Nanocrystalline MnO2 on an activated carbon fiber for catalytic formaldehyde removal

Abstract

Three different types of nanocrystalline MnO₂, namely, α-MnO₂, γ-MnO₂ and δ-MnO₂, were successfully synthesized via a co-precipitation method, which has the advantages of easy preparation, low cost, size uniformity and excellent crystallinity. It also avoids operating at high temperatures and pressures. The nanocrystalline MnO₂ were then tested for formaldehyde catalytic oxidation at 25 °C. The results suggested that δ-MnO₂ had the highest catalytic activity. Hence, δ-MnO₂ was synthesized using the same method to modify an activated carbon fiber (ACF) substrate. Further tests showed that the as-prepared MnO₂/ACF samples can significantly improve the removal of formaldehyde at room temperature. The MnO₂ content in MnO₂/ACF had great influence on the breakthrough time and we found that the MnO₂ content did not best perform at greater magnitudes but were optimal at 16.12 wt%. The formation method developed in this study may become a promising technique to improve the catalytic activity in formaldehyde removal.