A study of ion adsorption onto surface functionalized silica particles

The surface charging properties of silica micro-particles in aqueous solutions before and after surface chemical amination were measured and analysed using a new approach to the theoretical modelling of ion adsorption. The surface of aminated silica microspheres were further modified by chemical adsorption of l-cysteine groups to determine their ability to adsorb low levels of arsenic ions from aqueous solution. The adsorption of arsenic ions was observed both from changes in particle surface charge and from direct solution analysis, using ICP-OES. The results obtained indicate adsorption levels of about 2-5% of the cysteine surface density, from low-level arsenic solutions (i.e. less than 1 ppm). These initial results indicate that a suitable silica-based depth filter could be developed for the removal of low-level arsenic ions from contaminated water.