Study On Removal Of Formaldehyde From Carbon Carrier / Manganese Dioxide Composites

Formaldehyde is a common pollution in indoor environment, and the removal of formaldehyde attracts more and more attention recently. Cryptomelane mangese dioxide （OMS-2） is one of the oxides of transition metals, which possesses high activity in removal of formaldehyde. So far, there are two ways to improve the catalytic activity of OMS-2, including the method of supporting noble metals and the method of introducing carbon materials as supports. Because of the high cost for the method of supporting noble metals, the method of introducing carbon materials as supports was chosen as the way to improve the catalytic activity of OMS-2. Here, OMS-2 nanoparticles supported on multi-walled carbon nanotube （MWCNT） and graphene to form corresponding composites, and then the composites were assembled into films or aerogels to avoid dust pollutions.MWCNT/MnO₂ nanocomposites with various mass percentages of acid-treated MWCNT （a-MWCNT） were fabricated by co-precipitation. Among them, the MWCNT/MnO₂ nanocomposites with highest activity in removal of formaldehyde were assembled into composite films to study their catalytic activity in removal of gaseous formaldehyde. In addition, reduced graphene oxide （RGO）/Mn02 aerogels were fabricated by a mild hydrothermal method, and the catalytic activity of the RGO/Mn02 aerogels in removal of gaseous formaldehyde was also studied. The structure and properties of those composites were characterized using scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, atomic force microscope （AFM）.The results show that, MnO₂ nanocomposites were successfully coated on the a-MWCNT. MWCNT/MnO₂ nanocomposites possess good performance in removal of formaldehyde. Among the MWCNT/MnO₂ nanocomposites, those with 30 wt% of a-MWCNT show the highest performance in removal of formaldehyde （41.6%） in low concentration formaldehyde solution. MWCNT/MnO₂ composite film shows a homogeneous morphological structure and high performance in removal of gaseous formaldehyde （53.1%）. MWCNT/MnO₂ composite film possesses 68.0% higher performance in removal of gaseous formaldehyde than that of the corresponding composite film with MnO₂.RGO/MnO₂ aerogels show a three-dimensional porous structure and high performance in removal of gaseous formaldehyde （62.5%） which is 92.3% higher than that of MnO₂ aerogels.