Pyrolysis kinetic behavior and TG-FTIR-GC-MS analysis of end-life ultrafiltration polymer nanocomposite membranes

This is the first research to be concerned with end-life ultrafiltration polymer nanocomposite membranes and their valorization into high added-value products using the pyrolysis treatment. Polysulfone membrane (PES) as a commercial product and their nanocomposites (CNTs/PES and graphene/PES) were used as a feedstock in the present research. The experiments started with fabrication of membranes loaded with 0.04 wt% of CNTs and graphene (GNs). The elemental analysis and proximate analysis of the fabricated membranes were studied. Subsequently, thermogravimetric coupled with Fourier-transform infrared spectroscopy (TG-FTIR) system was used to study the thermal and chemical decomposition of the membranes at different heating rates (5-30C/min). The volatile products released from the pyrolysis process of the membranes were analyzed using TG coupled with gas chromatography-mass spectrometry (GC-MS) unit. Finally, pyrolysis kinetic parameters of PES membrane and its nanocomposites were studied using model-free models. Also, thermogravimetry and differential thermal gravimetry (TG/DTG) experimental data were simulated using the distributed activation energy model and the independent parallel reactions kinetic model with high predictability. The results showed that sulfur dioxide, benzene, phenol, and diphenyl ether compounds represented the main compounds in the released volatile components with high total abundance, especially at high heating rate and estimated at 85% (PES), 94% (CNTs/ PES), and 99% (GNs/PES). Meanwhile. the kinetics analysis showed that the whole activation energies decreased significantly in case of nanocomposites by this trend 206.4 kJ/mol (PES), 187.8 kJ/mol (CNTs/PES), and 139.30 kJ/mol (GNs/PES), what indicates that CNTs and GNs act as self-catalysts and end-life polymer membranes can be used as a new source for renewable energy.