Design of Graphene Oxide Polysulfone Mixed Matrix Membrane for Direct Contact Membrane Distillation

For desalination purposes, Membrane Distillation (MD) is a promising technology due to the capability of the process to utilize alternative energy sources, such as waste heat and solar. However, the development of low-cost membranes specific to MD remains a major barrier to the commercialization of the technology, whereas Reverse Osmosis (RO) membranes are readily available. The ideal properties and morphology of a MD membrane (hydrophobic, porous, with channels) are fundamentally different from those of a RO membrane (hydrophilic, dense, smaller voids). In this research, the properties of graphene oxide (GO) were used to develop GO-PSF membranes using a simple, low cost method known as wet phase inversion. The effects of thickness and Graphene Oxide (GO) content on the performance of direct contact membrane distillation (DCMD) were studied. During the DCMD experiments using pure PSF and GO-PSF membranes, the process parameters were kept constant across all the membrane trials, namely the temperature of the feed (90°C) and permeate (20°C) streams, flowrates (1.5 gpm), and feed concentration (2.5% wt. NaCl). Morphological studies of the membranes were conducted using Scanning Electron Microscopy (SEM). The thinnest pure PSF membrane provided for the highest permeate flux, but also the lowest salt rejection, and it was demonstrated that by adding GO to the membrane matrix, the salt rejection performance improved. It was also found that there is a limit in the amount of GO that can be beneficial to the GO-PSF membrane.