Schiff-Base System of Glutaraldehyde Crosslinked Chitosan-Algae-Montmorillonite Clay K10 Biocomposite: Adsorption Mechanism and Optimized Removal for Methyl Violet 2B Dye

Heren, chitosan (CH), algae (AL), and montmorillonite clay K10 (MK10) were used in the hydrothermal synthesis of a new Schiff-base system of glutaraldehyde-crosslinked chitosan-based biocomposite (CH-AL-MK10/GL) for the removal of a model cationic dye [MV (2B)] from aqueous environments. Various analytical methods were employed to evaluate the characteristics of the synthesized biocomposite (e.g., BET surface analysis method, elemental analysis, FTIR, SEM-EDX, XRD, and point of zero charge). The key adsorption parameters (CH-AL-MK10/GL dose, pH, and time) were optimized using the BBD model and the optimum adsorption (%) value of 86.4% was achieved at the following operating conditions: CH-AL-MK10/GL dose: 0.99 g/100 mL, pH: 8.3, time: 418 min and a quadratic model was generated for predicting the dye removal values based on the adsorption conditions. The adsorption equilibrium data revealed great compatibility with the pseudo-second order kinetic model and Langmuir and Freundlich isotherm models, achieving a maximum adsorption capacity of 98.3 mg/g at 25 degrees C. Hence, the adsorption of MV (2B) by CH-AL-MK10/GL was through chemisorption in an initially monolayered fashion which then proceeds to a multilayered model after the surface layer reaches a saturated state. The results of all the characterization methods as well as the adsorption equilibrium studies were utilized to determine the possible interactions between the CH-AL-MK10/GL surface and MV (2B) dye molecules and the electrostatic forces, hydrogen bonding, Yoshida hydrogen bonding and n- pi stacking interactions were concluded to be responsible for the adsorption process.