Critical micelle concentration and phase behavior of aqueous mixtures of dodecylsulfates and sodium ethoxydodecylsulfate

Mokrushina, Liudmila; Churyusova, T. G.; Savchuk, K.; Morozova, Julia E.; Smirnova, N. A.

doi:10.1016/s0378-3812(01)00718-x

Cited by 5 publications

(3 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The values of the critical micelle concentration (CMC) are about 0.24 wt% (SLS) and 0.11 wt% (ESLS) [7,[44][45][46][47][48][49][50]. These results are unexpected as the hydrophilic part in the ESLS molecule is expanded by addition of two molecules of ethylene oxide which should increase water solubility and ''shift'' the CMC value towards higher concentrations.…”

Section: Micellar Solutions Of Alkyl Sulfatesmentioning

confidence: 98%

The Effect of Concentration on Lubricating Properties of Aqueous Solutions of Sodium Lauryl Sulfate and Ethoxylated Sodium Lauryl Sulfate

2010

View full text Add to dashboard Cite

The objective of this study was to formulate new ecological lubricating substances, primarily water-based, and to verify their tribological and physicochemical properties. Initially, simple binary solutions were investigated. Then, various additives were added depending on application targets. Two alkyl sulfates were selected as additives modifying lubricating properties of water: sodium lauryl sulfate (SLS) and ethoxylated sodium lauryl sulfate (ESLS). They have an identical hydrophobic part in the form of an alkyl chain consisting of 12 carbon atoms. The SO 4 2-anion forms the hydrophilic part in SLS molecules, whereas an ESLS molecule also contains two mers of ethylene oxide which cause an increase in its hydrophilicity relative to SLS. Both SLS and ESLS exhibit high surface activity measured by their surface tension. Micelles form in aqueous solutions of alkyl sulfates at low concentrations of the order of 1%, whereas the presence of liquid crystalline phases can be found at the concentrations of 40 and 70%. High surface activity and formation of structures in the solutions (micelles, mesophases) formed the basis for application of the compounds as additives modifying lubricating properties. Tribological properties of aqueous solutions of alkyl sulfates were verified with a four-ball machine (T02 tester) at a constant load of 2 kN. The values of friction coefficient (l) were a measure of motion resistance, while the wear scar diameter (d) was a measure of wear. Alkyl sulfates significantly improve tribological properties of water. The coefficient of friction decreased sixfold and the wear scar diameter decreased by as much as twofold relative to the base. Non-monotonic changes in the tribological properties measured were observed as a function of concentration of additives. An attempt was made to relate those atypical changes with the presence of micelles and mesophases in both the surface phase and the bulk phase. In the model proposed the whole concentration range was divided into four areas in which tribological properties correspond well with physicochemical properties, particularly with the structures formed in solutions and at the interface.

show abstract

Section: Micellar Solutions Of Alkyl Sulfatesmentioning

confidence: 98%

The Effect of Concentration on Lubricating Properties of Aqueous Solutions of Sodium Lauryl Sulfate and Ethoxylated Sodium Lauryl Sulfate

2010

View full text Add to dashboard Cite

show abstract

“…They were all of 99% purity. The critical micelle concentration (CMC) values of LAS and SDS are 2.0 and 8.45 mM at 30 °C, respectively. , The CMC of HDSA was determined in the lab by measuring the conductivity values of HDSA solutions at various concentrations, and the value was found to be 0.36 mM.…”

Section: Methodsmentioning

confidence: 99%

Nickel Removal from Waters Using Surfactant-Enhanced Hybrid PAC/MF Process. I. The Influence of System-Component Variables

Aydıner

Kara

Keskinler

et al. 2006

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

This study takes aim at exploring the effectiveness of a surfactant-added powdered activated carbon/microfiltration (PAC/MF) hybrid process in the removal of nickel ions from water and wastewater as a promising technology. For this aim, the influence of system-component variables related to membrane material and pore size, and adsorbent and surfactant types was investigated. Nickel rejection (R M), surfactant rejection (R S), and steady-state flux (J*) were taken into account for more elaborately assessing the technical performance of the process. It was determined that the use of a surfactant in this process is justified only above the critical micellar concentration (CMC). Despite the increasing of nickel rejection with the addition of surfactant into the hybrid membrane process, a considerable decrease in steady-state flux is a major drawback of process. The flux decline observed was strongly dependent on surfactant type. This was interpreted as being due to a secondary membrane layer formed by surfactant micelles on the surface and within the membrane pores. The flux decline could also be related to PAC layer formation. Membrane, adsorbent, and surfactant types seem to have the highest relative influence on R M, R S, and J*, respectively. As a conclusion, surfactant type and membrane pore size were established as having the biggest and the smallest total influence on process performance, respectively.

show abstract

“…The data on physicochemical properties of the compounds investigated and their solutions can be found in literature [29][30][31][32][33][34][35]. As commercial products were used in this investigation, additional tests were carried out to verify and supplement the available data.…”

Section: Adsorption Of Water Solution Compoundsmentioning

confidence: 99%

Antiseizure properties of aqueous solutions of compounds forming liquid crystalline structures

Sułek

Wasilewski

2005

Tribol Lett

View full text Add to dashboard Cite

Amphiphilic compounds composed of a hydrophilic part and a hydrophobic alkyl chain were investigated. The compounds-sodium lauryl sulfate (SLS) and ethoxylated sodium lauryl sulfate (ESLS)-exhibit strong affinity for solid surfaces and form liquid crystalline structures in water. It is expected that they may become effective additives that could significantly modify antiseizure properties of water. They may extend the possibilities for applying water as an ecological base for lubricating substances. Rheological and structural X-ray studies as well as measurements of conductance and wetting angle were carried out. Their aim was to verify and validate the structures being formed in aqueous solutions of the compounds studied. Tribological studies were conducted to measure friction torque as a function of linearly increasing load by means of a four-ball apparatus. The tests were followed by measurement of the wear scar diameter on the balls. Based on the results obtained, antiwear properties were characterized by seizure and scuffing loads as well as by limiting pressure of seizure. The test results are highly surprising. The systems in which simple one-component aqueous solutions were the lubricating substance did not undergo seizure up to the maximum load of 8 kN designed for the tribological tester used. A number of typical antiwear additives in suitable oil bases do not exhibit such good characteristics. Also, the quantities characterizing seizure show relatively high values. Local maxima for the two compounds tested are formed in the area of low concentrations in the dependences of antiseizure properties as a function of concentration. It can be assumed that this is due to ordered structures being formed in the surface phase. The hexagonal phase of high viscosity of the order of several thousand PaAEs which forms in the bulk phase for ESLS and SLS solutions has no visible effect on antiseizure properties, whereas the existence of the lamellar phase for a 70% solution of ESLS affects an increase in the values being measured.

show abstract

Critical micelle concentration and phase behavior of aqueous mixtures of dodecylsulfates and sodium ethoxydodecylsulfate

Cited by 5 publications

References 11 publications

The Effect of Concentration on Lubricating Properties of Aqueous Solutions of Sodium Lauryl Sulfate and Ethoxylated Sodium Lauryl Sulfate

The Effect of Concentration on Lubricating Properties of Aqueous Solutions of Sodium Lauryl Sulfate and Ethoxylated Sodium Lauryl Sulfate

Nickel Removal from Waters Using Surfactant-Enhanced Hybrid PAC/MF Process. I. The Influence of System-Component Variables

Antiseizure properties of aqueous solutions of compounds forming liquid crystalline structures

Contact Info

Product

Resources

About