BENZENE TRANSPORT THROUGH LANDFILL LINERS CONTAINING ORGANOPHILIC BENTONITE

The mineral surface of Wyoming bentonite was modified by replacing ino rganic ions by different quaternary ammonium compounds of known molecu lar structure by an ion-exchange process. The resulting organically mo dified bentonites (organobentonites) were evaluated for their suitabil ity as components of compacted earthen liners for waste-disposal sites . Varying weight percentages of an Ottawa sand, either of five types o f organobentonites, untreated bentonite, and water were mixed uniforml y and compacted to simulate sand-and-bentonite liners for waste-dispos al facilities. The hydraulic conductivities of the compacted soil spec imens were measured in triplicate. The hydraulic conductivities of com pacted specimens composed of 88% (by mass) Ottawa sand, 8% untreated b entonite, and 4% organobentonite were on the order of 10(-8) cm/s. Ben zene sorption from water to Ottawa sand, bentonite, and two of the org anobentonites was measured experimentally. Benzene sorption to each or ganobentonite was significantly greater than benzene sorption to bento nite or Ottawa sand. The sorption and permeability data were input int o a one-dimensional solute transport model to simulate benzene transpo rt through a conventional earthen liner and two liners containing orga no-bentonites. Results of the simulations indicate that earthen liners containing organobentonites significantly retard the transport of ben zene relative to a conventional liner.