Showing papers on "Precipitated silica published in 1970"

Behavior of a pyrogenic silica in simple electrolytes

Abstract: Adsorption of hydrogen and hydroxyl ions on a nonporous pyrogenic silica was determined by potentiometric titration in LiCl, KCl, and CsCl electrolytes over the pH range 1.8–9.0. No evidence of hydrogen ion adsorption was found. The sequence of counterion adsorption was Cs+ > K+ > Li+. An attempt was made to increase the extent of surface hydration of this silica by treatment in aqueous solution. This product had the same properties as untreated silica, except for slightly lower charge densities above pH 6. This difference was attributed to adsorption of impurities during treatment rather than to any significant effect of hydration state. Charge densities were found to be somewhat higher than those reported for precipitated silica, but much lower than those reported for microporous silica. Differential capacitance curves indicate the counterions for precipitated silica to be further away from the surface. It is suggested that Cs+, classed as a structure breaker in aqueous solution, is better able than Li+ to penetrate any structured water phase existing at the silica surface, in accordance with observed adsorbabilities.

Production of finely divided organically modified silicas

Abstract: A finely divided organically modified silica is formed by adding an inorganic acid at an elevated temperature to an aqueous alkali methyl silicate solution in contact with a water-soluble reactive organic polymer which is present in an amount of from about 3 to about 24 percent by weight relative to the weight of the thus precipitated silica.

Method of treating cotton for fire retardation

Abstract: THE METHOD DISCLOSED COMPRISES THE STEPS OF FIRST EXPOSING THE INDIVIDUAL PORES OR FIBERS OF A MATERIAL AS MUCH AS POSSIBLE, THEN DISPERSING A DESIRED HYGROSCOPIC POWDER, E.G., UREA-DIAMMONIUM PHOSPHATE WITH A FREE-FLOWING, ANTI-CAKING AGENT SUCH AS PRECIPITATED SILICA, INTO THOROUGH CONTACT WITH THE EXPOSED FIBERS, HUMIDFYING THE EXPOSED FIBERS TO DISSOLVE THE POWDER AND PENETRATE THE FIBERS, E.G., BY A FOG OBTAINED BY MIXING STEAM WITH SATURATED AMBIENT AIR, AND FINALLY DRYING AND/OR CURING THE PENETRATED FIBERS TO GIVE RISE TO THE DESIRED CHARACTERISTIC IMPARTED BY THE PENETRATING SOLUTION SUCH AS FIRE RETARDATION. THE HYGROSCOPIC POWDER IS PREPARED BY DRYING THE CONSTITUENTS PRIOR TO PULVERIZING TO REDUCE THE MOSITURE CONTENT THEREOF TO LESS THAN TEN PERCENT, CIRCULATING HOT AIR DURING THE PULVERIZING PROCESS, AND ADDING A FREE-FLOWING, ANTI-CAKING AGENT BEFORE OR AFTER THE PULVERIZING PROCESS.