Effect of the Structure of Water-in-Oil Microemulsions of Sodium Di-(2-ethylhexyl)phosphate and Sodium Dodecyl Sulfate on the Efficiency of Microemulsion Leaching of Copper
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引用次数: 0
Abstract
A relationship has been found between the structure of microemulsions based on sodium dodecyl sulfate (SDS) and sodium di-(2-ethylhexyl)phosphate (D2EHPNa) and the efficiency of microemulsion leaching of copper. The dependences of electrical conductivity on the volume fraction of water have been studied for microemulsions containing D2EHPNa or a mixture of SDS and butanol, decane, water, and di-(2-ethylhexyl)phosphoric acid as an extractant for copper extraction. A gradual passage from water-in-oil microemulsions with the predominance of isolated droplets to microemulsions with the predominance of dynamic clusters of droplets (percolated structure) takes place with the increase in the volume fraction of water. The conductivity percolation thresholds are approximately 0.18 and 0.20 for the microemulsions based on D2EHPNa and SDS, respectively. The temperature dependence of the logarithmic electrical conductivity is linear in a range of 20–80°C for the microemulsions with water volume fractions below (0.13 and 0.07, respectively) and above (0.30 and 0.23) the percolation threshold; in this temperature range the structure of the considered microemulsions remains unchanged. The experiments on microemulsion leaching performed with the use of a CuO-based model system at T = 80°C have shown that, for the microemulsions with the percolated structure (having water volume fractions of 0.30 for D2EHPNa microemulsions and 0.23 for SDS microemulsions), copper extraction is higher than that for the microemulsions with the predominance of isolated droplets (water volume fraction of 0.13 and 0.07, respectively).
期刊介绍：
Colloid Journal (Kolloidnyi Zhurnal) is the only journal in Russia that publishes the results of research in the area of chemical science dealing with the disperse state of matter and surface phenomena in disperse systems. The journal covers experimental and theoretical works on a great variety of colloid and surface phenomena: the structure and properties of interfaces; adsorption phenomena and structure of adsorption layers of surfactants; capillary phenomena; wetting films; wetting and spreading; and detergency. The formation of colloid systems, their molecular-kinetic and optical properties, surface forces, interaction of colloidal particles, stabilization, and criteria of stability loss of different disperse systems (lyosols and aerosols, suspensions, emulsions, foams, and micellar systems) are also topics of the journal. Colloid Journal also includes the phenomena of electro- and diffusiophoresis, electro- and thermoosmosis, and capillary and reverse osmosis, i.e., phenomena dealing with the existence of diffusion layers of molecules and ions in the vicinity of the interface.
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