Highly active Fenton-like catalyst derived from solid waste-iron ore tailings using wheat straw pyrolysis

Abstract

The pollutants degradation rate of iron ore tailings-based heterogeneous catalysts is the main factor limiting its application. Herein, an iron ore tailings-based Fenton-like catalyst (I/W(3:1)-900-60) with a relatively fast catalysis rate was constructed by co-pyrolysis (900°C, 60 min holding time) of iron ore tailings and wheat straw with a mass ratio of 3:1. With wheat straw blending, the generated I/W(3:1)-900-60 presented a larger surface area (24.53 m²/g), smaller pore size (3.76 nm), reduced iron species (Fe²⁺ from magnetic), and a higher catalytic activity (0.0229 min^-1) than I-900-60 (1.32 m²/g, 12.87 nm, 0.012 min^-1) pyrolyzed using single iron ore tailing under the same pyrolysis conditions. In addition, biochar and iron ore tailings in I/W(3:1)-900-60 were tightly combined through chemical bonding. The optimal catalyst remains active after three cycles, indicating its catalytic stability and recyclability. The good Fenton-like methylene blue degradation efficiency of I/W(3:1)-900-60 was ascribed to the sacrificial role of biochar, as well as the electron transfer between biochar and iron active sites or the redox cycles of ≡Fe³⁺/Fe²⁺. This finding provides a facile construction strategy for highly active iron ore tailings-based Fenton-like catalyst and thereby had a great potential application in wastewater treatment.

Keywords: Biochar; Decomposition rate; Heterogeneous catalyst; Iron ore tailings; Wheat straw.