Optimization of extraction and characterization of cellulose from edamame pod waste for active biofilm applications

Edamame pod waste, a by-product of soybean processing, represents a promising lignocellulosic biomass source for biopolymer development. This study aimed to optimize cellulose extraction from edamame pod waste using Response Surface Methodology (RSM) with a Box–Behnken Design (BBD) and to characterize the extracted cellulose for potential biofilm applications. Four independent factors—particle size (40– 80 mesh), extraction temperature (60–90 °C), extraction time (1–3 h), and NaOH concentration (5–10%, w/v)—were investigated, with cellulose yield (%) and whiteness index (WI) as responses. The optimized conditions (80 mesh, 75°C, 1 h, 7.5% NaOH) produced cellulose with a yield of 54.5% and a WI of 70%. Subsequent alkaline hydrogen peroxide (AHP) washing enhanced cellulose purity, increasing cellulose content from 41.25% to 65.14% and reducing hemicellulose and lignin to 19.07% and 9.21%, respectively. FTIR analysis confirmed successful delignification through the disappearance of lignin-associated peaks (1508–1512 cm⁻¹) and the presence of characteristic β-1,4-glycosidic linkages. Thermal characterization using Thermogravimetric Analysis (TGA) and Derivative Thermogravimetry (DTG) showed a single-step degradation pattern with Tonset ≈ 275 °C, Tmax ≈ 350 °C, and ~13% residue at 600 °C, indicating high thermal stability and purity comparable to commercial cellulose. These findings demonstrate that edamame pod waste can be efficiently converted into high-purity, thermally stable cellulose through an eco-friendly alkaline extraction process, providing a sustainable raw material for the development of biodegradable biopolymers and active biofilms as alternatives to synthetic plastics.