Microwave assisted green synthesis of palladium nanoparticles using dragon fruit peel extract for catalytic reduction of 4-nitrophenol and methylene blue

This study investigated the use of waste dragon fruit peel extract (DF) as a reducing and stabilizing agent for preparing palladium nanoparticles (PdNPs) using a microwave-assisted technique. The effects of various synthetic parameters including pH, PdCl2 concentration, and DF concentration on PdNPs production were examined in detail. Several techniques were employed to characterize the morphology, microstructure, functional groups, and crystallinity of as obtained nanoparticles (DF@PdNPs). The formation of PdNPs in the reaction solution was confirmed by a visible black color and broad surface plasmon absorption in the UV-vis spectrum. FTIR studies revealed the role of phytochemicals in nanoparticle reduction and stability. The produced PdNPs were spherical/oval in shape, evenly polydisperse, had an average size of 9 +/- 1.5 nm, and were well stabilized (zeta potential = - 36.3 mV) by the extract phytochemicals. They also had a face-centered cubic crystal structure. The catalytic performance of DF@PdNPs was assessed by the NaBH4 assisted reduction of 4-nitrophenol to 4-aminophenol, with a kinetic constant value of 0.155 +/- 0.029 min-1. Furthermore, the catalyst successfully reduced methylene blue dye within 6 min, with a rate constant of 0.422 +/- 0.021 min-1