Surface modification of a polyethersulfone microfiltration membrane with graphene oxide for reactive dyes removal

Polyethersulfone microfiltration membranes (mPES) were modified with polyethilenimine (PEI) and graphene oxide (GO) by layer-by-layer self-assembly method via electrostatic interaction using a pressurized filtration system. The high positively charge of PEI allowed it to be easily assembled on the polyethersulfone substrate, and also to receive the negative layer of GO. Several techniques were applied to characterize the modified membranes (i.e. ATR-FTIR, SEM, water angle contact and zeta potential), and proved that the modification was successfully achieved. The effect of PEI and GO concentrations in the modification was investigated, and the best performance of all membranes was achieved with a Blue Corazol (BC) dye rejection of 97.8% and a pure water permeability of 99.4 L m−2 h−1 bar−1. The membrane also presented a flux recovery ratio of >80% after being hydraulically cleaned for 30 min. Moreover, the membrane performance was evaluated in terms of rejection of BC dye in a real dye bath wastewater, and an excellent performance with a maximum rejection rate of 96% was observed. Therefore, the proposed study may provide an efficient alternative to feasible the use of microfiltration membranes, by modifying them, in order to improve its surface characteristics and its filtration capacity, aiming to apply it in the removal of dyes of textile industries wastewater.