Enhanced efficient catalytic oxidation of formaldehyde using lignin-based fibers supported manganese dioxide

MnO 2 has been proven to be highly reactive to HCHO, but the form of powder limits its application. The problems of easy agglomeration and difficult recovery of MnO 2 powder can be solved by loading it onto fibrous materials, and improved its catalytic efficiency. However, the loading amount and stability are the challenges encountered in application. In this study, MnO 2 nanosheets were in-situ grown on lignin fiber (LFs) pads by a simple impregnation method, and the morphology and chemical structure of the synthesized MnO 2 -LFs composites were characterized. The results show that the fibers prepared by centrifugal spinning have a smaller diameter than traditional fibers, allowing for more MnO 2 loading. Due to the presence of abundant functional groups on the LFs surface, strong Mn–O and hydrogen bond interactions promote robust MnO 2 anchoring, achieving uniform distribution of MnO 2 on the LFs surface. Subsequently, δ-MnO 2 formed on the LFs surface after 72 h of impregnation in KMnO 4 solution exhibited the best HCHO degradation performance. After 2 h of reaction, the HCHO removal rate was as high as 80.14%, and it had good stability and reusability. Therefore, LFs are expected to be used as carrier materials for MnO 2 in the purification of indoor air HCHO.