TITLE:
Surface Cation Exchange Capacity Measurements on Solid and Pulverised Granitic Rock Samples
AUTHORS:
Ebong Fidelis Sameh, Asoba Gillian Nkeudem, Nick Evans
KEYWORDS:
Exchange Capacity, Granitic Material, Leached Elements
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.14 No.1,
January
30,
2026
ABSTRACT: CEC, a major control on the distribution of mobile cationic species between the mineral phase and pore water or groundwater. It influences retention and release of essential nutrients in soil systems, or mobility, retardation, and migration of contaminants in the environment. Many analytical methods to estimate CEC have been developed using BET surface area measurement. This study aimed at determining the CEC of granitic samples in both the powdered and intact state. Two ways of measuring cation exchange capacity were studied, utilising rock beakers designed at the British Geological Survey using Biotite Mica, Muscovite Mica and Weardale Granite. The rock beakers together with the powered samples were used in cation exchange experiments. The Bascomb method buffered at pH of 8.1 was used. Granitic samples were used. 1 g of pulverised granitic samples using 50 cm3 of buffered reagents (mixture of BaCl2, triethanolamine, and 2 mol·dm−3 HCl) in a dual wash process, equilibrating for 24 h, followed by elemental analysis using ICP-AAS. K is the most leached element from the granitic rocks studied. After background reductions the effective metal concentration of metals leached was in the order K >> Ca > Fe, this is probably the case due to the high content of feldspars, which are rich in K. a relationship between the CEC of an intact sample and a crushed sample is established considering a unit surface area of both the crushed and intact samples. However, this relationship showed a vast difference between the CEC of the intact sample and the crushed sample.