# Photo-Enhanced Peroxymonosulfate Activation via Well-Dispersed Cobalt Nanoparticles Encapsulated on Carbon Nitride for 2,8-Dichlorodibenzo-p-dioxin Removal

## TL;DR

This study develops a new catalyst using cobalt nanoparticles on carbon nitride to efficiently remove a toxic chemical from water using visible light and peroxymonosulfate.

## Contribution

A novel photocatalytic system using well-dispersed cobalt nanoparticles on carbon nitride for efficient 2,8-DCDD degradation under visible light.

## Key findings

- 2CoCN achieved 90.5% degradation of 2,8-DCDD within 160 minutes under visible light and PMS.
- The catalyst showed excellent reusability and pH adaptability, working well under neutral conditions.
- SO4•−, •OH, and 1O2 were identified as the primary reactive oxygen species responsible for degradation.

## Abstract

The removal of polychlorinated dibenzo-p-dioxins (PCDDs) via advanced oxidation processes (AOPs) poses a significant challenge due to their high toxicity and chemical stability. In this study, a series of well-dispersed cobalt nanoparticles supported on carbon nitrides (xCoCNs) was synthesized to activate peroxymonosulfate (PMS) for 2,8-dichlorodibenzo-p-dioxin (2,8-DCDD) degradation under visible light. The catalysts prepared were characterized using SEM, XPS, photoluminescence (PL), and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). Among them, 2CoCN with an optimal Co content exhibited the highest photocatalytic efficiency, achieving 90.5% degradation of 2,8-DCDD within 160 min under visible light/persulfate oxidation (Vis+PMS+2CoCN system). Compared with other catalysts, 2CoCN exhibited superior optical performance and a narrower bandgap, enabling efficient excitation under visible light (Vis). Notably, all xCoCNs demonstrated pH adaptability, achieving complete degradation of 2,8-DCDD under neutral conditions (pH = 7) without additional acid/alkali adjustment. Through rigorous free radical capture experiments, it was demonstrated that SO4•−, •OH and 1O2 were the primary reactive oxygen species (ROS) in the Vis+PMS+2CoCN system. The catalyst exhibited excellent reusability, with stable activity retained over five cycles. Based on these findings, degradation pathways and mechanisms of 2,8-DCDD in the 2CoCN+Vis+PMS system were proposed. This study presents an effective approach for PCDD abatement in wastewater treatment applications.