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.
Highlights
Mining industry is an important activity to extract mineral products around the world
We found that a unite mass wheat straw could produce about 5 mg/g H2 and 18 mg/g CH4 (Gao and Goldfarb 2019)
The pyrolysis preparation mass ratio, reaction time and heating rate were fixed at 3:1, 60 min and 10 °C/min, respectively, and catalysts were obtained under different pyrolysis temperature
Summary
Mining industry is an important activity to extract mineral products around the world. Tailings are solid waste remaining after mining valuable minerals, which are usually disposed at waste dams or landfills that present potential environmental damage (Rico et al 2008; Kossoff et al 2014). In March 2020, a miserable accident involving a waste dam occurred when the Yichun waste dam (Harbin, China) for the storage of iron ore tailings collapsed. This accident caused 60,000 m3 of mining tailings disclosing and 3 million m3 of wastewater releasing, leading to 70 kilometers of river pollution and serious economic loss. A number of other tailings dam accidents have occurred in different countries (Batista et al 2020). Among all types of tailings, iron ore tailings have the largest amount of production, about 4.76 billion tons, accounting for about 39.31% of the total tailings production (Huang et al 2020)
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