Entry in emulsion polymerization using a mixture of sodium polystyrene sulfonate and sodium dodecyl sulfate as the surfactant

A mixture of sodium polystyrene sulfonate (NaPSS) and anionic surfactant, sodium dodecyl sulfate (SDS), was used as the emulsifier in the emulsion polymerization of styrene at 60 °C. The latexes prepared were stable, bearing the better resistance to the addition of electrolyte, and have the larger values in particle size and the higher polymerization rates than those counterparts prepared using SDS only. The NaPSS was prepared by a series of process: a concentrated cyclohexane solution of an anionically polymerized polystyrene (PS) was sulfonated with sulfuric acid at 80 °C, and then neutralized and purified through dialysis. The data of average polymer number per particle (n_p) were found useful in investigating the surfactant content effect on the entry of radicals into particles, where the latex particle size plays an important role.     

Electrochemical investigations of an anticancer drug in the presence of sodium dodecyl sulfate as an enhancing agent at carbon paste electrode

In the present work, the electrochemical behavior of an anticancer drug, gemcitabine hydrochloride (GMB) was studied in the presence of a surface active agent (surfactant) at carbon paste electrode (CPE). GMB showed an oxidation peak at 1.101 V. The presence of sodium dodecyl sulfate (SDS) in the electrolyte was found to enhance the oxidation signal of GMB at CPE. The oxidation peak current of GMB in the presence of SDS was observed to be the function of accumulation time, scan rate, pH of the medium, and concentration of GMB. Accumulation time greatly influenced the peak current but did not exhibit significant influence on the peak potential. Based on this, a novel, sensitive, and convenient differential pulse voltammetric method was developed for the determination of GMB in the concentration range of 5.0 × 10⁻⁸–3.0 × 10⁻⁴ M with a limit of detection value of 8.2 × 10⁻⁹ M. The proposed procedure was successfully applied for the determination of GMB in pharmaceutical formulations and spiked biological samples.     

十二烷基硫酸钠干燥新技术的研究

在对十二烷基硫酸钠性能研究的基础上,采用新型复合式干燥设备对十二烷基硫酸钠干燥工艺进行了研究。研究结果表明,十二烷基硫酸化物在60℃～70℃下,中和到70%～75%后,预热到90℃～100℃,以1.0t/h～1.5t/h的流量进入复合式真空干燥器中进行干燥,干燥后的产品经孔板孔径为1mm～1.5mm的双螺杆挤出机造粒,钢带冷却可制得水含量低于2%的针状十二烷基硫酸钠。     

Separation and estimation of anionic surfactants by thin layer chromatography: i. Mixtures of sodium dodecyl benzenesulfonate,sodium dodecyl sulfate and sodium dodecanesulfonate

The conditions for separation and quantitative determination of anionic surfactants such as sodium dodecylbenzenesulfonate, sodium dodecanesulfonate and sodium dodecyl sulfate by thin layer chromatography (TLC) were investigated. Analytical results for mixtures of 2 or 3 components under optimal TLC conditions were in satisfactory agreement with known values. The absolute errors and variation coefficients both were within ca. 4%.     

膜法脱硝与元明粉的生产工艺探讨

介绍河南神马氯碱发展有限责任公司30万t/a离子膜法烧碱除硝和元明粉生产装置及工艺流程。     

低浓度瓦斯气体水合分离过程中十二烷基硫酸钠和高岭土的影响

为了探寻有效改善瓦斯水合分离动力学条件的方法,本文研究了十二烷基硫酸钠(SDS)和高岭土对瓦斯水合物生成过程及CH₄分离效果的影响。实验获取了低浓度瓦斯在4个体系中,即：SDS质量分数为10.34%的SDS溶液及高岭土质量分数为1.47%、5.64%和8.23%的SDS-高岭土复配溶液中瓦斯水合物生成过程压力-温度-时间（p-T-t）曲线,利用气相色谱仪测定了分离产物中CH₄的浓度。结果表明：SDS和SDS-高岭土复配体系缩短了瓦斯水合物生成诱导时间,提高了瓦斯水合物生成速率。4个体系中,瓦斯水合物生成诱导时间最短为72 min,平均生成速率最大可达5.261×10^-6 m³·h^-1;一级水合分离产物中CH₄浓度比原料气提高了12.40%～20.61%;在SDS-高岭土复配溶液中,瓦斯水合物分形生长,CH₄提纯浓度最高可达58.41%。     

Interactions between sodium tetradecyl sulfate and a series of homogeneous polyoxyethyleneglycol- n- dodecyl ethers

The surface tensions of a mixed system of sodium tetradecyl sulfate (STS) and a series of polyoxyethyleneglycol-n-dodecyl ethers (nED) were measured at temperatures of 30 and 40 C, respectively. When the STS concentration was fixed, the surface tension curves of the mixed system showed a flat portion in the range of which the mixed micelles would be formed. With a decrease of the added STS concentration, the length of the flat portion in these curves decreased gradually, and finally disappeared in the presence of 0.05 mM STS. Furthermore, when the concentration of STS was fixed at 1.0 mM, which is below the critical micelle concentration (CMC), the flat portion length in the surface tension curves de-creased with decreasing ethylene oxide chain length in nED and with increasing temperature. The influence of increment of temper-ature was comparable to that for reducing the length of ethylene oxide chain in nED.     

Influence of sodium dodecyl sulfate on the characteristics of bovine serum albumin solutions and foams

Results from surface tension measurements on mixed solutions of the protein bovine serum alburnin (BSA) and an anionic surfactant (SDS: sodium dodecyl sulfate) suggested that at an air-liquid interface, adsorption was affected by the protein-surfactant interaction and by the relative concentration of each component in solution. Two plateaus corresponding to the critical aggregation concentration (CAC) and the critical micelle concentration (CMC) of SDS, respectively, were observed in the surface tension isotherms of SDS in the presence of BSA. The CAC and CMC depended on the concentration of BSA. Effects of SDS concentration on the conformational changes of BSA were investigated by Fourier transform-Raman spectroscopy. The results showed that the contents of α-helix decreased while the contents of random coil increased. The presence of the anionic surfactant SDS had a negative influence on the way that proteins adsorb at an air-liquid interface, leading to the change of behavior of protein-stabilized film.     

Simultaneous determination of dopamine and uric acid on nafion/sodium dodecylbenzenesulfonate composite film modified glassy carbon electrode

A novel electrochemical sensor has been constructed by using a glassy carbon electrode (GCE) coated with nafion/sodium dodecylbenzenesulfonate (SDBS). Differential pulse voltammetry (DPV) was used to study the electrochemical behaviors of dopamine (DA) and uric acid (UA). An optimum of 5 mM SDBS together with 0.05 wt% of nafion was used to improve the resolution and the determination sensitivity successfully. In 0.1 M phosphate buffer solution (pH 6.5), the modified electrode exhibited high electrocatalytical activity toward the oxidation of DA and UA with obvious reduction of overpotential. Compared with bare GCE, the modified electrode resolved the voltammetric response of DA and UA into two well-defined voltammetric peaks by DPV, which can be used for simultaneous determination of these species in mixture. The peak currents obtained from DPV were linearly related to the concentrations of DA and UA in the ranges of 4.0 × 10⁻⁷–8.0 × 10⁻⁵ M and 4.0 × 10⁻⁶–8.0 × 10⁻⁴ M, respectively. The detection limit of DA and UA (signal-to-noise ration was 3) were 5.0 × 10⁻⁸ and 4.0 × 10⁻⁷ M, respectively.     

Effect of various parameters on sodium dodecyl sulfate (SDS) flux through a collagen membrane

The influence of various experimental parameters on the flux of sodium dodecyl sulfate (SDS) through a collagen membrane has been studied. The variables evaluated were donor concentration, time, temperature, pH and ionic strength. Data on the influence of both surfactant concentration and time on surfactant diffusion through the collagen film allow one to postulate a diffusion process mainly of the monomeric type. This diffusion mechanism based on surfactant monomers has been corroborated by studying the effect of ionic strength. Thisin vitro technique could be a useful tool to predict the effect of diverse experimental parameters on the percutaneous absorption of surfactants.     

The effect of micellar lifetime on the rate of solubilization and detergency in sodium dodecyl sulfate solutions

The slow relaxation time (τ₂) of sodium dodecyl sulfate (SDS) micelles, measured by the pressure-jump technique, was maximum at 200 mM concentration at 25°C, indicating that the most stable micelles are formed at this concentration. This is presumably related to the optimum molecular packing in the micelle. The rate of solubilization of benzene and Orange OT dye into SDS solutions was also maximum at 200 mM concentration. The results are explained as follows: The distance between micelles (i.e., intermicellar distance) decreases as the surfactant concentration (or the number of micelles) increases, resulting in a stronger electric repulsion between micelles. Therefore, the micelles become more rigid, due to the compressive force of intermicellar repulsion, as the concentration increases up to 200 mM SDS. With further increase in the SDS concentration, the micellar shape changes from spherical to cylindrical to accommodate more surfactant molecules in the solution and to minimize the free energy of the system. The interior of the tightly packed micelles is more hydrophobic than that of loosely packed micelles and, therefore, the tightly packed micelles induce rapid solubilization of nonpolar molecules (e.g., benzene, Orange OT) into these micelles.     

糖基双子阳离子表面活性剂与十二烷基硫酸钠复配性能研究

测定了糖基双子阳离子表面活性剂(SGCS)与十二烷基硫酸钠(K_(12))复配体系的稳定性和表面性能。由实验结果可知,在宽的复配范围内不同碳链长度的SGCS与K_(12)均有良好的复配稳定性;C_(14)-SGCS/K_(12)复配体系表现出明显的协同增效作用,当n(C_(14)-SGCS)∶n(K_(12))为3∶5时复配溶液临界胶束浓度(cmc)、cmc时的表面张力(γ_(cmc))和降低表面张力的效率(pc_(20))分别为1.1×10~(-5) mol/L、23.69 mN/m和5.48,均明显优于C_(14)-SGCS和K_(12)自身的表面性能。     

Selective electrochemical determination of dopamine in the presence of ascorbic acid using sodium dodecyl sulfate micelles as masking agent

From differential pulse voltammetry, DPV, it was determined the electrochemical behaviour of dopamine, DA, and ascorbic acid, AA, using a carbon paste electrode, CPE, with the surfactant sodium dodecyl sulfate, SDS, present at concentrations around the critical micellar concentration, CMC. It is shown that without SDS in solution, the oxidation peak potential of AA, E_AA, and DA, E_DA, completely overlap, however when [SDS] > CMC separation is possible between them (E_AA ? E_DA = 238 mV). Moreover, at variance with other proposed systems, the DA potential peak becomes less positive than AA potential peak. Therefore, separation of signals allows selective determination of DA even when AA is present in the same solution. Optimization of the experimental conditions permitted to obtain a calibration plot for the DA in the presence of the AA, having a 0.01–0.2 mM linear range, a detection limit of 5 μM and a 0.04812 μA μM^?1 sensitivity. This new approach was used effectively to determine dopamine in real pharmaceuticals obtaining satisfactory results.     

Influence of sodium dodecyl sulfate and cetyl trimethylammonium bromide upon calcium carbonate precipitation on bacterial cellulose

Calcium carbonate was deposed on bacterial cellulose (BC) never-dried membranes in the presence of different concentrations of sodium dodecyl sulfate (SDS) and cetyl trimethylammonium bromide (CTAB) by a precipitation reaction between aqueous solutions of calcium chloride (CaCl₂) and sodium carbonate (Na₂CO₃) containing, or not, surfactant in their composition. Different shapes of crystals were obtained from rhombohedral ones to flowerlike, depending on surfactant type and concentration. From the two surfactants tested, SDS has a greater influence on calcium carbonate morphology than CTAB. The only polymorph obtained in all studied cases was calcite. The composite films BC-calcite were characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and color measurements. The obtained BC-calcium carbonate composites could be used in paper manufacturing.     

XY-1型缓蚀阻垢剂对工业水的缓蚀阻垢试验

介绍了XY-1型缓蚀阻垢剂对工业水的缓蚀阻垢试验方法和计算公式,并将XY-1型缓蚀阻垢剂与其他厂家的缓蚀阻垢剂进行了室温和高温对比试验,认为采用XY-1型缓蚀阻垢剂效果较好。     

The effect of sodium dodecyl sulfate on mean drop size in a horizontal mixer–settler extractor

The effects of surfactant concentration, impeller speed, and holdup on mean drop diameter, D₃₂, during emulsification have been studied in a mixer–settler. Two well‐defined regions for the dependence of D₃₂ on surfactant concentration were observed. At low surfactant concentrations, D₃₂ decreased significantly with an increase in surfactant concentration, whereas D₃₂ did not depend on surfactant concentration at high surfactant concentrations. The decreasing rate of change of D₃₂ with impeller speed and the increasing rate of change of D₃₂ with holdup both decreased when a surfactant was added to the system. Moreover, an empirical correlation has been derived to predict D₃₂.     

Effect of resistivity on the corrosion mechanism of mild steel in sodium sulfate solutions

Electrochemical impedance spectroscopy (EIS) was used to study the corrosion behavior of mild steel samples immersed in 1, 0.1, 0.01 and 0.001% Na₂SO₄ aqueous solutions at room temperature in order to analyze the corrosion mechanism and obtain representative values of corrosion rates in environments with different resistivity. The EIS technique was used to measure corrosion current densities in 1 to 0.01% Na₂SO₄ solutions, and the measurement corresponding to 0.001% concentration gave a scattered Nyquist plot, whereas in the Bode representation a response associated with solution resistance was obtained. Other electrochemical techniques such as linear polarization resistance, LPR, Tafel extrapolation method and electrochemical noise (EN) were used in order to compare the results obtained by EIS. The charge-transfer resistance (R _ct) parameters obtained in the EIS technique agree well with the corresponding values of polarization resistance (R _p) values obtained by the LPR technique, whereas the electrochemical noise resistance (R _n) parameters obtained by the EN technique gave the highest values for all concentrations. These parameters generally tended to increase as the concentration of the solution decreased.     

PS-12缓蚀杀菌剂的缓蚀性能及机理研究

研究了含有膦酰基、羧基的季铵盐缓蚀杀菌剂PS-12对45#碳钢在模拟循环冷却水中的缓蚀性能、杀菌性能及缓蚀机理。失重法和极化曲线测度结果说明：PS-12对45#碳钢具有良好的缓蚀作用,属混合型缓蚀剂。XPS分析结果表明PS-12能与Fe^2 、Ca^2 等离子螯合,生成螯合物覆盖在金属表面形成性能良好的缓蚀膜。杀菌测试说明PS-12有良好的杀菌性能。