An improved process for the manufacture of semi-permeable separators such as diaphragms, diffusion walls and the like

摘要

Diaphragms are made by immersing a porous body in a solution containing a substance such as sodium silicate capable of forming a gelatinous medium and a coagulent therefor such as sulphuric or other acid, the mixture gelatinizing in the porous material after an appreciable lapse of time. The mixture is preferably prepared by pouring a solution consisting of one part 40 DEG Bae. sodium silicate and two parts water in a thin stream and with rapid stirring into one part of 66 DEG Bae. sulphuric acid diluted with two parts of water and cooled. The excess sulphuric acid and sodium sulphate may be removed or retained. When the diaphragm is removed from a liquid it may be treated with sulphuric acid or other hygroscopic substance. The porous body is preferably of material having a granular structure such as "filtros" or "alundum," but fibrous materials such as wood or asbestos may be used.ALSO:An impregnating-liquid is made by stirring a mixture of one part of sodium silicate solution of density 40 DEG Bae. and two parts of water into a cooled mixture of one part of sulphuric acid of density 66 DEG Bae. and two parts of water. The mixture gelatinizes after 20-30 minutes.