Noble metallic nanoparticles from waste Nypa fruticans fruit husk: Biosynthesis, characterization, antibacterial activity and recyclable catalysis

Biogenic synthesis of noble metal nanoparticles is particularly interested due to the effective applications for plasmonic catalysis and bioactivity. In this work, aqueous extract of waste Nypa fruticans (NF) fruit husk was utilized to synthesize silver nanoparticles (NF-AgNPs) and gold nanoparticles (NF-AuNPs). The effected parameters on the green reduction of metallic nanoparticles (MNPs) were investigated. Under optimum conditions of concentration, temperature and time, the biosynthesized NF-AgNPs and NF-AuNPs showed spherical nanoparticles with average size of 10-15 nm and 15-20 nm, respectively. The presence of AgCl in NF-AgNPs has been demonstrated by X-ray diffraction analysis. The elemental components of all samples confirmed the presence of anions and cations come from the aqueous extract. The biosynthesized nanoparticles were evaluated bacterial activity against three bacterial strains. NF-AgNPs exhibited selective antibacterial activity against Bacillus cereus but no activity against Staphylococcus aureus and Salmonella typhimurium at all tested concentrations. The recyclable catalysis activity of the biosynthesized nanoparticles was evaluated for the reduction of nitrophenols in the presence of sodium borohydride which possessed good catalytic performance in six running numbers. Additionally, AgCl played role as a source supplying AgNPs has been demonstrated in catalytic reduction of p-nitrophenol. For study of catalytic kinetic, NF-AgNPs possessed higher rate constant in comparison with NF-AuNPs whereas TOF values of NF-AuNPs was determined to be higher than those of NF-AgNPs. (C) 2020 The Author(s). Published by Elsevier B.V. on behalf of King Saud University.