Design Principles, Analytical Methods, and Membrane Development for High-Pressure Reverse Osmosis

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In the proposed work, we are partnering with a water-engineering firm with the primary aim of developing membrane materials that extend the operating range of reverse osmosis (RO). In RO, the applied hydraulic pressure must exceed the solution's osmotic pressure, which is a function of the salinity of the solution. Current membranes have typical maximum pressures of ~80 bar (~1200 psi), enabling a maximum salinity of ~1.4 M NaCl. We aim to develop membranes that operate up to ~150 bar (~2200 psi), almost doubling the attainable salinity to ~2.7 M NaCl. This high-pressure RO (HPRO) would be revolutionary for water management in the Canadian natural-resource industries, including mining, oil & gas, and pulp & paper. HPRO would efficiently maximize water recycling while minimizing waste for disposal. Our work will be divided into four main aims. In the first, we will assess the performance (and limitations) of current RO membranes at pressures up to 150 bar, particularly aiming to understand how performance is impacted by "compaction." In this process, the porous structure of the membrane becomes denser (less porous) because of the applied hydraulic pressure. The effect of compaction on transport remains understudied. In the second aim, we will use advanced microscopy tools to assess in detail how compaction impacts the pore structure of the membranes. In the third aim, we will use machine learning to develop a tool that would generate statistical 3D pore structures based on 2D electron micrographs. Such a tool would enable rapid generation of important pore structural data, which currently can only be assessed using highly time-intensive analytical tools. The tool will be useful for studying compaction. In the fourth aim, we will use high-throughput experimentation to optimize membrane synthesis, with the goal of creating membranes that will be resistant to compaction. Through this research scope, we hope to develop innovations that will be translated into commercial HPRO products for use by Canadian resource industries.