Defective iron-based metal-organic framework derived from discarded plastics for rapid and efficient adsorptive...

Metal-organic framework (MOF) has gained widespread attention as potential adsorbents for the removal of methylmercury (CH₃Hg⁺). This study synthesizes a defective MIL-88A(Fe) (D-MIL-88A(Fe)) from waste polyethylene terephthalate (PET). Structural characterization via XRD, SEM, N₂ adsorption-desorption, and FT-IR confirmed the crystalline MIL-88A(Fe) framework with hierarchical porosity (0.6 nm micropores and 1.95 nm mesopores) and retained carboxyl/Fe-O functional groups, enhancing mass transfer and adsorption accessibility. Adsorption equilibrium studies revealed 93.4% CH₃Hg⁺ removal with a maximum adsorption capacity of 4.91 mg/g (Langmuir model), indicating monolayer adsorption dominated by physical interactions. Kinetic analysis demonstrated ultrafast removal (90% within 500 min, k₁ = 0.0076 min^-1), aligning with pseudo-first-order kinetics. The material exhibited robust regeneration, retaining > 90% efficiency after five cycles. By utilizing discarded PET as a low-cost ligand source, this work not only reduces MOF production costs but also offers a dual solution for CH₃Hg⁺-contaminated wastewater remediation and plastic waste value assessment.