Solvent extractions surfactant-mediated

Sayari et al [202,203] extended the LCT technique to the synthesis of mesostructured zirconium oxide. The use of long chain quaternary ammonium salts or primary amines as templates led to the formation of hexagonal and lamellar Zr02 phases, respectively. Zr(S04)2 was used as zirconium source, which provided a highly acidic medium, pH < 1.5. Consistent with the synthesis conditions and EDX analysis data a S X I mechanism where the surfactant-inorganic interaction is mediated by sulfate anions was proposed. Unfortunately, both structures collapsed upon removal of the surfactant either by high temperature calcination or by solvent extraction [203]. However, the hexagonal form was successfully... 

Morooka and coworkers [104,105] and Kawai et al. [106] prepared zirconia nanoparticles by the microemulsion-mediated alkoxide sol-gel method. In all cases, zirconium tetrabutoxide (ZTBO) served as the alkoxide precursor. In the work of Morooka and coworkers [104,105], the surfactant was dioleyl phosphoric acid (DOLPA) and the microemulsion was prepared by a solvent extraction process [Eq. (20)]. After phase separation, zirconia particles were produced by introducing a butanol solution of ZTBO into the microemulsion solution. The resulting zirconia particles had an average size of 2 nm. 

The solubilisation of proteins and amino acids in organic solvents by reversed micelles provides a new method for the selective recovery, separation and concentration of bioproducts using liquid->liquid extraction techniques. Selectivity is affected by electrostatic interactions between the charged residues or moieties of the solute and the surfactant headgroups. These interactions are mediated by electrostatic screening as affected by solution ionic strength. The more hydrophobic the amino acid residue, the more favourable is the solubilisation of this residue in the partially structured water pool of the reversed micelle relative to the bulk, unstructured water phase. 

Cloud-point extraction (CPE) and micelle-mediated extraction are methods that utilize aqueous solutions of nonionic or zwitterionic surfactant concentrations above their critical micelle concentrations. The addition of ions or solvents as well as increasing temperature of the solution... 

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