Fabrication of tannic acid-(3-amino)propyltriethoxysilane with zwitterionic carbon quantum dots coating on cellulose acetate tubular membrane for oil-water emulsion separation

• TA+APTES hydrophilic layer incorporated with ZQDs was successfully prepared. • The pyrogallol groups of TA enhance the wettability of the CA membrane. • TA+APTES+ZQDs layer results in super hydrophilicity of CA membrane. • TA+APTES incorporated with ZQDs layer improves the permeability of the CA membrane. • The ZQDs in the TA+APTES layer improves antifouling properties of the CA membrane. The discharge of large volumes of oily wastewater from industries has been a serious global concern. In recent years, membrane filtration has been considered an effective method for treating oily wastewater. However, membrane fouling is a major challenge inherent to this approach. This study integrated zwitterionic carbon quantum dots (ZQDs) into a tannic acid-(3-aminopropyl)triethoxysilane (TA-APTES) coating on cellulose acetate (CA) tubular membranes to explore the potential for improve the hydrophilicity and anti-fouling properties of the membrane. The CA tubular membrane was fabricated by dry/wet spinning method. A green and one-step synthesis of TA-APTES with ZQDs was utilized to modify the surface of the CA pristine membrane. Incorporating ZQDs enhanced the membrane's hydrophilicity. Results showed that the modified membrane with ZQDs (CA/T 0.4 A+ZQDs) displayed super hydrophilicity with a water contact angle of 12.53 ± 0.9°, pure water permeance of 987.13 ± 57.9 L m -2 h -1 bar -1 , diesel-water emulsion permeance of 577.10 ± 64.7 L m -2 h -1 bar -1 , and enhanced oleophobicity with oil rejection rate of > 99 %. Furthermore, the CA/T0.4A+ZQDs membrane showed the best anti-fouling property, with the highest flux recovery ratio (FRR), lowest irreversible fouling ratio (R ir,1 ) of 94.98 % and 5.05 %, respectively and mechanical stability after 5 cycles of oil-water separation.