<p>The hydraulic conductivity (HC) of landfill liners exposed to inorganic salt solutions exhibits mass transfer effects leading to increased permeation of contaminants. Though diffusion is considered as the primary mass transfer mechanism, the thermochemical attributes of the charged species (preferably cations) cause further mass transfer limitations on the interception and migration that need further attention in order to elucidate the driving factors. The present study is focused on evaluating the hydraulic and mechanical behavior of modified geosynthetic clay liner (GCL) composite subjected to different molar concentrations (MC) of NaCl, NH₄Cl, and CaCl₂ salt solutions. An innovative blend of native black cotton soil (BCS) (with an optimized proportion of 25%) along with an anionic polymer (8% carboxymethyl cellulose) added with bentonite is fabricated and tested in a flexible wall flow cell to evaluate the functional restrictions of GCL under diverse hydraulic conditions. The results demonstrated that increasing the proportion of BCS in conjunction with higher salt solution concentrations led to a reduction in HC up to the 25% BCS level. Likewise, at 20 and 50&#xa0;mM salt concentrations, a marked decline in HC was observed with increasing BCS content. The statistical analysis demonstrated a direct relationship between the HC and MC values and an inverse relationship with swell index values. In conclusion, the hydraulic barrier performance reflected the microstructural changes induced by the thermochemical interactions of the transmigrating ions, thereby confirming the cation interception effects of the GCL.</p>