Reversible Removal of SO2 with Amine-Functionalized ZIF8 Dispersed in n‑Heptanol

In this work, amine-functionalized ZIF8 (i.e., ZIF8-A) was dispersed in n-heptanol (ZIF8-A/n-heptanol) to remove SO2. The effects of ZIF8-A proportion, SO2 concentration, and absorption and desorption temperatures on the removal of SO2 were systematically investigated. The experimental results showed that the activity of ZIF8-A on SO2 removal was enhanced after being dispersed in n-heptanol. The SO2 saturation capacity increased with increasing proportion of ZIF8-A and SO2 concentration. The optimal temperatures for SO2 absorption and desorption were found to be 25 and 120 °C, respectively. Under the optimal experimental conditions (25 °C and 4% SO2), the SO2 saturation capacity was 589 mg/g. Five continuous absorption–desorption cycles suggested a good regeneration performance. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, ultraviolet analyses, and computational simulation indicated that SO2 mainly interacted with ZIF8-A via hydrogen bonds besides physical absorption. The simulation results further indicated that the enhanced SO2 adsorption performance of ZIF8-A when dispersed in n-heptanol was due to the lower self-diffusion coefficient and higher isosteric heat of SO2 molecules in ZIF8-A/n-heptanol.