Activation of persulfate using a biochar polyacrylic acid composite loaded with nanoscale zero-valent iron for the in situ remediation of anthracene-contaminated soil

Synthesizing highly efficient, low toxicity catalysts for the remediation of polycyclic aromatic hydrocarbons (PAHs) contaminated soils is crucial. Nanoscale zero-valent iron (n-ZVI) is widely used in the treatment of pollutants due to its high catalytic activity. However, n-ZVI is prone to aggregation and passivation. Therefore, to design an environmentally friendly, efficient, and practical catalyst material, this study designed a nanoscale zero-valent iron-loaded biochar (BC) polyacrylic acid (PAA) composite materials. Biochar and polyacrylic acid can prevent the aggregation of zero-valent iron and provide a large number of functional groups. The iron on the carrier is uniformly distributed, exposing active sites and activating persulfate to remove anthracene (ANT) pollutants from the soil. The BC/PAA/Fe⁰ system can achieve an anthracene degradation efficiency of 93.7% in soil, and the degradation efficiency of anthracene remains around 90% under both acidic and alkaline conditions. Free radical capture experiments indicate that the degradation of anthracene proceeds through the radical pathways SO₄^·-, ·OH, O₂^·- and the non-radical pathway ¹O₂. In addition, possible degradation pathways for anthracene have been proposed. Plant planting experiments have shown that the catalyst designed in this study has low toxicity and has excellent application prospects in the field of soil remediation.