The alkaline sites integrated into biomass-carbon reinforce selective adsorption of acetic acid: In situ implanting MgO during activation operation

The alkaline site-modified biomass-carbon adsorbents through in-situ implanting MgO can be fabricated for reinforcing the adsorption abatement of polar VOCs of acetic acid. • Alkaline site-modified biomass-carbon adsorbents through in-situ implanting MgO was obtained. • MgO occupied a higher surface forming ratio in in-situ synthesized 10MgO/C compared to post-impregnated 10MgO/C-P. • The optimal sample of 10MgO/C afforded excellent structural properties. • 10MgO/C showed improved acetic acid adsorption capacity, reversible desorption behavior, and lower adsorption heat. • The constructed AC affords great selective adsorption separation of CH 3 COOH/C 6 H 6 binary mixture. The adsorption separation of volatile organic compounds affords an efficient potential solution to address VOC emission. In this work, we reported alkaline sites-modified biomass-carbon adsorbents through in situ implanting MgO for reinforcing the adsorption abatement of polar VOCs. We revealed that the dispersed MgO alkaline sites in situ formed over the activated carbon during the KOH activation process by placing the magnesium acetate and KOH into grapefruit peel-based biochar together, which avoids the repeated postmodification. By tuning the mass proportion of Mg precursor and KOH activator, the optimized loading of magnesium oxide in AC was explored and compared with the MgO post-modified AC using a two-step procedure. The physicochemical properties of MgO-modified AC were characterized by various techniques. Impressively, MgO occupied a higher surface formation ratio (82.6%) in whole Mg species of the in-situ synthesized 10MgO/C compared to that (51.4%) in postimpregnated 10MgO/C-P. The adsorption properties of polar acetic acid and nonpolar benzene over the above comparative adsorbents were systematically studied by the gas-static adsorption method. The results revealed that the optimal sample of 10MgO/C afforded excellent structural properties (S BET = 2646 m 2 g −1 , V total = 1.59 cm 3 g −1 ) and a large adsorption capacity of polar acetic acid reaching 16.64 mmol g −1 at 30 °C. More importantly, compared to unmodified and nitrogen-doped AC, 10MgO/C showed improved acetic acid adsorption capacity, reversible desorption behavior, and lower adsorption heat. The calculation of Ideal Adsorption Solution Theory (IAST) for selective adsorption separation of the CH 3 COOH/C 6 H 6 binary mixture(50/50) over 10MgO/C showed the highest selectivity (3.42). This work offers new insight into the in-situ modification of AC and polar VOCs selective adsorption separation.