Enhanced degradation of old landfill leachate in heterogeneous electro-Fenton catalyzed using Fe3O4 nano-particles encapsulated by metal organic frameworks

Organic contaminants in old landfill leachate could cause large harm to human and environment without a proper treatment. In the present study, Fe3O4 nano-particles encapsulated by metal organic frameworks (Fe(3)O(4)NPs@MOF) was prepared, characterized and then applied to construct heterogeneous electro-Fenton (hetero-EF) process treating old landfill leachate. Increasing catalyst dosage, current density, plate distance and lower pH promoted the hetero-EF performance, COD removal efficiency could reach 66.67 +/- 4.36% with catalyst dosage of 0.75 g/L, current density of 15 mA/cm(2), plate distance of 1.5 cm and pH of 3. .OH played a more remarkable effect on organic contaminants degradation and contributed 76% of the COD removal. The MOF shell might protect Fe3O4 NPs in the core from reacting with acid solution, and mesoporous pore allowed e(-), H+ and H2O2 to cross MOF shell and react with Fe3O4 NPs. Heterocycles, phenols and esters in old landfill leachate were dramatically degraded by hetero-EF, and the relative abundance of low molecular weight organics (<1 kDa) increased from 62.8% to 71.56% with BOD5/COD increasement from 0.025 to 0.39. It is suggested that heterogeneous electro-Fenton using Fe(3)O(4)NPs@MOF as catalyst would be an effective method to remove organic contaminants in old landfill leachate.