Trimesoyl chloride crosslinked chitosan: An efficient adsorbent for Congo red dye removal from water - kinetic and isotherm analysis

Abstract

In this study, chitosan biopolymer was successfully synthesized using trimesoyl chloride as a cross-linking agent to improve their adsorption efficiency and stability. The structural and surface properties of the synthesized trimesoyl chloride-crosslinked chitosan (TMC-CS) adsorbents were thoroughly characterized using advanced techniques, including FTIR, XPS, BET, TGA/DTG, and SEM. These analyses confirmed the successful formation of crosslinked chitosan with enhanced properties for adsorption applications. The adsorption efficiency of the synthesized TMC-CS adsorbents was systematically examined for the removal of Congo Red (CR) dye from synthetic aqueous solutions. Optimal adsorption conditions were determined to be a dosage of 40 mg of adsorbent, 100 mg/L dye concentration, neutral pH (pH 7), and a contact time of 9 h. Under these conditions, the adsorbent achieved a maximum adsorption efficiency of 99.4 % for CR dye. Kinetic studies indicated that the adsorption process followed a pseudo-first-order kinetic model, with strong correlation between the model and experimental data. Furthermore, equilibrium data were best described by the Langmuir isotherm model, indicating monolayer adsorption on a homogeneous surface, with a maximum adsorption capacity of 82.4871 mg/g. These results demonstrate the high efficiency and potential of TMC-CS adsorbents for use in dye removal, a promising solution for wastewater treatment applications.

Keywords: Chitosan; Congo red; Cross-linking; Isotherm and kinetic model; Trimesoyl chloride.