Abiotic humification is important in the formation and evolution of organic matter in soil and compost maturing processes. However, the roles of metal oxides in abiotic humification reactions under micro-aerobic remain ambiguous. The aim of this study was to use non-destructive measurement methods to investigate the role of MnO₂ in the evolution of humic substances (HSs) during oxidative polymerization of polyphenol-amino acid. Our results suggested a synergistic effect between MnO₂ and O₂ in promoting the polymerization reaction and identified that MnO₂ alone had a limited ability in accelerating the transformation of fulvic acid (FA) to humic acid (HA), whereas O₂ was the key factor in the process. Two-dimensional correlation spectroscopy (2D-COS) showed that the evolution in the UV-vis spectra followed the order of 475–525 nm>300–400 nm>240–280 nm in the humification process, indicating the formation of simple organic matter followed by FA and then HA. ¹³C nuclear magnetic resonance (¹³C NMR) analysis revealed that the products under both air and N₂ conditions in the presence of MnO₂ had greater amounts of aromatic-C than in the absence of MnO₂, demonstrating that MnO₂ affected the structure of the humification products. The results of this study provided new insights into the theory of abiotic humification.

非生物腐殖化对于土壤和堆肥成熟过程中有机物的形成和演化至关重要。然而，金属氧化物在微需氧条件下的非生物腐殖化反应中的作用仍然不明确。这项研究的目的是使用非破坏性的测量方法来研究多酚氨基酸氧化聚合过程中MnO ₂在腐殖质（HSs）演变中的作用。我们的研究结果表明MnO ₂和O ₂在促进聚合反应中具有协同作用，并确定仅MnO ₂促进黄腐酸（FA）转化为腐殖酸（HA）的能力有限，而O ₂是该过程中的关键因素。二维相关光谱（2D-COS）显示，在增湿过程中，紫外可见光谱的变化遵循475–525 nm> 300–400 nm> 240–280 nm的顺序，表明形成了简单的有机物质其次是FA，然后是HA。¹³ C核磁共振（¹³ C NMR）分析表明，空气和氮气氛下将产品_2个中的MnO的存在条件₂有更大量的芳族-C的比不存在的MnO ₂，表明的MnO ₂的影响的结构增湿产品。这项研究的结果为非生物腐殖化理论提供了新的见解。