Determination of Sodium Dodecyl Sulfate by Means of Photometric Titration with o‐Toluidine Blue Dye

A convenient technique for the determination of sodium dodecyl sulfate is titration with a metachromatic dye using in situ absorbance measurements. A suitable color reagent is ortho‐Toluidine Blue dye. Commercially available immersion optical probe Optrode® possesses a working wavelength of 640 nm, well matching the dye spectrum. The surfactant concentration is linearly related to the titrant volume at a certain solution absorbance. Optimal values of end point absorbance fall in the range from 0.7 to 2. The lower limit of quantitation is equal to 29 mg L^?1. The highest concentration determined in this study was 52 g L^?1. The required determination range may be adjusted by the appropriate selection of analyte volume and titrant concentration. The developed method is intended for routine process control in the surfactant industry. This method needs minimal manual efforts due to the lack of the dilution stage. Application of an automatic titrator looks to be a suitable solution for any industrial lab.     

分光光度法测定水中微量阴离子表面活性剂

在用HCl溶液调节pH=12.0的NaOH溶液中,5-甲基-2-[3-(4-苯基-2-噻唑基)三氮烯基]苯磺酸(MPTTBSA)与氯化十六烷基吡啶(CPC)形成离子缔合物MPTTBSA-CPC。在该溶液中加入阴离子表面活性剂时,能定量置换出离子缔合物中的MPTTBSA,使缔合物在最大吸收波长556 nm处的吸光度下降,阴离子表面活性剂的浓度与溶液的褪色程度呈良好线性关系,从而建立了阴离子表面活性剂光度测定法。实验结果表明,十二烷基磺酸钠(SLS)和十二烷基苯磺酸钠(SDBS)的表观摩尔吸光系数分别为1.24×104 L·mol-1·cm-1和1.07×104 L·mol-1·cm-1,在0～2.5×10-5 mol·L-1范围内服从比尔定律。该方法应用于生活污水中微量阴离子表面活性剂(以SLS计)的测定,结果与亚甲基蓝法测定结果基本一致。     

Spectrophotometric Determination of Benzalkonium Bromide in Pharmaceutical Samples with Alizarin Green

A direct, extraction‐free spectrophotometric method was developed for the determination of benzalkonium bromide (BAK). The method is based on the formation of mixed dye–surfactant aggregates between alizarin green (AG) and BAK in alkaline medium by measuring the decrease in absorbance of AG at 460 and 700 nm. Beer's law was obeyed in the concentration range 3–40 μg mL^?1 with good precision and accuracy. The limits of detection were 0.4 μg mL^?1 at 460 nm and 0.3 μg mL^?1 at 700 nm, which reduced to 0.2 μg mL^?1 by combining the absorbance at the two wavelengths. The proposed method was successfully applied to the determination of BAK in disinfectant solution and eye drops. The analytical results of the real samples were in good agreement with those of an HPLC method.     

褪色光度法测微量CTMAB

利用阳离子表面活性剂十六烷基三甲基溴化铵(CTMAB)与偶氮兰形成离子缔合物,使染料发生明显的褪色,体系吸光度的降低与CTMAB浓度成正比,用分光光度法测定CTMAB含量,实验了最佳方法:波长选用554 nm处,CTMAB浓度在0~60μg/25 mL范围内符合比耳定律,方法的线性关系良好(r=0.998 3),检测限为0.18μg/mL(以3σ计),21种常见共存离子不影响CTMAB含量的测定。本法对环境水体中CTMAB含量进行了测定,稳定性和选择性较好,回收率较高(96.0%~103.0%),是一种良好的CTMAB测定方法。     

Development of an Ultraviolet‐Spectrophotometric Method for Analysis of Esterquat‐Containing Flotation Collectors in Aqueous Solutions

In this study, a rapid and simple ultraviolet‐spectrophotometric method was developed and validated for the quantitative determination of esterquat‐containing flotation collector FLOT 2015 in aqueous solutions. This method is based on the formation of an ion pair by FLOT 2015 and bromocresol purple, an anionic dye, and the subsequent measurement of the reduction in absorbance without extraction by organic solvents. The optimum conditions for FLOT 2015 detection and analysis were established. Sample solutions were stable up to 3 h. Maximum absorbance was obtained at 574 nm. The proposed method showed linearity in the range of 5–45 μg mL^?1 with a correlation coefficient of 0.9917. Standard and relative standard deviation obtained by intraday and interday precision tests of the proposed method were within the permissible bias range and considered satisfactory. This method was found to be selective and specific for successful determination of FLOT 2015 in aqueous flotation systems.     

Simple,Rapid and Precise Determination of Free Sulfuric Acid in Unstabilized Cellulose Nitrate by the Lead Nitrate–Dithizone Titration Method

Simple, rapid and precise determination of free sulfuric acid in unstabilized cellulose nitrate is accomplished by dissolving in 90 % v/v acetone–water solution and subsequent titration of sulfate by the lead nitrate–dithizone titration method. The method is proved accurately and sensitively for tracing very small amounts of free sulfuric acid present in all types of unstabilized cellulose nitrates. One more advantage of the method is that free nitric acid do not interfere in the determination, and, hence, there is no need to estimate its value and to correct the value for the free sulfuric acid content; the determination of free nitric acid, which is likely to be present with sulfuric acid in unstabilized cellulose nitrate is a very difficult problem.     

改进的同时测定法测定混合染液各组分浓度

针对常规同时测定法存在测定周期长且对于多峰吸光度曲线不适用的问题,提出一种改进的同时测定法测定混合染液中各组分的浓度。首先运用高斯逼近法拟合固定浓度下各单一染液的吸光度、波长的模型。然后根据朗伯-比尔定律推导出各单一染液的吸光度、波长与浓度的模型,并给出了求混合染液各组分含量的具体步骤。最后以3种活性染料的混合染液浓度测定说明算法的可行性和有效性。     

Interaction of Phenol Red with cetyltrimethylammonium bromide in aqueous solution

This paper studies the interaction of anionic dye Phenol Red with cationic surfactant cetyltrimethylammonium bromide in aqueous solution and its influence on the formation of cetyltrimethylammonium bromide micelles for the first time. We obtain a series of thermodynamic parameters of the interaction by establishing a reasonable physical model of the association. Moreover, an in‐depth study on the variation in the absorption spectrum finds that the value of absorbance at the maximum absorption peak changes regularly with increase in the cetyltrimethylammonium bromide concentration. By establishing the micellisation models and measuring the changes in electrical conductivity with different cetyltrimethylammonium bromide concentrations, the critical micelle concentration values are obtained, which are essentially the same as the range of concentrations of regular change in absorbance, which shows that the formation of the cetyltrimethylammonium bromide micelles have an impact on the association interaction between Phenol Red and cetyltrimethylammonium bromide. All these data and phenomena illustrate a strong interaction between Phenol Red and cetyltrimethylammonium bromide.     

Electrokinetic properties of polyformaldehyde fibers

Electrokinetic properties, namely, zeta potential (ζ), surface charge density (σ), and surface conductivity (K_s) of polyformaldehyde fibers [poly(oxymethylene) fibers] have been studied in the presence of direct dyes, with or without surfactants and an electrolyte. The anionic dyes increased the negative zeta potential of fibers. The increase in ζ was found to be a function of concentration and basicity of the dye in the streaming solution. Thus, the tetrabasic dye gave higher value of negative ζ than the equivalent concentration of the dibasic dye. The cationic surfactant brought about a decrease in negative ζ, giving a point of inflection, while the anionic surfactant increased it. The nonionic surfactant brought about a certain reduction in negative ζ, but failed to give a point of inflection. In the presence of a direct dye, the cationic surfactant brought about considerable reduction in negative ζ, to give a point of inflection. The presence of an electrolyte in the streaming dye solution progressively lowered the negative ζ. In general, σ increased with the increase in the concentration of either a dye or an electrolyte in the presence of a given concentration of the dye in the streaming solution. Results on K_s indicated that the surface conductivity of the fibers is a function of concentration of dye, surfactant, and electrolyte. It was, however, observed to be independent of the nature of the surfactant. Although both the dibasic and tetrabasic direct dyes brought about an increase in K_s, the extent of increase was dependent upon the basicity of the molecules.     

粒子滤波算法测定混合染液染料浓度

针对如何准确测定混合染液染料浓度,尤其当混合染液浓度太大时由于染料自身发生如水解等化学变化以及染料之间的相互作用,其吸光度体系呈非线性的情况,提出了通过建立非线性吸光度模型,并利用粒子滤波算法同时测定混合染液中各染料浓度的解决方法。以3种活性染料的混合染液为例,对该方法的可行性进行验证,并与扩展卡尔曼滤波算法进行滤波效果对比。实例证明,非线性吸光度模型是准确的,基于粒子滤波算法的测定方法是有效可行的。     

浮选光度法测定饮用水中亚硝酸根

基于亚硝酸根在弱酸性的条件下重氮化反应 ,重氮化盐再与 N,N-二甲基苯胺进行偶合反应 ,生成黄色甲基橙 ,酸化后甲基橙变成红色 ,用十二烷基硫酸钠浮选富集 ,在正丁醇中收集浮选液 ,进行分光光度测定 ,从而求得亚硝酸根的含量。摩尔吸光系数ε为 9.7× 1 0 4L/ mol· cm(正丁醇为溶剂 ) ,亚硝酸根的浓度在 0 .0 4 1～ 0 .0 0 4 1μg/ m L与吸光度有良好的线性关系。该法可检出纯净水中痕量亚硝酸根的含量     

紫外分光光度法测定双酚S(英文)

建立了测定双酚S的紫外分光光度法。在pH值为6.0的磷酸盐缓冲溶液中,双酚S浓度在4.8×10-7~4.0×10-5mol.L-1范围内与其吸光度值呈显著线性相关,相关系数为0.9999,相对标准偏差为0.12%,检测限为4.0×10-7mol.L-1。该方法快速、灵敏,可用于常见样品中双酚S的测定。     

分光光度法测定蛹虫草子实体中硒的含量

建立了氯酸钾-盐酸苯肼-变色酸分光光度法测定蛹虫草子实体中硒含量的方法,并对其精密度、准确度进行研究。在测定范围内,该方法的线性相关系数R2=0.9991,加标回收率为92%～96%,硒含量相对标准偏差是1.8%,该方法用于蛹虫草子实体中硒含量的测定,结果良好,操作方便,成本低,为富硒蛹虫草菌株筛选和生产上的应用提供了简便易行的硒含量检测方法。     

Influence of Nonionic Surfactant on Hydrolysis of Vinyl Sulfone Reactive Dye

Nonionic surfactants are widely used in reactive dyeing processes, and the interaction between surfactants and reactive dyes affect the hydrolytic property of reactive dyes. In this study, reactive brilliant blue KN‐R (C.I. reactive blue 19) was employed as a model dye, and fatty alcohol polyoxyethylene ether (AEO‐9) was selected as a model nonionic surfactant. The interaction was first investigated in aqueous solutions by a UV‐spectrophotometry method, then the effect of surfactant concentration on the hydrolytic behavior of KN‐R was studied using high performance liquid chromatography method. Below the critical micelle concentration, the surfactant served as dispersant; the hydrolysis of reactive dye was accelerated. However, when the concentration of surfactant was above its critical micelle concentration, the dye was solubilized into the micellar phase, which was revealed from the changes in absorbance intensity and wavelength of the maximum absorbance. This led to slowed hydrolysis of reactive dye. These findings are useful in understanding the effect of concentration of nonionic surfactant on the hydrolysis of vinyl sulfone reactive dyes.     

Interactions and Solubilization of Disperse Dye with Modified Gemini Surfactants: Investigation Using the Taguchi Method

Since the interaction of a disperse dye with a surfactant in micelles plays an important role in textile industry, the purpose of this study was to find out the optimal conditions that describe the dye?Csurfactant interaction. The effects of temperature, gemini surfactant concentration and ethylene-oxide chain length of gemini surfactants were investigated and optimized using the Taguchi method. First, this method was adopted to carry out the parameter design, and the interaction parameters that would affect the absorbance of UV?Cvisible spectrum were chosen as the control factors. After the selection of an appropriate orthogonal array, an analysis of variance was applied to decide upon the optimal conditions of solubilization parameters and determine the significant factors of the UV?Cvisible absorbance. The optimized conditions were as follow: surfactant concentration 5.6 × 10^?4 M, length of ethylene oxide chain 20, and temperature 40 °C. Finally, the experimental results of confirmation tests with a confidence interval of 95%, indicated that the experiment is reliable and reproducible. Under these optimum conditions, it was also determined that the solubilization of disperse dye using modified gemini surfactants increased when the surfactant concentration and the ethylene oxide chain length increased.     

Determination of critical micelle concentrations of some surfactants by keto-enol tautomerism of benzoylacetone

Benzoylacetone, keto-enol tautomer, was dissolved in aqueous solutions of sodium dodecyl sulfate, dodecyl trimethyl ammonium chloride, hexaethyleneglycol dodecyl ether, polyoxyethylene tert-octyl phenyl ether, and polyoxyethylene nonyl phenyl ether, respectively. The effect of surfactants on this keto-enol equilibrium was examined by measuring the intensity of two spectral bands at ca. 250 nm and 315 nm due to ketonic and enolic form of this compound. The existence of keto-enol equilibrium of the benzoylacetone was indicated by an isosbestic point among the two bands. The absorbances of the two bands showed hardly any change in the range of surfactant concentrations below the critical micelle concentration (cmc) but, in the concentration range above the cmc, the absorbance of the enolic form increased and that of the ketonic form decreased abruptly. These changes at cmc were very noticeable in the case of ionic surfactant solution. The concentrations corresponding to abrupt change of the spectra used for the determination of cmc were in fair agreement with data obtained by other methods. However, in the case of nonionic surfactant solutions, the absorbance due to the enolic form increased gradually with increase of the surfactant concentration, and the distinct break point was not observed at cmc.     

Solubility of Two Disperse Dyes Derived from <Emphasis Type="Italic">N</Emphasis>-Alkyl and <Emphasis Type="Italic">N</Emphasis>-Carboxylic Acid Naphthalimides in the Presence of Gemini Cationic Surfactants

The solubility of naphthalimide-based monoazo dyes containing N-ethyl and N-ethanoic acid groups was investigated in the presence of a conventional monomeric counterpart (DTAB) and two cationic gemini surfactants (12-4-12 or 14-4-14) individually. The effective parameters on dye solubility such as temperature, time and concentration of surfactants were investigated by UV–Visible spectrophotometry. The results demonstrate that the solubility of both dyes was considerably increased at concentrations above the surfactant CMC. The wavelength for the maximum absorbance of dyes in the aqueous solution shifts toward longer wavelengths with changes in the concentration of the cationic surfactants. A kinetic study of solubilization of dyes in cationic surfactants solution showed that the rate of solubilization follows the pseudo-first-order reactions. Rates of solubilization were in the range of 0.5 × 10⁻³ to 6.8 × 10⁻³ min⁻¹ for both dyes. The disperse dye containing a carboxylic acid group (dye 2) has a higher solubility rate than the dye containing an alkyl group (dye 1). The type of surfactant has a very low effect on adsorption of dye 1 onto the polyester fibers, whereas changing the surfactant type from DTAB to 12-4-12 or 14-4-14 causes adsorption of dye 2 on polyester to decrease.     

硫酸铵、羟基乙酸混合液中各组分的定量分析方法研究

硫酸铵、羟基乙酸(GA)混合溶液中各组分定量分析时均存在另一组分的严重干扰。在甲醛法测定硫酸铵含量、酸碱滴定法测定羟基乙酸含量基础上,引入乙酰丙酮分光光度法,改进并建立了混合溶液中各组分定量分析方法。探讨了检测波长、羟基乙酸浓度、乙醇浓度、恒温时间、反应温度、p H值对3,5-二乙酰基-1,4-二氢二甲基吡啶(DDL)溶液吸光度的影响。该方法的适宜条件为:p H=5~7,ω(GA)90%,60℃恒温15 min,测定波长414 nm。线性方程Ar=0.242 5 C+0.004 0,线性范围0.05~4.00μg/m L,R2=0.999 9。方法测硫酸铵含量RSD1.5%,羟基乙酸含量RSD1.8%。此分析方法快捷、简便、灵敏、准确。     

次氯酸钠氧化法测定聚丙烯酰胺浓度的研究

阐述了次氯酸钠氧化法（浊度法）测定部分水解聚丙烯酰胺浓度的反应机理，研究了聚丙烯酰胺的相对分子质量、次氯酸钠溶液浓度、反应时间对吸光度值的影响，针对大庆油田杏二中三元复合驱采出水中含有碱和表面活性剂、pH值高、黏度大、富集硫化物和亚硫酸根等特点，提出采用过硫酸铵一浊度法检测三元复合驱采出水中聚丙烯酰胺浓度。     

Controlling the dispersion of multi-wall carbon nanotubes in aqueous surfactant solution

The sonication-driven dispersion of multi-wall carbon nanotubes (MWCNTs) in aqueous surfactant solution has been monitored by UV-vis spectroscopy and transmission electron microscopy. Time dependent sonication experiments reveal that the maximum achievable dispersion of MWCNTs corresponds to the maximum UV-vis absorbance of the solution. With higher surfactant concentration the dispersion rate of MWCNTs increases and less total sonication energy is required to achieve maximum dispersion. Dispersion of higher MWCNT concentrations requires higher total sonication energy. For effective dispersion the minimum weight ratio of surfactant to MWCNTs is 1.5-1. The surfactant molecules are adsorbed on the surface of the MWCNTs and prevent re-aggregation of MWCNTs so that a colloidal stability of MWCNT dispersions could be maintained for several months. The maximum concentration of MWCNTs that can be homogeneously dispersed in aqueous solution is about 1.4 wt%.