Impact on Bentonite Due to the Presence of Various Concentrations of Lead and Copper Solutions

Abstract

Heavy metals are directly introduced to the environment, groundwater and waterways by means of several industrial activities. Migration of metal from the landfill to the surrounding environment is a serious environmental issue worldwide. A liner is a low permeable material used in the waste disposal sites to prevent the migration of toxic pollutants to contaminate the surrounding atmosphere and groundwater resources. Compacted bentonite is used as a liner material because of its high sorption capacity, low hydraulic conductivity and high swelling capacity. The presence of chemicals in the leachate can shrink the thickness of the diffuse double layer (DDL) and may reduce the effectiveness of the liner by reducing its swelling capacity and increasing hydraulic conductivity. Therefore, in the present study, high swelling bentonite is analysed on the change in their behaviour due to the presence of copper (Cu2+) and lead (Pb2+) solutions. One of the essential behaviours of bentonite is consolidation, which is necessary for investigating the settlement analysis of the liner. The study was conducted to determine the impact of lead (Pb2+) and copper (Cu2+) solutions of different concentrations, on the consolidation behaviour of bentonite. In the existence of lead (Pb2+) and copper (Cu2+) of concentrations of 0, 500 and 1000 mg/L, various consolidation parameters, such as compression index (Cc), coefficient of consolidation (cv), volume change (mv) and time, are required for the completion of 90% of consolidation (t90), which were studied. Result shows that cv increases with an increase in concentration of the heavy metal, whereas Cc, mv and t90 of the bentonite decrease. The study also indicates that the rate of consolidation of the bentonite increases in the presence of copper and lead. The results of this study may deliver a general idea for estimating the liner performance in the presence of different kinds of toxic chemicals existing in the leachate.