Enhanced degradation of reactive black 5 via persulfate activation by natural bornite: influencing parameters, mechanism and degradation pathway

ABSTRACT

Reactive black 5 (RBk5) is a refractory azo dye that constitutes a serious threat to the environment and humans. Herein, natural bornite (Nbo) was utilized to activate persulfate (PDS) for the RBk5 removal. The particle size of the Nbo catalyst was optimized and the RBk5 degradation rate constant that responded positively to the particle size of the Nbo catalyst was exhibited. Then, the operational factors affecting RBk5 removal were comprehensively investigated. With the addition of 1.5 g L⁻¹ Nbo and 1.5 mM PDS, 99.05% of the RBk5 (20 mg L⁻¹) was removed in 150 min compared with 0.46% removal with PDS only, which was caused by the additional reactive oxygen species (ROS) produced by the synergistic action of Fe-Cu bimetallic metal and reductive sulfur species. The Nbo catalyst presented high stability and reusability toward RBk5 removal. Identification of reactive oxygen species revealed that ${\mathrm{SO}}_4^{\cdot -}$, ·OH, ${\mathrm{O}}_2^{\cdot -}$ and ¹O₂ collectively participated in RBk5 removal. Additionally, a possible degradation pathway for RBk5 was proposed, including cleavage of the azo, C–S and S–O bonds, hydroxylation, hydrolyzation, direct oxidation and other pathways. This work developed a highly effective and low-cost natural mineral-based bimetallic sulfide material for PDS activation for the degradation of contaminants and environmental remediation.

GRAPHICAL ABSTRACT

KEYWORDS:

• Bornite
• persulfate
• reactive black 5
• synergistic effect
• mechanism

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article.

Additional information

Funding

This work was financially supported by the National Key Research and Development Program of China [grant number 2022YFC2904303] and the Shaanxi Provincial Department of Education Scientific Research Program Serving Local Special Project [grant number 22JC041].