ACC-010

The impact of adsorbent pore size distribution (PSD) and adsorbate critical oxidation potential (COP) on competitive adsorption on activated carbon were investigated in this study. Three activated carbons with different pore size distribution were used as adsorbents--granular activated carbon (GAC) F400, and two activated carbon fibers (ACFs), namely ACC-10 and ACC-15. Binary adsorptions of 2-methylphenol/2-chlorophenol and 2-methylphenol/2-nitrophenol were conducted on all three adsorbents. Ternary adsorption of 2-methylphenol/2-nitrophenol/2-chlorophenol was conducted on ACC-15 and F400. 2-Nitrophenol was more physically adsorbable than the other two adsorbates, while 2-methylphenol was the easiest to get oligomerized due to its low COP. ACC-10, which has the smallest critical pore size and narrow PSD, was shown to be effective in hampering oligomerization of phenolic compounds in all binary adsorption systems. ACC-15, which has larger critical pore size than ACC-10 and also narrow PSD, showed somewhat effectiveness in hampering oligomerization in binary adsorption systems and total effectiveness in ternary adsorptions. On the other hand, the wide pore size variations of F400 played a role in the oligomerization of the phenolic compounds. The Ideal Adsorbed Solution Theory (IAST) well predicted the multicomponent adsorption systems that did not undergo oligomerization.

The impact of pore size of activated carbon fibers (ACFs) on adsorption capacity and on the potential for oligomerization of phenolic compounds on the surface of ACFs in the presence of molecular oxygen has been investigated in this study. Compared with granular activated carbon (GAC), ACFs have unique pore size distributions, suitable to be used to elucidate the effect of pore structure on adsorption. Adsorption isotherm data were collected for o-cresol and 2-ethylphenol on four ACFs (ACC-10, ACC-15, ACC-20, and ACC-25) with different micropore volumes and BET surface area and on one type of GAC bituminous base. These isotherms were collected under anoxic (absence of molecular oxygen) and oxic (presence of molecular oxygen) conditions. No significant impact of the presence of molecular oxygen on adsorption capacity was noted for ACC-10. ACC-10 has an average pore width of 19.2 A and total pore volume of 0.43 cm3g(-1). On the other hand, for the remaining ACFs, which have larger average pore width and larger pore volume, significant increase in the adsorptive capacity had been observed when molecular oxygen was present. The GAC gave the greatest difference between anoxic and oxic conditions when compared to all the ACFs studied. Binary adsorption of o-cresol and 2-ethylphenol on ACFs with the least pore size (ACC-10) also showed no significant differences between oxic and anoxic environment. The binary system under both anoxic and oxic conditions was well predicted by the ideal adsorbed solution theory (IAST).