Effect of mineralogy and surface area on the adsorption of organic compounds

Abstract

Adsorption of organic compounds in a saturated porous media is controlled by solute and solid characteristics. This research investigated the role that surface area and mineralogy of the solute and solid play in adsorption. Four tracers, fluorescein, rhodamine B, thiocyanate and methylpyridone, were tested on weathered granite, unweathered granite, silica sand and kaolinite. Adsorption isotherm tests were conducted in order to determine whether chemisorption or physical adsorption was occurring. The role of surface charge and chemical structure of the adsorbing species were investigated to ascertain their influence on the adsorption process. From the studies conducted, surface area and surface charge were not found to be a dominating influence on adsorption. An analysis of the mineralogy of the solid and chemical structure of the solute can provide qualitative tools to predict possible adsorption mechanisms. For definitive assessment of the adsorption characteristics of a particular solid-solute system, empirical analysis for each system is necessary.