Adsorption of Volatile Organic Compounds and Microwave Regeneration on Self-prepared High-surface-area Beaded Activated Carbon

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Self-prepared beaded activated carbons (SBAC) were derived from carbonized phenolic formaldehyde (PF) resins through an optimal activation procedure (900°C for 4 h) using CO2 and compared with a commercial BAC (termed KBAC) over physicochemical properties, adsorption performance against methyl ethyl ketone (MEK) and toluene (TOL), and their regenerability. Langmuir, Freundlich, and Dubinin‒Radushkevich (D‒R) isotherm models showed good fitting results. The isosteric heat of adsorption was calculated using the Clausius-Clapeyron equation; the parameters obtained from the D‒R isotherm indicate that the physisorption predominates the adsorption process. Microwave heating was applied to regenerate the saturated adsorbents to examine the effect of irradiation power and heating time on the desorption behavior. Within 12 min of microwave irradiation, excellent desorption efficiencies were shown, reaching 110 ± 14.4%, 104 ± 2.6%, 90.2 ± 2.3%, and 85.5 ± 5.7% for MEK-SBAC, MEK-KBAC, TOL-SBAC, and TOL-KBAC samples, respectively. Kinetic models were further employed to illustrate the desorption behavior, showing that intraparticle diffusion in SBAC and KBAC was the rate-limiting step during microwave heating. The core kinetic parameters could provide insights for lab-scale or practical engineering scale design. In conclusion, this study demonstrates the excellent adsorption performance of SBAC and the feasibility of microwave regeneration of BACs.

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