MIL-100(Fe)@cotton fiber as permeable reactive barrier for heavy metal contaminated soils: Preparation, performance and mechanism

Due to their toxicity and serious threat to human health and the environment, heavy metals in soil have drawn attention on a global scale. In our research, a new material MIL-100(Fe)@cotton fiber (CM100) was prepared by using waste cotton fiber as a substrate and loading MIL-100(Fe) particles by in-situ growth under green and mild preparation conditions. Its morphological characteristics and adsorption mechanism were investigated. It was used as a barrier to study the remediation characteristics of electrokinetic-permeable reactive barrier (EK-PRB) under different electrolytes. Results showed that CM100 was able to remove Pb2+ and Cd2+ with efficiencies of 96.1% and 78.7%, respectively. The adsorption is in accordance with the pseudo-second-order kinetic model and is dominated by chemisorption. Under different electrolyte compositions, the remediation efficiencies of CM100 and EK-PRB on heavy metal soils reached more than 90.0%. When the electrolyte was KCl/citric acid (CA), it could regulate soil pH and promote the migration of metal ions, which increased the remediation efficiency to 98.0%. Experimental results demonstrate that CM100/EK-PRB can effectively remediate heavy metal soil, and this study also provides a reference for the resource utilization of waste textiles.