Physicochemical Properties and Heavy Metal Content of Mpraeso and Vume Clays of Ghana

Earthenware clay deposits used in producing ceramics may be a potential source of heavy metals that could leach into food prepared in them. However, little attention has been focused on the heavy metal concentrations in these clays. The study was carried out to determine the physicochemical properties and heavy metal concentration of clays in two popular traditional earthen ware production centres in Ghana; Mpraeso and Vume which produce lot of traditional pottery for food preparation in most homes in Ghana. Munsell Colour Chart was used to determine the colour of the clays. While the pH and EC of samples were measured using pH and EC probe. Heavy metals (Cd, Pb, As, Fe, Zn, Co, Ni, Mn, Cr and Cu) were analysed by atomic absorption spectrometry. Both clays were of hue properties with Mpreaso having a range of 2.5- 5YR described as pale to light yellow whiles Vume hue range was between 7.5-10YR described as orange to dull yellowish colour by the Munsell colour chart. The grains of both localities were very fine of less than 4µm. The pH results of three types of pottery materials (raw clay, additive and mixed clay) showed most samples been slightly acidic with a few alkaline ones ranging from 5.2-8.9. The EC of these pottery materials also ranged from 2.2-653. Results of AAS on metals analysed were found to be within the FAO/WHO and EU limits except Cd (4.4- 11.2) in Vume clays and Ni in Mpraeso (52-115) and Vume (61.4-93.3) pottery materials. With the exception of Cd and Ni which need some remediation, the quality of pottery materials used in Mpraeso and Vume were found to be generally good for earthenware production.

Keywords: Atomic Absorption Spectrometry Analysis; physicochemical properties; heavy metal concentration; clays; ceramics; pottery; Mpreaso; Vume.