Differences in pretreatment effects and mechanisms of permonosulfate activated by different iron-based catalysts on lignocellulose.

Pretreatment is essential for enhancing the energy potential of lignocellulose and also a significant bottleneck for their utilization. Advanced oxidation processes (AOPs), especially those based on permonosulfate (PMS), have become a research focus due to their mild conditions and high efficiency. However, activation of peroxides in PMS-based AOPs poses a critical challenge, necessitating the development of catalysts that can minimize sulfate consumption while enhancing the pretreatment efficacy. Here, we compared the pretreatment effects of PMS activated by three monometallic iron-based catalysts and LaFeO on sugarcane bagasse. We assessed the enzymatic saccharification yield, chemical component transformation, and substrate physical-chemical properties changes. The LaFeO-activated PMS system outperformed other systems in hemicellulose removal rate (87.73 %), cellulose removal rate (12.12 %), enzymatic saccharification yield (76.39 %), and sugar conversion rate (92.04 %). Compared with α-FeOOH-activated PMS system, LaFeO-activated PMS system produced more free radicals of •OH and SO at the initial stage, and then the free radicals dropped sharply. This free radical generation model enabled the removal of large amounts of lignin and hemicellulose while kept more cellulose, and resulted in the best enzymatic saccharification efficiency. This pretreatment creates favorable conditions for further processing.