Construction of an EDTA-assisted biochar-supported nanoscale zero-valent iron catalyst from betel nut shell and blast furnace dust for enhanced H2O2 generation and Fenton-like degradation of 4-fluorophenol.

4-Fluorophenol (4-FP), as a typical fluorinated pharmaceutical intermediate, is difficult to be removed by conventional biological treatments due to its environmental persistence and biological toxicity. In addition, the reprocessing of blast furnace dust (BFD), a by-product of the steel production process, remains an important industrial challenge. To address the challenges of remediation of difficult-to-degrade fluorinated pollutants and resource utilization of industrial wastes, a green catalytic system based on synergistic utilization of industrial wastes and waste biomass was developed in this study. By preparing biochar-supported nanoscale zero-valent iron composites (nZVI@C) through carbothermal reduction of blast furnace dust (BFD) with betel nut shell biochar, and constructing an nZVI@C/EDTA catalytic system, the efficient removal of typical refractory fluorinated pollutants was achieved. The experimental results show that under the conditions of a nZVI@C-900 dosage of 1.5 g/L, an initial pH of 4, and an EDTA-2Na concentration of 3 mmol/L, the system can degrade 91.7% of a 20 mg/L 4-FP solution within 10 min. In addition, consecutive cycling experiments were performed to evaluate the reusability of the catalyst. Quenching experiments confirmed that superoxide radical (·O2-) and hydroxyl radical (·OH) were the main reactive oxygen species (ROS) dominating the reaction pathway. By converting BFD, a by-product of iron and steel industry, and betel nut shell, an agricultural waste, into an efficient catalyst, this method not only achieves the sustainable goal of "treating waste with waste", but also provides an innovative solution for the environmental remediation of fluorinated organic pollutants.