Study On GAC Modification And Phenol Degradation In Spent GAC By Dielectric-barrier Discharge Plasma

Activated carbon considered as one of the effective sorbents has been used to remove many kinds of contaminants existing in air and water because of its well-developed porous structure and affluent surface functional groups. But activated carbon has bad problems such as its expensive price, large consume and environment pollution for spent activated carbon. The dielectric-barrier discharge (DBD) is applied to making ozone, treating surface of material, degradation of organic matter and sterilization, because the DBD has the advantage of simple configuration and operation. In this paper, DBD plasma was applied for granular activated carbon (GAC) treatment. Explore the optimal discharge condition of enhancing adsorption capacity of GAC and removing organic contamination in GAC. In this study, plank-plank DBD plasma was used. The high voltage AC power supply presented 200 Hz. The reactor was full of O₂ and the electrodes distance was set as 8 mm to insure that GACs could be placed. According to the study of input voltage, O₂ flux rate and water containing of GAC, the effect of adsorption capacity of GAC and removal rate of phenol in waste GAC in different treatment time and O₂ flux rate were discussed in this paper. The results showed that: (1) GAC's chemical and physical characters were changed by DBD plasma. The phenolic groups were selectively removed by DBD plasma, which increased adsorption capacity of GAC. But BET surface areas of GAC decreased when enhancing treatment time, which was disadvantage for GAC adsorption. (2) In the different input voltage, DBD treatment time and O₂ flow rate, adsorption capacity of GAC changed. When we controlled these effect factors at optimal values, the adsorption capacity of GAC could be improved. When we controlled the condition in 18 kV, 1.0 L/min O₂ flow rate and 20 min treatment time, the adsorption capacity of GAC would enhance 30.8%. (3) Phenol of spent GAC was removed by DBD treatment. When the discharge condition was 18 kV, 1.0 L/min O₂ flow rate and 60 min treatment time, the concentration of phenol in spent GAC changed from 252.9 mg/g to 61.1 mg/g. The degradation rate is 75.8%. The degradation caused by O₃ and other active particles oxidation.