Removal of Methylene Blue Dye from Water using Chitosan/ Sulfonated Lemon (Citrus limon L.) Peel Biocomposite: Characterization and Adsorption Modeling

The current work aims to develop a chitosan/sulfonated lemon peel biomass (CTO/SLP) biocomposite for for treating water contaminated with methylene blue dye. The physicochemical properties of CTO/SLP were comprehensively investigated using various analytical techniques including CHNS-O, pHpzc, XRD, FTIR, FESEM, and BET. To maximize CTO/SLP's adsorption efficiency, a Box-Behnken Design (BBD) based on response surface methodology (RSM) was adopted, considering factors such as CTO/SLP dose (A: 0.03-0.09 g), pH (B: 4-10), and time (C: 10-50 min). The experimental data of methylene blue dye adsorption by CTO/SLP were well-fitted to the pseudo-first-order and Freundlich isotherm models. Impressively, CTO/SLP exhibited a excellent adsorption ability of 755.49 mg/g. The electrostatic forces, hydrogen bonding, and n-pi interactions between the methylene blue dye cation and the acidic groups of CTO/SLP were the main causes of the substantial methylene blue dye adsorption onto CTO/SLP. The study introduces a sustainable, green approach for producing highly effective adsorbent in removing methylene blue dye from water systems.