Photocatalytic decomposition behavior and reaction pathways of organic compounds using Cu nanoparticles synthesized via a green route

Abstract

The present article depicts a green, facile and environmentally friendly biosynthetic methodology for the fabrication of Cu nanoparticles (Cu NPs) using an aqueous extract of Anas platyrhynchos egg shells. This method is free from the use of any external reducing agents, stabilizing agents, solvents and templates. The Cu NPs were characterized by UV-Vis, TEM, SAED, FTIR, XRD and SEM-EDX. The synthesized Cu NPs were predominantly spherical in nature with an average size of 5–18 nm. The EDX pattern revealed the presence of elemental copper in the Cu NPs. The prepared NPs were used for the remediation of three carcinogenic dyes, namely, Rose Bengal (RB), Methylene Blue (MB) and Methyl Violet 6B (MV6B) from aqueous solution. Approximately, 98.2, 93 and 96% of RB, MB and MV6B dye were degraded within 165, 135 and 150 min, respectively, using the synthesized Cu NPs. To acquire an improved understanding of the mechanistic details of the degradation products, the intermediates were identified using LC-MS. It is assumed that fragmentation of the oxy group takes place for RB, while for MB and MV6B, N-demethylation and N-demethylenation of the substituent on the amine group takes place. It is believed that finally, the conjugated chromophoric structure undergoes cleavage to form the mineralization products. The probable mechanisms for the degradation of the dyes have been presented. The high efficiency of NPs as photocatalysts has opened a promising application for the removal of hazardous dyes from industrial effluents.