The potential of a natural iron ore residue application in the efficient removal of tetracycline hydrochloride from an aqueous solution: insight into the degradation mechanism

In the existing research, most of the heterogeneous catalysts applied in the activation of persulfate to degrade organic pollutants were synthesized from chemical reagents in the laboratory. In this paper, we have obtained a spent iron ore (JO) residue directly collecting from the iron ore plants, and efficiently activating peroxydisulfate (PS) to produce reactive free radicals. The experimental results demonstrated that the IO could effectively activate PS to degrade tetracycline hydrochloride (TCH), with TCH removal rate reaching up to 85.6% within 2 h at room temperature. The TCH removal rate was increased with increasing iron ore dosage, while the more acidic pH condition would be favorable to TCH removal process. The material characterization results demonstrated that the dominant components of IO were Fe3O4 and FeOOH. The transformation from Fe(II) to Fe(III) at the surface IO was observed after TCH degradation. What's more, the quenching experiment and EPR detection results confirmed that the sulfate radical (SO4 center dot-) and hydroxyl radicals (center dot OH) would be acting as the main free radicals for TCH degradation. This study could not only explore a novel way to recycle the discarded iron ore, but also further expand its application in an effective activation of PS in an aqueous solution.

Automated summary

In this study, a spent iron ore residue was collected from iron ore plants and used as a heterogeneous catalyst to activate peroxydisulfate for the degradation of tetracycline hydrochloride. The experimental results showed efficient removal of tetracycline hydrochloride with increasing iron ore dosage and acidic pH conditions. Characterization results revealed the dominant components of the iron ore and the transformation of Fe(II) to Fe(III) during tetracycline hydrochloride degradation. Quenching experiments and EPR detection confirmed the involvement of sulfate and hydroxyl radicals as the main reactive species. This study not only explores a novel way to recycle discarded iron ore but also expands its application in the activation of peroxydisulfate.