Effective scavenging and selective adsorption of salicylic acid from wastewater using a novel deep eutectic solvents-based chitosan-acrylamide surface molecularly imprinted hydrogel

Abstract

A novel chitosan (CS)-acrylamide (AM) surface molecularly imprinted hydrogel (CAMIH) using deep eutectic solvents (DESs) as synthetic solvent was successfully prepared to remove salicylic acid (SA) from wastewater. Hydrogels prepared with choline chloride-ethylene glycol (ChCl-EG) as solvent had the highest SA adsorption capacity, indicating that ChCl-EG was the most suitable DESs solvent to prepare CAMIH. Structural analysis showed that CAMIH possessed a mesopore and irregular sheet structure, and the BET surface area of CAMIH was 5.2-folds than that of the non-molecular imprinted materials (CANIH). The selective adsorption capacity of SA by CAMIH were 44.87 mg/g, 28.23 mg/g, 28.57 mg/g, and 28.71 mg/g in single SA, SA and PHBA binary, SA and TC binary, and SA, PHBA, and TC ternary systems, respectively, which was higher than that of the CANIH. Electrostatic attraction and hydrogen bonding were involved in the removal of SA by the CAMIH through FT-IR and XPS analyses. The adsorption equilibrium reached within 20 min and the maximum adsorption capacity of SA by CAMIH was 106.5 mg/g, which was 1.2 times that of the CANIH. Results indicated that CAMIH could effectively and selectively remove SA from wastewater and had great potential in the field of SA polluted wastewater treatment.