Dual functional performance of aminolyzed PET-g-AA membranes: adsorption and photodegradation of methylene blue for enhanced water treatment applications

Abstract

This work presents dual‑functional aminolyzed PET‑g‑AA membranes capable of capturing and photodegrading methylene blue (MB). Surface aminolysis introduces amide sites and allows UV‑initiated grafting of acrylic acid, creating carboxylated interfaces that enhance electrostatic, hydrogen‑bonding, and π–π interactions. Gaussian fitting of UV–Vis spectra identifies monomer (~ 610 nm) and dimer (~ 660 nm) species: adsorption follows pseudo‑second‑order kinetics with qe approximately 89% (monomer) and 98% (dimer), and half‑lives of about 105 and 130 min, respectively. Under 255 nm irradiation, photodegradation occurs via second‑order kinetics, with qe around 43% (monomer) and 75% (dimer), and half‑lives of roughly 7.8 and 9.1 min. FTIR and XRD analyses confirm successful functionalization and maintain framework integrity despite reduced crystallinity. The membranes retain about 90% performance after five regeneration cycles. By targeting dimeric MB—which is typically more difficult to remove—the membranes combine high capture efficiency with effective ROS‑assisted degradation, providing a durable and scalable solution for dye remediation.