Band 46, Heft 2

Silica gel 60 F 254 plates were used with mixed aqueous-organic solvent systems consisting of dioxan and lithium chloride for the chromatography of three nonionic surfactants. The resolution of coexisting Triton X-100, Brij-57 and Brij-78 was achieved with the solvent system 1,4-dioxan:1% aqueous LiCl (40:60, v/v). The effect of concentration of Li + ions in the solvent system on the mobility of the three surfactants was studied. The interference on the resolution of the mixture of Triton X-100, Brij-57 and Brij-78, due to the presence of metal cations as impurities, is also examined. The limits of detection of Triton X-100, Brij-57 and Brij-78 estimated were 0.075, 0.150 and 0.20 μg/zone respectively. The practical applicability of proposed method was tested for the identification of three coexisting nonionic surfactants after their separation from the spiked aqueous systems.

Most of the world iron ores are associated with siliceous impurities. Upgrading schemes depend mostly on the removal of these impurities by flotation and/or selective flocculation techniques, which mainly influenced by the adsorption of collectors on both valuable and gangue minerals. In this study, the adsorption of amphoteric collector (dodecyl-N-carboxyethyl-N-hydroxyethyl-imidazoline) on silica and hematite was studied. The collector adsorption exhibits the preferential adsorption on silica at acidic pH range. While in case of hematite, the adsorption was the same over entire the studied pH range. The temperature was kept constant at 298 K and contact time of 60 min was found, from kinetic study, to be adequate to achieve equilibrium. In addition, two simplified kinetic models including a pseudo first-order equation and pseudo second-order equation were used to determine kinetic parameters, rate constants, and equilibrium sorption capacities. It was shown that the pseudo first-order equation perfectly describes the adsorption of collector. Moreover, the analysis of experimental isotherm data using the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich equations showed that the Freundlich model reasonably fits the experimental data in the studied concentration range.

This paper investigated the interaction of α-Na 2 Si 2 O 5 and β-μNa 2 Si 2 O 5 with surfactants sodium dodecylbenzene sulfonate (LAS), sodium lauryl sulfate (K12), alkyl polyglycol ether-9 (AEO-9) and α-olefin hydrocarbon sulfonate (AOS) under condition approximating the detergent spray drying process. The interaction samples were characterized by XRD and TG. The experimental results showed that α-Na 2 Si 2 O 5 and β-Na 2 Si 2 O 5 sustained their phases after interacted with surfactants. The relative crystallinity of α-Na 2 Si 2 O 5 had little change after interacting with surfactants exception of AOS because it had better adsorbable effect on the surface of α-Na 2 Si 2 O 5 than LAS, K12 and AEO-9. At the same conditions, the amount of H 2 O and surfactants were both important factors on the relative crystallinity of β-μNa 2 Si 2 O 5 . It also was proved that the temperature had little influence on the relative crystallinity of both α-Na 2 Si 2 O 5 and β-Na 2 Si 2 O 5 . Compared with Al-δ-Na 2 Si 2 O 5 , α-Na 2 Si 2 O 5 and β-μNa 2 Si 2 O 5 were more stable than Al-δ-Na 2 Si 2 O 5 after interacted with surfactants.

The properties of new thermo-responsive functional surfactants, capable of forming a metal chelate, synthesized by grafting a diamide group (amino-acid residue) to the tip hydrophilic endgroup or in a branched position to polyoxyethylene nonionic surfactants [C i E j : C i H 2i+1 (OCH 2 CH 2 ) j OH)], are studied. Their use in cloud point extraction of uranyl nitrate is tested. The reversible temperature-dependent behavior of classical non-ionic surfactants associated to phase separation of micellar solutions known as clouding behavior is exploited for separation based on cation specific binding to the chelating group. The functional surfactants under investigation combine surface-active properties and characteristic thermoreversible behavior with a capacity to bind uranyl cation. The influence of the complexation on the cloud points of functional surfactants is determined. The chelating surfactants are found efficient for the cloud point extraction of uranyl nitrate at low surfactant-to-uranyl ratio. These new thermoresponsive surfactants with chelating properties hold most promise for the development of new solvent free extraction processes.

This paper is focused on the phase behavior, interaction with anionic surfactant sodium dodecyl sulfate SDS, adsorption and wetting investigations of new hydroxy mixed ether nonionic surfactants HME n . The phase diagrams of (0.1–100) %wt of HME n (n-value is the ethoxylation number EO) at the temperature range 20–100°C have shown that the increasing of n-value raises the cloud boundary toward higher temperature. Remarkable result was obtained from the interaction between SDS and HME B , at which the mixed system exhibits a unique homogeneity and a liquid crystal phase formation. Macroscopically, the liquid crystal region was found when the SDS concentration range between 8 and 24 mM mixed with 10% wt HME B . The interaction between HME n and mica was also investigated using atomic force microscopy AFM and a pronounced adsorption of HME n on mica was observed. Moreover, contact angle results reveal that glass substrate shows strong wettability of HME n surfactant solutions compared with polyethylene PE and polymethylmethaacrylate PMMA substrates. This wettability however also decreases with EO number.

Starting from a variety of monomers as building blocks, a whole range of synthetic homopolymers and random copolymers can be easily synthesized in the laboratory and many of these polymers are commercially available. Acrylic acid in particular is a convenient and versatile starting point leading to a huge range of different polymer structures generally known as polycarboxylates. A great deal of work has been published on the effects polycarboxylates provide in laundry detergents. They have a pronounced dispersing capacity for particulate soil and sparingly soluble salts such as calcium carbonate and thus they are able to counteract incrustation and redeposition of soil onto fabrics. The incorporation of side chains of different lengths and chemistry opened the field of highly efficient rheology modifiers. This synthetic development has been aided by an increased understanding of the mode of action on a molecular level. Knowledge about the interaction of water-soluble polymers with nonionic and ionic surfactants and with particles has grown significantly and is still an area of great interest. Further, recent studies have shed more light on the dynamics of crystal growth of calcium carbonate in various environments and the role of polycarboxylates and other polymers in this process.

N,N-bis-(2-hydroxyethyl)oleamide (NHEO) was synthesized using oleic acid and diethanolamine in 1:1 molar ratio using orthophosphoric acid as catalyst. The reaction kinetics at 140°C has been evaluated. The latter follows a first order reaction rate which is in accordance with the reaction mechanism proposed. Yield optimization has been performed implementing an L 4 Taguchi orthogonal array. The chemical analysis, rheological behavior and stabilizing ability of the product for metal and metal oxide slurries has been investigated.