Rapid degradation of formaldehyde using Fe coupled with walnut shell biochar with high surface defect in Fenton-like reaction

The Fenton technology used for treating formaldehyde-containing wastewater (HCHO) has limitations in terms of pH, efficiency, and cost. To address these issues, a Fex-HT Fenton-like catalyst was developed in this study. This catalyst combines active Fe with walnut shell biochar (HT) that contains surface defects, resulting in a highly effective solution for the rapid purification of formaldehyde wastewater in complex environments. The carbon defects on the HT surface play a crucial role in stabilizing the active Fe binding, while the appropriate loading of Fe further enhances the specific surface area of HT. Additionally, the porous structure of HT provides ample contact sites for formaldehyde. Furthermore, the Fe3-HT catalyst exhibits superparamagnetism, allowing for convenient recovery of the catalyst after use. Experimental results demonstrate that Fe3-HT achieves an impressive 90% degradation rate for systems containing HCHO concentrations ranging from 200-800 mg/L. The effects of feed ratio, pH, and formaldehyde concentration on the performance of Fe3-HT were thoroughly investigated. Moreover, a possible mechanism for the degradation of HCHO by the Fe3-HT Fenton catalyst was proposed. The environmentally friendly catalyst developed in this study boasts numerous advantages, including low cost, high treatment capacity for wastewater, and strong adaptability to complex wastewater environments.