Functionalization of nanosilica via guanidinium ionic liquid for the recovery of gold ions from aqueous solutions

A new adsorbent was prepared via modifying nanosilica with guanidinium ionic liquids for effectively adsorbing gold ions from aqueous solution. Fourier transform infrared spectrometer (FT-IR), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) were used to characterize the adsorbent. Batch experiments were applied to investigate the effects of initial pH, initial gold ions concentration, contact time and coexisting ions on the removal of gold ions from aqueous solutions. The adsorbent exhibits an excellent selectivity for gold ions in the presence of Pb(II), Mg(II), Ba(II) and Cu(II) ions. The removal rate of gold ions is higher than 97.06% in the pH ranges from 2 to 5. The maximum uptake was 120.56   mg/g under pH   5. The adsorption kinetic was well described by the pseudo-second-order model. The adsorption isotherm followed Hill model very well. Therefore, the new adsorbent has a potential application in the field of separation of gold ions from aqueous solutions.