Engineering Multifunctional S-Scheme Sn-MOF/NiFe2O4 Heterostructure for Abolition and Detection of Contaminants: In-Silico Ecotoxicity Assessment and DFT-Assisted Mechanism Elucidation

Abstract

Amalgamation of advantages of the adsorption and photocatalytic degradation process encouraged the designing of multifunctional S-scheme Tin-dicarboxylate metal-organic framework (Sn-MOF)/Nickel ferrite (NF) heterostructures (SBNF-x, x = 10, 20 and 30). The fabricated heterostructures are applied for the adsorptive-photodegradation of Methylene Blue (MB) from an aqueous medium. SBNF-20 demonstrated the maximum MB removal (≈98%), complying with pseudo-first-order kinetics. The rate constant value for SBNF-20 is discovered to be 38.0- and 5.5-times pristine Sn-MOF and NF, respectively. Moreover, density functional theory (DFT) analysis is employed to obtain the global and local reactivity descriptors. The global reactivity descriptors showed MB as the most reactive dye for the initial adsorption phenomenon. Meanwhile, Fukui functions and Liquid chromatography-mass spectroscopy (LC-MS) technique revealed the possible degradation pathways. The ecotoxicity profile of generated reaction intermediates are assessed using in silico toxicity analysis. Further, fluorescent SBNF-20 is utilized for the selective and sensitive Fluorescence detection (FL) of Uranium U(VI), with a limit of detection of as low as 15.0 µM. The practical applicability of the sensor is confirmed by real sample analysis. The recyclability test corroborated the reusability and stability of SBNF-20. Thus, the findings of the designed multifunctional system have great potential prospects for wastewater treatment.