Process for the preparation of substances with ion exchanging and adsorbing properties

摘要

A granular material having ion-exchanging and adsorbent properties is prepared by covering pieces or granules of a solid material, which is compatible with acid sludge, with a thin coating of acid sludge and heating so that a solid product is formed from the acid sludge, whereupon the covering of the granules with a thin coating of acid sludge and heating is repeated one or more times the temperature not exceeding 300 DEG C. and total duration of the heating being at least 3 hours. The solid starting material may itself have been obtained by heating acid sludge. Other suitable starting materials include wastes from other preparations of ion-exchange materials, charred wood, activated carbon, wood powders, coal, asphalt or porous apatite granules. Solid materials which are liquid at the reaction temperature such as thick acid sludge, pitch tar or molasses may also be used. Sulphuric acid, oleum, or chlorsulphonic acid may also be added intermittently to the reaction mixture. To obtain ampholytes, anion-exchangers, substances from which anion exchangers are formed or substances which introduce amino, imino or quaternary ammonium groups, e.g. pyridine, may be added to the reaction mixture. Preferably not more than one-third part by weight of the reaction components should be solids. The acid sludge may be sprayed on the granules or added in small portions, and the solid material broken by stirring. Preferably the heating is gradual, initial temperature being between 60 DEG and 140 DEG C., and the reaction period may vary from 3 hours to one or more days. The acid properties of the product vary according to the temperature used in the final phase, higher temperatures producing a weaker ion-exchanger. The product may be washed to remove acid and alkali may be added before the final heating phase. The capacity of the product may be increased by treating with oxidizing agents such as nitric acid, nitrous vapours, nitrates, oxygen or air, preferably at high temperatures, and by boiling with caustic lye. The process may be carried out discontinuously or continuously. The apparatus used in the examples comprises an inclined or horizontal tube, heated indirectly with oil or directly with air, and provided with a slowly rotating stirrer the blades of which almost touch the walls; acid sludge is supplied at several points spaced along the tube and the exhaust is controlled so that the tube remains practically filled with product. Detailed examples are given in which the initial granules are obtained from acid sludge itself or by addition of solid materials selected from those mentioned above. Other forms of apparatus mentioned are rotating cylinders, mixing devices or vertical cylinders to which acid sludge is supplied intermittently.ALSO:An ion-exchanging and adsorbent material is prepared (see Group IV (b)) by covering granules of a solid material with a thin coating of acid sludge and heating to form a solid product, the coating of the granules and heating being repeated one or more times, the temperature not exceeding 300 DEG C. and total duration of the heating being at least 3 hours. The solid starting material may be obtained by heating acid sludge itself. Other suitable materials include waste from other ion-exchanger preparations, charred wood, activated carbon, wood powders, coal, asphalt, apatite, thick acid sludge, pitch, tar or molasses. To obtain ampholytes, anion exchangers, substances from which anion-exchangers are formed or pyridine may be added to the reaction mixture. The products are useful as cation or hydrogen ion exchangers and the acid properties may be varied by varying the reaction temperature, especially during the final stage; the higher the temperature the weaker the acid character of the product. To obtain a very weakly acid cation exchanger, the last phase of heating is carried out after washing the acid from the product. An addition of alkali to the washed product before or during the final stage increases the activity of the product. The ion-exchaning capacity of the product may also be increased by treatment with oxidizing agents such as nitric acid, nitrous vapours, nitrates, oxygen or air, preferably at high temperatures. By boiling the final product with caustic lye the cation-exchanger may be improved without increasing the acid character. Detailed examples of the preparation and after-treatment of the ion-exchange materials are given and the exchanging capacity of the product with sodium hydroxide, calcium acetate and calcium chloride solution is demonstrated.