用氯离子电极同时测定阳离子表面活性剂的CMC及反离子缔合度

临界胶束浓度(CMC)是研究表面活性剂的一个重要参数，胶束的反离子缔合度(K)是重要的特性参数。本文以阳离子表面活性剂十烷基三甲基氯化铵(DTMAC)、十二烷基三甲基氯化铵(DTAC)、十四烷基三甲基氯化铵(TTAC)、十六烷基三甲基氯化铵(CTAC)和十八烷基三甲基氯化铵(OTAC)水溶液体系为研究对象，用氯离子选择电极分别测定了其水溶液体系胶束的CMC和K。     

邻羟基苯基重氮氨基偶氮苯与季铵盐型表面活性剂显色反应的研究及应用

研究了显色剂邻羟基苯基重氮氦基偶氛苯(HDAA)与季铵盐型表面活性剂的显色反应。在0．1mol·L-1的氢氧化钠介质中,试剂与溴化十六烷基三甲胺(CTMAB)、溴化十六烷基吡啶(CPB)和氯化十六烷基吡啶分别形成玫瑰红色离子缔合物,缔合比均为13,CTMAB体系λmax＝558nm,CPB和CPC体系λmax＝562nm,表观摩尔吸光系数分别为1．34×104,1．03×104和1．47×104L·mol-1·cm-1。探讨了微量CTMAB、CPB和CPC的测定方法,结果满意。     

溴代十六烷基三甲基胺存在下铅与苯基荧光酮显色反应的研究

研究了溴代十六烷基三甲基胺 (CTMAB)存在下 ,铅与苯基荧光酮的显色反应。试验表明 ,铅与苯基荧光酮在CTMAB存在下能够形成稳定的络合物 ,该络合物的λmax=6 2 0nm ,摩尔吸光系数ε =2 .0 7× 10 5L·mol- 1·cm- 1,铅量在 0～ 6 .2 2 μg/ 10ml范围内服从比耳定律。     

槲皮素-钨(Ⅵ)-十六烷基三甲基溴化铵荧光光度法测定中药中槲皮素

1引言槲皮素（3,5,7,3’4-五羟基黄酮）,是许多天然中草药的主要成份,并有较好的祛痰、止咳及一定的平喘作用。目前,测定槲皮素的方法主要有高效液相色谱法,分光光度法,而基于槲皮素-钨（Ⅵ）-十六烷基三甲基溴化铝（CTMAB（）体系的荧光光度法尚未见报道。2实验部分2．1仪器与试剂930型荧光分光光度计（上海第三分析仪器厂）。1．0x10－4mol/L橡皮素乙醇溶液;1．0x10－3mol/L钨（VI）溶液;其它试剂为分析纯,实验用水为去离子水。2．2实验方法于10ml比色管加入一定量棚皮素标准溶液,依次加入1．0mLX10－3钨（Ⅵ）溶液,2．…     

Cu（Ⅱ）—CAS—CTMAB—邻菲罗啉显色反应的研究

络天青 S( CAS)光度法测定铜的报道较多[1,2 ] 。作者对显色体系进行了改进 ,引入溴化十六烷基三甲基铵 ( CTMAB)、邻菲罗啉 ,在 p H 8.5时 ,形成Cu2 + - CAS- CTMAB-邻菲罗啉四元显色体系 ,在波长 61 0 nm处测定 ,εmax=1 .3× 1 0 5。1　试验部分1 .1　主要仪器与试剂72 1型分光光度计 (上海第三分析仪器厂 )铜标准溶液、CAS溶液 :2 .0× 1 0 -4 mol·L-1CTMAB、邻菲罗啉溶液 :2 .0× 1 0 -4 mol· L-1硼砂 - HCl缓冲溶液 :p H 8.51 .2　试验方法准确移取铜标准溶液 1 ml于 50 ml容量瓶中 ,依次加入缓冲溶液 5ml、2 .0× 1 0…     

新试剂二(2，4-二硝基苯肼)缩乙二醛的合成及应用-废水中溴化十六烷基三甲铵的测定

合成了新试剂二 (2 ,4-二硝基苯肼 )缩乙二醛 (GDPH) ,在氢氧化钠碱性介质中 ,该试剂与十六烷基三甲铵 (CTMAB)形成 1∶ 2的深蓝色离子缔合物。该缔合物的 λmax位于 630 nm,表观摩尔吸光系数为 3.6× 1 0 4 L· mol-1· cm-1,CTMAB的含量在 0～ 1 0 0 mg· L-1范围内符合比尔定律。使用此体系和高灵敏手持式光度计进行废水中 CTMAB的现场测定。     

斯巴沙星-三辛基氧化膦-溴化十六烷基三甲基铵吸光光度法测定混合稀土中钕

研究了钕 斯巴沙星 (SPLX) 三辛基氧化膦 (TOPO) 溴化十六烷基三甲基铵 (CTMAB)体系的光度特性 ,确定了测定混合稀土中钕的最佳条件 ,提出了一种灵敏度较高、选择性好的测定钕的方法。在最佳试验条件下 ,钕的线性范围为 0 .4～ 5 .0× 10 -4 mol·L-1,检出限为 1.0× 10 -6mol·L-1(S N =3)。采用标准曲线法测定混合稀土中钕 ,结果满意     

光度法测定水中溴化十六烷基三甲铵

研究采用光度法,在pH5.0的缓冲溶液中,2 羟基 5 磺苯偶氮苯亚甲基肼基 2′ 羟基苯(R)与溴化十六烷基三甲铵(CTMAB)相互作用,当向R中加入CTMAB,立即生成红色配合物,其最大吸收峰为540和570nm;摩尔吸光系数ε=2.2×104L·mol-1·cm-1。由此建立了高灵敏度的吸光光度法测定水中微量的CTMAB。试验了该体系的酸度、温度、时间、浓度等最佳反应条件。在0.005×10-5～2.2×10-5mol·L-1浓度范围内呈良好的线性关系。检出限为1μg·ml-1。     

钛-甘露醇-邻苯三酚红-CTMAB 四元络合体系的研究及应用

在溴化十六烷基三甲基铵(CTMAB)存在下,Ti(Ⅳ)同甘露醇和邻苯三酚红在pH 3.4时形成蓝色的四元配合物,配合物的组成为n(Ti(Ⅳ))n(甘露醇)n(邻苯三酚红)n(CTMAB)=1123,配合物的最大吸收波长为630 nm,Ti在0～1.40μg/mL范围内符合比耳定律,摩尔吸光系数为3.1×105L·mol-1·cm-1.用抗坏血酸掩蔽Fe(Ⅲ),体系不需要分离可直接用于钢中微量钛的测定.     

聚乙二醇萃取—络天青S光度法测定原油及润滑油中的铝

以聚乙二醇 -硫酸铵 -铝试剂体系萃取分离干扰离子 ,采用络天青 (CAS) -溴化十六烷基三甲基胺 (CTMAB)为显色体系测定原油中的铝。试验了测定条件及萃取分离干扰离子的条件。测定范围在 0～ 1 0 μg/ 2 5ml,ε64 5nm=4.95× 1 0 4 L· mol-1· cm-1,合成样品回收率为 97.3%～1 0 2 .7% ,原油分析结果的相对标准偏差≤ 2 .6%。该方法灵敏简便 ,整个萃取操作具有安全、无毒、快速的优点。     

Aggregation Number of Ionic Surfactants and its Application for Alkyltrimethyl Ammonium Bromides and Sodium Tetradecyl Sulfate by Potentiometric Technique

A potentiometric technique based on surfactant ion selective electrode has been used for various cationic and anionic surfactants. The data obtained contain m ₁ (surfactant monomer concentration); m ₂ (free counterion concentration) and α (degree of dissociation of micelle) were used for determination of aggregation number at and above cmc (critical micelle concentration). Data fitting show a relationship between aggregation number with such parameters. The correlation equation obtained shows that size of ionic micelle vary sharply after cmc. Also, the equation obtained shows size of micelle growth with increase in counterion concentration.     

Thermodynamic parameters and counterion binding to the micelle in binary anionic surfactant systems

Competitive counterion binding of sodium and calcium to micelles, and mixed micellization have been investigated in the systems sodium dodecylsulfate (NaDS)/sodium decylsulfate (NaDeS) and NaDS/sodium 4-octylbenzenesulfonate (NaOBS) in order to accurately model the activity of the relevant species in solution. The critical micelle concentration (CMC) and equilibrium micelle compositions of mixtures of these anionic surfactants, which is necessary for determining fractional counterion binding measurements, is thermodynamically modeled by regular solution theory. The mixed micelle is ideal (the regular solution parameter β(M)=0) for the NaDS/NaOBS system, while the mixed micelle for NaDS/NaDeS has β(M)=-1.05 indicating a slight synergistic interaction. Counterion binding of sodium to the micelle is influenced by the calcium ion concentration, and vice versa. However, the total degree of counterion binding is essentially constant at approximately 0.65 charge negation at the micelle's surface. The counterion binding coefficients can be quantitatively modeled using a simple equilibrium model relating concentrations of bound and unbound counterions.     

Aggregation behaviour and thermodynamics of mixed micellization of 1-hexadecylpyridinium bromide and ionic liquid in ethylene glycol/water binary mixtures

Micellar behavior of binary combinations of ionic liquid, 1-tetradecyl-3-methylimidazolium bromide, with conventional cationic surfactant 1-hexadecylpyridinium bromide was investigated by means of conductometry to study the effect of cosolvent and water content and temperature. The critical micelle concentration and the degree of counterion association were calculated from the conductometry data. Thermodynamic parameters were obtained from the temperature dependence of the critical micelle concentration. The standard Gibbs energy of micellization increased with the increasing percentage of cosolvent as well as the mole fraction of C₁₄mimBr. The standard enthalpy and standard entropy of micelle formation were both decreased with the increasing temperature and the concentration of cosolvent. The entropy contribution was larger than the enthalpic one in pure water, whereas in the ethylene glycol/H₂O mixture the enthalpy contribution was predominant     

Counterion condensation and release in micellar solutions

Counterion condensation and release in micellar solutions are investigated by direct measurement of counterion concentration with ion-selective electrode. Monte Carlo simulations based on the cell model are also performed to analyze the experimental results. The degree of counterion condensation is indicated by the concentration ratio of counterions in the bulk to the total ionic surfactant added, alpha< or =1. The ionic surfactant is completely dissociated below the critical micelle concentration (cmc). However, as cmc is exceeded, the free counterion ratio alpha declines with increasing the surfactant concentration and approaches an asymptotic value owing to counterion condensation to the surface of the highly charged micelles. Micelle formation leads to much stronger electrostatic attraction between the counterion and the highly charged sphere in comparison to the attraction of single surfactant ion with its counterion. A simple model is developed to obtain the true degree of ionization, which agrees with our Monte Carlo results. Upon addition of neutral polymer or monovalent salts, some of the surfactant counterions are released to the bulk. The former is due to the decrease of the intrinsic charge (smaller aggregation number) and the degree of ionization is increased. The latter is attributed to competitive counterion condensation, which follows the Hefmeister series. This consequence indicates that the specific ion effect plays an important role next to the electrostatic attraction.     

Effect of Short Chain Alcohols upon Viscosity of TTAB Solution

The effect of ethanol (C2H5OH), propanol (C3H7OH), and butanol (C4H9OH) upon the viscosity of tetradecyltrimethylammonium bromide (TTAB) solution in the presence or absence of KBr at 30 o C was investigated, where the surfactant concentration CS is kept constant. In the absence of KBr, the relative viscosity ηr of TTAB solution increases linearly with the alcohol concentration CA, indicating that the alcohols do not promote micelle formation of TTAB. In the presence of KBr, ′r linearly decreases with CA for C2H5OH, but it exhibits a maximum with increasing CA for C3H7OH or C4H9OH. The facts reveal that C2H5OH or C4H9OH promotes the micelle formation of TTAB. A possible explanation is that the hydrophobicity of the micellar interior is enhanced by KBr, so that C2H5OH or C4H9OH can dissolve in micelle and promotes micelle formation. In the presence of KCl, which is less efficient in promoting the micelle formation of cationic surfactant, both C3H7OH and C4H9OH have only a slight effect on the micelle formation. In contrast, due to the hydrophilicity, C2H5OH cannot dissolve in micelles in the presence of KBr or KCl.     

The Correlation of the Degree of Counterion Binding with the Composition of Ionic–Nonionic Mixed Micelles

Two simple expressions for calculating the degree of counterion binding of mixed micelles are presented. These approximate expressions for the spherical micelle are derived from the relationship of the degree of counterion binding with the surface charge density. One of them works quite well for the estimation of the degree of counterion binding of mixed micelles when the mole fraction of the ionic component in mixed micelles is high.     

Structural organization of cetyltrimethylammonium sulfate in aqueous solution: The effect of Na2SO4

We used dynamic light scattering (DLS), steady-state fluorescence, time resolved fluorescence quenching (TRFQ), tensiometry, conductimetry, and isothermal titration calorimetry (ITC) to investigate the self-assembly of the cationic surfactant cetyltrimethylammonium sulfate (CTAS) in aqueous solution, which has SO(2-)4 as divalent counterion. We obtained the critical micelle concentration (cmc), aggregation number (N(agg)), area per monomer (a0), hydrodynamic radius (R(H)), and degree of counterion dissociation (alpha) of CTAS micelles in the absence and presence of up to 1 M Na2SO4 and at temperatures of 25 and 40 degrees C. Between 0.01 and 0.3 M salt the hydrodynamic radius of CTAS micelle R(H) approximately 16 A is roughly independent on Na2SO4 concentration; below and above this concentration range R(H) increases steeply with the salt concentration, indicating micelle structure transition, from spherical to rod-like structures. R(H) increases only slightly as temperature increases from 25 to 40 degrees C, and the cmc decreases initially very steeply with Na2SO4 concentration up to about 10 mM, and thereafter it is constant. The area per surfactant at the water/air interface, a0, initially increases steeply with Na2SO4 concentration, and then decreases above ca. 10 mM. Conductimetry gives alpha = 0.18 for the degree of counterion dissociation, and N(agg) obtained by fluorescence methods increases with surfactant concentration but it is roughly independent of up to 80 mM salt. The ITC data yield cmc of 0.22 mM in water, and the calculated enthalpy change of micelle formation, Delta H(mic) = 3.8 kJ mol(-1), Gibbs free energy of micellization of surfactant molecules, Delta G(mic) = -38.0 kJ mol(-1) and entropy TDelta S(mic) = 41.7 kJ mol(-1) indicate that the formation of CTAS micelles is entropy-driven.     

Temperature effect on formation of sodium cholate micelles

The micellization of sodium cholate (NaC) at 293.2, 298.2, 303.2, 308.2, and 313.2 K by cholate anion concentration was studied over the pH range from 6.0 to 7.2. Using a stepwise association model of cholate anions without bound sodium counterions, the aggregation number (nmacr;) of the cholate micelles was evaluated and found to increase with the total concentration, indicating that the stepwise association model is applicable. The nmacr; values go up and down with increasing temperature; 17 at 298.2 and 12 at 313.2 K and at 60 mM of the sodium cholate. The fluorescence of pyrene was measured in sodium cholate solution to determine the critical micelle concentration (CMC), indicating a narrow concentration range for CMC. A sodium-ion-specific electrode was used to determine a relatively low degree of counterion binding to micelles, supporting the validity of the present association model of cholate anions. The aggregation numbers evaluated at a constant ionic strength of 0.15 and at lower but variable ionic strengths were similar except for higher cholate concentrations.