New methods for scalable water desalination has been identified as the most impactful and necessary scientific technology for human prosperity in a 2015 report by the Institute for Globally Transformative Technologies, surpassing malaria vaccines, synthetic fertilizers, and improved TB drugs. Due to the climate change, rapidly expanding global population, and worldwide water scarcity, the demand for purification of non-traditional sources such as brackish and seawater with low environmental impacts is extensively growing. There is an increasingly urgent need for low-cost methods for water desalination that can effectively couple to, or piggyback on, renewable energy sources. In this talk I will describe our efforts in developing new materials to enhance the efficacy and utility of forward osmosis using new plasmonically-enhanced hybrid materials.

Classical membrane-based water separation and purification processes such as forward osmosis (FO) is gaining renewed attention as a potentially low-energy alternative technique to energy intensive methods such as distillation, reverse osmosis (RO), multiple effect distillation (MED), etc. Unlike RO, the industry standard for desalination, where energy intensive hydraulic/external pressure drives water flow, here an internal pressure (osmotic) drives flow. It has the characteristics of no/low pressure operation compared to standard RO processes. Consequently, membrane fouling is potentially much less severe and thinner membranes can be used. These advantages make FO extensively applied to a variety of fields to date, which could potentially relieve the stress of freshwater scarcity. As the draw solution is one of the main contributing factors to the FO process, the lack of suitable draw agent has become the obstacle jeopardizing the real application of FO in desalination process. In general, an ideal draw agent needs to provide high osmotic pressure and expel water from itself with minimal energy input. Present FO technology relies on either non-reusable draw agents or draw agents that require complicated process for regeneration.

This talk will discuss development of new classes of inorganic/organic hybrid draw agents, which exhibit high osmolalities and easy regeneration process by utilizing industrial waste heat or naturally abundant (solar, geothermal) sources. Results on the design, performance, and integration of these new draw agents will be discussed.