Effect of oxidized pyrite activating persulfate on the degradation of aniline aerofloat: Mechanism and degradation pathway

•Pyrite oxidized in natural air was more effective to remove DDA through activating PS.•The key operational conditions were studied and determined.•The DDA degradation mechanism in the oxidized pyrite-PS system was revealed.•The degradation products were measured and a degradation pathway was hypothesized. Aniline aerofloat (dianilinodithiophosphoric acid, DDA) is a common flotation collector for sulfide minerals, but it is also toxic and difficult to be degraded. In this study, oxidized pyrite was used to degrade DDA through activating persulfate (PS). It was found that oxidized pyrite was far more effective than fresh pyrite at removing DDA from a PS system over a wide pH range. The effect of the pyrite oxidation time, initial pH, PS concentration, pyrite dosage and pyrite particle size on DDA degradation in the pyrite-PS system were studied and optimal conditions determined. Through analysis of the total Fe ions concentration, radical species identification and XPS analysis of the change of surface species Fe and S, the DDA degradation mechanism in the oxidized pyrite-PS system was determined. The degradation products were measured by gas chromatography-mass spectrometry (GC–MS) and a potential DDA degradation pathway was hypothesized. The results in this study suggest a template for the utilization of oxidized pyrite in gangue minerals to remove DDA from the wastewater in mineral processing plants.