An investigation into the adsorption of sulphate onto mica surfaces

Abstract

There are some known phenomena in soil chemistry, radiochemistry and analytical chemistry which are difficult to explain in terms of known physical chemical phenomena. Among these is the apparent absorption of anions onto cation exchange materials. The purpose of this investigation is to study, in particular, sulphate adsorption onto a mica surface. There are several reasons why mica was chosen as the adsorbing surface. The structure of mica has been extensively studied by Pauling Pauling, L. - The Structure of Micas and Related Minerals. Proc. Natl. Acad. Sci., U.S., 16, 123-129 (1930). (1930), Hendricks and Jefferson Hendricks, S.B., and Jefferson, M. - Polymorphism of the Micas with Optical Measurements. Am Mineral, 24, 729-771 (1939). (1939), Jackson and West Jackson, W.W., and West, J. - The Crystal Structure of Muscovite. Z. Krist., 76, 211-227 (1930)., Jackson, W.W., and West, J. - The Crystal Structure of Muscovite. Z. Krist., 85, 160-164 (1933). (1930, 1933).Consequently, the nature of the surface of mica is well known and it would be of interest to soil chemists to study anion adsorption onto a known clay mineral surface. Mica is distinguished by a perfect basal cleavage which causes it to split into thin elastic plates. The surfaces of these plates are smooth down to a molecular level. The mica surface is very similar to that of many clay minerals (e.g., one surface of Halloysite, one surface of Kaolinite, and both surfaces of Montmorillinite). End window geiger counters provide an extremely simple method of measurement of adsorption onto a mica surface. Commercial end window geiger counters are manufactured with mica windows, which is particularly fortunate for the studies of fundamental phenomena of interaction of adsorbed ions. This technique should, then, provide a method of study of some of the fundamental problems in soil chemistry.