The sorption of sulphur dioxide on silica gel

Abstract

Adsorption isotherms of sulphur dioxide on silica xerogels have been obtained for the range 263–323°K. High purity xerogels were used after various degrees of heat treatment at 240, 500, 600, 650, 700, 900, and 1100°. These materials were characterised by low-temperature nitrogen adsorption and by measurement of the density by immersion in mercury. Comparative isotherms were measured at 263°K on commercial silica gels of widely different surface characteristics. Heats of adsorption (q_st) were determined from isosters for the monolayer region (θ= 0–0·85). The q_st values show a steady decrease with increasing surface coverage from 9·3 to 7·8 kcal. mole^–1(240° xerogel). The sorption process is discussed in terms of a physical model.