MOF incorporated Polyethersulfone/Polylactic Acid ultrafiltration membranes for the catalytic removal of dyes via persulfate activation

• PES/PLA-CNF@ZIF-8 membranes catalysed the activation of persulfate to degrade Rhodamine B. • Sulfate radicals were the predominant oxidizing agents in the oxidative degradation of Rhodamine B. • CNF@ZIF-8 blended PES/PLA membranes showed enhanced overall membrane properties. • The synthesized membranes showed good reusability and stability over five cycles. This study synthesized novel nanocellulose/zeolitic Imidazolate Framework nanocomposite blended Polyethersulfone/Polylactic Acid (PES/PLA-CNF@ZIF-8) membranes through a modified phase inversion process. This is the first time that a nanocellulose-MOF composite catalytic nanomaterial has been synthesized and used as an additive in polymeric membranes. The morphology and chemical structure of the membranes and nanoparticles were characterised by scanning electron microscopy (SEM), atomic force microscopy (AFM) and Fourier transform infrared (FTIR) respectively. Membrane wettability and crystalline structure were characterised by contact angle, and X-ray diffraction (XRD) analysis respectively. CNF@ZIF-8 modified membranes showed improved contact angle which decreased from 76° in the pristine membranes to 40° in 2 wt% membranes, bulk porosity increased from 74.3.3 % to 81.06 % while the pure water flux increased from 208.30 Lm -2 h −1 to 348.73 Lm -2 h −1 . Further, the modified membranes showed an increase in surface roughness reaching 84.14 nm in 2 wt% membranes. The synthesized membranes have been used as catalysts in the activation of persulfate to degrade Rhodamine B dye. The modified membranes displayed a high catalytic effect (>90 %) in activating persulfate to degrade RhB dye when compared to pristine membranes which showed a degradation efficiency of < 35 %. The study found that the optimum parameters for pH, membrane (catalyst) dosage, oxidant and initial dye concentration were 5, 0.3 g, 0.4 mM and 10 ppm respectively. Quenching experiments showed that •SO 4 - and •OH radicals were responsible for the dye degradation, with •SO 4 - radicals playing a major role in the oxidative degradation of the RhB dye. The synthesized membranes showed good stability when tested within five cycles, with the membranes showing degradation efficiency ranging from 92.1 % in the 1st cycle to 91.9 % in the 3rd cycle, before decreasing to 75.3 % in the 5th cycle. This study has therefore shown that the synthesized PES/PLA-CNF@ZIF-8 membranes have potential for use as catalysts in the degradation of cationic dyes in wastewater treatment through persulfate activation.