Functionalized materials such as silica have been used in a variety of applications such as catalysis, chromatography, and adsorption. Recently there has been increased interest in functionalization of non-carbon materials for the development of effective mercury sorbents, as alternatives to activated carbon sorbents. Previous work has shown that functionalization of both silica and copper doped iron nanoaggregates (1) with tetrasulfur silane compounds leads to particles which have proven effective in lab- and pilot-scale studies for the efficient adsorption of mercury from coal-fired power plant streams.

This study presents the in-depth sulfur functionalization and characterization of functionalized silica and other non-carbon based sorbents, and gives a fundamental understanding of the synthesis and applications of this alternative technology. The functionalization reaction of non-carbon materials is probed using diffuse reflectance infrared spectroscopy (DRIFTS) and other techniques. Preliminary DRIFTS results have given extents of functionalization for various materials. The adsorption of mercury onto these functionalized materials is then presented, including temperature-dependent results. These sorbents undergo various thermal transitions in the temperature ranges of interest, and pyrolysis of the tetrasulfur silane (for example) occurs at about 230 °C. The species involved in these transitions, their impact on mercury adsorption, and the adsorption products, are analyzed using DRIFTS as well as differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), scanning and transmission electron microscopy (SEM & TEM) and X-ray diffraction (XRD).

1. Meyer, D. E.; Sikdar, S. K.; Hutson, N. D.; Bhattacharyya, D., Examination of sulfur-functionalized, copper-doped iron nanoparticles for vapor-phase mercury capture in entrained-flow and fixed-bed systems. Energy & Fuels 2007, 21, (5), 2688-2697.