Cold-adapted Ligninolytic Nanozyme Unveiling New Horizons in Black Liquor Treatment Under Mild Condition

Kraft black liquor, characterised by high lignin content, poses significant challenges for efficient treatment under mild conditions. This study unveils a pioneering solution via a novel cold-adapted ligninolytic nanozyme constructed from an amorphous manganese-containing metal-organic framework (aMnMOF). The aMnMOF features low-coordination Mn within mixed-valence trinuclear Mn-O clusters integrated with a long-range disordered MOF architecture. This unique design significantly lowered the reaction energy barrier of the rate-determining step to an exothermic process, endowing it with broad-spectrum oxidase-like activities over a wide temperature range (4°C-37°C) without additional oxidants. Based on these advancements, aMnMOF serves not only as a superior nanozyme for oxidative degradation of monomeric, dimeric and complex lignin compounds, but also as a sustainable pathway for real kraft black liquor treatment even under cold conditions, underscoring its superiority over existing methods. This innovative discovery not only advances the rational design of cold-adapted nanozymes but also provides a significant breakthrough in the field of industrial wastewater treatment.