Development of Polymer Modified Graphene Oxide Nanocomposite Membranes to Reduce both Scaling and Biofouling

In seawater reverse osmosis (SWRO), membrane scaling is one of the major issues affecting its widespread application in the desalination industry. In this research, the effect of concentration of calcium and sulfate ions from 20 to 150 mM and temperature from 5 to 35̊C on calcium sulfate scaling of reverse osmosis (RO) and Graphene oxide functionalized RO membranes was investigated. It was found that increase of concentration as well as temperature enhances the mineral scaling, where morphology of crystals varies from rod shaped to rosette structures. It was also observed that commonly found seawater bacteria can use antiscalants as an energy/carbon source thereby degrading them and reducing their efficiency to reduce mineral scaling. Moreover, bacteria were found to be capable of inducing/mediating calcium sulfate precipitation on RO membranes, further enhancing the mineral scaling. Therefore, it was important to modify RO membranes capable of simultaneously reduce both mineral scaling and biofouling. For this purpose, RO membrane was modified with antibacterial graphene oxide and polymer antiscalants using microwave radiation technique. It was found that the modified membranes were able to inhibit microbial growth up to 95%, while, mineral scaling was also reduced by 97%. Hence, it was concluded that the coating of polymer modified graphene oxide nanocomposites on RO membranes can simultaneously reduce both biofouling and scaling. So far, such dual characteristics of modified membranes have not been reported in the literature.