Organoclay Amended Bentonite for Enhanced Barrier Performance under Lead (II) Permeation

The current study investigated the comparative hydraulic barrier performance of two liner materials, compacted bentonite and organoclay-amended bentonite (BNC), in the presence of lead (Pb²⁺) contaminants. Laboratory experiments were conducted to assess the physico-chemo-hydro-mechanical performance of both liner materials. The zeta potential and adsorption behaviour of bentonite and organoclay under lead ion permeation were experimentally analysed. Additionally, the pH variation, swelling behaviour, consolidation parameters, compressibility characteristics, and hydraulic behaviour of bentonite and BNC were examined in the presence of varied Pb²⁺ concentrations, supported by microstructural investigations. The results indicated that increased lead ion concentrations led to a decrease in zeta potential and an increase in metal adsorption capacity for bentonite and organoclay. Additionally, the rise in Pb²⁺ concentrations increased hydraulic conductivity while reducing pH, liquid limit, swelling, and compressibility of both bentonite and BNC. However, the extent of these variations was notably less for BNC compared to bentonite, indicating its lower chemical sensitivity and higher mechanical stability under Pb²⁺ permeation. The findings suggest that organoclay-amended bentonite exhibits superior barrier performance compared to conventional bentonite, particularly at elevated concentrations of Pb²⁺ ions, making it a viable choice for hydraulic barriers in hazardous landfills and tailing impoundments.