STUDIES ON THE PHYSICAL STRUCTURE AND SURFACE-PROPERTIES OF ESTERIFIED SILICA-GELS

The esterified silica gel has been prepared by the reaction between the surface hydroxyl groups of silica gel and n-heptanol or n-octanol. The physical structure, water vapor adsorption isotherms, heat of wetting, DTA and IR for esterified silica gel were determined. The results indicate: (1) for all esterified silica gel d(T), S and V are all decreased, and d(A) is increased, but rBAR suffers only a small change; (2) the esterified silica gel is hydrophobic, it shows a remarkable decrease in water vapor adsorption, and in heat of wetting for water and cyclohexane; (3) the surface ester groups of esterified silica gel are destroyed at 235-350-degrees-C in air; (4) the esterification reaction is reversible and the surface ester groups of silica gels were hydrolyzed in water by about 41-47%.