Effect of Zeolite Content on Permeability of Stone Chip-Bentonite-Zeolite Mixture Using a Single Solution

Abstract

Bentonite is frequently utilized as a landfill lining material due to its high impermeability. Due to the fact that heavy metal ions in leachate can alter the permeability of bentonite liner, the impermeability and metal adsorption effect of bentonite liner is typically enhanced by the use of external admixtures. In this investigation, zeolite was combined with stone chips and bentonite. Using a flexible wall permeation test, zeta potential test, and X-ray diffraction test, the effect of zeolite on the permeability and adsorption properties of the mixture was investigated. The results indicate that the addition of zeolite can enhance the impermeability of the mixed soil. The permeability coefficient of the mixed soil in DIW is 3.74 × 10−7 cm/s when bentonite is incorporated at 11% and decreases to 6.55 × 10−8, 4.65 × 10−8, and 5.10 × 10−8 cm/s when 12.50%, 25%, and 50% of zeolite are incorporated; the permeability coefficient of the mixed soil in DIW was 3.74 × 10−7 cm/s when the permeate concentration was 0.01 mol/L of ZnCl2 solution, the permeation coefficients were 5.73 × 10−7, 5.98 × 10−8, 5.8 × 10−8, and 5.7 × 10−8 cm/s when the zeolite doping was 0, 12.50, 25, or 50%, respectively, and the Zn2+ concentration of the leachate decreased compared to the no-zeolite case by 92.48, 97.29, and 98.65%, respectively; the competitive adsorption of metal ions by zeolites in ionic solutions of different concentrations reduced the ionic concentration in the solution and decreased the inhibition of bentonite swelling, while the adsorption characteristics of stone chip-bentonite-zeolite mixture on Zn2+ were measured by the Langmuir and Freundlich et al. model.