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) composing of choline chloride (ChCl) and ethylene glycol (EG) as synthetic solvent was successfully prepared to remove salicylic acid (SA) from wastewater. 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, SA and TC, and SA, PHBA, and TC ternary systems, respectively, which was higher than that of the non-molecular imprinted materials (CANIH). In addition, hydrogels prepared with ChCl-EG as solvent had the highest SA adsorption capacity than those prepared with acetonitrile, methanol, and dimethyl sulfoxide, which indicated that ChCl-EG was the most suitable DESs solvent to prepare CAMIH. The mechanism analysis indicated that the electrostatic attraction and hydrogen bonding were involved in the removal of SA by CAMIH. The adsorption equilibrium was reached within 20 min and the maximum adsorption capacity of SA by CAMIH was 106.5 mg/g, which was 1.2-fold higher than that of CANIH. The result indicated that CAMIH could effectively and selectively remove SA from wastewater and had great potential in the field of SA polluted wastewater treatment.

Keywords: Chitosan, Deep eutectic solvents, Salicylic acid, Response surface method, Adsorption