Efficient removal of Sunset yellow food dye from aqueous environment using bimetal-organic frameworks encapsulated with chitosan: Synthesis, characterization, adsorption analysis, and optimization

Abstract

In this work, the adsorbent Sunset yellow (SSY) dye, a hazardous food colorant, was to be removed from aqueous solutions using lanthanum/silver bimetal-organic frameworks (La/Ag-MOF) encapsulated onto chitosan (La/Ag-MOF@CS). According to the findings, La/Ag-MOF@CS is a successful adsorbent for removing SSY dye from water. Numerous tests, such as FT-IR, PXRD, SEM, TEM, XPS, and BET analysis, studies of the material’s characteristics were carried out. A substantial pore volume of 1.683 cm3/g and a high surface area of 842 m2/g were found in the data, suggesting the possibility of a high adsorption capacity. The study of surface charge showed that a positive charge below the point of zero charge (pH 6) and a negative charge above it had an impact on the adsorption behavior. The maximal SSY dye adsorption onto La/Ag-MOF@CS was found to reach 443.53 mg.g−1. Pseudo-second-order kinetic models were used to clarify the reaction’s kinetics, and the Langmuir isotherm model, demonstrated a chemisorption process. The adsorption process utilizing the adsorbent La/Ag-MOF@CS is anticipated to have endothermic and spontaneous nature. The synthetic La/Ag-MOF@CS adsorbent showed exceptional flexibility and cyclability, successfully completing up to eight adsorption–desorption cycles. In order to maximize the adsorption results, the Box-Behnken Design was utilized, demonstrating how La/Ag-MOF@CS may be applied to address real-world wastewater treatment challenges in a sustainable and useful way.