Comparative study of green synthesised sulphur nanoparticles in different acidic media

Abstract Sulphur nanoparticles (SNPs) are of great importance, due to their tremendous use in agriculture and industries. In the present work, a comparative study has been conducted to find the most suitable combination to produce desired sulphur nanoparticles, using different acidic mediums along with different green surfactants. An eco-friendly and benign method has been discussed here for the synthesis of SNPs using two different acidic mediums (citric acid and oxalic acid). Catharanthus roseus and Aloevera plant extracts have been taken as stabilising and capping agents in the process. A series of characterisation techniques have been carried out such as scanning electron microscopy (SEM), x-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR) and UV–vis for morphological, structural and optical study. UV–vis absorption spectra have shown that the absorption peak is in the range of 287−296 nm for all the synthesised nanoparticles and confirm the formation of SNPs. XRD data has revealed the crystalline nature of SNPs and the smallest crystalline size of 69 nm for oxalic acid with Aloevera leaf extract. It has been observed that the size reduces due to the bonding/ adsorption of biomolecules at the surface of SNPs. Aloevera leaf extract gives the maximum adsorption as conveyed by the FTIR graph. The morphology and uniformity of SNPs are observed using the scanning electron microscope. SNPs synthesised using citric acid as a reducing agent have been found spherical in shape while the ones synthesised using oxalic acid are hexagonal. The study reveals that the SNPs synthesised using Aloevera and oxalic acid are more uniform and monodispersed.