MnO_2 Nanoparticles Supported on Porous AI_2O_3 Substrate for Wastewater Treatment: Synergy of Adsorption, Oxidation, and Photocatalysis

摘要

Even though photocatalyst nanoparticles can offer effective degradation of organic pollutants, this can stimulate another pollution problem related to contamination with nanoparticle themselves. Furthermore particle aggregation could cause reduction of interfacial surface area and photocatalytic efficiency. One effective approach for wastewater treatment is superimposing photocatalyst on a high surface area porous support. MnO2 has attracted attention as its electronic structure is semiconducting. The d-d electronic transitions can take place under illumination as the d-orbitals are not completely occupied. This study reports on a new approach of sustainable fabrication of mono-dispersed MnO2 particles (20nm average particle size) with a constant product quality using hydrothermal synthesis procedures. TEM and SEM procedures were utilized to study the particle size and morphological structure of the prepared MnO2 particles. While the crystalline phase was measured using XRD. The synthesized colloidal MnO2 particles were supported onto porous aluminum oxide and physically attached to the support free surface via calcinations at 500 degrees C. MnO2-coated Al2O3 demonstrated an extensive surface area of 140m(2)/g. The catalytic activity of MnO2-coated AL(2)O(3) was evaluated by degrading organic contaminant. Catalytic process in presence of UV-irradiation and H2O2 removed 95% of contaminant within 10min. The mechanism of dye-removal was reported to be a novel combinatorial synergistic effect of adsorption, oxidation, and photocatalysis. Coupling different semiconductor metal oxides together extended sample's light response to visible region and enhance photo-generated e(-)-h(+) separation efficiency. This study shaded the light on novel high interfacial surface area photocatalyst; that can be easily isolated avoiding contamination with nanoparticles.