FeS2-Fe1-xS heterostructure as a high-efficient Fenton-like catalyst for ultrafast degradation of orange II.

[Display omitted] • The right amount of cobalt ions could induce the formation of Fe 1-x S. • 100 mL orange II solution (30 mg/L) was degraded to 99.9% within 15 min. • OH and h+ played an important role in the photo-Fenton-like process. • FeS 2 -Fe 1-x S exhibited excellent stability and high catalytic degradation activity for other dyes. It is a challenge to develop heterogeneous Fenton-like catalysts with excellent performance and stability in the field of wastewater treatment. In this work, the FeS 2 -Fe 1-x S heterostructure catalyst was prepared by solvothermal method through adding cobalt element to change the particle nucleation process and inhibit the transformation process of pyrrhotite (Fe 1-x S) phase to pyrite (FeS 2) phase. Then, a series of experiments were devised to clarify the catalytic activity of FeS 2 -Fe 1-x S heterostructure. The degradation experiments exhibited that 99.9% degradation efficiency was achieved for 30 mg/L orange II solution within 15 min at the conditions of 0.2 g/L FeS 2 -Fe 1-x S, 2 mM H 2 O 2 and pH = 3.0. In addition, the reusability of the FeS 2 -Fe 1-x S catalyst was also investigated and the result displayed that degradation efficiency of orange II can reach 95.2% after eight cycles. The degradation of orange II was enhanced by Fenton reaction between FeS 2 -Fe 1-x S and dissolved oxygen, which could smoothly release Fe2+ and Fe3+ for the activation of H 2 O 2 to produce more hydroxyl radicals. Finally, the degradation pathway of orange II was proposed by detecting intermediates produced in FeS 2 -Fe 1-x S/H 2 O 2 photo-Fenton-like system by liquid chromatography-mass spectrometry (LC-MS). In short, FeS 2 -Fe 1-x S is a promising catalyst for removing the organic pollutants from solutions. [ABSTRACT FROM AUTHOR]