Hyperbranched thiourea-grafted electrospun polyacrylonitrile fibers for efficient and selective gold recovery

Research on the recovery of precious metals (including gold, Au), attracts attention of scientists worldwide. This paper reports synthesis of a novel fiber adsorbent consisting of hyperbranched thiourea-grafted electrospun polyacrylonitrile (HS-PAN) for Au(III) ion recovery. High-density functional groups of the hyperbranched structure allowed HS-PAN fibers to exhibit much higher affinity and selectivity towards Au(III) than towards Pt(IV), Cr(VI), Pb(II), Ni(II), Co(II), Fe(III), Mg(II), Cu(II) and Na(I). Au(III) adsorption proceeded according to the pseudo-second-order kinetic model and could be fitted very well using Langmuir isotherm. The maximum adsorption capacity of these fibers relative to Au(III) was 3257.3 mg/g, which is higher than the values reported in the literature for other Au(III) adsorbents. Our novel HS-PAN fibers can extract Au from real electronic waste with 99% recovery yield in just 1 h. Thus, this study demonstrates a very efficient and low-cost way to recover gold.