Abstract
<title>Abstract</title> <p>The present study investigated, the effect of different process intensification techniques like, hydrothermal, microwave, ultrasound and enzyme pretreatments on extraction of cellulose from groundnut shell (GS). The extracted cellulose samples were compared with commercial cellulose (CC). Further, the impact of different particle sizes i.e., 300, 450 and 600 µm, on the extraction process has been analysed, and found that particle size of 450 µm showed better results. The cellulose yield ranged from 49.80 - 56.75%, indicating efficient removal of lignin and hemicellulose and enrichment of α-cellulose content. The structural analysis showed that the obtained cellulose had the same cellulose I crystalline structure, where the XRD peaks were found at 2θ = 22–23°. Also, the FTIR analysis showed that the samples had distinct O-H (3342 cm⁻¹) and C-H (2893 cm⁻¹) stretching vibrational peaks. The thermal analysis showed degradation between 280–360 °C, indicating high thermal stability due to increased crystallinity. The morphological analysis showed a change in morphology from compact structures to fibrous and porous structures after extraction. Particle size analysis showed that ultrasound treatment produced smaller and more refined cellulose particles compared to other treatments. The values for the lightness parameter (L*), which was close to commercial cellulose. Overall, the extracted cellulose exhibited physicochemical and structural properties comparable to CC. Among the pre-treatment, ultrasound was selected as the optimized extraction approach due to its improved cellulose purity and controlled delignification behaviour. This study demonstrated the potential of GS as a sustainable alternative source for high-quality cellulose production.</p>