Improved performances of self-healing polyethersulfone (PES) membrane with amine-functionalized carbon quantum dots (NCQDs)

Physical damages to the membrane often cause membrane performance deterioration. Self-healing membranes have emerged as an alternative to tackle the dif;iculty in detecting the exact microscopic damage location. Previously, polyethyleneimine (PEI) and poly(acrylic acid) (PAA) have successfully demonstrated self-healing ability in water filtration via surface modi;ication of polyethersulfone (PES) membrane through a layer-by-layer (LbL) approach. The unsatisfactory self-healing performance of the membrane raises the concern. This study aims to improve the membrane performance of the previous PEI/PAA membrane using amine-functionalized carbon quantum dots (NCQDs) nanoparticles. From the study, the NQDS membrane showed that the self-healing ef;iciency based on pure water flux (PWF) improved by 5.6 % from 75.9 % to 80.4 %, while the tartrazine rejection recovery rose from 35.8 % to 43.7 % when the damaged membrane was healed in the distilled water for 6 hours. These observations can be explained by the intrinsic self-healing mechanism, at which the formation of hydrogen bonds between the functional groups on the membrane surface with water molecules when the membrane is immersed in distilled water. Additionally, other membrane performances were also improved with NCQDs nanoparticles. For example, the PWF and tartrazine rejection increased from 16.0 L/m2.h and 71.9 % of the non-NCQDs membrane to 33.8 L/m2.h and 85.5 % of the NCQDs membrane. The increment in PWF was correlated to the hydrophilic nature of NCQDs nanoparticles to drive water molecules from permeating through the membrane. Meanwhile, the negatively charged membrane surface with NCQDs nanoparticles is responsible for the tartrazine rejection through electrostatic repulsion. To conclude, the incorporation of NCQDs nanoparticles enhanced with self-healing ef;iciency, PWF and rejection of the water-responsible self-healing PEI/PAA membrane. © Published under licence by IOP Publishing Ltd.