Spontaneous formation of gold microplates during reduction-coupled removal of noble metals using Dowex M4195 resin

The present work reports the novel phenomenon of spontaneous formation of gold microplates. The effect is observed as a consequence of AuCl4-, PtCl62-, PdCl42-, and ReO4- sorption on the Dowex M4195 resin. Therefore an attempt to explain the phenomenon mechanism is made. The research is covering sorption, kinetic and thermodynamic studies. The shapes of formed gold single plates are determined. The uptakes of Au(III), Pt(IV), Pd(II), and Re(VII) tests have been conducted using a batch method from single-component metals solutions in 0.1 M HCl. The sorption-reduction phenomenon has been assessed by executed SEM, FTIR, XRD, and XPS studies. The greatest sorption capacity, combined with reduction-coupled removal phenomenon, has been achieved for gold (5.5 mmol Au.g(-1) at 9 degrees C). Executed SEM and XRD analyzes prove formation of gold single crystals during present process, furthermore reduction of rhenium is indicated by XPS analysis. Based on the obtained FTIR and Raman's spectra, the reduction phenomenon is probably followed by resins' functional groups oxidation. (C) 2015 Wiley Periodicals, Inc.