Sorption of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) to synthetic resins.
Me tert-Bu ether (MTBE) is a widely used gasoline oxygenate. Contamination of MTBE and its major degrdn. product tert-Bu alc. (TBA) in groundwater and surface water has received great attention. However, sorption affinity and sorption mechanisms of MTBE and TBA to synthetic resins, which can be potentially used in removal of these contaminants from water, in passive sampling, or in enrichment of bacteria, have not been studied systemically. In this study, kinetic and equil. sorption expts. (single solute and binary mixts.) on four synthetic resins were conducted. The sorption affinity of the investigated sorbents for MTBE and TBA decreases in the order Ambersorb 563 > Optipoer L493 > Amberlite XAD4 > Amberlite XAD7, and all show higher sorption affinity for MTBE than for TBA. Binary expts. with o-xylene, a major compd. of gasoline as co-contaminant, imply that all resins preferentially sorb o-xylene over MTBE or TBA, i.e., there is sorption competition. In the equil. aq. concn. (Ceq) range (0.1-139.0 mg/L for MTBE, and 0.01-48.4 mg/L for TBA), exptl. and modeling results as well as sorbent characteristics indicate that micropore filling and/or some other type of adsorption process (e.g., adsorption to specific sites of high sorption potential at low concns.) rather than partitioning were the dominant sorption mechanisms. Optipore L493 has favorable sorption and desorption characteristics, and is a suitable sorbent, e.g., in bacteria enrichment or passive sampling for moderately polar compds. However, for highly polar compds. such as TBA, Ambersorb 563 might be a better choice, esp. in water treatment.
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