Montmorillonite materials with paramagnetic metal complexes: Structural studies and catalytic degradation of emerging pollutants

Abstract

The aim of this work was to characterize and propose the use of new heterogeneous catalysts based on montmorillonite (Mt) materials bearing organic copper metal complexes to remove a variety of emerging pollutants such as antibiotics, azo dyes and antimycotics. The incorporation of Cu2+ ions and their coordination by 4-methyl-5-imidazolecarboxaldehyde (Im) or 4-acetylpyridine (Py) ligands in the interlayer space of the clay were studied by NMR, XRD, EPR and XPS, which provided information about the surface chemical composition of the copper centers and the ligands present in the materials. The ligands were incorporated into different zones of the Mt-Cu structure, being the Im and Py ligands (L) preferentially located outside and inside the interlayer space, respectively, showing different incorporation degrees. The catalytic activity of the composites (Mt-Cu-L) was demonstrated by their capacity to generate ROS and to degrade pollutants, producing an environmentally non-toxic waste, as assessed by the brine shrimp toxicity assay.