Sustainable Cationization of Viscose Fabric via Chitosan Nanoparticles for Enhanced Acid Blue Dye Adsorption: Synthesis, Material Characterization, and Adsorption Performance Evaluation

ABSTRACT Herein, the novelty presented here encompasses the use of our newly synthesized and fully characterized chitosan nanoparticles, which have particle sizes ranging from 60 to 100 nm, as a sustainable alternative for synthetic cationizing agents of viscose fabric. This method aims to enhance the adsorption of acid blue 78 dyes through the pad‐dry‐cure surface coating technique, in alignment with Sustainable Development Goal 6. Three levels of cationized viscose fabrics with varying degrees of cationization and increasing order were prepared and designated as CVF‐I, CVF‐II, and CVF‐III. The so obtained CVF‐III was characterized using FTIR, SEM, XRD, TGA, BET, elemental analysis, add‐on %, and strength properties. Various factors affecting the adsorption capacity of Acid dye onto the prepared adsorbent, like pH, degree of cationization, contact time, and dye concentrations, was systematically explored. Kinetic models, including pseudo‐first‐order and pseudo‐second‐order as well as isothermal models (Langmuir, Freundlich, and Tempkin), and thermodynamic investigations were applied. The results signposted that (a) the above‐mentioned characterization techniques confirmed the presence of fixed amine functional groups on the viscose fabric; (b) the maximum adsorption capacity was found to be 80.0 mg/g at pH 5, with a dye concentration of 100 mg/l, amination extent of 1.98 N%, adsorption time of 90 min, and 0.1 g of adsorbent; and (c) kinetic and isothermal studies revealed that the PFO and Langmuir models exhibited superior fit with higher R 2 values. To the best of the author's knowledge, no prior studies have been published regarding the adsorption of Acid Blue78 dye onto viscose fabric treated with CNPs by varying the degree of cationization using the Pad‐Dry‐Cure method.