A number of cement-based fixation processes are available for cost-effective stabilization of inorganic wastes, but these processes are not generally so effective for treating organic wastes or organic/inorganic mixtures. With a view to possible extension of such methods to organic wastes, the use of charcoal and tetra-alkylammonium-substituted clays as pre-stabilization adsorbents has been investigated. Charcoal is a well-known adsorbent, while the use of the substituted clays exploits the hydrophobic properties of the alkyl groups to fix organic materials within the clay matrix.

Wyoming Bentonite substituted with hexadecyltrimethyl ammonium bromide and benzyl-dimethyltetradecylammonium chloride were found to be very effective in adsorbing chlorinated phenols with adsorption capacities of 150 mg of chlorinated phenol per gram of clay. There appears to be a clear trend between the chain length of the alkylammonium ion in the exchanged clay and the ability of the clay to adsorb a particular phenolic compound. Activated charcoal was found to effectively adsorb 180 mg of phenol or chlorinated phenols per gram of charcoal.

The exchanged clays and charcoal together with the respective adsorbed phenols were incorporated into a number of cementitious matrices. Following hydration, leachability and physical strength measurements were carried out and the results were used to make a preliminary assessment of the longer-term potential of clays and charcoal in stabilization/solidification applications.