Potential performance of pillared inorgano- organo bentonite for soil mix technology permeable reactive barrier (Invited)

Modified bentonite has gained more interest for their effect in contaminant removal and environmental protection. This study is investigating the use of three different modified inorgano-organo bentonite (IOB) in soil mixing permeable reactive barrier. IOB were prepared using pillaring agents and quaternary ammonium cations (QAC) with different loading ratios. The permeabilities of compacted specimens containing IOB with two different soil types (sandy and gravelly soil) were measured for site contaminated groundwater, pure water and TEX compounds to study the potential of soil mix permeable reactive barrier (PRB). The soil permeability decreased by 1-2 order of magnitude once mixed with IOB. It also decreased by about 100 in case of TEX compound and site groundwater. The IOB was tested to remove Toluene, Ethyl-benzene, and o-Xylene (TEX) compound from model contaminated water in both batch and column test. Physical characteristics such as pore volume, porosity and specific structure in addition to level of surfactant loading were determined. Materials removal efficiency varied due to the surfactant loading, soil type and contaminant molecular weight. Sorption isotherm showed that the adsorbates preference increased in the order of T>E>X in all IOB types. Maximum TEX compound sorptive capacity varied also due to soil type with the highest was 86.89% 93.19% and 90.2% for T,E,X respectively on sandy soil. Key words: Inorgano-organo bentonite, permeability, reactive barrier, soil mix, sorption