1. Structure and potential application of surfactant-free microemulsion consisting of heptanol, ethanol and waterMartina Gudelj, Marina Kranjac, Lucija Jurko, Matija Tomšič, Janez Cerar, Ante Prkić, Perica Bošković, 2024, original scientific article Abstract: Microemulsions, which are thermodynamically stable and isotropic mixtures of water, oil, and surfactants, attract significant research interest due to their unique physicochemical properties and diverse industrial applications. Traditional surfactant-based microemulsions (SBMEs) stabilize the interface between two typically immiscible liquids, forming various microstructures such as oil-in-water (O/W) droplets, water-in-oil (W/O) droplets, and bicontinuous phases. However, the use of surfactants poses environmental concerns, cost implications, and potential toxicity. Consequently, there is increasing interest in developing surfactant-free microemulsions (SFMEs) that offer similar benefits without the drawbacks associated with surfactants. In this study, we explore the formation and characteristics of a new surfactant-free microemulsion in a ternary system comprising water, ethanol, and heptanol. Advanced techniques are employed to characterize the microstructures and stability of surfactant-free microemulsions. These include electrical conductivity measurements, surface tension analysis, dynamic light scattering (DLS), and Fourier transform infrared spectroscopy (FTIR). These methods have been extensively used in previous research on surfactant-free microemulsions (SFMEs) to reveal the properties and interactions within microemulsion systems. The area of interest is identified using these techniques, where silica nanoparticles are subsequently synthesized and then visualized using transmission electron microscopy (TEM).
Keywords: surfactant-free microemulsions, ternary system, nanoparticles
Published in DKUM: 03.10.2024; Views: 0; Downloads: 5
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2. Potentiometric surfactant sensor with a pt-doped acid-activated multi-walled carbon nanotube-based ionophore nanocompositeNada Glumac, Milan Momčilović, Iztok Kramberger, Darko Štraus, Nikola Sakač, Elvira Kovač-Andrić, Bojan Đurin, Marija Kraševac Sakač, Kristina Đambić, Marija Jozanović, 2024, original scientific article Abstract: Two new surfactant sensors were developed by synthesizing Pt-doped acid-activated multiwalled carbon nanotubes (Pt@MWCNTs). Two different ionophores using Pt@MWCNTs, a new plasticizer, and (a) cationic surfactant 1,3-dihexadecyl-1H-benzo[d]imidazol-3-ium-DHBI (Pt@MWCNT-DHBI ionophore) and (b) anionic surfactant dodecylbenzenesulfonate-DBS (Pt@MWCNT-DBS ionophore) composites were successfully synthesized and characterized. Both surfactant sensors showed a response to anionic surfactants (dodecylsulfate (SDS) and DBS) and cationic surfactants (cetylpyridinium chloride (CPC) and hexadecyltrimethylammonium bromide (CTAB)). The Pt@MWCNT-DBS sensor showed lower sensitivity than expected with the sub-Nernstian response of ≈23 mV/decade of activity for CPC and CTAB and ≈33 mV/decade of activity for SDS and DBS. The Pt@MWCNTDHBI surfactant sensor had superior response properties, including a Nernstian response to SDS (59.1 mV/decade) and a near-Nernstian response to DBS (57.5 mV/decade), with linear response regions for both anionic surfactants down to ≈2 × 10−6 M. The Pt@MWCNT-DHBI was also useful in critical micellar concentration (CMC) detection. Common anions showed very low interferences with the sensor. The sensor was successfully employed for the potentiometric titration of a technical grade cationic surfactant with good recoveries. The content of cationic surfactants was measured in six samples of complex commercial detergents. The Pt@MWCNT-DHBI surfactant sensor showed good agreement with the ISE surfactant sensor and classical two-phase titration and could be used as an analytical tool in quality control
Keywords: potentiometric surfactant sensor, metal-doped MWCNT, surfactants, carbon nanocomposite, sensors
Published in DKUM: 23.08.2024; Views: 110; Downloads: 5
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3. Rheological study of interactions between non-ionic surfactants and polysaccharide thickeners used in textile printingRebeka Fijan, Sonja Šostar-Turk, Romano Lapasin, 2007, original scientific article Abstract: The influence of four non-ionic surfactants (isododecyl and cetyl polyoxyethylene ethers) on aqueous polysaccharide solutions (sodium alginate, guar gum, and sodium carboxymethyl guar), applicable for textile printing pastes, were studied via rheological measurements. Rheology of polysaccharide-surfactant solutions in aqueous matrices is primarily governed by polymer content, which imparts marked shear-thinning and viscoelastic character to the system. Such properties are modulated in moderate but sensible way by changes in surfactant concentration or type. Above 3% surfactants addition to non-substituted guar gum solutions results in a significant impact leading to phase separation and a particular strongly associated phase is formed due to hydrogen bonds between ethylene oxy units from the surfactant and primary hydroxyl groups in guar. A satisfactory fitting of viscosity data is obtained with both the Cross equation and the Roberts-Barnes-Carew model. The experimental results of mechanical spectra can be described quite satisfactory with both the Friedrich-Braun and the generalized Maxwell models.
Keywords: textile printing, polysaccharide thickeners, rheology, non-ionic surfactant, polymer-surfactant interactions, viscoelasticity
Published in DKUM: 01.06.2012; Views: 2016; Downloads: 91
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4. Effects of surfactants and their mixtures on inhibition of the corrosion process of ferritic stainless steelRegina Fuchs-Godec, 2009, original scientific article Abstract: The corrosion inhibition characteristics regarding mixtures of cationic/zwitterionic types of surfactant (Myristyltrimethylammonium bromide/Palmitylsulfo-betaineas), and non-ionic surfactant TRITON-X-405 mixed with 1 mM of KBr, as corrosion inhibitors for stainless steel (SS) (type X4Cr13) in aqueous solutions of 2 M H2SO4 were investigated using potentiodynamic polarisation measurements. The polarisation data showed that mixtures of the surfactants used in this study acted as mixed-type inhibitors, adsorbing on the stainless steel surface in agreement with the Flory-Huggins adsorption isotherm. The tensiometric results of this study suggest the existence of a second state of aggregation for zwitterionic/cationic surfactant mixtures. From these values of the free energy of adsorption, which in both mixtures decreased with respect to a single surfactant, we concluded that the adsorption in mixtures was stronger. The mixtures studied here showed good inhibition properties for ferritic stainless steel type X4Cr13 in 2 M H2SO4 solution.
Keywords: corrosion inhibitor, cationic surfactant, Zwitterionic surfactant, Flory-Huggins isotherm, Sulphuric acid
Published in DKUM: 01.06.2012; Views: 1817; Downloads: 120
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