Bioleaching assisted conversion of refractory low-grade ferruginous rhodochrosite to Mn-Fe based catalysts for sulfathiazole degradation

Abstract

Ferruginous rhodochrosite with high impurity is difficult to be utilized by traditional beneficiation process due to the complex characteristics. Herein, a bioleaching process driven by Acidithiobacillus ferrooxidans was proposed to recover Mn and Fe in ferruginous rhodochrosite with economic and environmental benefits. The biogenic Fe3+, H+ and extracellular polymeric substances produced in bioleaching process significantly promoted the metal recovery and reduced the H2S emission. Optimal metal leaching efficiencies (95.94% of Mn and 97.54% of Fe) were achieved in bioleaching group. Furthermore, the Mn and Fe mixed leaching solutions could be directly adopted to fabricate Mn-Fe oxide based materials (MFO). When applied as catalysts for peroxymonosulfate (PMS) activation, the as-synthesized MFO performed well for sulfathiazole (STZ) degradation with a 98.66% removal efficiency in 40 min. Both radical process and non-radical process occurred in the advanced oxidation process, which induced the generation of abundant active species of ̇OH, SO4 ̇− and 1O2. Meanwhile, charge transfer also contributed to STZ degradation. Favorably, MFO-3 exhibited good reusability in recycle study and showed adaptability towards various natural water matrixes. This research not only provided novel insights into the utilization of recalcitrant ferruginous rhodochrosite resources, but also enriched the strategy of PMS activator design for environmentalremediation.