Deep regeneration of waste mercury catalyst supported carbon by ultrasonic synergistic ozone oxidation

• Ultrasonic synergistic ozone oxidation enables deep regeneration of waste carbon. • Ultrasound generates intense jet impact to enlarge the mesopores of carbon. • Ultrasonic cavitation crystallizes amorphous carbon into chaoite. Spent mercury catalyst carrier carbon, a typical waste product from the calcium carbide-based vinyl chloride industry, has long faced core challenges in its regeneration process: significant carbon loss and reduced mechanical strength, severely limiting resource recycling. This paper proposes a novel method for deep regeneration of waste mercury catalyst carrier carbon through ultrasonic-assisted ozone oxidation, achieving efficient recovery. The study employs ultrasonic-enhanced water leaching to efficiently remove KCl impurities from the waste carbon. Response surface methodology was used to systematically optimize process parameters, yielding a highly accurate model that identifies key factors influencing regeneration efficiency. Ultrasonication during oxidation creates a high-temperature, high-pressure environment through cavitation, inducing amorphous carbon to transform into ordered graphitic domains and enhancing mechanical strength. Simultaneously, it promotes ozone decomposition to generate more hydroxyl radicals, achieving deep degradation of pollutants. Combined with the physical pore-opening effect of ultrasonic microjet impingement, this approach constructs a highly interconnected pore network, significantly improving adsorption activity. The regenerated carrier carbon in this technology meets GB/T 31530-2015 requirements and can be recycled for mercury catalyst production.