(462a) Studies on the Potential of Graphene-Oxide Based Membranes for Waste Water Treatment

Membranes constructed by stacking atomic layers of graphene-oxide into a large self-assembled permeable film has gathered considerable attention in the last few years. Despite many outstanding properties regarding the ability to sieve small molecules and ions in combination with high water permeance, a generic consensus is that these membranes are difficult to upscale and produce in a commercially viable manner. Over the past few years, we have pioneered a novel approach to manufacture these membranes by harnessing the liquid crystalline nature and viscoelastic properties of colloidal dispersions of graphene oxide. Using conventional printing processes such as gravure, we have demonstrated feasibility for translation to a roll-to-roll approach. In this talk, I will discuss the performance of the membranes towards removal of natural organic matter such as tannic acid, and perfluoro-octanoic acid (PFOA) - a typical compound associated with degradation of fluorinated organics. The performance of these membranes were investigated by undertaking mass balance of species, and ability to concentrate these species in a dead-end filtration mode showing 60-80 % rejection of PFOA and >95% rejection of tannic acid. Results from cross-flow filtration of tannic acid indicates excellent long term stability (> 200 h) and high rejection of tannic acid (>95%). The membranes can be cleaned by hypochlorite and are resistant to significant damage at dosage of bleach treatment (upto 1000s ppm) typically much larger than what is used in typical membrane cleaning operations. Finally, we will discuss some preliminary results on the use of the membranes in the form of 1812 membrane modules for treatment of secondary waste water. These membranes are in various stages of development, so performances discussed here are indicative of samples used & ongoing investigations for enhancing the permeance and flux as a result of various post-fabrication membrane modification steps are in progress.