Abstract: The cation-exchange capacity of montmorillonite decreased in consequence of fixation of ion is restored by subjecting the montmorillonite to a hydrothermal treatment.

Abstract: An amorphous substance obtained by mixing volcanic ash with or without added clay and water and, if necessary, a surfactant, kneading the mixture, and shaping and firing. Additives such as camphor or naphthalene may be included prior to firing for plasticity and to form pores. The resultant mixture possesses an ability to adsorb phosphorus selectively. When this substance is placed in contact with a phosphorus-containing liquid, it removes phosphorus from the liquid.

Abstract: A microporous separating material is produced by a method which comprises preparing a mixture of (1) macromolecular quaternary ammonium salt having a quaternary amine linked to a water-soluble macromolecular compound and possessing basicity, (2) a polymer of a polyoxyethylene alkylvinyl monomer and a vinyl monomer possessing basicity, or (3) a polymer of a halogenide of a quaternary amine, i.e. a basic macromolecular compound, and at least one water-soluble macromolecular substance selected from the group consisting of cellulose, polyvinyl alcohol, polyethylene oxide, and polyacrylamide with a smectite type mineral, mixing the aforementioned mixture with an inorganic substance in a water-soluble state, drying the resulting mixture, and firing the dried mixture.

Abstract: Finely porous clay having crystal layers separated by intervals of at least 20 .ANG. and having a smectite type mineral as a main component thereof. This finely porous clay is manufactured by mixing the smectite type mineral with water, a water-soluble polymer, and an inorganic substance and drying or heating the resultant mixture.