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In a world increasingly focused on environmental sustainability and the imperative of efficient waste management, innovative approaches in material science are becoming crucial. This research is centered on the synthesis of cellulose nanocrystals (CNCs) from post-use exam waste paper and the development of a chitosan-CNC (CS-CNCs) composite. CNCs were successfully isolated from waste paper by alkali treatment, bleaching, and sulfuric acid hydrolysis with FTIR and XRD analyses confirming successful extraction and a crystallinity index of 66.3%. TEM imaging revealed CNCs with a unique spherical morphology and diameters of 6-7 nm, significantly smaller than those reported in existing literature. Chitosan (CS), derived from shrimp shell waste, was integrated into the CNCs to form a composite thin film. This film, as revealed by SEM, had a homogeneous and consistent structure. The CS-CNCs composite demonstrated superior mechanical properties, with tensile strength increasing from 17.74 megapascal (MPa) in pure CS film to 22.08 MPa in composite, indicating its potential for robust and sustainable packaging materials. Soil degradation tests over 25 days showed a 24.7% degradation for CS-CNCs films, compared to 9.09% for CS films, underscoring their enhanced biodegradability. The composite exhibited notable antibacterial activity against Escherichia coli, suggesting its suitability for medical and hygiene applications. The measured contact angle of 80.4 degrees indicates the film's hydrophilicity, making it an excellent candidate for self-cleaning surfaces, such as textiles and windows. Remarkably, the CS-CNCs composite demonstrated exceptional photocatalytic degradation of Alizarin Red S dye, achieving 99.7% efficiency in 45 min, far surpassing the 87% efficiency of standalone CS films. The study showcases the green-synthesized CS-CNCs composite from waste paper offering an effective, eco-friendly, and economical approach for wastewater treatment due to its dual capabilities in dye degradation and antibacterial properties, while also opening avenues for its prospective application in self-cleaning surfaces, environmental remediation, and packaging thereby presenting a sustainable and economical solution for environmental cleanup and material innovation.

来源平台：BIOMASS CONVERSION AND BIOREFINERY