Extraction and recovery of precious metal ions in wastewater by polystyrene-coated magnetic particles functionalized with 2-(3-(2-aminoethylthio)propylthio)ethanamine

Cobalt ferrite magnetic particles were coated with polystyrene through atom transfer radical polymerization (ATRP), followed by surface functionalization with 2-(3-(2-aminoethylthio)propylthio)ethanamine. The obtained products (AEPE-PS-MPs) were employed in the extraction of Ag(I) and Au(III) ions in solution. The modified magnetic particles showed a good affinity toward Ag(I) and Au(III) ions and the stability of the particles in acidic solutions was also improved by the coating. The optimal pH for Ag(I) and Au(III) extraction was pH 5.0 and pH 4.0, respectively. The adsorption of the metal ions onto AEPE-PS-MPs followed Langmuir isotherm model with the maximum adsorption capacity of 0.44 mmol Ag(I) g−1 and 0.19 mmol Au(III) g−1. The recovery of Ag and Au from the adsorbents could be achieved by using 1.0 M thiourea in 1% HNO3 and 1.0 M thiourea in 2% HCl, respectively. The reuse of the adsorbents is possible. The products were shown to have potential in the extraction of Ag and Au in real wastewater.