Adsorption of Alkyltrimethylammonium Bromides on Negatively Charged Alumina

Abstract

A four-region model based on electrostatic and hydrophobic interactions adequately explains adsorption of anionic surfactants on positively charged solids such as alumina. In this study, cationic surfactants were used instead for adsorption on negatively charged alumina at pH 10 and at a constant ionic strength of 0.03 M NaCl. In this case, only three distinct regions were observed in the adsorption isotherms and there seemed to be a lack of adsorption region III. In order to elucidate the adsorption mechanisms involved, the electronic spin resonance and fluorescence techniques were used along with vacuum flotation technique. The results suggest that adsorption region III may still exist; the difficulty in detecting it from the adsorption isotherm is probably the result of similar slopes for regions II and III. And this may be attributed to the loose and interpenetrating solloid structure in the case of the cationic amine/negatively charged alumina system. This possibility is discussed with the help of the results of the spectroscopic and flotation studies.

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

“…They exhibit high surface activity. They can form micelles and liquid crystalline structures both at the interface and in the bulk phase [17][18][19][20][21][22][23][24][25][26][27][28][29][30]. The ample experimental material makes it possible to predict the effect of the structure of a compound and the share of the hydrophilic and hydrophobic parts on adsorption properties [27,28,[31][32][33].…”

“…The ample experimental material makes it possible to predict the effect of the structure of a compound and the share of the hydrophilic and hydrophobic parts on adsorption properties [27,28,[31][32][33]. An increase in the hydrophobic part generally brings about a considerable increase in the excess values and a decrease in the critical concentration of surface and bulk micelles [17][18][19][20][21][22][23][24][25][26][27][28][29][30]. According to Traube's rule, an alkyl chain growth by a CH 2 group causes a threefold reduction in CMC and CSAC [24], but a growth of the hydrophilic part results in a decrease in the amount of the adsorbed compound and a shift in the values of CMC and CSAC towards higher concentrations.…”

“…The SLS molecule has a higher share of the hydrophobic part compared to ESLS and its concentration in that space should be higher. In the second stage, adsorption of monomers from the bulk phase and monomers formed due to decomposition of micelles takes place [17][18][19][20][21][22][23][24][25][26][27][28][29][30]56]. This process becomes complicated because solvated surfactant molecules adsorb on the surface [17][18][19][20][21][22][23][24][25][26][27][28][29][30]57].…”

Analysis of phthalates via HPLC-UV in environmental water samples after concentration by solid-phase extraction using ionic liquid mixed hemimicelles

“…Langmuir) very well, which was probably because adsorbing RTILs onto silica surface was not a simple surface phenomenon but a multistep process involving different kinds of interactions. Generally, ionic surfactant adsorption isotherms on metal oxides can be divided into three regions [40,41]. In the first region the adsorbed ionic surfactant molecules spread themselves on the surface to form singlelayer coverage (hemimicelles), probably through coulombic attractive interactions between charged metal oxides surface and the oppositely charged surfactants head group.…”

Adsorption of di-ethyl-phthalate from aqueous solutions with surfactant-coated nano/microsized alumina

“…Langmuir) very well and might be explained as follows: adsorbing SDS on alumina surface was not a simple surface phenomenon but a multistep process involving different kinds of interactions. Generally, ionic surfactant adsorption isotherms on metal oxides can be divided into three regions [20]. In the first region the adsorbed surfactant molecules spread themselves on the alumina surface to form single layer coverage (Hemimicelles), probably through coulombic attractions between charged alumina surface and the oppositely charged surfactant head group.…”