The aminated covalent organic polymers for reversible removal of concurrent perfluorooctane sulfonate and dichromate

Abstract

The reversible removal of concurrent perfluorinated compounds and heavy metal ions is highly desirable but challenge in water remediation. Herein, we present a tetraethylenepentamine-modified covalent organic polymer (COP-NH2) containing flexible multi-amines and hydrophobic triptycene through post-synthetic amidation reaction of carboxyl-containing covalent organic polymer. The sorption behaviors of COP-NH2 toward perfluorooctane sulfonate (PFOS) and dichromate were investigated in terms of the adsorption kinetics, isotherms, simultaneous removal capability and reusability. The maximum uptake capacities of PFOS and dichromate on COP-NH2 are 1.40 mmol g−1 and 304.9 mg g−1, respectively, while their initial adsorption rates are as high as 6.45 mmol g-1h−1 and 164.2 mg g−1 min−1, respectively. Both of them surpass majority of the sorbents of the environmental contaminants. Importantly, PFOS and dichromate in the stimulated electroplating wastewater could be simultaneously and reversibly removed in high uptake efficiency over 99%. The promising performance is mainly attributed to protonation of the amines in COP-NH2, the resultant electrostatic interactions have been confirmed to play dominant roles in both PFOS and dichromate adsorption. This work provides multifunctional sorbents for reversible removal of concurrent contaminants from wastewater.