With the world’s population growing rapidly, the need for clean water is greater than ever. Among water purification methods, membrane-based separations draw attention because of their energy efficiency (unlike distillation, they do not require an energy-intensive phase-change step), small footprint, and ability to eliminate trace contaminants. In particular, desalination using reverse osmosis (RO) membranes is an economically competitive method for obtaining clean water from salt water. As a result, 60% of the production in desalination plants worldwide relies on RO membranes, and the market share is expected to increase in the coming years. However, only a few membrane materials and formation methods are used in industry today, and current desalination membranes often lack the chemical stability for use with chlorine, a disinfectant used in over 98% of all water treatment facilities. Moreover, most membranes currently used in industry are prepared by solvent processing using large volumes of hazardous solvents. Despite the negative environmental impact, solvent processing is the only method to form thin film membranes on the order of 10-200 nm thickness. Therefore, there is a great need to prepare highly chlorine-tolerant desalination membranes without using toxic solvents.<br/><br/>Here, in stark contrast to conventional solvent processing, robust ion-exchange membranes based on chlorine-tolerant sulfonated polysulfones were prepared by solvent-free melt processing for water purification and desalination, for the first time. Sulfonated polysulfones have been explored as candidate materials for desalination and power generation because of their low cost, excellent transport properties, and strong chlorine tolerance. Sulfonated polysulfone thin film membranes were produced without using solvent with the aid of adequate miscible additives. The transport mechanism in the polymer membranes is studied from the fundamental perspectives of polymer-penetrant interactions and templating diffusion pathways for selective transport of small molecules. The transport of small molecules in resultant membranes is significantly affected by different membrane formation methods.

Highly chlorine-tolerant desalination membranes by solvent-free melt processing

2019 Fall National Meeting

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