Efficient SO2 capture using an amine-functionalized, nanocrystalline cellulose-based adsorbent

Adsorbents made from cellulose derivatives have been widely studied for removal of contaminants such as toxic gases, pharmaceutical ingredients, dyes, and metals due to the availability, cost-effectiveness, and non-contaminating nature of these adsorbents. In this study, amine-functionalized cellulose is proposed as a green adsorbent for SO2 capture. Cellulose nanocrystals were chemically modified with ethylenediamine (EDA) using a solvent-free method. The surface modification was confirmed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), solid-state carbon nuclear magnetic resonance (13C NMR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and elemental analysis. The effects of functionalization time, temperature, and amount of EDA on the SO2 capture capacity were assessed. During these investigations, the highest adsorption capacity obtained was 2.07 mg-SO2/gsorbent, which is six times higher than for pristine nanocrystalline cellulose (NCC) used under the same conditions. Furthermore, the effect of various operating adsorption temperatures and flow rates was investigated. When the temperature was reduced, there was a significant increase in capture capacity and breakthrough time, confirming an adsorption mechanism for SO2 capture. It was also confirmed that as the flow rate of the feed gas increases, the breakthrough time decreases, as expected, with a steeper breakthrough curve, because of the faster transport of the adsorbate molecules.