Adsorption equilibria of ester VOCs (ethyl and butyl acetates) on activated carbon in supercritical CO2: Measurement and modeling by the Dubinin–Astakhov equation

• Published in: The Journal of supercritical fluids 2022-10, Vol.189, p.105719, Article 105719
• Main Authors: Ushiki, Ikuo, Ueno, Yuji, Takishima, Shigeki, Ito, Yasuyuki, Inomata, Hiroshi
• Format: Article
• Language: English
• Subjects: Activated carbon; Adsorption equilibria; Dubinin–Astakhov (DA) equation; Ester; Supercritical CO2; Volatile organic compound (VOC)
• ISSN: 0896-8446; 1872-8162
• DOI: 10.1016/j.supflu.2022.105719

The adsorption equilibria of ethyl and butyl acetates, the main volatile organic compounds (VOCs) used in the printing industry, on activated carbon were measured in supercritical CO2 at 10–20 MPa and 313–353 K. The measured adsorption equilibria of the VOCs decreased with increasing pressure and decreasing temperature. The amount of butyl acetate adsorption was greater than that of ethyl acetate, owing to differences in the affinities of the VOCs for the adsorbent and in their volatilities in supercritical CO2. The measured adsorption equilibria were correlated using the Dubinin–Astakhov equation to within an average relative deviation of 3.1 %. Furthermore, the parameters determined by this correlation strongly depended on the CO2 density and VOC properties. These analyses enabled us to evaluate the adsorption phenomena of the ester VOCs in supercritical CO2, including the effects of the interaction between the VOC and adsorbent, and the CO2 density. [Display omitted] •Experimental adsorption data for ester VOCs on activated carbon in supercritical CO2 reported.•Adsorption equilibria depend strongly on CO2 density.•Adsorption equilibria characterized by Dubinin-Astakhov equation.•Trend of model parameters allows quantitative understanding of adsorption phenomena.