Highly Efficient Removal of Organic Contaminant with Wide Concentration Range by a Novel Self-Cleaning Hydrogel: Mechanism, Degradation Pathway and Dft Calculation

Abstract

A novel carbon nitride based self-cleaning hydrogel photocatalyst (KI-PCN gel, potassium and iodine co-doped carbon nitride confined in alginate) has been successfully constructed by a facile method. Fabricated catalyst showed enhanced synergistic adsorption-photocatalytic degradation property on a high concentration of methylene blue (HMB) because of enhanced carrier separation efficiency and widen bandgap of KI-PCN. As expected, the KI-PCN gel showed the highest apparent rate constant value( [[EQUATION]] =0.0301 min -1 ), which was about 27.4 and 5.2 times as that of bank hydrogel and PCN gel, respectively. Meanwhile, KI-PCN gel can continuously adsorb low concentration MB (LMB), and the MB-adsorbed KI-PCN gel can self-cleaning under light irradiation. For example, the bench-scale experimental simulating real river showed that KI-PCN gel can effectively and continuously remove LMB (0.1-20 ppm) with a removal rate of 91.33%, indicating the possibility for the removal of contaminants in natural rivers. Furthermore, the intermediates were identified through liquid chromatography-mass spectrometry (LC-MS), and the possible degradation pathways were proposed by combining the density functional calculations. This work might propose a new perspective to acquire a novel self-cleaning and easily recyclable photocatalyst for the wide concentration range of organic wastewater treatment as well as remediation of natural waterbody.

Keywords: Hydrogel, K and I co-doped C3N4, DFT calculation, Solar light driven, Self-cleaning