Synthesis of silica nanosphere for the recovery of gold from aqueous solution

Precious metals, such as gold, silver, platinum, palladium, and rhodium, play a significant role in our modern life. Due to the dwindling of natural resources, secondary resources, such as waste, hold significant importance as an alternative resource for these precious metals. Over the years, silica nanoparticle has taken great interest due to their unique properties, high thermal stability, high surface area, and homogenous pore size distribution. Recent studies showed that silica is mainly used in drug delivery, absorbent, hydrogen storage, and chromatography support. Functionalized silica nanosphere was used in the adsorption of Au(III) from an aqueous solution. The adsorbent was characterized by using SEM, XRD, and FTIR. Various parameters were carefully studied, such as pH, kinetic, and isothermal. The functionalization process did not significantly alter the physicochemical characteristic of the silica nanosphere. The results showed that functionalized silica nanosphere exhibit a fast reaction kinetics for the adsorption of Au(III). According to the results, Au(III) was chemically adsorbed onto the adsorbent, and the reaction followed a pseudo-second-order kinetic model. The equilibrium data fitted well with the Langmuir isotherm model with a maximum adsorption capacity of 103 mg g−1. This study highlighted a simple process of functionalizing silica-based adsorbent that could allow the adsorption of precious metals onto the adsorbent. The adsorbent performed excellently in recovering precious metals, providing insight into a sustainable way to acquire precious metals.