Biogenic Silica Nanoparticles from Arachis hypogaea Shell Waste: Synthesis, Characterization and Agricultural Applications

In light of the urgent need for sustainable agricultural practices to preserve ecological health, this study introduces an innovative approach for synthesizing silica nanoparticles (SiO₂ NPs) from agricultural waste, specifically groundnut shell powder (Arachis hypogaea). The SiO₂ NPs were produced through sequential acid and alkali treatments of the groundnut shell residues under varying thermal conditions. Comprehensive characterization of the resulting SiO₂ NPs was conducted using UV-Visible spectroscopy, Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Dynamic Light Scattering (DLS), and Energy Dispersive X-ray Spectroscopy (EDX). The antimicrobial properties of the SiO₂ NPs were subsequently evaluated, along with their effects on the physiological and biochemical responses of bengal gram (Cicer arietinum). As global food demand rises, implementing environmentally friendly innovations in agriculture becomes essential to reduce ecological impact. Utilizing agricultural by-products in nanomaterial synthesis presents an eco-friendly solution with promising applications in crop enhancement. The synthesized SiO₂ NPs demonstrated distinct physicochemical properties across the employed characterization techniques. Notably, the nanoparticles exhibited effective antimicrobial activity against both gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus) and gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli). When applied to Bengal gram seeds at concentrations ranging from 300 to 600 µg L⁻¹, SiO₂ NPs significantly improved germination rates, achieving up to 95.5% to 98.7%, and enhanced growth characteristics compared to untreated controls. Applications at 500 to 600 µg L⁻¹ also resulted in notable increases in protein (up to 14.8 mg g⁻¹) and chlorophyll content (up to 4.08 mg g⁻¹) in plant leaves. These outcomes support existing findings on the beneficial role of nanoparticles in promoting plant growth. This research underscores the potential of SiO₂ NPs synthesized from groundnut shell waste as a valuable tool in sustainable agriculture, offering both antimicrobial benefits and significant growth-promoting effects in Cicer arietinum. The findings contribute to developing eco-conscious strategies for agricultural productivity while addressing environmental challenges.