Influence of the Presence of Zinc on the Behaviour of Bentonite

Abstract

In landfill disposal sites, bentonite is used as liner material because of its high contaminant adsorption limit, high swelling capacity and low hydraulic conductivity. However, the effectiveness of liner may reduce due to the chemicals present in the leachate. Swelling and sorption capacity of bentonite may effect in the presence of various chemicals present in the leachate, which in turn reduces the thickness of the diffuse double layer (DDL). Consolidation is an important parameter of liner material, which is essential for settlement calculation. Therefore, it is necessary to study the change in the behaviour of bentonite in the presence of heavy metal. In this investigation, the effects of zinc (Zn2+) of varying concentrations were studied on the behaviour of bentonite. Solutions of zinc 0 (i.e. de-ionized (DI) water), 100 and 1000 ppm concentration were prepared by dissolving salts of zinc nitrate. The results revealed that rate of consolidation and hydraulic conductivity increases with the increase in concentration because of the presence of Zn2+ in pore water. However, liquid limit, swelling pressure and swelling potential were decreased. Results also illustrate that at higher concentration, the impact of Zn2+ on the behaviour of the bentonite is more significant.