Alternative Sorbents for Removing MTBE from GasolineContaminated Ground Water

The objective of this work is to provide a preliminary screening of the effectiveness of alternative sorbents for treating ground water contaminated with methyl tert-butyl ether (MTBE). Sorbents studied include synthetic carbonaceous resins, porous graphitic carbon, C18 silicas, and acrylic resins. Activated carbon was also tested for comparison purposes. Bottle point isotherms show that porous graphitic carbon and two synthetic carbonaceous resins have a greater capacity for MTBE than activated carbon. However, the required addition of a wetting agent to suspend and activate the porous graphitic carbon makes this sorbent unsuitable for drinking water purposes. The synthetic carbonaceous resins tested were found to have capacities three to five times greater than activated carbon at an MTBE concentration of 1 mg/L. The application of the DubininAstakov isotherm to data for the synthetic carbonaceous resins suggests that the mechanism of adsorption is micropore filling. Additional bisolute experiments with mxylene as a representative gasoline contaminant indicate that the m-xylene is preferentially sorbed, depleting the micropore volume available for MTBE sorption. The extent of this competitive adsorption was directly predicted from measured concentrations of the monoaromatic hydrocarbon.