Core-Shell-Like Structured Co3O4@SiO2 Catalyst for Highly Efficient Catalytic Elimination of Ozone

Co3O4 is an environmental catalyst that can effectively decompose ozone, but is strongly affected by water vapor. In this study, Co3O4@SiO2 catalysts with a core-shell-like structure were synthesized following the hydrothermal method. At 60% relative humidity and a space velocity of 720,000 h−1, the prepared Co3O4@SiO2 obtained 95% ozone decomposition for 40 ppm ozone after 6 h, which far outperformed that of the 25wt% Co3O4/SiO2 catalysts. The superiority of Co3O4@SiO2 is ascribed to its core@shell structure, in which Co3O4 is wrapped inside the SiO2 shell structure to avoid air exposure. This research provides important guidance for the high humidity resistance of catalysts for ozone decomposition.

Comparative Studies of Carbon Materials Synthesized From Waste as Catalysts for Ozonation of Real Textile Wastewater

In the present work, evaluation of two catalysts, Activated carbon (AC) synthesized from agricultural waste and Multiwalled carbon nanotubes (MWCNT) synthesized from plastic waste, were done for the ozonation of real textile wastewater using para- chloro benzoic acid (p-CBA) as a probe compound. The effect of pH and catalyst dose were studied in terms of •OH exposure, Rct, rate of p-CBA degradation and ozone degradation. The rate constant for the reaction of organic matter with hydroxyl radicals was determined using competition kinetics. The threshold ozone dose for real textile wastewater was found to be 0.51 gm/gm of TOC. With an increase in specific ozone dose, the rate of p-CBA degradation was found to be increasing and has shown a positive effect on •OH exposure and Rct. The increasing pH had shown a positive effect on the rate of degradation and decomposition of p-CBA and ozone respectively in the case of AC catalyzed ozonation. A similar trend was observed in the case of MWCNTs catalyzed ozonation. A positive effect of pH was observed on •OH exposure and Rct, in AC as well as MWCNTs catalyzed ozonation. The effect of catalyst loading has shown significant enhancement in p-CBA degradation, ozone decomposition, •OH exposure and Rct in both AC as well as MWCNTs catalyzed ozonation. However, MWCNTs have proved better than AC as a catalyst for ozonation in studied experimental parameters.