Microwave-assisted green synthesis of Palladium nanοparticles using aqueous decoction of Psidium guajava leaf extract and kinetic analysis in the reduction of 4-Nitrophenol

Abstract

In the current investigation, we have successfully synthesized biogenic Palladium nanoparticles via a green approach by using the Psidium guajava (PG) leaf extract through microwave-assisted method. The biogenic synthesized PdNPs were studied by various characterizations. From the TEM analysis, the spherical morphology and average diameter of the synthesized PdNPs is 10 ± 2 nm. From the XRD patterns, PdNPs have crystalline nature and FCC structure without any impurities. The formation of PdNPs from PG leaf extract is strongly evidenced through FTIR analysis by the identification of certain functional groups in leaf extract that are responsible for the reduction and stabilizing activity. The as-prepared PdNPs showed improved catalytic activity in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP), with pseudo-first order kinetics, in excess sodium borohydride (NaBH4). In the catalytic reduction of 4-NP, the effects of 4-NP and NaBH4 concentrations, temperature, and PdNPs concentration were investigated. The catalytic reduction characteristics from this investigation, such as activation enthalpy and entropy, are also assessed. An environmentally friendly PdNPs synthesis technique using PG leaf extract is a productive and affordable way to produce PdNPs for use as effective catalysts in environmental applications.