Filtration materials comprising heat-treated metal-doped precipitated silica or silica gel materials with sulfur-containing functional silane surface treatments are provided. Such materials exhibit excellent mercury removal properties from flue gas emissions through the trapping of mercury vapors within a smokestack (or other like site). The metal dopant and the sulfur-containing functional silane components applied to the surface of the target metal-doped gels effectuate the desired mercury reactions to permit capture thereof. In combination, such components permit versatile utilization in either a fixed bed configuration or through a dynamic mercury removal procedure. Methods of using and specific filter apparatuses are also encompassed within this invention.