Efficient Adsorptive Removal of Anionic Dye Using Cost‐Effective Chitosan/Agarose Membrane

ABSTRACT In this work, the composite membrane based on chitosan (CS) and agarose (AG) is developed for removing methyl orange dye (MO). The morphology and physical properties of membranes in various compositions of CS/AG as 100:0, 80:20, 60:40, 40:60, and 20:80 are investigated. The AG addition significantly increases the film stiffness and fracture resistance but causes a notable reduction in flexibility. The swelling of the CS membrane significantly increases upon blending with AG, facilitating efficient dye adsorption. The 6C4A membrane containing 60% CS and 40% AG effectively adsorbs anionic MO, while it shows trivial adsorption toward cationic dye. The effects of various conditions, including pH of the solution, shaking time, initial MO concentration, and solution temperature, are explored. Maximum adsorption capacity of 229.546 mg g −1 is recorded at 270 min, pH 6, 200 mg L −1 MO concentration, and room temperature. The thermodynamic study reveals the spontaneous, favorable, and exothermic behaviors of the adsorption process. The experimental data fit well with the nonlinear pseudo‐first‐order and pseudo‐second‐order kinetic models and the Temkin and Langmuir isotherm models. The composite membrane can be recycled four times, as an ideal option to remove anionic azo dyes from real wastewater efficiently.