Ionic liquid-modified chitosan fibers for Au(I) recovery from waste printed circuit boards bioleachate: Preparation, adsorption mechanism, and application

The purpose of this study is to develop an ionic liquid (IL)-based eco-friendly adsorbent to selectively recover Au(I) from bioleachate and to elucidate its adsorption mechanism. IL-modified chitosan fibers (ILCFs) with fast and high adsorption performances were prepared for Au(I) (Au(CN)₂^- in this study) recovery under alkaline conditions. The cross-sectional diameter of the prepared ILCFs was a uniform 31.2 ± 1.1 μm. The characterization of ILCFs and the Au(I) adsorption mechanism were examined through scanning electron microscopy (SEM), fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Based on the Langmuir model, the maximum Au(I) adsorption capacity of the ILCFs was 357.0 ± 13.2 mg/g. An adsorption equilibrium was reached within 7 mins, and the rate constants of pseudo-1st-order and pseudo-2nd-order were 0.8912 ± 0.0569 1/min and 0.0049 ± 0.0002 g/mg min, respectively. Moreover, the ILCFs showed high Au(I) selectivity from waste printed circuit board bioleachate. The developed ILCFs are an effective selective adsorbed of Au(I) and potentially have a role to play in its recovery from urban mining bioleachates.