Microfluidic Fabrication of Micropolymer Inclusion Beads for the Recovery of Gold from Electronic Scrap

Abstract

A composite material, referred to as micropolymer inclusion beads (μPIBs), was fabricated for the first time using a microfluidic technique and applied successfully for the recovery of Au(III) from simulated digests of electronic scrap. Best results for the extraction of Au(III) were achieved with μPIBs consisting of 55% (m/m) poly(vinyl chloride) as the base polymer, 35% (m/m) Aliquat 336 as the extractant, and 10% (m/m) 1-tetradecanol as a modifier. The size and surface morphology of the μPIBs were examined using optical microscopy and scanning electron microscopy, respectively. A batch of 200 mg μPIBs allowed the complete and selective extraction of Au(III) (2.85 mg) from 50 mL of a simulated digest of electronic scrap containing other metal ions, including 1365 mg Cu(II). The extracted Au(III) was quantitatively stripped from the μPIBs into 50 mL of 0.1 mol L −1 solution of thiourea. No Cu(II) and only sub-microgram levels of Cd(II) and Zn(II) were detected in this solution, thus confirming the suitability of the μPIBs for the efficient recovery of Au(III) from digests of electronic scrap. The microfluidic method used in this study is expected to be applicable for the fabrication of μPIBs for the selective separation of other chemical species by varying the composition of the beads.