Influence of deposition of a porous material layer on mechanical properties of membranes by using a tissue tester Authors: Anne Barlas, Marcia R. Silva*, Byron Edwards and David Garman School of Freshwater Sciences – Water Technology Accelerator (WaTA), University of Wisconsin-Milwaukee, 247 W. Freshwater Way, Milwaukee, Wisconsin, 53204 (USA).*E-mail: msilva@uwm.edu.

Outline Introduction Methodology: Synthesis of Membrane Methodology: Tensile Test Results Future Research Acknowledgements Sources Questions

Introduction One of the most common water technologies used to produce high-quality clean water from unusable water is by use of membranes [1]. These are very effective purification systems but their efficiency is reduced by biofouling, shown in Figure 1. By combining multiple treatment techniques, biofouling can be reduced [2]. Figure 1: Biofouled membrane

Introduction Continued Tissue testing equipment shown in Figure 2 has historically been applied in the medical and biological fields of research. This project seeks to explore how the technology can be applied to membranes for water filtration. Figure 2: Tissue Tester

Methodology: Synthesis of Membrane The first membranes were synthesized using a vacuum pump, shown in Figure 3. Porous material was mixed into a slurry, and deposited onto a membrane as shown in Figure 4. This represents Membrane Version 1. The membrane was dried, and put into tissue testing machine. Figure 3: Vacuum Pump Figure 4:Membrane Version 1

Methodology: Synthesis of Membrane Evolution of Version 2 Membrane Nucleation begins on Amorphous layer placed on support Crystallization of porous material on Amorphous layer Crystallization complete 24 hours 36 hours 0 hours This represents Membrane Version 2. This membrane is currently being developed following the above procedure [3].

Methodology: Tensile Test Figure 5 represents the live feed resulting from the tissue tester. Live video and graphs were the output of the test. Figure 5: Live feed from tissue tester The Plain Membrane and Membrane Version 1 were stretched to failure to develop mechanical profile. This is shown in Figure 6. Figure 6: Tensile test resulting in failure of membrane

Results Figure 7: Stress-Strain Relationship Comparison Results indicate that porous material layer on Membrane Version 1 improved membrane’s mechanical profile. The membrane exhibited a 2% increase in elongation compared to a plain membrane.

Future Research Synthesize membrane using crystallization technique. This will represent Membrane Version 2. Preform tensile test on Membrane Version 2 and compare with Membrane Version 1 and Plain Membrane. Expected outcomes include that Membrane 2 will have a weaker mechanical profile than Membrane 1 due to gel structure. Pair Version 1 Membrane and Version 2 Membrane with commonly used membrane such as reverse osmosis (RO). Quantify decrease in biofouling.

Acknowledgements The authors acknowledge Barlas’ Senior Excellence in Research Award for making this project possible. The authors thank Heather Owen for her assistance in developing test parameters.

References Figure 1: Fouled membrane image: global-membrane.com Figure 2: Tissue Tester image: cellscale.com [1] Miller, Benny D. Freeman, James E. McGrath, and Donald R. Paul. "Water purification by membranes: The role of polymer science." Journal of Polymer Science Part B: Polymer Physics. Wiley Subscription Services, Inc., A Wiley Company, 25 June 2010. Web. 21 Mar. 2017. [2] "Coupling of membrane processes for brackish water desalination." Coupling of membrane processes for brackish water desalination - ScienceDirect. N.p., n.d. Web. 21 Mar. 2017. [3] Xu, X., W. Yang, J. Liu, and L. Lin. "Synthesis of a High-Permeance NaA Zeolite Membrane by Microwave Heating." Advanced Materials 12.3 (2000): 195-98. Web

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