In-situ Synthesis Of Manganese Oxide On Fibers And Their Application In Oxidative Decomposition Of Formaldehyde At Room Temperature

Formaldehyde is one of the main indoor pollutants, which is mostly produced from man-made plank used for indoor decoration, such as plywood, joinery board, particleboard and medium density fiberboard(MDF). Formaldehyde is a known carcinogen recognized by the World Health Organization. It is well-known that long exposure to indoor air with concentrations of formaldehyde that exceed safe limitations is greatly harmful to human health, especially for preschoolers. Therefore, it is stringent to remove indoor formaldehyde.At present, the removal methods of indoor formaldehyde include physical adsorption, chemical treatment, biodegradation, photocatalytic and catalytic oxidation, etc, among which the transition- metal oxide is favored by public due to its low cost, excellent oxidation of formaldehyde and no harmful by-product during oxidation process. As one of transition- metal oxides, manganese oxides have good oxidizability for formaldehyde that is even better than catalyst materials loaded with precious metal. Fiber manganese oxides catalytic materials have been a research focus because of their low cost, excellent performance and easy application.In this study, two kinds of fiber-supported manganese oxide catalysts were synthesized by in situ oxidation-reduction method with polyester and luffa fibers chosen as supports. The morphology, crystal form and phase properties of the Mn Ox/cellulose composites were characterized by Scanning Electron Microscope(SEM), X-Ray Diffraction(XRD), Raman Spectro(Raman). The conversion of HCHO and the formation of CO2 were determined by an on- line GC. The reasons that cause catalysises out of active have been analyzed by in-situ FTIR. The activity of the as-synthesized catalysts for formaldehyde decomposition was tested.polyester fiber-supported manganese oxide(Mn Ox/PET) catalysts were synthesized by in situ reduction of potassium permanganate(KMn O4) with methanol at room temperature. By changing the parameters of preparation, the concentration of potassium permanganate, methanol and CTAB, we know how they affect the load capacity and activity. The catalytic activities of Mn Ox/PET composites were investigated for the oxidative decomposition of HCHO. The formaldehyde could be totally oxidized into CO2 in 2 hours when the concentration of formaldehyde is 105mg/m3 over Mn Ox/PET. The morphology, oxidation state, and crystal phase of the supported manganese oxide by kinds of characterization methods. Based on the characterization, the as synthesized manganese oxide turn out to be mixed valent porous amorphous manganese oxides due to the low temperature(room temperature) processing. And the of manganese oxides on the surface of polyester fibers is 100~500nm.luffa fiber supported manganese oxide(Mn Ox/LF) catalysts were synthesized by in situ reduction of potassium permanganate(KMn O4) with luffa fiber itself at room temperature. By changing the parameters of preparation, the concentration of potassium permanganate and reaction time, and the as-prepared Mn Ox/LF catalyst with an optimal synthesize condition: impregnating potassium permanganate solution(10 g/L) into a luffa fiber matrix(0.2 g) and shaking for 16 h. The catalytic activities of Mn Ox/PET composites were investigated for the oxidative decomposition of HCHO. The formaldehyde could be totally degraded in 5 hours when the concentration of formaldehyde is 105 mg/m3 over Mn Ox/LF. The CO2 selective convertion was determined by GC and it turns out that the HCHO can be completely oxidized into CO2 within 4 days over Mn Ox/LF. Comparing to Mn Ox/PET catalyst, the rate of CO2 conversion for Mn Ox/LF is lower due to the low loading quantity of Mn Ox on the surface of luffa fibers. The morphology of Mn O x on the surface of luffa fibers is nano-particles with a size of ~50 nm by scanning electron microscope. Taking into account the relative high HCHO conversion(97.5%) and preparation time of catalysts, the Mn Ox/ luffa sponge composite from 10 g/L of aqueous KMn O4 and 16 h of preparation time is a promising candidate for formaldehyde removal. The two-staged removal process, the adsorption of formaldehyde in the LF vascular bundle followed by the oxidative decomposition by the deposited Mn Ox nanoparticles, was found to afford the superior formaldehyde removal performance of the developed hybrid catalyst, Mn Ox/ LF.