Cation interception and permeability characteristics of bentonite barriers exposed to NaCl and NH 4 Cl solutions.

High concentrations of Na + and NH 4 + in landfill leachate lead to deterioration of bentonite barrier and pose a threat to the environment. This study focused on the pollution interception and permeability characteristics of the bentonite barrier exposed to NaCl and NH 4 Cl solutions. Based on previous findings, salt solution concentrations were established at 74.80, 37.40, 18.70, and 9.4 mmol/L. The bentonite contents in the mixture were set at 0, 5, 10, and 15%. The results indicate that the samples exhibit better interception of NH 4 + compared to Na + . This difference arises from the cation exchange sequence, the size of the hydration radius, and the hydrogen bonding of the two cations. Additionally, the difference in hydration enthalpy between the two cations leads to variations in the swelling of bentonite, resulting in a higher hydraulic conductivity coefficient in NH 4 Cl solution. This study shows that although bentonite barriers have better interception for NH 4 + , they exhibit greater hydraulic conductivity in NH 4 Cl solution, increasing the risk of leachate carrying other contaminants.