Catalyst system investigation in biomimetic delignification of oil palm empty fruit bunches

Biomimetic delignification of oil palm empty fruit bunches with the bio-inspired chemical catalyst system was investigated by mimicking the ligninolytic enzyme's redox mediator formation, i.e., Mn 3+ and H 2 O 2 . The radical hydroxyl formation from the catalyst system was prevented using Mn 2+ ions and suitable ligands. The Mn 3+ ion and H 2 O 2 formations were investigated by combining transition metals, suitable ligands, and oxygen from the air. This study aimed to investigate which of the acidic and alkaline environment biomimetic catalyst systems obtained a high delignification degree: Mn 2+ -Fe 2+ solution in malate, lactate, and malate-lactate buffer at pH 4 or 6, and Cu 2+ -Mn 2+ pyrophosphate suspension in triethanolamine and trisodium phosphate solution at pH > 8. The biomimetic delignification experiment was carried out at 100 °C and a solid-to-liquid ratio of 1:20 for 6 hours. The highest delignification degree in acidic and alkaline environment biomimetic catalyst systems was 11.76 % and 67.74 %, respectively. Mn 3+ , as the primary biomimetic delignification redox mediator was not formed in the acidic catalyst system, but Mn 3+ was formed in the alkaline catalyst system. This study facilitates simple operation and faster delignification time than biological delignification. • Acidic and alkaline OPEFB biomimetic delignification catalyst system investigation. • Hydroxyl radical formation was prevented by using Mn 2+ ion and suitable ligand. • Mn 3+ ions were not formed in the acidic catalyst system with suitable ligand. • Cu 2+ -Mn 2+ pyrophosphate, TEA, and TSP alkaline catalyst system gave highest result. • Possible mechanism that could form Mn 3+ ions and H 2 O 2 successfully.