Development of Polyamide 6/Calcium Alginate/Aminated Graphene Oxide Nanofibrous Composite as a High-Performance Membrane for Efficient Oil–Water Emulsion Separation

Graphene oxide (GO) membranes are widely employed in the separation of oil–water emulsions because they can be readily functionalized, offer a large surface area, and contain a variety of hydrophilic functional groups. However, attaining maximum efficiency in membranes modified with GO still poses a difficulty. In this research, diethylenetriamine (DETA) was grafted on the surfaces of GO to prepare aminated GO (AGO) nanosheets. AGO was then incorporated into a matrix of polyamide 6 (PA6) and calcium alginate (CA) at different loading levels and electrospun to prepare high-performance nanofibrous composite membranes for separating oil–water emulsions, named PA6-CA-AGO. Membranes containing 1 wt % AGO (PA6-CA-AGO1) demonstrated the best hydrophilic characteristics (water contact angle of 3°) and mechanical strength (about 33.47 MPa). Additionally, they exhibited remarkable underwater superoleophobicity, achieving an underwater–oil contact angle of 155°. Furthermore, during the pressurized emulsion filtration, PA6-CA-AGO1 exhibited an outstanding water flux rate (1092 L/m² h) and a high oil rejection capability (98.84%). Additionally, this membrane demonstrated high antifouling properties by maintaining a water flux rate of 357 L/m² h and an oil exclusion capability of 97.72% throughout 15 sequential cycles of filtration.