The effects of anionic and cationic surfactants on the hydrolysis of sodium barbital

Alkaline hydrolysis reactions of sodium barbital in micelles of sodium dodecyl sulfate (the anionic surfactant SDS), micelles of cetyl trimethylammonium bromide (the cationic surfactant CTAB), and mixed micelles of surfactant/n-C₅H₁₁OH/H₂O were studied by ultraviolet-visible spectrometry. The reaction rate and the activation energy of the hydrolysis of sodium barbital were calculated. The results showed that the rate of sodium barbital hydrolysis decreased with an increase in CTAB content, whereas it increased in the presence of SDS and n-C₅H₁₁OH. The different effects of CTAB and SDS on the hydrolysis of sodium barbital may be related to their interaction with sodium barbital.     

Altering the wettability of bitumen-treated glass surfaces with ionic surfactants

The abilities of three ionic surfactants—sodium methylnaphthalene sulfonate (SMNS), sodium dodecyl sulfate (SDS), and cetyl trimethylammonium bromide (CTAB)—to alter the wettability of bitumen-treated glass surfaces was examined. Surface wettability was characterized by contact angles, and all measurements were carried out under alkaline conditions by having sodium carbonate (Na₂CO₃) dissolved in the aqueous phase. It was found that Na₂CO₃ alone could slightly increase the hydrophilcity of bitumen-treated glass surfaces. With surfactants added to the system, it was demonstrated that SMNS and SDS (both anionic surfactants) were much more effective in enhancing the water wettability of bitumen-treated glass in comparison to CTAB (a cationic surfactant). X-ray photoelectron spectroscopy (XPS) analyses were also conducted to determine the functional groups and relative mass concentrations of various elements on the glass substrates. Based on these results, we speculate that most or all of the adsorbed hydrocarbon material could be removed from a glass substrate through synergistic effects between sodium carbonate, which provides the alkaline condition, and anionic surfactants, which likely interacted with adsorbed cationic materials. This resulted in dramatic alteration in the wettability of bitumen-treated glass surfaces—from oil-wet to water-wet.     

Effect of Surfactants on Catalytic Activity of Diastase α-Amylase

The enzyme amylase is one of the hydrolyzing enzymes used in detergent formulation in order to remove soil based on polysaccharides. The effectiveness of the enzyme depends on its compatibility with other ingredients of the formulation. Among the studied additives, comprising anionic surfactants sodium dodecyl hydrogen sulfate (SDS) and dioctyl sodium sulfosuccinate, the cationic surfactant cetyl trimethyl ammonium bromide (CTAB), nonionic surfactants polyoxyethylene sorbitan monooleate and polyoxyethylene octyl phenyl ether, carboxy methyl cellulose and sodium sulfate, only the anionic surfactant SDS and cationic surfactant CTAB showed catalytic enhancement of α-amylase. The kinetic parameters, K _m and k _cat, showed an increase in catalytic activity in the micellar pseudophase. The decrease in optimum temperature from 55 to 30 °C and the shift in optimum pH from 5.5 to 7 on the addition of SDS and CTAB for the hydrolysis of starch are very favorable to enhance the washing characteristics.     

Effect of cefoperazone sodium on the physicochemical properties of surfactants

The effects of cefoperazone sodium (CS), a pharmaceutical compound, on the critical micelle concentration (CMC) of surfactants with different charges [cetyl trimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Triton X-100], the cloud point of Triton X-100, and the Krafft temperatures of SDS and CTAB were studied. The interaction of CS with differently charged surfactants was determined by ultraviolet and fluorescence spectrophotometry. The results show that with increasing CS concentration, the Krafft temperature increases and the CMC decreases in the SDS/H₂O system, whereas the opposite results are obtained in the CTAB/H₂O system. Both the cloud point and the CMC of Triton X-100 increase with the addition of CS. The above results are attributed to the different micellar interactions between CS and surfactants with different charges.     

Rheo-kinetics of bovine serum albumin in catanionic surfactant systems

The effects of catanionic surfactant systems consisting of mixtures of cationic cetyltrimethylamonium bromide (CTAB) and anionic sodium dodecyl sulfate (SDS) on the rheological properties and kinetics of bovine serum albumin (BSA) were investigated. The ionic strength of the solution was varied by using different mixing ratio of SDS and CTAB. Gelation curves observed in dynamic viscoelastic measurements were fitted with gelation kinetics models to describe the gelation under isothermal and non-isothermal conditions. Overall, the gelation of BSA in cationic-rich solutions was found to be more energetically favorable when compared with BSA solvated in anionic-rich solutions. Consequently, highest gel temperature (T_gel) and time (t_gel) were observed for anionic-rich solutions with SDS/CTAB molar ratio of 4.0 (i.e., SDS/CTAB=4.0), while lowest gel temperature and time were found for cationic-rich solutions with SDS/CTAB molar ratio of 0.25 (SDS/CTAB=0.25). BSA in equal molar ratio of the mixed surfactants (SDS/CTAB=1.0) showed a gel temperature and time in the halfway between the anionic and cationic-rich regions. Interestingly, under isothermal and non-isothermal conditions, BSA in equimolarly mixed and anionic-rich solutions showed a heat-dependent protective effect against thermal denaturation and gelation. The protective effect on BSA gelation in equimolar and anionic-rich solutions was diminished by increasing the catanionic concentration under non-isothermal conditions, while under isothermal conditions, protective effect on BSA gelation increased with catanionic concentration. On the other hand, cationic-rich solutions did not protect BSA from thermal denaturation and gelation, and therefore the gelation rate increased with catanionic concentration in all heating conditions examined.     

Studies on aggregation of AOT and NaDEHP via the energy transfer between AO and RB molecules

The aggregation behaviours of sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and sodium bis(2-ethylhexyl)phosphate (NaDEHP) solutions are studied via the energy transfer of acridine orange (AO) and rhodamine B(RB) molecules. The approximate apparent energy transfer efficiency (ϕ_a) of the dye molecules reaches its maximum value when the concentrations of AOT and NaDEHP are far lower than their cmc. This might be caused by the formation of surfactant–dye mixtures. The anionic surfactants (SDS, AS, AOT and NaDHEP), cationic surfactant (CTAB) and nonionic surfactant (Triton-X-100) are chosen to investigate the effect of the structure of surfactant on the ϕ_a between AO and RB molecules. The results indicate that the effective energy transfer may occur in the anionic surfactant systems and it is not obvious in the nonionic and cationic surfactant systems.     

A Comparative Study on the Aggregation and Thermodynamic Properties of Anionic Sodium Dodecylsulphate and Cationic Cetyltrimethylammonium Bromide in Aqueous Medium: Effect of the Co-solvent N-Methylacetamide

The effect of co‐solvent N‐methylacetamide (NMA) (0.035, 0.046, 0.127, and 0.258 mol kg^?1) on the micellization behaviour of anionic surfactant sodium dodecylsulphate (SDS) (3.21–10.35 mmol kg^?1) and cationic surfactant cetyltrimethylammonium bromide (CTAB) (0.19–3.72 mmol kg^?1) in aqueous solution was explored by employing conductivity measurements at different temperatures (298.15–313.15 K). The critical micelle concentration (CMC) values for SDS and CTAB in aqueous solutions of NMA were determined from the conductivity versus surfactant concentration plots. The variations in the CMC values of SDS with NMA concentration are in striking contrast to those observed in the case of CTAB. The various relevant thermodynamic parameters of micellization, viz. standard enthalpy change, ΔH_m^o, standard entropy change, ΔS_m^o, and standard Gibbs free energy change, ΔG_m^o, were determined using the temperature variation of the CMC values and counterion binding. The results not only relate these thermodynamic parameters to the consequences of intermolecular interactions but are also able to differentiate between SDS–water–NMA and CTAB–water–NMA systems in terms of contributions from head groups as well as alkyl chains of surfactants.     

Pulsed electrodeposition of Zn in the presence of surfactants

The preparation of Zn deposits has been performed by galvanostatic pulsed electrolysis, from acidic zinc sulphate solutions, on a stainless steel substrate. The influence of the surfactants (cetyl trimethyl ammonium bromide (CTAB), sodium dodecyl sulphate (SDS) and octylphenolpoly(ethyleneglycolether)_n, n = 10, Triton X-100) on the voltammetric behaviour, structural and morphological characteristics of the deposits have been investigated. The characterization of the samples was made by X-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDS). The experimental data shows that the presence of surfactants affects the zinc deposition process. The electrodeposits are mainly composed by Zn with different texture, crystal shape and size (grain size ranging from 40 to 20 nm). The obtained results led us to conclude that the Zn deposits prepared in the absence of surfactants and in the presence of SDS are more crystalline and with a higher grain size than the ones obtained in the presence of CTAB and Triton X-100. These facts may be justified by the increase on the overpotential deposition as the electrochemical studies confirm.The XRD results show that the deposits prepared, in the absence of surfactant and in the presence of SDS, contain ZnSO₄ and Zn₄SO₄(OH)₆ as oxidation products. ZnO is also detected on the deposits obtained in the presence of CTAB and Triton X-100.     

碳酸钙中空微球的制备及机理

采用沉淀反应方法,利用聚乙烯吡咯烷酮(PVP)和十二烷基磺酸钠(SDS)复合添加剂作为有机模板,制备了中空球状方解石型碳酸钙,同时考察了不同温度、SDS和PVP浓度对碳酸钙结晶和聚集行为的影响,进而对其反应机理进行了初步探讨。     

Effects of sodium dodecyl benzenesulfonic acid (SDBS) on the morphology and the crystal phase of CaCO<Subscript>3</Subscript>

The effects of anionic surfactant on the morphology and crystallization of calcium carbonate precipitated from CaCl₂ and Na₂CO₃ were investigated. Although reaction temperature did not have an effect on the morphology of calcium carbonate, it did have an effect on the cluster size. The cluster size became bigger with high reaction temperature. With the addition of sodium dodecyl benzenesulfonic acid (SDBS), the morphology of precipitated calcium carbonate changed from cubic to porous spheres with over 98% of the crystal phase transformed from calcite to vaterite. The analysis of precipitates formed by the reaction of CaCl₂ solution (from limestone (CaO 50% content)) and Na₂CO₃ found that the morphology of precipitated calcium carbonate changed from cubic to spherical, and the crystal phase changed from calcite to over 94% vaterite with the addition of sodium dodecyl benzenesulfonic acid. These vaterite structures were solid spheres rather than hollow ones.     

Effect of Ionic Strength on Oil Removal from Stainless Steel in the Presence of Ionic Surfactant

Abstract

Contact angles of oil droplets on solid surfaces provide useful insight into surfactant cleaning behavior. Contact angles of hexadecane and MAR‐TEMP^® 355, an industrial quench oil, on stainless steel were measured for ionic surfactant solutions as a function of ionic strength. The ionic strength of sodium dodecyl sulfate (SDS) and cetyl trimethyl ammonium bromide (CTAB) solutions was modified by the addition of sodium chloride. Increases in the contact angle with additions of 1.0 mM and 2.5 mM NaCl were observed for the two oils in SDS and for hexadecane in CTAB. For the industrial quench oil, detachment occurred in CTAB concentrations above the critical micelle concentration; as a result, the equilibrium contact angle measurements were not measured. The critical concentration of CTAB decreased with increasing NaCl concentration. Oil‐removal studies indicate that increasing ionic strength by as little as 2.5 mM can result in improved cleaning. A theoretical insight previously used to explain contact‐angle behavior for a hexadecane‐gold system is used to describe the results obtained with the current system.     

三种表面活性剂对Fe3O4纳米颗粒的形貌影响

选用十六烷基三甲基溴化铵(CTAB)、聚乙烯吡咯烷酮(PVP)、十二烷基磺酸钠(SDS)3种表面活性剂,研究了这3类不同表面活性剂和不同添加量对Fe3O4纳米颗粒的形貌调控作用,利用透射电镜(TEM)对样品进行表征分析,并给出了机理解释。结果表明:1)3种不同的表面活性剂的加入都获得球形或近球形的纳米颗粒。根据TEM及沉积时间的综合分析,3种活性剂的平均粒径比较:SDS相似文献   

Effect of organized anionic surfactant system on the kinetics of V(V)-organic substrate-initiated polymerization of acrylonitrile

The kinetics of polymerization of acyrlonitrile (AN) initiated by a V(V)-cyclohexanone redox system in the presence of a surfactant was studied over a temperature range of 30–50°C in acidic medium. The anionic surfactant sodium dodecyl sulfate (SDS) enhances the rate of polymerization (R_p) as well as rate of V(V) consumption (−R_v). The cationic surfactant, cetyltrimethylammonium bromide (CTAB), decreases both R_p and −R_v, while the nonionic surfactant, Triton-X-100, has no effect on the rate. The change of concentration of the surfactant, monomer, acid, and cosolvent on the rate of polymerization were examined. Both R_p and −R_v are computed in the presence of different organic substrates, i.e., cyclohexanone, cyclopentanone, glycerol, and citric acid. The viscosity-average molecular weight (M_v) of the polycrylonitrile, obtained at different [SDS], was determined using the Mark-Howink relationship. A suitable mechanistic scheme was proposed for the process. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1825–1833, 1997     

Foamability of Detergent Solutions Prepared with Different Types of Surfactants and Waters

In the development of new detergent products, it is important to test the foaming behavior of different types of surfactants. Different types and concentrations of surfactant solutions prepared with three types of water are expected to present differences in their foamability. In this study, foam volumes produced by cetyl trimethyl ammonium bromide (CTAB; C₁₉H₄₂BrN), Tween 80^® (T80; C₆₄H₁₂₄O₂₆) and sodium dodecylsulfate (SDS; C₁₂H₂₅NaO₄S) aqueous solutions (0.5, 1.0 and 1.5%, w/v) were compared using a stirring system, rotating at 8,000, 9,500 and 13,500 rpm. The foamability produced by CTAB, SDS and T80 solutions, in a concentration range between 0.2 and 1.0% (w/v), prepared using deionized, hard and hypersaline water were also compared. Foam volumes were higher at a stirring speed of 9,500 rpm than at 8,000 rpm. However, the results obtained at 9,500 and 13,500 rpm were not significantly different. In general, SDS solutions produced higher foam volumes than CTAB and T80 solutions. Water characteristics did not seem to influence significantly the foamability of the three types of surfactants in the studied concentrations. These studies related with foaming behavior appear to be an important step in the pre-formulation of detergent products, particularly in cosmetics and pharmaceutics.     

加压碳化体系对纳米碳酸钙粒度和分散性的影响

利用加压碳化体系制备粒径均一、高分散性纳米碳酸钙材料。考察氢氧化钙浓度、表面活性剂添加量、反应温度、CO2压力对制备纳米CaCO3粒子尺寸和分散程度的影响,采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、Zeta电位和傅立叶变换红外光谱(FT-IR)对制备的纳米碳酸钙粒子进行表征。结果表明,最优加压碳化反应条件是Ca(OH)2质量浓度为2%、表面活性剂添加量为3%(占碳酸钙理论产量的百分比)、反应温度为40℃、CO2压力为6 MPa,所得立方形碳酸钙平均粒径为117 nm,晶型为方解石型碳酸钙。碳化反应加入表面活性剂十六烷基三甲基溴化铵(CTAB)使CaCO3表面形成的正电荷增大至+37.7 mV并高于标准值30 mV,表明制备的CaCO3产品具有良好的分散性且稳定。通过FT-IR和Zeta电位对CTAB改性前后CaCO3纳米粒子进行表征,探讨了CTAB对合成纳米CaCO3分散性的影响机理,为纳米碳酸钙制备提供了一种新的方法。     

Tl(III) initiated polymerization of methyl methacrylate in micellar phase

The polymerization kinetics of methyl methacrylate (MMA) was studied, using Tl(III)‐cyclohexanone (CH) redox system as initiator, in the presence of emulsifier [i.e., sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and thallium triacetate (TX‐100)] over a temperature range of 25–45°C. The effect of various concentrations of MMA, Tl(III), cyclohexanone, H⁺, and varying ionic strengths on the rate of polymerization, rate of Tl(III) consumption (?R_Tl), and the percentage of monomer conversion were examined in the presence of 0.015M SDS. The kinetic results of polymerization in the absence and presence of 0.015M SDS were compared in terms of overall activation energy (E_a) for the process. The viscosity‐average molecular weight (M_V) of the polymers, obtained in the presence of varying concentrations of anionic surfactant (SDS), was also determined. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2480–2485, 2004     

Aggregation Behavior of Sodium Dodecyl Sulfate and Cetyltrimethylammonium Bromide Mixtures in Aqueous/Chitosan Solution at Various Temperatures: An Experimental and Theoretical Approach

A conductometric study of the mixed micellization behavior between cetyltrimethylammonium bromide (CTAB, a cationic surfactant) and sodium dodecyl sulfate (SDS, an anionic surfactant) was carried out in the absence/presence of various percentages of chitosan in the temperature range of 298.15–318.15 K. The deviations of critical micelle concentration (cmc) from the ideal values indicate the interaction between CTAB and SDS. The micellar mole fraction values according to different proposed models X₁^Rub (Rubingh), X₁^M (Motomura), X₁^Rod (Rodenas), and X₁^id (ideal mole fraction) were estimated and the results obtained reveal the high contribution of CTAB in the mixed micellization, which enhances with the increase of the mole fraction of CTAB. The negative magnitudes of indicate the spontaneous formation of mixed micelles between CTAB and SDS. The values of activity coefficients (f₁ and f₂) were less than unity and the values of the interaction parameter (β) are negative in all cases, which indicate the attractive interaction between CTAB and SDS. The negative values of excess free energy of micellization (ΔG_ex) signify the stability of the mixed micelles. The negative values of in the chitosan systems indicate that micellization is exothermic. The values of were found to be positive in all cases.     

Experimental and theoretical investigation of micellization behavior of sodium dodecyl sulfate with cetyltrimethylammonium bromide in aqueous/urea solution at various temperatures

Mixed micelle formation behavior of cationic surfactant-cetyltrimethylammonium bromide (CTAB) and anionic surfactant sodium dodecyl sulfate (SDS) in aqueous as well as in urea medium from 303.15 K to 323.15 K at 5 K interval was carried out by conductometric method. The differences between the experimental values of critical micelle concentrations (cmc) and ideal critical micelle concentrations (cmc^id) illustrate the interaction between the amphiphiles studied. The values of micellar mole fraction (\(\text{X}_1^{Rub}\) (Rubingh), \(\text{X}_1^{M}\) (Motomura), \(\text{X}_1^{Rod}\)(Rodenas) and \(\text{X}_1^{id}\)(ideal) of surfactant CTAB determined by different proposed models and outcome indicate high involvement of CTAB in SDS-CTAB mixed micellization, which enhance by means of the augment of mole fraction of CTAB. The negative value of interaction parameter (β) showed an attractive interaction involving CTAB and SDS. Activity coefficients were less than unity in all case, which also reveals the presence of interaction between CTAB & SDS. The negative \(\Delta{\text{G}}_m^0\)values imply the spontaneous mixed micellization phenomenon. The attained values of \(\Delta{\text{H}}_m^0\)were positive at inferior temperature, while negative at superior temperature. The negative \(\Delta{\text{H}}_m^0\)values in urea (NH₂CONH₂) medium illustrate exothermic micellization process. The magnitudes of \(\Delta{\text{S}}_m^0\)were positive in almost all cases. The excess free energy of mixed micelle formation (ΔG_ex) was found to be negative, which indicates the stability of mixed micelle as compared to the individual’s components micelles.     

Effect of organized anionic surfactant system on kinetics of polymerization of acrylonitrile initiated by Ce(IV): Citric acid and other organic substrates

The polymerization of acrylonitrile (AN) using the Ce(IV)–citric acid (CA) redox system as an initiator in aqueous nitric acid solution, in the presence of an anionic surfactant, sodium dodecyl sulfate (SDS), has been kinetically studied at a temperature range of 25–45°C. The rate of polymerization (R_p) and disappearance of Ce(IV) (–R_ce) increase with increasing concentration of SDS, above its critical micelle concentration (cmc), when the surfactant molecules are organized. R_p was found to be proportional to [AN]^1.5 and [CA]^0.5. With other organic substrates, R_p follows the increasing order of sorbitol ≥ mannitol > glycerol > CA. But it was found to decrease considerably in the presence of cationic surfactant (CTAB), and nonionic surfactant (Triton-X-100) had no effect on the rate. –R_ce varies linearly with [Ce(IV)] and [CA]. Both R_p and –R_ce increase with increasing temperature. The overall activation energy was found to be 18.31 and 13.72 kcal/mol in the absence and presence of 0.015M SDS, respectively. The chain length of the polyacrylonitrile has also increased with increasing SDS concentration. © 1996 John Wiley & Sons, Inc.