Unlocking lignocellulosic polymer recalcitrance. the mechanochemical activation of cryogenic milling on olive prunings

Abstract The effects of recalcitrance reduction by mechanical activation under liquid nitrogen on olive prunings (OPs) were studied with thermogravimetric analysis. That technique was used to calculate the kinetic triplet using the Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, and Friedman model-free isoconversional methods. Criado’s methodology was used to study the reaction mechanism involved. Crucially, the results revealed a massive 51% reduction in activation energy at the final conversion stages (dropping from 557 to 270 kJ mol −1 ), proving the effectiveness of the treatment against the most recalcitrant components. In addition, enthalpy, entropy, and Gibbs free energy were used to assess the reaction’s thermodynamic viability. It was revealed that the milling induced recalcitrance reduction leads to lower thermodynamic parameter values. Finally,the results showed a dramatic reduction in the reaction mechanism complexity of the multi-step pyrolysis degradation of the OP biomass, which can lead to simplifying the design of the large-scale biomass reactor process.