Synergistic thermal behavior and kinetics in the co-pyrolysis of walnut shell and Enteromorpha clathrate

In this paper, the non-isothermal co-pyrolysis of walnut shell (WS), Enteromorpha clathrata (EN), and their blends (WEB) was studied using a thermogravimetric analyzer (TGA). For all the samples, three different decomposition stages were identified by the thermogravimetric analysis. At the same temperature, the mass loss of WEB was always stable between the values of WS and EN. In addition, different heating rates resulted in different TG–DTG profiles. The interaction between WS and EN showed a gradual enhancement with temperature increase, and the most significant interaction was generated when the blending proportion of WS and EN was 7:3. The Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO), and masterplots methods were used to determine the kinetic triplets. The results show that for different blending ratios, the effective activation energies of WS and EN co-pyrolysis vary from 86.21 to 247.86 kJ mol⁻¹ when the conversion rate is 0.2–0.8. The most appropriate mechanism for the pyrolysis of 70WS30EN is g(α)=[-ln(1-α)]^1/2 with kinetic parameters: apparent activation energy 86.21 kJ mol^-1 and pre-exponential factor 8.99 × 10¹⁶ s⁻¹. The findings in this paper provide a reference for further research on the co-pyrolysis of aquatic and terrestrial biomass.