Metal-Organic Frameworks (Mil-101) Decorated Biochar as a Highly Efficient Bio-Based Composite for Immobilization of Polycyclic Aromatic Hydrocarbons and Copper in Real Contaminated Soil

Real-contaminated soils are a significant source of combined polycyclic aromatic hydrocarbons and potentially toxic elements, which call for special methods of immobilization. Herein, for the first time, Fe-based metal-organic frameworks (MIL-101(Fe)) were composited with biochar to use as an amendment to a real highly contaminated soil in dynamic column leaching experiments. In this regard, MIL-101(Fe) composites were successfully mounted on the surface of rice husk biochar (RBC) to create a composite. Response surface methodology was used to model Cu contents in the leachate by considering two independent parameters: sorbent-to-soil mass ratio and leaching time. The effectiveness of Cu immobilization was observed to improve in the presence of 3% RBC-MIL and a leaching period of two days with a minimum concentration of 0.2 mg L−1. According to the chemical fractionation findings, RBC-MIL remarkably eliminated the acid soluble fraction of Cu by deploying it in the residual fraction. It was found that the composite was more effective at polycyclic aromatic hydrocarbon retention by having a capacity of 15.70 μg g−1, as opposed to RBC, which had a capacity of 4.86 μg g−1. Overall, our results demonstrate that MIL-based biochar composites can be utilized as advanced amendments for remediating real contaminated soil.