Confinement effect and efficient adsorption of furfural onto ZIF-8-derived microporous carbon

BACKGROUND The separation of furfural from a low-concentration multicomponent and acid-containing aqueous solution is a highly demanding process; traditional distillation requires an excessive amount of energy. Herein, we demonstrated ZIF-8-derived microporous carbon (C) as a promising adsorbent for the separation of furfural using adsorption isotherms, dynamic column adsorption, adsorption kinetics and desorption studies. RESULTS In the competitive adsorption kinetics experiments with a furfural/acetic acid concentration of 50/20 g L −1 , the acetic acid adsorbed in the micropores of NC ZIF-8 1000C-800A gradually was replaced by furfural, whereas the amount of acetic acid in the mesopores of NC ZIF-8 800C-800A slowly increased. In addition, the micropores of NC ZIF-8 1000C-800A exhibited highly efficient and fast adsorption characteristics toward furfural over a wide furfural/acetic acid concentration range (0–50/0–20 g L −1 ) with the furfural adsorption capacity reaching an adsorption equilibrium within 10 min. The results show that the high Brunauer–Emmett–Teller surface area of NC ZIF-8 1000C-800A is responsible for the high furfural adsorption capacity (1205.3 mg g −1 ) and the confined microporous structure can strengthen the π–π interactions between porous C and furfural, thereby enhancing the selectivity of furfural/acetic acid (61.4) in the furfural/acetic acid (50/20 g L −1 ) dynamic column adsorption system. Meanwhile, the desorption ratio of furfural in the dynamic desorption system reached as high as 98.6%. CONCLUSION The unique micropore-confinement effect and excellent adsorption behavior make NC ZIF-8 1000C-800A an efficient adsorbent for furfural in the furfural–acetic acid system. © 2023 Society of Chemical Industry (SCI).