Photocatalytic and antibacterial activities of green-mediated Khaya senegalensis-silver nanoparticles and oxidized carbon nanotubes

Abstract

This study investigated the photocatalytic and antibacterial activities of plant-mediated silver nanoparticles (AgNPs) from a medicinal plant extract of Khaya senegalensis (K. senegalensis) and oxygen functionalized carbon nanotubes (oCNTs), respectively. The CNTs were functionalized using acid treatment. The green synthesized AgNPs from K. senegalensis (KS-AgNPs) and oCNTs were characterized by UV–Visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), transmission emission microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The formation of KS-AgNPs was confirmed by the UV–Vis absorption spectra, which showed an absorption band at 427 nm with a color change from yellow to brown. The morphology of KS-AgNPs was spherical in shape, with an average particle size of 9.30 nm. The FTIR analyses revealed distinctive functional groups, such as, hydroxyl (O-H), amines (N-H), and carbonyl (C-O), which were directly involved in the synthesis and stability of AgNPs. The XRD spectra was distinctive with five intense peaks at 2theta angles of 38.12°, 44.28°, 64.43°, 77.48°, and 81.54o while oCNTs gave intense peaks at 2theta angles of 26.43o, 42.36o, 44.46o, 54.51o, 59.98o, and 77.40o. The photocatalytic property of green synthesized KS-AgNPs was determined to be 40.7 % higher than that of oCNTs when applied for treatment of industrial waste water. The ability of green-mediated KS-AgNPs to inhibit against gram-positive and gram-negative bacteria was observed to be that gram (-) bacteria (E. coli) was more susceptible to KS-AgNPs than the gram (+) bacteria (S. aureus), in which case their susceptibility was least in oCNTs for both bacteria, respectively.