In the scope of this study, radically and coupling functionalized polyethersulfone (RPES-CPES) was synthesized using the diazotization route to prepare high-performance nanofiltration (NF) membranes. The filtration performance of licorice aqueous solution by prepared membranes was evaluated systematically in a cross-flow filtration set-up for simulated produced water treatment. Compared with the bare-PES membrane, RPES and CPES incorporated membranes were found to possess an enhanced permeability and antifouling capability. The influence of driving force, cross-flow velocity, and feed concentration on the output permeated flux, rejection capability and fouling tendency of membranes were investigated. The more extreme fouling tendency accompanied by higher output permeated flux of the membranes was observed with enhancing the driving force and cross-flow velocity parameters. The results were shown that, when the concentration of foulants feed was increased, the output permeated flux of the membranes was decreased significantly. The chemical stability of modified membranes was also studied by evaluating the effect of harsh acidic and alkaline conditions on the membrane licorice filtration for a 96-h period. RPES blended membrane indicated great resistance in the acidic and basic environments, indicating surprising membrane resistance capability to chemical reagents. Diazotization-inspired modification has great potential for practical application in water treatment with advanced characteristics.