元配合物 ,其最大吸收波长为 5 6 8nm,表观摩尔吸光系数 ε=2 .33× 10 5L·mol-1· cm-1,在 2 5 m L溶液中镓含量 0— 10 μg遵守比耳定律。经乙酸丁酯萃取镓与干扰元素分离后 ,本方法用于岩石样品中微量镓的测定 。

十六烷基三羟乙基溴化铵促进1-辛烯氢甲酰化水/有机两相反应研究

研究了水/有机两相体系中表面活性剂十六烷基三羟乙基溴化铵(CTHAB)对Rh/TPPTS(TPPTS:三[间-磺酸钠基苯基]膦)催化的1-辛烯氢甲酰化反应的促进作用,初步证实了CTHAB分子中的羟基可与催化活性物种的铑之间发生配位.与传统表面活性剂十六烷基三甲基溴化铵(CTAB)相比,表面活性剂CTHAB的添加不仅加速了水/有机两相1-辛烯氢甲酰化反应,而且提高了成醛的正/异比,促进作用明显.在[Rh]=0.8 mmol/L,[TPPTS]/[Rh]=40,[CTHAB]=4.0mmol/L,90℃,0.5 MPa,1.5 h时,生成醛的TOF为497 h-1,正/异比(L/B)可达25.6.催化剂经7次循环后,反应活性和成醛正/异比无明显下降.该催化体系对不同长链烯烃氢甲酰化反应同样具有促进作用.

Effect of cetyltrimethylammonium bromide on morphology and porous structure of mesoporous hydroxyapatite

The mesoporous hydroxyapatite （HA） was synthesized by hydrothermal method utilizing cationic surfactant cetyltrimethylammonium bromide （CTAB） as template. The crystalline phase, morphology and porous structure were characterized respectively by different detecting techniques. The results reveal that the particles are highly crystalline hydroxyapatite phase. The surfactant has little influence on the morphology of the crystals, but affects the porous structure obviously. The sample without CTAB has a low surface area not exceeding 33 m^2/g, and no distinct pores can be observed by TEM. While the samples obtained with the surfactant get better parameters. Numerous open-ended pores centered at 2-7 nm spread unequally on the surface of the hydroxyapatite nanorods. The N2 adsorption-desorption experiments show type IV isotherms with distinct hysteresis loops, illustrating the presence of mesoporous structure. When the mole ratio of CTAB to HA is 1：2, the sample has the largest surface area of 97.1 m^2/g and pore volume of 0.466 cm^3/g.

Binding tendency with oligonucleotides and cell toxicity of cetyltrimethyl ammonium bromide-coated single-walled carbon nanotubes

Functionalized carbon nanotubes （CNTs） were made for the delivery of genes and drugs and CNT-based biosensors. The basis of CNTs is for binding with biomolecules in biomedical applications. The binding tendency with small interfering RNA oligonucleotides and cytotoxicity of cetyltrimethyl ammonium bromide （CTAB）-coated single-walled carbon nanotubes （SWNTs） were studied. The field emission scanning electron microscopy and transmission electron microscopy results show that a SWNT suspension in CTAB solution was well-dispersed and stable. CTAB is the cross-linker between SWNTs and oligonucleotides. The CTAB-coated SWNTs have less cytotoxicity to human umbilical vein endothelial cells than single SWNTs and the cytotoxicity of CTAB-coated SWNTs depended on the concentration of CTAB-coated SWNTs.

Inclusion Complex of β-cyclodextrin with CTAB in Aqueous Solution

Cetyltrimethylammonium bromide （CTAB）/potassium bromide （KBr） micellar system has been used as a viscosity probe to study the inclusion complexation between β-cyclodextrin （β-CD） and CTAB. Viscosity measurements show that the inclusion complexation between β-CD and CTAB may cause the breakdown of CTAB/KBr wormlike micelles, resulting in the decrease of the solution viscosity. The viscosity minimum at Cβ-CD/CCTAB=2 indicate the molecular ratio of host molecule to guest molecule is 2：1 in the β-CD/CTAB inclusion complex.

Determination of Ciprofloxacin Lactate by Sodium Tetraphenylboron Method

This paper describes an effective method for determining ciprofloxacin lactate. An excess of sodium tetraphenylboron was added to precipitate ciprofloxacin lactate in HAc-NaAc buffer solution (pH=4.0). After filtering off the precipitate, the excessive sodium tetraphenylboron in the filtrate was titrated with cetyltrimethylammonium bromide standard solution, with bromophenol blue as indicator. The method is simple and rapid, it has been applied to the determination of ciprofloxacin lactate raw material with satisfactory results. The recovery was between 99.66% and 100.2%, the relative error was less than ±0.40%. Experiments showed that the method gave the same results as the approach using nonaqueous titration (ChP).

Determination of Chlordiazepoxide by Sodium Tetraphenylboron Method

This paper describes an effective method for determining chlordiazepoxide. An excess of sodium tetraphenylboron is added to precipitate chlordiazepoxide in HAc NaAc buffer solution (pH=4.0). After filtering off the precipitate, the excessive sodium tetraphenylboron in the filtrate is titrated with cetyltrimethylammonium bromide standard solution, with bromophenol blue as indicator. The method is simple and rapid, it has been applied for the determination of chlordiazepoxide raw materials with satisfactory results. The recovery is between 99.58% and 100.4%, the relative error is less than ± 0.50% . Experiments show that the method gives the same results as the approach using nonaqueous titration (ChP).

Synthesis and characterization of porous cobalt oxide/copper oxide nanoplate as novel electrode material for supercapacitors

A promising Co3O4/Cu O composite electrode material was successfully synthesized through a facile hydrothermal and calcination process. Effects of the surfactants hexadecyltrimethyl ammonium bromide（CTAB） and polyvinylpyrrolidone（PVP） on the morphology and electrochemical performance of the composite were investigated. Powder X-ray diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM） and nitrogen adsorption-desorption experiment were employed to characterize the microstructures and morphologies of the composite. Meanwhile, the electrochemical performances of the samples were studied using cyclic voltammetry（CV）, galvanostatic charge-discharge test and electrochemical impedance spectroscopy（EIS）. The results show that the porous Co3O4/Cu O-CTAB nanoplates own the best performance and exhibits a high specific capacitance of 398 F/g at 1 A/g with almost 100% capacitance retention over 2000 cycles, and it retains 90% of capacitance at 10 A/g.

Cytotoxicity effect assessment of acid purified carbon nanotubes modified with cetyltrimethyl ammonium bromide

The cytotoxicities of single-walled carbon nanotubes （SWNTs） and acid purified single-walled carbon nanotubes （SWNT-COOH） were investigated by spectroscopic analysis. Cell viability and cell apoptosis were applied to assessing the cytotoxicity of SWNT-COOH, cetyltrimethyl ammonium bromide （CTAB） and acid purified carbon nanotubes modified with cetyltrimethyl ammonium bromide （SWNT-COOH/CTAB）. The results indicate that SWNTs are more toxic than SWNT-COOH. Concentration and time-curve analyses indicate that cytotoxicity of SWNT-COOH/CTAB is more related to the toxicity of the surfactant CTAB. The cytotoxicity effect of CTAB and SWNT-COOH/CTAB is acceptable at low concentrations （0.5-25μg/mL）. The cytotoxicity observation suggests that SWNT-COOH/CTAB can safely applied to biomedical field at low concentrations （0.5-25μg/mL）.

Sol-gel Transition of Methylcellulose Solution in the Coexistence of Hexadecyltrimethylammonium Bromide and Sodium Chloride

The sol-gel transition of methylcellulose （MC） solution in the presence of NaCl and hexade- cyltrimethylammonium bromide （HTAB）, together with MC/NaCl solution in the presence of HTAB and MC/HATB solution in the presence of NaCl, was investigated by the rheological measurements. It has been found that the sol-gel transition temperature of MC solution decreases linearly with the concentration of NaCl in solution but increases linearly with the concentration of HTAB in solution, respectively. However, the sol-gel transition temperature of MC/NaCl solution in the presence of HTAB keeps the same value, independent of the concentration of HTAB in solution. On the other hand, the sol-gel transition temperature of MC/HTAB solution decreases linearly with the concentration of NaCl in solution. The experimental results suggest that, for MC/NaCl solution in the presence of HTAB, the salt- induced spherical micelles of HTAB should have formed in bulk solution. For MC solution in the absence of NaC1, no spherical micelles have been formed in bulk solution, though the concentration of HTAB in our experiment is almost one order of magnitude higher than the critical mieelle concentration of HTAB in polymer-free solution. In fact, due to adsorption of HTAB on MC chains, the realconcentration of HTAB in bulk solution, is much less than the apparent concentration of HTAB dissolved in MC solution.

Synthesis, characterization, and catalytic performance of hierarchical ZSM-11 zeolite synthesized via dual-template route

Hierarchical zeolite materials were prepared via one‐pot synthesis of ZSM‐11zeolites with different molar ratios(R)of a mesoporogen,i.e.,cetyltrimethylammonium bromide template(CTAB),to a microporogen,i.e.,tetra‐n‐butylammonium bromide(TBABr).The structures,morphologies,and textural properties of the resultant materials were investigated.Initially,with increasing R,the crystal size of the synthesized product decreased,the number of intercrystalline mesopores increased,and a pure ZSM‐11zeolite phase was present.Then an MCM‐41‐like phase was produced and embedded in the ZSM‐11zeolite phase.Finally,an MCM‐41‐like phase was obtained.The alkalinity had important effects on the physicochemical and textural properties of the prepared samples.A possible mechanism of formation of the hierarchical ZSM‐11zeolite was proposed on the basis of a combination of various characterization results.The role of CTAB varied depending on the R value,and it showed a capping effect,micellar effect,and template effect.These effects of CTAB were synergetic in ZSM‐11synthesis,but they were competitive with the structure‐directing effect of TBABr.In addition,the impact of the acidic properties and porosities of the hierarchical ZSM‐11catalysts on their performances in the alkylation of benzene with dimethyl ether was investigated.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.

Membrane preconcentration of iron in seawater samples and on-site determination in spectrophotometry

A novel method for on-site determination of trace iron was developed using membrane preconcentration and spectrophotometric detection. Fe（II）-ferrozine complex was reacted with cetyltrimethylammonium bromide （CTAB） to form a Fe（II）-ferrozine-CTAB paired compound, which was collected on a membrane by filtration under vacuum. The membrane was immersed in 2 mL of ethanol-nitric acid and the absorbance of the solution measured for quantitative analysis. Various factors affecting the iron collection and determination were investigated. With different sample preconcentration volumes, the range of determination was broadened to 0.5-120 ~tg/L. The detection limit of this method reached 0.19 ktg/L and the recoveries were between 97.2 and 109% when the concentration enrichment was about 45. The relative standard deviation （n = 7） was 1.9% for samples containing 10 ~g/L Fe. Twelve seawater samples were analyzed on-site using the proposed method, and two were also analyzed in inductively coupled plasma mass spectrometry. No significant difference was shown between the two methods by the Student＇s t-test. The method has also been used on-site for iron enrichment experiments with phytoplankton and concluded to be simple, accurate and inexpensive.

Selective Affinity Separation of Yeast Alcohol Dehydrogenase by Reverse Micelles with Unbound Triazine Dye

The reversed micelles were formed with cationic cetyltrimethylammonium bromide (CTAB) as surfactant and n-hexanol as cosolvent in the CTAB (50mmol.L-1)/hexanol (15% by volume)/hexane system. Cibacron Blue 3GA (CB) as an affinity ligand in the aqueous phase was directly introduced to the reversed micelles with electrostatic interaction between anionic CB and cationic surfactant. High molecular weight (Mr) protein, yeast alcohol dehydrogenase (YADH, Mr = 141000) from baker's yeast, has been purified using the affinity reversed micelles by the phase transfer method. Various parameters, such as CB concentration, pH and ionic strength, on YADH forward and backward transfer were studied. YADH can be transferred into and out from the reversed micelles under mild conditions (only by regulation of solution pH and salt concentration) with the successful recovery of most YADH activity. Both forward and backward extractions occurred when the aqueous phase pH＞pI with electrostatic attraction between YADH and CTAB. The recovery of YADH activity and purification factor have been improved with addition of a small amount of affinity CB. The recovery of YADH activity obtained was ～99% and the purification factor was about 4.0-fold after one cycle of full forward and backward extraction. The low ionic strength in the initial aqueous phase might be responsible for the YADH transfer into the reversed micellar phase.

Adsorption of sulfate in aqueous solutions by organo-nano-clay:Adsorption equilibrium and kinetic studies

The adsorption of sulfate in aqueous solutions onto organo-nano-clay prepared by natural zeolite and cationic surfactant cetyltrimethylammonium bromide （CTAB） was studied.Parameters such as adsorbent dosage,contact time and temperature were investigated using batch adsorption studies.The results show that the uptake of sulfate increases with the increase of contact time and temperature,and decreases with the increase of dosage.The Freundlich isotherm model is fit to explain the sulfate adsorption onto organo-nano-clay.The maximum adsorption capacity is found to be 38.02 mg/g at 40 ℃.The kinetic data fit well the pseudo-second-order and Elovich models with a R2 more than 0.98.It is suggested that chemisorption is the rate-controlling step for adsorption of sulfate onto organo-nano-clay,meanwhile both intraparticle diffusion and boundary layer diffusion also contribute as well.Ion-exchange between sulfate anions and bromide ions and complexation between sulfate anions and CTAB cations are responsible for the mechanism of sulfate adsorption.Keywords：organo-nano-clay; cetyltrimethylammonium bromide （CTAB）; modification; sulfate; adsorption

Photocatalytic degradation of formaldehyde using mesoporous TiO_2 prepared by evaporation-induced self-assembly

The mesoporous Ti O2 has been synthesized by evaporation induced self assembly(EISA) method. The thermogravimetric/differential scanning calorimetric(TG/DSC), X-ray diffraction(XRD), high-resolution transmission electron microscopy(HR-TEM) and N2 adsorption desorption and adsorption are used to study the effects of the synthesized process condition on the microstructure of the as-synthesized mesoporous Ti O2. The photocatalytic performances of as-synthesized samples are evaluated by the degradation of the formaldehyde under ultraviolet light irradiations. The results demonstrate that the as-synthesized mesoporous Ti O2 are anatase with the uniform size about 20-40 nm. The sample is prepared using cetyltrimethyl ammonium bromide(CTAB) as the template with average pore size distribution of 8.12 nm, specific surface area of 68.47 m2/g and pore volume of 0.213 m L/g. The samples show decomposition of formaldehyde 95.8% under ultraviolet light irradiations for 90 min. These results provide a basic experimental process for preparation mesoporous Ti O2, which will posses a broad prospect in terms of the applications in improving indoor air quality.

Dynamic Adsorption of Microwave Modified Attapulgite on Micro-polluted Phenol Wastewater

[Objective] The paper was to study the dynamic adsorption of microwave modified attapulgite on micro-polluted phenol wastewater. [Method] Cetyl trimethyl ammonium bromide （CATB） modified attapulgite was used to modify attapulgite, and conducted dynamic test on micro-polluted phenol wastewater. The dynamic charac- teristics of phenol removal were also studied. [Result] Attapulgite modified by CATB has strong adsorption ability on phenol in micro-polluted water, the phenol removal rate increased with the decrease of flow rate of wastewater. When pH value was 6- 8, phenol concentration in wastewater was 17.74 mg/L, flow rate was 2 m/s and ad- sorption time was 25 rain, the removal rate reached 93.07%. The modified atta- pulgite could be regenerated with alkali, and its adsorption ability after regeneration had no obvious decline. The dynamic adsorption process of phenol accorded with the first-order kinetic equation. [Conclusion] The study provided basis for further study on ＂organic matter removal in wastewater.

Cracking of Palm Oil over H-AIMCM-41 Catalyst

The objective of this research was to develop a catalyst for efficient cracking of palm oil to produce biogasoline. Mesoporous alumino-silicate, A1MCM-41, was synthesized by hydrothermal treatment to the mixture of sodium silicate, sodium aluminates, TMAOH （tetramethylammonium hydroxide）, and CTMAB （cetyltrimethylammonium bromide）, in Aquadest as a solvent. This process was carried out within 12 h of aging time at 100 ℃ in a teflon-lined stainless steel autoclave. The solid phase was filtered, then washed with distilled water, and dried in an oven at 80 ℃ for 24 h. The surfactant CTMAB was removed by calcination at 540 ℃ for 6 h using heating rate of 2 ℃/min. The as-synthesized and calcined powder was characterized by using FTIR （frontier transform infra red spectroscopy）, XRD （X-ray diffraction）, and TEM （transmission electron microscopy） methods. The product of AIMCM-41 was then converted into H-AIMCM-41 by ion exchanged in 0.5 M of NHaCI solution followed by filtration, drying at 80 ℃ for 24 h, and calcination at 540 ℃. The product of catalyst was used for catalytic conversion of PO （palm oil） to biogasoline in a fixed bed reactor at 200-400 ℃, under atmospheric pressure, and ratio of PO to catalyst was 200. The product of cracking was then distilled at 60 ℃ and analyzed using GC-MS （gas liquid chromatography - mass spectrometry） method. Result of the works shows that the catalyst had 4.49 nm of lattice parameter, and the cracking of PO gave 56.6% conversions with 29.4% selectivity to biogasoline like fraction.

Solubilization of Phenanthrene and Fluorene in Equimolar Binary Mixtures of Gemini/Conventional Surfactants

This study deals with the enhanced solubilization of polycyclic aromatic hydrocarbons （PAHs） such as phenanthrene （PHE） and fluorene （FLR） in a pure cationic gemini （G6） and three conventional surfactants [polyethylene glycol dodecyl ether （Brij35）, cetyltrimethyl ammonium bromide （CRAB） and sodium lauryl sulfate （SDS）] as well as in their equimolar binary combinations （G6-Brij35, G6-CTAB and G6-SDS）. Their solubilization efficiency toward PHE and FLR has been quantified in terms of the molar solubilization ratio （MSR） and the micelle-water partition coefficient （Kin）. The ideality/nonideality of the mixed micelles is discussed with the help of Clint, Rubingh and Rosen＇s approaches. These theories determine the deviation of experimental critical micelle concen- tration （CMC） values from ideal critical micelle concentration, which was measured by evaluating the interaction parameters （/3m and/3）. Negative values ofβm were observed in all the equimolar binary systems, which show synergism in the mixed micelles. Whereas at air/liquid interface synergism was observed in the systems G6-CrAB and G6-Brij35; G6-SDS exhibited an antagonistic effect. The order of MSR and Km was G6-CTAB 〉 G6- Brij35 〉 G6-SDS for phenanthrene as well as for fluorene.

Photorheology and rheokinetics of CTAB/chlorocinnamic acid micelles

The photosensitive micellar system with prospect in drag reduction and heat transfer enhancement has been the research focus of science and industry.In this paper,a new type of photosensitive micellar system formed by cetyl trimethylammonium bromide(CTAB) and trans-chlorocinnamic acid(trans-CICA) was investigated.The effects of counter-ion concentration,surfactant concentration,UV irradiation time,and the position of substituent groups of counter-ion on photorheological properties were discussed.The results indicate that after UV irradiation the relative viscosity and thixotropy of micellar systems reduce obviously.At the same time,the relative viscosity of micelle systems and concentration of trans-CICA decline during UV irradiation time.The flow curves of micellar solutions before and after UV irradiation could be described by non-linear co-rotational Jeffreys model correctly.The rheokinetic equation was firstly established to describe the relationship between relative viscosity of micelle systems and conversion of trans-CICA.

Photocatalytic Reduction of 6-Chloro-3-Nitrotoluene-4-Sulfonic Acid in Presence of Surfactants

Photocatalytic reduction of 6-chloro-3-nitrotoluene-4-sulfonic acid (CNSA) was studied in UV-irradiated TiO2 suspensions in the presence of methanol and surfactants. A mixture of CNSA, TiO2, water, additives and surfactants was put into a quartz glass reactor with a jacket, which was irradiated with a high pressure Hg lamp in the purging of nitrogen gas. With methanol, the conversion of CNSA increased from 7.7% to 34.6%. Three surfactants significantly promoted the photocatalytic reduction conversion in reduced order of sodium dodecylbenzenesulfonate (DBS), cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulfate (SDS). In suspensions involving DBS and CTAB respectively, CNSA conversion increased in consistence with the adsorption ratio with methanol, but varied inversely with the adsorption ratio without methanol. But no obvious influence on the adsorption ratio was observed with or without methanol added when the SDS concentration was critical micelle concentration (cmc). The photocatalytic reduction of CNSA was enhanced in UV-irradiated TiO2 suspensions in the presence of methanol and surfactants. Methanol inhibited the recombination of photogenerated holes and electrons efficiently. Surfactants around 1 cmc led to the highest reduction conversion.