MnO2 Nanoparticles Supported on Porous Al2O3 Substrate for Wastewater Treatment: Synergy of Adsorption, Oxidation, and Photocatalysis

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. MnO 2 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 MnO 2 particles (20 nm 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 MnO 2 particles. While the crystalline phase was measured using XRD. The synthesized colloidal MnO 2 particles were supported onto porous aluminum oxide and physically attached to the support free surface via calcinations at 500 °C. MnO 2 -coated Al 2 O 3 demonstrated an extensive surface area of 140 m 2 /g. The catalytic activity of MnO 2 -coated AL 2 O 3 was evaluated by degrading organic contaminant. Catalytic process in presence of UV-irradiation and H 2 O 2 removed 95% of contaminant within 10 min. 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.