Organically modified clays are prepared by replacing the exchangeable inorganic cations present in the natural clays. Organic cations used in this replacement process are then able to adsorb other organic compounds. Thus, an organically modified clay can adsorb organic constituents that are otherwise unaffected or possibly adversely affected by unmodified clays. Organically modified clays may be mixed with additional stabilisation agents (such as cement, cement kiln dust, or fly ash) to solidify contaminated soils or organic wastes into a stable mass. The stabilised mass has improved bearing properties and a reduced potential for leaching hazardous constituents into the environment. Because organically modified clays swell in the presence of organic fluids, such as gasoline or fuel oil, they may also be used as sorbents in spill control or in liners for fuel oil tank containment areas. The sorption capabilities of a number of both unmodified and organically modified clays are compared. Data are also presented on the use of organically modified clays for organic sludge stabilisation. The findings indicate the feasibility of stabilisation technology for remediation of organically contaminated sites as compared with the excavate-and-remove option. The adsorption of organics by organically modified clays is critical to this process.
Samenvatting