Efficient adsorption of hydroxychloroquine by carboxylated lignin-based sponge: Quantification of the adsorption contribution of interactions

Hydroxychloroquine (HCQ) as an antiviral pharmaceutical has been widely detected in the aquatic environment. Adsorption is an effective method for removal of HCQ, but the quantitative study of the adsorption interactions is unclear. In this study, a carboxylated lignin-based sponge (PLC) was fabricated, and the adsorption contributions of electrostatic attraction (EA), hydrogen bond (HB), and π-π electron donor–acceptor (π-π EDA) interactions were quantitatively investigated. The results showed that PLC exhibited excellent adsorption performance under wide pH range (4.0 < pH < 11.0), with the highest adsorption capacity of 0.165 mmol/g. Inhibitor and molecular probe experiments showed that EA and HB were the main contributors to adsorption at neutral and basic pH ranges, respectively. A linear correlation model of the carboxyl groups of lignin-based sponges with the adsorption capacity of EA, HB, and π-π EDA interactions of HCQ ( R 2  > 0.822) and three molecular probes ( R 2  > 0.749) was established, respectively. The optimal adsorption capacity was achieved by the synergistic combination of the deprotonated carboxyl of PLC with the HB of Ka1 amino, EA of Ka2 amino, and the π-π EDA of the quinoline ring. This study provided a new strategy for the quantitative construction of structure–activity relationships of adsorbents.