A weathered bentonite (Japanese acid clay), a natural resource found as a by-product in the production of bentonite, was altered by an environmentally friendly treatment, where the Japanese acid clay was mechanochemically mixed with sodium carbonate without the addition of solvent, to give sodium type bentonite. The product was subsequently purified by conventional dispersion-sedimentation method to obtain purified sodium bentonite. The altered acid clay and the purified product exhibited useful swelling properties, which are satisfactory for industrial uses of conventional high quality sodium bentonites, and further functionalization of the product was possible through ion exchange. As an example, an organophilic clay, which is useful as adsorbent for toxic organic compounds from environments, was successfully prepared by the ion exchange of the present product with a cationic surfactant. The present mechanochemical process is an important environmentally benign option for the modification of the natural resources for the practical uses.
