COMPARISON OF ADSORPTION CHARACTERISTICS FOR VOCS ON ACTIVATED CARBON AND OXIDIZED ACTIVATED CARBON

In this investigation, the selected activated carbon is treated in NaOH solution or gas fluid with ozone from an ozone generator. FTIR, BET specific surface area and element analysis instruments were used to identify the difference in the chemical and physical characteristics between the activated carbon and oxidized activated carbon. The system of adsorption apparatus consists of a fixed adsorption column, quartz pan, electronic balance, and data acquisition system to measure the adsorption capacities and adsorption rates for VOCs under various operating conditions. VOCs, n-hexane, methyl-ethyl-ketone, and benzene were selected to evaluate the effect of adsorption characteristics on the activated carbon and oxidized activated carbon. The results of chemical analysis with the FTIR instrument indicate the absorption bands and peaks measured at 1632 cm-1 on the oxidized activated carbons (AOHO3 and AO3) are much stronger than on the activated carbon (AC). This shows that carbonyl (conjugated C = O) of the functional group is predominantly found to increase on the oxidized activated carbons (AO3 and AOHO3). Significant changes were observed for BET-specific areas for AOHO3 and AO3 but the carbon contents of AOHO3 and AO3 decreased slightly. Moreover, the oxidized activated carbons showed greater affinity for polar adsorbate than did AC, and the overall effective mass transfer coefficients, k(D), of AO3 for various VOC adsorption were larger than those of AC and AOHO3.