Soils with low permeability are widely used in solid waste landfills to prevent leakage of leachate into groundwater. By adding nanomaterials to clay soils, the permeability of the clay can be reduced as well as the retention of pollutants in the leachate. In this study, three different nanomaterials, iron oxide, aluminum oxide, and Oltu clay, were added to kaolin at two different rates (1% and 5%), and the effect of nanomaterials on permeability and heavy metal (iron, manganese, zinc, copper, and lead) removal rate was investigated. According to the experimental results, permeability decreased, and the heavy metal removal rate increased with increasing nanomaterial content in kaolin. With the addition of 5% iron oxide, 5% aluminum oxide, and 5% Oltu clay to kaolin, the average permeability decreased by 63%, 81%, and 96%, respectively. Iron (90-93%), manganese (47-75%), zinc (39-50%), copper (33-41%), and lead (36-49%) removal rates of nanomaterial-added kaolin samples were found to be higher than the removal rates of kaolin without nanomaterial addition. Oltu clay, which has the smallest size and high surface area, performed better than aluminum oxide and iron oxide in reducing the permeability of kaolin and retaining heavy metals.