Hydrophobic hollow fiber membranes for treating MTBE-contaminated water.

Soluble contaminants with low Henry's constant, such as methyl tert-butyl ether (MTBE), require innovative solutions for water treatment. Given the increased frequency at which MTBE is detected at contaminated sites, the development of new technologies is of considerable relevance. Hydrophobic hollow fiber membranes (HFM), used in industrial and medical applications, have interesting physicochemical properties that make them particularly suitable to deal with these contaminants. The hydrophobicity of the fiber maintains adequate separation between aqueous and gaseous phases, permitting an efficient separation of volatile and semivolatile compounds from water to gas. The hollow nature of the fiber and its high porosity permit high rates of mass transfer across the membrane. The mass transfer process can be accelerated using pervaporation and by increasing the solution's temperature to increase the Henry's constant and the overall mass transfer coefficient. In these studies, we evaluate the removal efficiency of MTBE from water using a commercial HFM module and develop the corresponding dimensionless mass transfer correlations necessary for the design of industrial-scale systems. We found that the Lévêque correlation for the tube-side mass transfer coefficient is in general applicable for MTBE pervaporation through a hydrophobic HFM. MTBE removal is a strong function of membrane length, water flowrate, and solution temperature but is almost independent of gas-phase parameters.