Membranes for Clean Water

The goal of this project is to develop quantitative
measurement methods for determining the structure, dynamics, and mechanical properties of polymer membranes used in water purification, enabling access to clean, safe, and affordable water. These measurement tools will enable industry to identify the fundamental properties of polymeric membranes that govern water transport, solute rejection, degradation, and fouling.

 

Highlights:

Soft Materials Buckle Up for Measurement

New Test Measures Key Properties of Polymer Thin Films and Membranes

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Membrane-based water purification technologies, such as reverse osmosis (RO), forward osmosis (FO) and nanofiltration (NF), rely on a very thin active layer traditionally comprised of a interfacially polymerized polyamide. Since these membranes are formed by diffusion of reactants through an actively-forming, highly crosslinked film, the resulting membrane structure is ill-defined and highly heterogeneous, making accurate measurements of the membrane structure/property relationships difficult. To this end, we are developing model membranes with defined structure to facilitate the development of measurement platforms for interrogating the fundamental aspects of transport in thin film composite (TFC) membranes.

 

Moreover, commercial TFC membranes are known to undergo chemical degradation due to the introduction of chlorine to prevent membrane fouling. We are developing measurement techniques to quantify the effect of chlorine degradation on the mechanical properties of the active layer in these types of membranes. Our approach combines surface wrinkling and thin film cracking to probe the elastic modulus, tensile strength and fracture strain of the active layer as a function of chlorine exposure. We relate our results to structural changes in the membrane due to disruption of internal hydrogen bonding upon chlorination.