DEVELOPMENT OF REACTIVE BARRIER MATERIAL FOR USE IN LANDFILL LINERS AND IN-SITU BARRIERS TO IMMOBILIZE CHROMIUM

This paper presents the development of a reactive media that consists of treatment mixtures of iron oxide coated sand (IOCS) and kaolin (K), known as Reactive Barrier Material (RBM), to use as liner or barrier material for effective containment of toxic hexavalent chromium (Cr(VI)). A series of batch kinetic experiments show that at equilibrium time, the percentage removal of Cr(VI) varies from 65 to 70% tested at initial pH of 8.61 ± 0.1. The percentage removal of Cr(VI) was decreased from 49 to 54% as sorbate concentrations in the solute were increased from 10mg/L to 50 mg/L keeping other experimental conditions similar. The results of isothermal studies conducted at different pH values show that adsorption data satisfied both the Langmuir and Freundlich isotherm models. The effect of pH on the Cr removal was negligible by RBM; however, the maximum sorption occurred at about pH 5.0 - 6.0 under the experimental conditions. The effective removal of Cr(VI) by RBM under dynamic flow conditions (column studies) suggests that RBM may be a viable alternative material to use in landfill liners to effectively contain Cr(VI) in leachate and in in-situ barriers to treat groun dwater contaminated by Cr(VI).