Musa paradisiaca peel and sludge co-pyrolysis: Thermal behavior and kinetic analysis

The thermal degradation behavior, synergistic interactions and reaction kinetics of the sewage sludge (SS) and Musa paradisiaca peel (MP) co-pyrolysis was studied. The blend with SS and MP in the mass ratio 1:3 (SS01MP03) showed the highest deviation from the calculated values with an increment as high as 19 % in the mass loss under thermogravimetric analysis (TGA) and hence it was considered the blend with the highest synergy. The estimation of activation energies (E_act) of the blends revealed that the synergistic interactions between SS and MP led to a 25.59 % reduction in the E_act of the pyrolysis reaction of SS01MP03 which increases pyrolysis efficiency. The TGA of SS01MP03 at various heating rates (10–40 ˚C/min) revealed a complex three step degradation mechanism with high mass loss in the 2nd stage. The kinetics of the pyrolysis of the most synergistic blend (SS01MP03) was performed using the Coats-Redfern model-fitting (CRM) method and the activation energies (E_act) were estimated by model-free (MF) methods like Flynn–Wall-Ozawa method (FWOM), Kissinger–Akahira–Sunose method (KASM), and Starink methods. The Zhuravlev equation in the CRM method proved to be the best fit (E_act = 68.46 kJ/mol), which was close to the values 65.389, 65.711 and 71.055 kJ/mol predicted by MF methods KASM, Starink and FWOM respectively. This suggests that the results are reliable.