To assess this variable, 10 g of exhausted activated carbon was
suspended in n-pentane at different volumes while the regeneration
time was held constant at 60 min. The COD change of the
n-pentane solvent was then determined, and the influence of the
volume ratio of n-pentane/activated carbon on the desorption of
the activated carbon was studied (Fig. 3).
Fig. 3 shows that at small volume ratios of n-pentane/activated
carbon, increases in n-pentane volume also increase the COD desorption
rate of the activated carbon. However, when the volume
ratio of n-pentane/activated carbon reached 5:1, the change slowed
down. The results can be explained that within a certain range,
with the increase of the amount of organic solvent in the system,
the equilibrium concentration of chemicals in the organic solvent
decreased, and the eluted amount of chemicals from activated carbon
surface increased gradually. When the organic solvent was increased to a certain amount, the equilibrium concentration of
chemicals in the organic solvent no longer changed significantly,
so the eluted amount of chemicals as well as the regeneration efficiency
of activated carbon no longer changed correspondingly.
Based on these trends, we determined that the volume ratio of
n-pentane/activated carbon was best at 5:1 in this study.