Versatile preparation strategy of negatively charged saccharide-based polymers for selective removal of cationic organic pollutants

Abstract

Pursuing special negatively charged adsorbents is critical to selectively removing cationic pollutants from effluent. Herein, we proposed a versatile preparation strategy of negatively charged saccharide-based polymers using easily available saccharides as building blocks and hexachlorocyclotriphosphazene as a linker in a facile “one-step” method. Because of the existence of numerous hydroxyl groups and phosphine nitrile units in the skeleton, these polymers show selective adsorption capacity towards cationic dyes and pharmaceuticals, but not for ionic dyes and uncharged bisphenol A. Notably, β-cyclodextrin-based polymers (β-CDPs) displayed remarkable adsorption towards methylene blue (Qm, 1563 mg g−1) and promethazine (Qm, 944 mg g−1). Systematic experiments revealed that the synergy of “host-guest” inclusion, electrostatic attraction, and π-π interaction promoted the selective and efficient adsorption of cationic pollutants. Given the efficiently selective adsorption of cationic dyes and pharmaceuticals, these negatively charged saccharide-based polymers should be candidates for the adsorption of other cationic pollutants, including heavy metal ions. This work expanded the scope of the special utilization of biomass-based adsorbents for water remediation.