Ionic liquids modified starch-based porous material for efficient formaldehyde capture

Formaldehyde (HCHO) is a major pollutant among indoor volatile organic compounds (VOCs) and has been categorized as a Group 1 carcinogen by the World Health Organization. Designing and preparing green and environmentally friendly porous bio-adsorbents for efficient adsorption of HCHO is essential. This study developed a novel porous starch-graft-styrene hypercrosslinked polymer (IL@H-St-g-PS) for efficient HCHO adsorption through post-modification strategy using ionic liquids (ILs). Firstly, [EMIm][OAc] was selected in four ILs by theoretical calculation due to the strongest binding energy with HCHO. Then, H-St-g-PS was modified with [EMIm][OAc] and thus the product IL@H-St-g-PS possessed abundant adsorption sites such as starch hydroxyl groups, acetate ions and imidazole groups in ILs. The prepared IL@H-St-g-PS had a high BET surface area (645 m²/g) with a micropore volume and reached an HCHO adsorption capacity at 15.0 mg/g at 350 ppm, which was approximately 2.0 times greater than that of the original H-St-g-PS. The adsorption of HCHO on glucose units of starch and ionic liquid units within IL@H-St-g-PS could be enhanced through hydrogen bonding and electrostatic interactions. These results suggested that the ILs modified starch-based polymer could provide an environmentally friendly and attractive candidate adsorbent for the adsorption of aldehyde VOCs in practical applications.