Accelerated degradation of sulfadiazine by wet mechanochemical synthesized nano-pyrite FeS2 based Fenton system: Performance, mechanism and applicability

• FeS 2 nanoparticles were newly prepared by a wet ball milling method with Fe and S. • The novel mechanochemical synthesized FeS 2 Fenton system was investigated. • This system exhibit superior degradation ability for sulfadiazine at wide pH range. • Amorphous phase induced homogeneous Fenton reactions dominate the degradation. Pyrite have been recognized as a promising Fenton reagent to degrade multitudinous organic contaminants. However, the dominating contribution of heterogeneous and homogeneous Fenton reaction to degradation in pyrite Fenton system is ambiguous. In this work, pyrite FeS 2 nanoparticles were newly prepared by a wet ball milling method with iron, sulfur and ethanol without protective gas. A subsequent heat-treatment was used to optimize the pyrite crystallinity. The degradation performance of synthesized FeS 2 Fenton system for sulfadiazine were systematically investigated for the first time. The synthesized FeS 2 Fenton system exhibited ultra-fast and superior degradation ability at wide pH range (3–9) compared with current pyrite Fenton system and 100% sulfadiazine was removed in 4 min with 0.4 g/L FeS 2 , 2.5 mmol/L H 2 O 2 and initial pH of 7. It’s found that ball milling process and heat-treatment affect the performance of synthesized FeS 2 Fenton system. The pH self-adjustment induced by accelerated dissolution of amorphous FeS 2 and the Fe 2+ /Fe 3+ cyclic regeneration ability resulted in the dominating homogeneous Fenton reaction to degrade sulfadiazine. The maintained excellent degradation ability of synthesized FeS 2 after reused three times, in scale-up system, exposed in air for 5 weeks or in real water system (tap water and river water) indicated its promising application possibility and the possible degradation pathways of sulfadiazine by synthesized FeS 2 Fenton system were also proposed.