The subsequent activated carbons of resorcinol-formaldehyde xerogels are synthesized and exposed to wide range of gamma irradiation dose. Xerogels and their subsequent activated carbons are characterized by diverse techniques; FTIR, Raman, porosity analysis, SEM, EDX and AFM. The composite membranes are fabricated from polyacrylonitrile and activated carbon xerogels as composite membranes to be utilized in ultrafiltration process of salted oily wastewater. The soybean oil is exploited as organic feeding solution. The results declared that values of flux and rejection reach 157 (L m−2 h−1) and 99.8 (%), respectively. Overall, the best performing composite membrane is conducted by maximizing pure water flux. The optimally synthesized membrane performs well for purification of salted oily wastewater, and a significant increment in permeate flux is obtained with soybean oil rejection is at ∼99.8% and with maximum flux is at 32 (L m−2 h−1). Further, the composite membranes showed good promise for ultrafiltration of salted oily wastewater.