Vibrating pervaporation modules: Effect of module design on performance

A commercial-scale vibrating pervaporation membrane module was fabricated and evaluated for the separation of volatile organic compounds (VOCs) from aqueous solutions. Experiments with surrogate solutions of four hydrophobic VOCs (1,1,1-trichloroethane (TCA), trichloroethylene (TCE), tetrachloroethylene (PCE), and methyl t-butyl ether (MTBE)) were performed. VOC removal performance for this module was compared to published data for two earlier full-scale vibrating modules of the same general design, but differing in design details. The three modules differed in membrane material (and membrane thickness), membrane area, liquid flow pattern, and permeate vapor pathway. A thinner membrane, less restrictive permeate pathway, and higher cross-flow liquid velocity were generally observed to improve performance, although each factor is expected to have a limit. The third module was also tested for the removal of hydrophilic organic compounds from water, including acetone, ethanol, n-butanol, and isopropanol. Process variables studied were vibrational amplitude, temperature, and liquid flow rate. As in previous studies, even small vibration amplitudes yielded significant performance gains. Performance of the vibrating systems was found to be similar to that of non-vibrating alternatives.