Depolymerization of PET wastes catalysed by Sn and Ag doped ZnO nanoparticles and evaluation of Embryonic Toxicity using Zebrafish

The present investigation focused on the catalytic evaluation of Sn and Ag doped ZnO for depolymerization of polyethylene terephthalate (PET) polyester wastes and embryotoxic evaluation of the doped ZnO nanoparticles using Zebrafish (Danio rerio) embryo model. Bimetallic ZnO NPs doped at 1 and 2 mol% of Sn and Ag synthesized by sol-gel method and characterized by XRD, UV-Vis, FT-IR, SEM-EDS and TEM. Diffraction studies confirmed doped ZnOs retained wurtzite structure as pristine ZnO. However, the electronic spectra showed that the optical bandgap reduced from 3.31 to 3.20 eV upon 2 mol% Sn and Ag doping. SEM-EDS study confirmed elemental composition of Ag and Sn doped ZnO as well as average crystallite size of 60–70 and 115–125 nm for 1 and 2 mol% doped ZnO NPs. Glycolytic and aminolytic depolymerization of PET wastes afforded 90% of bis(2-hydroxyethyl) terephthalate (BHET) and 95% of bis(2-hydroxyethyl) terephthalamide (BHETA) respectively catalysed by 2mol% Sn and Ag doped ZnO nanoparticles. The Sn doped ZnO NPs showed comparatively higher mortality than Ag doped ZnO without any developing deformity in zebrafish embryos.