Silver/Gold nanoparticles grafted on silica submicrospheres – promising sorbents for mercury speciation in surface waters

Abstract

Two types of core-shell nanocomposite particles were prepared by colloid mixing method. The silica core spheres were synthesized using Stober method and subsequently were functionalized with terminal amine groups.The shell is comprised of discrete starch-stabilized gold or silver nanoparticles. Various experimental techniques (SEM, TEM, AFM, ζ-potential measurement, UV-Vis spectroscopy) were used to characterize the morphology, surface properties, colloidal stability and optical properties of noble metal nanoparticles, SiO₂ spheres, SiO₂-NH₂/AuNPs and SiO₂-NH₂/AgNPs nanocomposite particles. The extraction efficiency and selectivity of the core-shell sorbents toward Hg species were studied by batch procedure. Several parameters such as acidity of the sorption media, amount of sorbent, time of sorption, type and concentration of the eluent were optimized in order to define chemical conditions for selective separation and enrichment of both iHg and methylHg. Analytical procedure for speciation and determination of Hg in surface waters was developed and verified for laboratory practice.