Isobutanol Vapor Adsorption on Activated Carbons: Equilibrium and Kinetic Studies

Activated carbon (AC) is commonly used to remove volatile organic compounds (VOCs) from the air. The purification efficiency depends on adsorbent characteristics (surface area, pore size, surface chemistry), adsorbate properties (size, functional groups, polarity), and process conditions. In the present study, the affinity of the Sorbonorit 4 (S4), Sorbonorit B4 (SB4), and BPL 4 x 6 (BPL) activated carbons toward the isobutanol (i-BuOH) vapor adsorption was investigated. The impact of vapor pressure and temperature on,the process efficiency was examined. Adsorption equilibrium and kinetic measurements were conducted at 293.15, 313.15, 348.15, 373.15, and 393.15 K using an intelligent gravimetric analyzer (IGA). Experimental isotherm data were analyzed using the multitemperature Toth, Sips, and hybrid Langmuir-Sips models. Results indicated that the Sips model gave somewhat better fit than the others. The adsorption capacities of ACs at the same vapor pressure followed the order: S4 > BPL > SB4. Adsorption kinetic measurements at a constant vapor pressure of i-BuOH (ca. S.6 Pa) showed that an increase in temperature affects an increase in the adsorption uptake and a decrease in the adsorbent efficiency. The pseudo-first-order model fitted very well the experimental data (R-2 > 0.99) which suggests that physisorption plays a decisive role in the process mechanism.