Barrier Performance of Bentonite-Polyacrylate Nanocomposite to Artificial Ocean Water

Abstract

The hydraulic conductivity and typical indicator parameters (viz. swell index, fluid loss) of a bentonite-polyacrylate nanocomposite (BPN) to artificial ocean water is evaluated. Thin layers of BPN and Na-bentonite simulating geosynthetic clay liners (GCLs) were permeated directly in flexible-wall permeameters under low average effective stress (20 kPa). BPN retained low hydraulic conductivity (less than 1.8 x 10 -12 m/s) to artificial ocean water at hydraulic and chemical equilibrium termination criteria. In contrast, Na-bentonite permeated with artificial ocean water had a hydraulic conductivity at least 4.5 orders-of-magnitude higher. BPN maintains low hydraulic conductivity in artificial ocean water despite having a low swell index (9.0 mL/2 g), similar to Na-bentonite in the same solution (9.3 mL/2 g). Despite low swelling, BPN exhibited a low fluid loss (8.1 mL) similar to BPN in deionized water (6.5 mL) and 8-times lower than Na-bentonite in artificial ocean water (66 mL). These data illustrate that BPN can be used to prevent saltwater intrusion, or for the containment of sodic solutions, but that swell index is not an accurate indicators for the hydraulic conductivity of BPN. Fluid loss appears to be a more useful indicator parameter for BPN.