Fast Gold Recovery from Aqueous Solutions and Assessment of Antimicrobial Activities of Novel Gold Composite

A novel porous gold polymer composite was prepared by the functionalization of a glycidyl methacrylate-based copolymer (pGME) with ethylene diamine (pGME-en), and activation by gold (pGME-en/Au), in a simple batch adsorption procedure in an acid solution, at room temperature. Detailed characterization of the pGME-en before and after activation was performed. The main focuses of this research were the design of a method that can enable the recovery of gold and the reuse of this multipurpose sorbent as an antimicrobial agent. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis pointed out amine groups as the primary binding sites for Au activation, while hydroxyl groups also contributed to the chelation reaction. pGME-en exhibited fast gold adsorption with an adsorption half-time of 5 min and an equilibrium time of 30 min. The maximal adsorption capacity was about 187 mg/g. The analysis of sorption experimental data with a non-linear surface reaction and diffusion-based kinetic models revealed the pseudo-second-order and Avrami model as the best fit, with unambiguous control by liquid film and intra-particle diffusion. The biological activity studies against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Candida albicans revealed moderate activity of pGME-en/Au against different bacterial and fungal species. pGME-en/Au was stable in a saline solution, with a release of approximately 2.3 mg/g after 24 h.