No abstract

The earliest recorded mention of clay consumption for healing remedy originated approximately 5,000 years ago. But edible clays have been implicated to contain microbial and metallic contaminants despite the inherent medical benefits. This work reports the remediation of some heavy metals, radionuclides and bacterial load from edible kaolin from Kankara, Nigeria. The remediation increased the pH of the samples except when HCl was used; though the colour and taste remained unaltered. The best extractant for arsenic in the kaolin sample was 0.1M HCl with efficiency of 19%, H2O with efficiencies of 98% and 75% was best for removal of Cr and Pb respectively. The extraction resulted to significant reduction of the concentrations of Cr and Pb in the clay(P < 0.05).The remediation of 232 Th and 238 U was best by using surfactant solution (Sodium dodecyl sulphate, SDS)with efficiencies of 46% and 35% respectively;while 0.1M CaCl2 with 17% efficiency was the best for 228 Ra removal. All the clay samples were contaminated with bacteria. Therefore, soil washing technique can be employed to reduce contaminants in edible clay while maintaining the inherent medical benefits of geophagy.