Oxygen Functionalization of Carbon Nanotubes Shifted the Formation Pathway of Hydroxyl Radicals in Catalytic Ozonation: The Overlooked Role of Hydrogen Peroxide
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引用次数: 0
Abstract
The oxygen functionalization of multiwalled carbon nanotubes (CNTs) could enhance their reactivity in catalytic ozonation for hydroxyl radical (•OH) formation. However, the detailed pathway for the transformation of ozone to •OH and the mechanism for the decreased treatment performance at acidic pH values remain unclear. In this study, surface oxygen-functionalized CNTs (O-CNTs) were prepared and used in catalytic ozonation to reveal the pathway for •OH formation. The efficiencies of ozone utilization and its conversion to •OH were increased by 2.7 and 554.8 times, respectively, under the catalysis of the O-CNTs. The great reactivity of the O-CNTs was related to their high surface oxygen contents and increased dispersion. Hydrogen peroxide was generated as a significant intermediate during the catalytic ozonation of the O-CNTs. The exposure of this substance linearly correlated with •OH exposure and pollutant degradation constants, with correlation coefficients of 0.991 and 0.911, respectively. The formation of hydrogen peroxide was relatively slower at acidic pH values, which explains the low performance of catalytic ozonation. A mechanism was proposed that involved the generation of hydrogen peroxide to trigger the peroxone process for free •OH formation. These findings deepen our understanding of oxygen functionalization and offer insights into the catalytic ozonation of surface oxygen-rich carbonaceous materials.
期刊介绍:
ACS ES&T Engineering publishes impactful research and review articles across all realms of environmental technology and engineering, employing a rigorous peer-review process. As a specialized journal, it aims to provide an international platform for research and innovation, inviting contributions on materials technologies, processes, data analytics, and engineering systems that can effectively manage, protect, and remediate air, water, and soil quality, as well as treat wastes and recover resources.
The journal encourages research that supports informed decision-making within complex engineered systems and is grounded in mechanistic science and analytics, describing intricate environmental engineering systems. It considers papers presenting novel advancements, spanning from laboratory discovery to field-based application. However, case or demonstration studies lacking significant scientific advancements and technological innovations are not within its scope.
Contributions containing experimental and/or theoretical methods, rooted in engineering principles and integrated with knowledge from other disciplines, are welcomed.