Facile Synthesis of Mesoporous α-MnO₂ Flower-Like Nanostructures and Their Catalytic Performance in the Degradation of Poly(ethylene terephthalate) Wastes

A simple hydrothermal method was developed for synthesis of the flower-like α-MnO₂ nanostructures composed of nanoflakes. The obtained MnO₂ nanostructures have an average diameter of 300–600 nm. Surface area and pore size distribution of the flower-like nanostructures were characterized by the nitrogen adsorption–desorption isotherm measurements. The catalytic performance of the flower-like MnO₂ nanostructures was evaluated in the degradation of poly(ethylene terephthalate) wastes using ethylene glycol as solvent, and the effects of various reaction conditions on the degradation were studied. FT-IR, ¹H NMR and DSC were used to identify the glycolysis products. It was found that bis(2-hydroxyethyl) terephthalate monomer was dominant in the product which was effectively separated from other oligomers in quite pure crystalline form.