On performance of polycarbonate/silica aerogel nanoparticle mixed matrix hollow fiber membrane coated with polydimethylsiloxane for membrane distillation

The membrane distillation process is one of the most important membrane technologies being developed for water desalination, which has the ability to compete with expensive processes such as reverse osmosis. In this study, the performance of polycarbonate (PC) hollow fiber membranes modified with silica aerogel nanoparticles (SIA-NPs) and polydimethylsiloxane (PDMS) coating solution for direct contact membrane distillation was investigated. The membranes were fabricated by dry jet-wet spinning method. In this respect, 0.25, 0.5, and 1 wt% of SIA nanoparticles were coated over the hollow fiber surface in order to improve the performance of the membranes. The results indicated that the optimum loading of SIA was 0.5 wt% at which the contact angle of the surface shifted from 77.5 degrees to 100 degrees relative to the unmodified PC membrane. Although the addition of SIA nanoparticles to the membrane matrix did not alter the membrane conductivity, it increased the membrane thickness, thereby reduced the heat loss of the membrane. Accordingly, the results of performance tests for the membrane distillation (MD) showed that by adding 0.5% SIA nanoparticles to the membrane bulk and coating the surface with 0.5% SIA nanoparticles in 1.0% PDMS solution and 96% increase in energy efficiency, 33% increase in water flux, as well as higher stability of salt rejection were obtained. This study proved that the application of SIA nanoparticles have a great potential to modify and improve MD performance.