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Anionic Polyelectrolyte-Cationic Surfactant Interactions in Aqueous Solutions and Foam Films Stability Interactions entre polyélectrolytes anioniques et tensioactifs cationiques en solutions aqueuses et stabilité des films de mousses  [cached]
Langevin D.,Asnacios A.,Argillier J. F.,Bergeron V.
Oil & Gas Science and Technology , 2006, DOI: 10.2516/ogst:1997012
Abstract: The objective of this work is to study polymer/surfactant interactions in aqueous solution and at the air/water interface. These interations are involved in many physicochemical phenomena, such as colloidal stabilization and wettability which are of major importance in oil application as for exemple drilling muds. More precisely, we have attempted to characterize interactions between a non surface active anionic copolymer (acrylamide/acrylamide sulfonate) and an oppositely charged cationic surfactant (C12 TAB). Our results show a synergestic surface tension lowering (coadsorption) at extremely low surfactant concentrations (10 to the power of (-3) to 10 to the power of (-1) CMC). At higher concentrations, namely above the so called Critical Aggregation Concentration (CAC), polymer-surfactant complexes form in the bulk and the macromolecules precipitate out of the solution. Foam films made from these mixed solutions are stable while C12TAB films are unstable. Disjoining pressure measurements on mixed films with surfactant concentration two orders of magnitude below the CAC show the existence of long range repulsive forces and a discrete film thickness transition. At the CAC, we obtain mixed films with gel-like networks that are strongly affected by the film thinning rate. L'objectif de cette étude est d'étudier les interactions polymère/tensioactif en solution aqueuse et à l'interface eau/air. Ces interactions interviennent dans de nombreux phénomènes physico-chimiques tels que la stabilisation de suspensions collo dales et la mouillabilité qui sont d'une importance majeure dans les applications pétrolières comme, par exemple, les boues de forage. Plus précisément, nous avons essayé de caractériser les interactions entre un copolymère anionique n'ayant pas d'activité de surface (acrylamide/acrylamide sulfoné) avec un tensioactif de charge opposée cationique (C12TAB). Nos résultats montrent une diminution synergique de la tension superficielle (coadsorption) à des concentrations en tensioactifs très faibles (10 puissance (-3) à 10 puissance (-1) CMC). à plus fortes concentrations, en particulier supérieures à la concentration critique d'agrégation (CAC), des complexes polymères/tensioactifs se forment en solution et les macromolécules précipitent. Les films minces réalisés à partir de ces solutions sont stables, alors que les films C12TAB sont instables. Les mesures de pression de disjonction sur des films mixtes avec des concentrations en tensioactifs de deux ordres de grandeur en dessous de la CAC montrent l'existence de forces de répulsion à longue por
INTERACTIONS BETWEEN CATIONIC POLYELECTROLYTE AND PULP FINES  [cached]
Elina Orblin,Pedro Fardim
BioResources , 2011,
Abstract: Papermaking pulps are a mixture of fibres, fibre fragments, and small cells (parenchyma or ray cells), usually called pulp fines. The interactions between pulp fines and a cationic copolymer of acrylamide and acryloxyethyltrimethyl ammonium chloride were investigated based on solid-liquid isotherms prepared under different turbulence, and subsequent advanced surface characterization using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The surface charge and surface area of pulp fine substrates were measured by methylene blue sorption-XPS analysis and nitrogen adsorption combined with mercury porosimetry, respectively. The driving force behind polyelectrolyte adsorption was the amount of the surface anionic charge, whereas surface area appeared to be of less importance. Based on a comparison of solid-liquid and XPS sorption isotherms, different polyelectrolyte conformations were suggested, depending on the types of fines: A flatter conformation and partial cell-wall penetration of polyelectrolytes on kraft fines from freshly prepared pulp, and a more free conformation with extended loops and tails on lignocellulosic fines from recycled pulp. Additionally, ToF-SIMS imaging proved that recycled pulp fines contained residual de-inking chemicals (primarily palmitic acid salts) that possibly hinder the electrostatic interactions with polyelectrolytes.
Phase Behavior of Pseudo-Ternary Gemini Surfactant + 1-Hexanol/Oil/Water Systems  [PDF]
Mohd Zul Helmi Rozaini
Journal of Atomic, Molecular, and Optical Physics , 2012, DOI: 10.1155/2012/839074
Abstract: Temperature dependent phase behavior of pseudo-ternary Gemini surfactant
Study at a molecular level of the transfer process of a anionic, cationic and non-ionic surfactants from water to β-cyclodextrin  [PDF]
D. Geetha,T. Thilagavathi1,P.S. Ramesh,C. Rakkappan
Journal of Engineering and Applied Sciences , 2009,
Abstract: Density and sound velocity data for aqueous solutions at 303K containing Sodium dodecyl benzene sulfonate (SDBS), Cetyl trimethyl ammonium bromide (CTAB) and Tween 20 in the absence and presence of β-Cyclodextrin were analyzed to calculate the apparent molar volume and adiabatic compressibilities. For the binary systems Фv and Фk values of the pure surfactants in water have been obtained as a function of the concentration. For the ternary systems, remarkable increases of both the molar volume and compressibility of the surfactant at infinite dilution with respect to the value in water is observed. The positive molar compressibility of the surfactant, when it is forming the complex, compared to the negative value in pure water, proves the hydrophobic components of the interaction. Both molar volumes and compressibility of the surfactants are the same in the absence and in the presence of β-CD at high surfactant concentrations, indicating the non participation of the complex into the micelles and the CMCs are displaced. Using FTIR spectroscopy, the complexation of β-CD at high with anionic, cationic and non-ionic surfactants.
Preliminary Testing For Anionic, Cationic and Non-ionic  [PDF]
Rezic, I.,Pusic, T.,Bokic, Lj.
Kemija u Industriji , 2007,
Abstract: Detergents present a major environmental problem due to large quantities of surfactants released from laundries. For this reason, it is important to apply an appropriate analytical method for their determination. In this work, we propose two simple, fast and inexpensive analytical methods for anionic, cationic and non-ionic surfactant determination: thin layer chromatography (TLC) separation for qualitative screening and quantitative potentiometric determination with ion-selective electrodes. These methods have been chosen because of their many advantages: rapidity, ease of operation, low cost of analysis and a wide variety of TLC application possibilities. The advantage of potentiometric titration is its very high degree of automation and very low detection limits obtained with different ion-selective electrodes applied for different surfactants.
Interaction of anionic azo dye and TTAB: cationic surfactant
Ghoreishi, Sayed Mehdi;Behpour, Mohsen;Shabani-Nooshabadi, Mehdi;
Journal of the Brazilian Chemical Society , 2009, DOI: 10.1590/S0103-50532009000300008
Abstract: interaction between three anionic azo dyes, c.i. acid red 14 (ar14), c.i. acid red 1 (ar1), c.i. acid orange 7 (ao7) and a cationic surfactant tetradecyltrimethylammonium bromide (ttab) has been investigated using surfactant selective electrode technique. the ttab selective electrode was constructed and used to determine the concentration of ttab monomers and also surfactant ions bounded to dyes by electromotive force data. the dye-surfactant complex formation constant, k1, and the standard free energy change, δg1o, could be obtained from the experimental data. the results indicate that in the ttab/ao7 system, where the more hydrophobic dye ao7 is used, the dye-surfactant interactions are stronger than in other systems. the results also indicate that both the electrostatic attractive and the hydrophobic interactions are very important for the formation of the complex between the oppositely-charged dyes and the surfactant. maximum binding capacities of the dyes and also the degree of binding of the surfactant to the dyes were calculated from the experimental data.
Adsorption of Ethylene on Neutral, Anionic and Cationic Gold Clusters  [PDF]
Andrey Lyalin,Tetsuya Taketsugu
Physics , 2009, DOI: 10.1021/jp909505y
Abstract: The adsorption of ethylene molecule on neutral, anionic and cationic gold clusters consisting of up to 10 atoms has been investigated using density-functional theory. It is demonstrated that C2H4 can be adsorbed on small gold clusters in two different configurations, corresponding to the pi- and di-sigma-bonded species. Adsorption in the pi-bonded mode dominates over the di-sigma mode over all considered cluster sizes n, with the exception of the neutral C2H4-Au5 system. A striking difference is found in the size-dependence of the adsorption energy of C2H4 bonded to the neutral gold clusters in the pi and di-sigma configurations. The important role of the electronic shell effects in the di-sigma mode of ethylene adsorption on neutral gold clusters is demonstrated. It is shown that the interaction of C2H4 with small gold clusters strongly depends on their charge. The typical shift in the vibrational frequencies of C2H4 adsorbed in the pi- and the di-sigma configurations gives a guidance to experimentally distinguish between the two modes of adsorption.
Complexation of DNA with Cationic Surfactant  [PDF]
P. S. Kuhn,Marcia C. Barbosa,Y. Levin
Physics , 1999, DOI: 10.1016/S0378-4371(99)00184-3
Abstract: Transfection of an anionic polynucleotide through a negatively charged membrane is an important problem in genetic engineering. The direct association of cationic surfactant to DNA decreases the effective negative charge of the nucleic acid, allowing the DNA-surfactant complex to approach a negatively charged membrane. The paper develops a theory for solutions composed of polyelectrolyte, salt, and ionic surfactant. The theoretical predictions are compared with the experimental measurements.
Infrared Spectroscopy of Anionic, Cationic, and Zwitterionic Surfactants  [PDF]
Rommel B. Viana,Albérico B. F. da Silva,André S. Pimentel
Advances in Physical Chemistry , 2012, DOI: 10.1155/2012/903272
Abstract: This paper describes the ordering degree of anionic, cationic, and zwitterionic surfactants with the increase of their packing density on Ge substrate by using Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy. This work shows new insights on the conformational order of sodium dodecyl sulfate (SDS), N-hexadecyl-N-N-dimethyl-3-ammonio-1-propane-sulfonate (HPS), hexadecyl-trimethylammonium bromide (CTAB), and dodecyl trimethylammonium bromide (DTAB). DFT and semiempirical calculations are also performed in order to evaluate the effect of headgroup hydration and counterion. The CH2 asymmetric and symmetric stretching bands for the SDS molecule show a shift of 1.7 and 0.9?cm?1 to higher frequencies as the packing density increases, while it is observed a shift of 2.6 and 2.7?cm?1 for the HPS molecule, respectively. The DTAB molecule shows a shift of 4.5?cm?1 to lower frequencies for both CH2 asymmetric and symmetric stretching bands as the packing density increases, indicating the decrease of gauche conformations and the increase of all-trans conformations over the aliphatic chain. 1. Introduction Surfactants have been widely studied due to its significance in both applied and fundamental processes: detergency, catalysis, flotation, lubrication, colloid stabilization, foaming, emulsification, protein denaturation, tension moderation in membranes, membrane permeation, and drug delivery [1]. Surfactants are also used to the syntheses of nano- and mesomaterials using their capability to form self-organized aggregate structures [2]. Therefore, the determination of the packing, ordering, and its relation to the properties of the surfactant aggregates is of fundamental importance [3, 4]. Sperline [5] and Sperline et al. [6] have studied several crystalline phases of sodium dodecyl sulfate (SDS) using transmission infrared techniques. They have pointed out some relevant aspects: (1) difficulty in assigning a degree of order to the packing of alkyl chains based on the asymmetric CH2 stretching band; (2) the molar absorptivities for the alkyl vibrational features of adsorbed structures may not be compared with those for SDS micellar solutions; (3) the relative abundances of the CH2 symmetric and asymmetric stretching bands of SDS change considerably with the crystalline phase. In other words, the nature of the packing of surfactant molecules may determine their molar absorptivities. Snyder et al. [7], Flach et al. [8], and Dicko et al. [9] show that the frequency of the CH2 asymmetric stretching feature decreases with the conformational
STUDYING THE EFFECT OF CATIONIC STARCH- ANIONIC NANOSILICA SYSTEM ON RETENTION AND DRAINAGE  [PDF]
Amir Khosravani,A. Jahan Latibari,Seyed Ahmad Mirshokraei,Mehdi Rahmaninia
BioResources , 2010,
Abstract: Nanoparticles are widely used in the papermaking industry as retention/ drainage aids, usually in conjunction with a high mass cationic polyelectrolyte such as cationic starch. However, little convincing knowledge of their role and mechanism in the wet-end system is yet found. This work focused on the role of nanosilica on papermaking wet end system in response to some processing parameters (drainage, retention, and electrostatic force of the whole system). The observations indicated that the nanosilica performance is defined by interactions of nanosilica with the complex aqueous environment of wet end system. The interaction mechanism seems to rely on introduction of nanoparticles into a cationic starch-fines-fibers network, converting the fiber mat on the forming wire into a porous structure that is responsive to retention and drainage.
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