Mechanism of Congo Red Dye Photocatalytic Degradation on Metal Organic Framework/Polyamide Electrospun Nanofiber

Pollution of the environment is a serious issue nowadays, and finding a proper wastewater treatment is only small part of challenges that humans are facing. In order to find innovative ways for wastewater treatment, different techniques are applied, which lead to the production of new materials, such as ones made of polymeric nanofibers and materials with photocatalytic properties. In this study, nanofibers composite, synthetized from polyamide (PA) and UiO-66 Metal Organic Framework (MOF) by electrospinning method was used for degradation of Congo red dye from 10 ppm aqueous solution in batch conditions. Ultra-thin PA nanofiber membranes were produced with different ratios of MOF - 0.5 wt.%, 1 wt.%, 2 wt.% and 10 wt.% and prior the experiments, in order to be easily applied and removed from the solution, cut in the rectangular shape 1cm x 2 cm. FTIR, XRD and SEM are used for characterization of selected composites, prior and after sorption and photocatalytic experiments, while for determination of dye concentration UV-ViS spectrophotometer was used. The best performance in Congo red degradation was shown by membranes which contained 1 wt.% of MOF. FTIR spectra have shown that, upon the introduction of MOF particles into the PA fiber, reduction of all the peaks by the same amount in intensity indicates no interaction between MOF additive and PA matrix. Further, a new peak appeared after sorption at 590 cm-1 and disappeared after dye degradation induced by sun irradiation. XRD analysis has shown that there are no observable microstructural changes in composites upon sorption and cycling. Decreasing of the band gap of composite compared to pure MOF indicated increased photocatalytic activity. Reusability of composite membranes was investigated by performing experiments in multiple cycles, and results have shown that electrospun UiO-66/polyamide membranes have no significant changes in degradation efficiency of Congo red upon 4 cycles.