Abstract
M.Tech. (Extraction Metallurgy)
Clay and its associated minerals are crucial materials with various applications ranging from industrial, health to traditional activities. Since time immemorial, the application of clays for traditional and health purposes have remained evident amongst Africans and rapidly gaining grounds in the world at large. Indigenous knowledge has constantly supported geophagia – the deliberate consumption of earthy material for several benefits such as mineral supplement to the body and treatment of diseases. In Southern Africa, geophagia is becoming a common practice irrespective of the social class, age and religion of the geophagists. Few reports on the characterisation of geophagic clays are available but none had considered probiotics and volatile fatty acids. Characterisation plays a vital role in the study of geophagic clays, as it provides useful information about the safety of its application by humans. The quality of such earthy material had been solely based on characterisation, which stirs issues of safety and environmental health. It was therefore imperative to consider other studies beside characterisation of geophagic clays to better appreciate the effects upon consumption by humans.
Probiotics are known to be beneficial as they help maintain a healthy gut in humans. The effect of clays on these microorganisms and the possible impacts on humans is necessary. This current research study considered the application of Atomic absorption spectroscopy (AAS) together with Infrared fluorescence (XRF) and Infrared diffraction (XRD) as well as a front-line chromatographic and mass spectrometric analytical technique, i.e. two dimensional gas chromatography coupled with a time-of-flight mass spectrometry (GC×GC-TOFMS) for investigating the production of volatile fatty acids (VFAs) by the probiotics upon interaction with geophagic clays.
The first phase of the study considered the physicochemical characterisation of geophagic clays sold in informal South African markets using 2g of the various samples moistened with 100mL of 0.5M, 1M and 2M HCl acid. The subsequent analysis of the filterate on AAS revealed the different clay samples containing several heavy metals such as copper (Cu), lead (Pb), zinc (Zn), iron (Fe), cobalt (Co), manganese (Mn), chromium (Cr). These heavy metals have been reported to have deleterious effects on humans when above the minimum permissible level. Further analysis using infrared fluorescence indicated average values of major elements such as SiO2 (54.02%), Al2O3...