n Octyl d Glucopyranosiduronic acid derivatives
In previous works in our laboratories, the synthesis of a new type of surfactants and the determination of their interfacial and flotation properties with Fe(III) have been described . Carboxylic and hydroxamic acids have been chosen for their known properties as metal collectors. These functionalities were obtained by oxidation of the primary alcohol of the sugar and coupling with hydroxylamine, glycine, aspartic PF-477736 and glutamic acid. In this paper, we report on the use of octyl glucoside based surfactants modified with carboxylic or hydroxamic acid group as collecting agents in flotation experiments to extract metallic cations (Fe(III), Cu(II), Cr(III), Cd(II), Zn(II), Ni(II) and As(III)) from aqueous solutions. The influence of structural features on the behaviour of this chelating surfactants is analyzed through changes in interfacial properties: CMC, the critical micellar concentration; Γm, the surface excess concentration at surface saturation, a useful measure of the effectiveness of adsorption; ams, the area per molecule at the interface at surface saturation; ΔG°mic, the standard free energy of micellisation; ΔG°ads, the standard free energy of adsorption; pC20, the negative logarithm of the bulk liquid phase concentration of surfactant required to depress the surface tension of the solvent by 20 mN/m, a good measure of the efficiency of the adsorption of the surfactant; and the CMC/C20 ratio, a convenient way of measuring the relative effects of structural factors on the micellisation and the adsorption processes. To better understand the extraction process, we analyzed the complexation for the best extraction experiments i.e. for compounds 2a and 2b and Fe(III). Complexes equilibrium constants for compounds 2a and 2b and Fe(III) were determined by multi-wavelength spectrophotometric pH titration. The species distribution diagrams allowed identifying the predominant species and the pH conditions for maximum efficiency in metal removal.