Silica Nanoparticles from Coir Pith Synthesized by Acidic Sol-Gel Method Improve Germination Economics

Lignin is a natural biopolymer. A vibrant and rapid process in the synthesis of silica nanoparticles by consuming the lignin as a soft template was carefully studied. The extracted biopolymer from coir pith was employed as capping and stabilizing agents to fabricate the silica nanoparticles ((n)Si). The synthesized silica nanoparticles ((n)Si) were characterized by ultraviolet–visible (UV–Vis) spectrophotometry, X-ray diffraction analysis (XRD), Scanning Electron Microscope (SEM), Energy-Dispersive X-ray Analysis (EDAX), Dynamic Light Scattering (DLS) and Fourier-Transform Infrared Spectroscopy (FTIR). All the results obtained jointly and independently verified the formation of silica nanoparticles. In addition, EDAX analysis confirmed the high purity of the (n)Si composed only of Si and O, with no other impurities. XRD spectroscopy showed the characteristic diffraction peaks for (n)Si and confirmed the formation of an amorphous nature. The average size of (n)Si obtained is 18 nm. The surface charge and stability of (n)Si were analyzed by using the dynamic light scattering (DLS) and thus revealed that the (n)Si samples have a negative charge (−20.3 mV). In addition, the seed germination and the shoot and root formation on Vigna unguiculata were investigated by using the (n)Si. The results revealed that the application of (n)Si enhanced the germination in V. unguiculata. However, further research studies must be performed in order to determine the toxic effect of biogenic (n)Si before mass production and use of agricultural applications.