Selective recovery of Au(III) from aqueous solutions by nanosilica grafted with cationic polymer: Kinetics and isotherm

A new adsorbent was synthesized via functionalizing nano-silica with poly(methacryloxyethyltrimethyl ammonium chloride) (PDMC) for selective recovery of Au(III) from aqueous solutions. The adsorbent was characterized by FT-IR, TGA, XPS and TEM. A batch adsorption experiment was conducted to evaluate the adsorption capacity, reusability and selectivity. The maximum adsorption capacity of Au(III) was 127.3 mg/g at room temperature and the optimum pH 3.0. The adsorption equilibrium was achieved within 20 min. The adsorption process followed preferably the pseudo-second order kinetics and the Langmuir isotherm model. Ion exchange between gold ions and amines/chlorine groups played an important role in the adsorption process. The adsorption desorption cycles indicated that the adsorbent had a stable adsorption performance and retained high adsorption efficiency. Moreover, the adsorbent can selectively adsorb Au(III) from coexisting ions in aqueous solution. Therefore, nano-silica modified with PDMC could be of great potential in recovering Au(III) from industrial effluents and waste e-products.