Life cycle assessment of carboxymethyl cellulose films from agricultural wastes

In Thailand, agricultural residues such as sugarcane leaves (SCL), corn leaves (CL), and rice straw (RS) are often burned, causing significant air pollution and environmental harm. This study presents a sustainable approach to managing these wastes by converting them into carboxymethylcellulose (CMC) and CMC-based films, highlighting their potential as biodegradable materials for industrial applications. Cellulose was successfully isolated from SCL, CL, and RS, achieving high α-cellulose purity through alkali and sodium chlorite treatments. The carboxymethylation process produced CMC with degrees of substitution (DS) ranging from 0.44 to 0.89, with CMCRS synthesized using 4 0 g/1 0 0 mL NaOH exhibiting the highest DS. Comprehensive characterization using FTIR, XRD, FE-SEM, TGA and ICP-MS confirmed the chemical structure, crystallinity, morphology, and purity (99. 36%) , with heavy metal content meeting safety standards. The resulting CMC films demonstrated uniform surfaces, with mechanical properties such as tensile strength (TS) and elongation at break (EAB) significantly influenced by NaOH concentration. Optimal TS and EAB values were achieved at moderate NaOH concentrations, while excessive NaOH led to polymer degradation. The films exhibited moderate water vapor permeability (WVP) and changes in whiteness index (WI) and color difference (ΔE) with increasing NaOH concentrations, reflecting their hydrophilic nature and suitability for various applications. Biodegradability tests confirmed complete degradation within five days under composting conditions, highlighting their environmental compatibility. However, life cycle assessment (LCA) revealed notable environmental impacts, particularly inwater depletion (7.08–10.36 m³/f.u.) and climate change (779.63–1152.64 kg CO2 eq./f.u.), driven by electricity and resource-intensive production processes. Freshwater eutrophication and terrestrial acidification impacts were higher compared to other bioplastics, emphasizing the need for energy-efficient technologies and sustainable practices. This research demonstrates the feasibility of converting agricultural waste into high-value bioplastic materials while addressing environmental challenges. Future work should focus on scaling up production, optimizing synthesis conditions, and incorporating renewable energy to enhance sustainability and industrial applicability.