Using chitosan made from modified chitosan (Crab shells) for dye adsorption, equilibrium, kinetic, and response surface methods

Adsorption techniques based on the use of natural polymers, such as non-toxic chitosan, which is made from leftover crab shells by demineralization (acid treatment) and deproteinization (alkaline treatment), have drawn more attention in recent years. The most popular method for advanced wastewater treatment is adsorption. Because of its many functional uses, chitosan is frequently employed as an efficient biomaterial in the field of adsorption. Chitosan’s hydroxyl (-OH) and amine (-NH2) groups make it one of the most appropriate and adaptable adsorbents. By adding more functions to its fundamental structure, chitosan adsorption capability and selectivity can be further enhanced. While the Langmuir, Freundlich Isotherms study and kinetics investigations demonstrated that the adsorption process was suited by pseudo-first-order and second order for dye, the results from isotherm models demonstrated that the adsorption of dye on chitosan corresponded well with the Freundlich model. These three distinct factors influencing methylene blue adsorption performance were chosen for modelling and optimization procedures utilizing response surface methods in a central rotating composite design. A second-degree polynomial equation was used to predict the percentage of methylene blue elimination by chitosan made from crab shells. With an R2 = 0.9934 and a Radj = 0.9849, the proposed model was valid and accurately described the phenomenon investigated in the experimental area.