Characteristics of Ultrasonically Enhanced Low-Temperature Thermal Regeneration of Powdered Activated Carbon: A Case Study of Acetone and Aniline

Effective regeneration of powdered activated carbon (PAC) is the key to reduce the operating cost of the PAC in wastewater treatment processes. In this study, volatile acetone and semi-volatile aniline were selected to investigate the regeneration characteristics of ultrasonically enhanced low-temperature thermal process. The results showed that the regeneration efficiency of the PAC that had adsorbed aniline or acetone increased with the increase in ultrasonic power, and optimal value of frequency and regeneration times were determined. The concentration and properties of organic solvents had a significant influence on the ultrasonic regeneration process. With the increase in heating temperature and regeneration time, the regeneration efficiency increased, but the loss of mass of the saturated PAC increased noticeably. With the combination of ultrasonic treatment in a solvent with low temperature heating, the PAC regeneration efficiency was successfully improved, and the PAC mass loss rate was noticeably reduced. The microjet, shock wave, and cavitation effects produced by ultrasonic treatment restored the specific surface area of the PAC, expanded its mesopore volume, and increased the pore diameter. A reasonable selection of the regeneration solution and optimization of the ultrasonic treatment conditions could create favorable conditions for subsequent low temperature thermal regeneration.