Biodegradable carboxymethylated lignin–tetra ethoxysilane (TEOS) nanocomposites (CML–T) were synthesized using lignin extracted from rice straw (RS) followed by surface modification through carboxymethylation. Composites were characterized by UV-spectroscopy, Fourier transform infrared (FT-IR), scanning electron microscope (SEM), X-ray diffraction pattern (XRD), atomic absorption spectroscopy (AAS) and particle size distribution (PSD). The average diameter (D50) of the CML–T composite particles was observed in the range of 160–560 nm. XRD spectra and SEM micrographs confirmed the high degree of crystallinity (peaks located at lower angle, 2θ = 12 and 22.0°) and porous nature of nanocomposites with increasing concentrations of TEOS. The composite exhibited nickel (Ni2+) and cadmium (Cd2+) adsorption up to 70.72 and 81.79 %, respectively in AAS analysis. The CML–T composite was investigated to assess their future applications as wound dressings and antimicrobial and packaging agents. Based on the antimicrobial properties and potential to remediate toxic heavy metals, the composites are proposed to be used for wastewater treatments, as packaging materials and for preparation of biofilters for environmental protection.