Kittur Subba Rao
Articles written in Proceedings – Section A
Volume 4 Issue 5 November 1936 pp 562-570
The effect of temperature of activation on the capillary space in alumina and ferric oxide gels has been studied. Structural changes in alumina gel have been noticed in the neighbourhood of 500°C. and 900°C. and their significance discussed.
Adsorption on alumina and ferric oxide gels from binary mixtures of liquids has been studied and the behaviour of these has been compared with that of silica. It is concluded that the chemical nature of a gel markedly affects selective adsorption from binary mixtures of liquids.
Volume 6 Issue 1 July 1937 pp 16-23
A microspring balance of quartz fibre of the McBain-Bakr type has been used for studying adsorption of vapours of water and pyridine on gels of silica and alumina.
The difference in adsorption on “glassy” and “chalky” gels of silica has been accounted for, by the wider capillaries in the latter.
Adsorption of pyridine on alumina gels activated at 400° C., 500° C. and 850° C. has been studied. The differences noticed are attributed to the variation in capillary size.
Volume 16 Issue 4 October 1942 pp 298-300
The permanent and reproducible hysteresis loop obtained in the sorption of water vapour at 30° C. on alumina gel has been scanned by traversing the loop from various points on the sorption and desorption curves.
The general characteristics obtained on scanning are in conformity with those of other systems, silica gel-water, titania gel-water, silica gel-carbon tetrachloride and ferric oxide gel-carbon tetrachloride.
These characteristics form a convincing evidence in support of the cavity concept.
Volume 16 Issue 4 October 1942 pp 301-304
In a series of sorptions and desorptions of carbon tetrachloride at 30°C. on titania gel, a permanent hysteresis effect is obtained. The hysteresis loop has been reproduced in the twelfth cycle of sorption and desorption.
The reproducible hysteresis loop has been scanned. The general characteristics of the results on scanning are in conformity with those of other systems, titania gel-water, silica gel-water, alumina gel-water, silica gel-carbon tetrachloride, ferric oxide gel-carbon tetrachloride.
The hysteresis effect in sorption is caused by cavities in the porous adsorbent. The shape and size of the hysteresis loop are dependent upon the shape and size of the cavities and are independent of the nature of the adsorbate. The general characteristics of the results on scanning of the hysteresis loop are independent of the nature of the adsorbent and adsorbate. These characteristics are explainable only on the basis of the cavity concept.
Volume 16 Issue 4 October 1942 pp 305-306
Sorption and desorption of water vapour at 30° C., 35° C. and 40° C. on silica gel have been conducted. The hysteresis effect is exhibited at all these three temperatures and the hysteresis loops are all identical.
Such an identity of the hysteresis loops, at different temperatures, in any rigid porous adsorbent is satisfactorily explainable in the light of the cavity concept.
Volume 17 Issue 2 February 1943 pp 46-49
In a system of closely packed spherical particles, formation of two different types of capillaries cavities and open pores—is indicated.
Assuming spherical particles of equiradius, the volume of an open pore is calculated in relation to particle radius. The total open pore is calculated in relation to particle radius. The total open pore volume just as the total cavity volume, decreases as the particle radius increases.
The ratio of the open pore volume to the cavity volume increases as particle radius increases. The value of this ratio when the particle radius is increased to the maximum limit at which the whole mass consists of four spheres producing a cavity and four open pores is twice the value when the particle radius tends to the limiting value of zero.