Activated Carbon for Removing Tetrachloroethylene from Alcohol Solutions

Alcohol (cosolvent) flooding is a relatively new, in situ technique for enhancing the removal of organic solvents from groundwater aquifers. Recovery of the alcohol for reinjection is important for ensuring the cost-effectiveness of this technology. The research goal was to investigate the ability of activated carbon to remove tetrachloroethylene (PCE) from alcohol solutions, allowing reuse of the alcohol in the cosolvent-flooding process. Laboratory studies were conducted using PCE (concentrations ranged from 10 to 100,000 mg∕L) and isopropyl alcohol or ethanol. Alcohol concentrations ranged from 0 to 80% (v∕v). A field application conducted at the Dover National Test Site in Delaware consisted of treating 60 to 70% (v∕v) ethanol solutions containing PCE concentrations ranging from 500 to 2,000 mg∕L with carbon-filled drums. PCE adsorbed onto activated carbon even at high alcohol concentrations; however, the Freundlich coefficient (Kf) was reduced by almost two orders of magnitude with increasing alcohol concentrations. In the field, activated carbon successfully treated ethanol solutions, allowing alcohol reinjection in the cosolvent flood. The results demonstrated technical and economic feasibility of the reuse of alcohol from cosolvent-flooding activities.