Piperazine-Linked Covalent Triazine Polymer as an Efficient Platform for the Removal of Toxic Mercury(II) Ions from Wastewater

Abstract

A piperazine-linked robust N-rich covalent organic polymer (COP), SMCOP-1, was synthesized by a catalyst-free method and characterized by Fourier transform infrared (FTIR), 13C CP/MAS, X-ray photoelectron spectroscopy (XPS), and powder X-ray diffraction (PXRD). This polymeric material can work as an efficient platform for removing toxic Hg2+ from wastewater. This system showed >97% Hg2+ removal, as confirmed by inductively coupled plasma atomic emission spectroscopy (ICP-AES), with a maximum uptake capacity of 1329 mg g-1. Hg2+ incorporation inside SMCOP-1 was confirmed by XPS, energy-dispersive spectrometry (EDS), and elemental mapping of field emission scanning electron microscopy (FE-SEM). The high Hg2+ removal capacity of SMCOP-1 can be attributed to the strong noncovalent interaction between the Hg2+ ion and the binding sites of the covalent organic polymer, as suggested by density functional theory (DFT) calculations, noncovalent interaction (NCI) analysis, and the electrostatic potential (ESP) map. The material's recyclability was studied for up to four consecutive cycles, and it was observed that it retained a high removal capacity without any change in the structure and morphology, as confirmed by FTIR and FE-SEM. ©