Research on the hydrothermal regeneration of powdered activated coke in wastewater treatment

Abstract

Powdered activated coke has potential application in the field of wastewater treatment due to its good adsorption performance and low cost. However, the coke becomes saturated due to the adsorption of pollutants, which renders its regeneration difficult and limits its wider applicability. A suitable solution to this issue would be the hydrothermal regeneration of powdered activated coke in water treatment, as this method does not require pre-drying, and the mass loss of active coke during this regeneration method is also small. Therefore, in the present study, the hydrothermal method was used for the regeneration of activated coke adsorbed with methylene blue. The results indicated that the temperature was an important factor in the regeneration process, and a higher temperature increased the regeneration efficiency. The analysis of the surface properties of activated coke prior to and after regeneration revealed that the micropores exerted little effect on the adsorption capacity of activated coke for methylene blue. Furthermore, the desorption and degradation pathways of the adsorption of methylene blue on activated coke, which have mostly been ignored in other studies, were explored in the present study. A higher temperature and the addition of H2O2 were observed to reduce the content of organic matter in the condensate. Finally, increasing the utilization times of the powdered activated coke was attempted. It was observed that the addition of H2O2 enhanced the regeneration efficiency even after several cycles of regeneration. After five cycles of regeneration with H2O2, the regeneration efficiency was increased from 48.3% to 58.2%.