Bio-mediated synthesis of CuO nano bundles from Gomutra (cow urine): Synthesis, characterization, photodegradation of the malachite green dye and SBH mediated reduction of 4-nitrophenol

Abstract

We synthesized CuO nano bundles-like structures from Gomutra (cow urine). Urea and uric acid, which are present in the gomutra, act as reducing and capping agents, resulting in unique CuO nano bundles-like structure formation. No such morphological formation was observed from synthetic urea. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDAX), UV–Visible, Fourier transforms infrared (FT-IR), Brunauer -Emmett-Teller (BET), and (photoluminescence) PL-Spectrofluorometer were used to analyze bio-mediated synthesized CuO nano bundle-like structures. From XRD analysis, the CuO nano bundle exhibits a monoclinic system with an average crystalline size of 15.76 nm. SEM results signified nano bacillus-like structures, resembling nano bundle-like designs in aggregate. EDAX anticipated the presence of only Cu and O atoms. FT-IR validates the existence of Cu and O bonds. The band gap was calculated using the DRS [Diffused reflectance mode] technique, and the value was found to be 1.29 eV. The BET and BJH [Barret-Joyner-Halenda] analysis estimated the surface area and pore size to be 28.24 Cm3/g and 11.5 nm. Intense emission peaks are seen at 465 nm from the PL spectrometer. Electron-hole transfer behavior in CuO nano bundles stemmed from Electrochemical impedance spectroscopy (EIS technique). The photocatalytic performance of malachite Green was examined in an aqueous medium, and degradation efficiency was found to be 98.2% in 70 min [min] with a rate constant of 0.0303 min−1. The catalyst ensured good activity for up to five cycles and was also found to be stable from SEM and XRD results. In addition, intermediated products were analyzed by the LC-MS, Electron Spin Resonance (ESR), and TOC [Total organic carbon] techniques. Required supporting evidence was elucidated in the Schematic pathway. CuO nano bundles also exhibited good catalytic behavior for reducing 4-nitrophenol in the ultrasonication method at room temperature with the whole reduction of nitro groups was proven by UV– Visible, FT-IR, and LC-MS technique, and the rate constant was found to be 0.3142 min−1. The present result clearly highlights that CuO nano bundles synthesized using gomutra can play a critical role in removing hazardous dyes from effluents of textile and dye industries. Further expanding the application of these nano bundles will promote an effective complementary and alternative strategy for treating refractory pollutants from wastewater.