A comparison of three methods to regenerate activated carbon saturated by diesel fuels



The three regeneration methods (thermal treatment, ultrasonication, and solvent extraction) were studied to regenerate the adsorptive capacity of the activated carbons (ACs) that were saturated by the nitrogen and sulphur containing compounds of diesel fuels. This is one of the few reports that give attention to the regeneration of heteroaromatic compounds contaminated ACs. Both model diesel and light cycled oil (LCO) were served as feedstocks. High regeneration rates can be obtained for all three approaches when model diesel was used as the feed. As model diesel was replaced by LCO, a significant drop in capacity restoration can be observed for the first few cycles and then the decrease rate slowed down. Solvent extraction outperformed the other two methods. The causes to lower regeneration performance were also analysed. It is shown that the regenerated carbons had a lower porosity and surface area and fewer surface oxygen functional groups than fresh carbon regardless of the regeneration methods employed. Significant micropore blockage was observed in the carbon regenerated by the thermal approach due to the coke deposit under thermal conditions. Mesopores formed during the regeneration by ultrasonication are considered to promote the carbon adsorption capacity.