(354i) Development of Pervaporation Membranes for Water Separations

Pervaporation is a membrane process that operates off of a vapor pressure differential between the feed and permeate sides of the membrane. Unlike other membrane processes such as reverse osmosis (RO) or membrane distillation (MD), pervaporation realizes separation by the application of either a sweep gas or vacuum pull on the permeate side of the membrane. While RO is one of the most common methods of water purification, it is limited in scope as conventional RO usually does not handle feed streams with a total dissolved solids (TDS) above 45 g L^-1. Pervaporation can handle highly contaminated feed streams not available to RO due to the fact is does not rely on hydraulic pressure on the feed side of the membrane. Additionally, while MD is an effective separation method, the porous, hydrophobic nature of MD membranes make them unsuited to certain conditions, such as when there are organic species present in the feed stream. Pervaporation can be tailored for specific species removal, with either hydrophilic membranes selecting for water transport, or hydrophobic membranes selecting for organics transport. Due to the tuneability of pervaporation membranes, they can also separate azeotropic mixtures not available to traditional thermal distillation methods. While pervaporation is a versatile process that can handle a variety of feed conditions, there is still room for improvement in membrane performance to better optimize process performance. This work will detail recent efforts our group has undertaken to develop pervaporation membranes with optimal water passage and contaminant rejection.