Iron-doped swine bone char as hydrogen peroxide activator for efficient removal of acetaminophen in water

Bone char is a functional material obtained by calcining animal bones and is widely used for environmental remediation. In this work, iron was inserted into porcine bone-derived bone char via ion exchange to synthesize iron-doped bone char (Fe-BC) for efficient catalysis of hydrogen peroxide. This is the first time that Fe-BC has been used as a catalyst for the activation of H₂O₂. The effectiveness of the Fe-BC catalyst was influenced by the annealing temperature and the amount of iron doping. The results showed that the activation of H₂O₂ by the Fe-BC catalyst with the best catalytic performance could achieve 97.6% of APAP degradation within 30 min. Insights from electron paramagnetic resonance (EPR), free radical scavenging experiments and linear sweep voltammetry (LSV) proposed a reaction mechanism based on free radicals dominated degradation pathways ([rad]OH and O₂[rad]⁻). Iron served as the primary active site in Fe-BC, with defect sites and oxygen-containing groups in the catalyst also contributing to the removal of pollutants. The Fe-BC/H₂O₂ system demonstrated resilience to interference from common anions (Cl⁻, NO₃⁻, SO₄²⁻ and HCO₃⁻) in water, but was less effective against humic acid (HA). Based on the detection of intermediates produced during APAP degradation, possible degradation pathways of APAP were proposed and the toxicity of intermediates was evaluated. This work provides fresh insights into the use of heterogeneous Fenton catalysts for the removal of organic pollutants from water.