Ultra-sustainable Fe₇₈Si₉B₁₃ metallic glass as a catalyst for activation of persulfate on methylene blue degradation under UV-Vis light

Abstract

Stability and reusability are important characteristics of advanced catalysts for wastewater treatment. In this work, for the first time, sulfate radicals (SO₄∙−) with a high oxidative potential (E⁰ = 2.5–3.1 V) were successfully activated from persulfate by a FeFe₇₈Si₉B₁₃ metallic glass. This alloy exhibited a superior surface stability and reusability while activating persulfate as indicated by it being used for 30 times while maintaining an acceptable methylene blue (MB) degradation rate. The produced SiO₂ layer on the ribbon surface expanded strongly from the fresh use to the 20th use, providing stable protection of the buried Fe. MB degradation and kinetic study revealed 100% of the dye degradation with a kinetic rate k = 0.640 within 20 min under rational parameter control. The dominant reactive species for dye molecule decomposition in the first 10 min of the reaction was hydroxyl radicals (∙OH, E⁰ = 2.7 V) and in the last 10 min was sulfate radicals (SO₄∙−), respectively. Empirical operating variables for dye degradation in this work were under catalyst dosage 0.5 g/L, light irradiation 7.7 μW/cm², and persulfate concentration 1.0 mmol/L. The amorphous Fe₇₈Si₉B₁₃ alloy in this work will open a new gate for wastewater remediation.