Removal of PET Microfibers from Simulated Wastewater Using Magnetic Nano-Ferric-Loaded Biochar: High Adsorption and Regeneration Performance

Polyethylene terephthalate (PET) microfibers in effluent are difficult to remove using technology. In this study, a novel nano-sized iron-oxide-loaded biochar (FBC) with robust magnetic response characteristics was prepared by the impregnation-pyrolysis method and used for the removal of PET microfibers in simulated wastewater. The results showed that the removal efficiency of FBC on PET exceeded 91.69% over a wide pH range (4~9) and was barely affected by co-existing COD (15~500 mg/L) at an initial PET concentration of 1 g/L and FBC dosage of 3 g/L. The adsorption kinetics and isotherms indicated that the adsorption was more consistent with the pseudo-second-order kinetics (PSO) model and the Langmuir model, suggesting that the adsorption involved both physical and chemical actions. In addition, the maximum PET adsorption capacity expected by the Langmuir model reached 4500 mg/g, confirming the high adsorption performance of FBC. The characterization of FBC before and after adsorption indicated that PET was adsorbed mainly by the formation of Fe-O-PET bonds, π-π interactions, and hydrogen bonding. In addition, the FBC maintained a high PET removal efficiency of over 95.59% after four consecutive regeneration cycles. This study provides new insights into the efficient removal of fibrous microplastics from wastewater.