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 (Si-n). The synthesized silica nanoparticles (Si-n) 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 Si-n composed only of Si and O, with no other impurities. XRD spectroscopy showed the characteristic diffraction peaks for Si-n and confirmed the formation of an amorphous nature. The average size of Si-n obtained is 18 nm. The surface charge and stability of Si-n were analyzed by using the dynamic light scattering (DLS) and thus revealed that the Si-n 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 Si-n. The results revealed that the application of Si-n enhanced the germination in V. unguiculata. However, further research studies must be performed in order to determine the toxic effect of biogenic Si-n before mass production and use of agricultural applications.