Application of an organic–inorganic hybrid membrane for selective gold(III) permeation

An organic–inorganic hybrid membrane was synthesized and evaluated for gold(III) transport from concentrated hydrochloric acid medium. The membrane was prepared by crosslinking of hydroxy terminated poly(dimethylsiloxane) with (3-aminopropyl) triethoxysilane in the presence of the commercial extractant Kelex 100. An optimization of the transport conditions was performed and selectivity with respect to copper(II) and zinc(II) determined. Around 70% of Au(III) was transported from an initially 10 ppm aqueous solution under optimized conditions with high selectivity towards 50 ppm of Cu(II) or 100 ppm of Zn(II) in 6 h. In addition the membrane extraction equilibrium reaction and its corresponding extraction equilibrium constant were evaluated and compared to those obtained in liquid–liquid solvent extraction. Membrane characterization was attained by ATR-FTIR spectroscopy.