DOI: https://doi.org/10.55373/mjchem.v26i5.34

Keywords: Adsorption; bentonite; chitosan; methylene blue; sodium alginate; sodium sulphate

Abstract

Organobentonite beads (CS/SA/SS/Ben-300 mg) were synthesised using the ionic gelation method by crosslinking bentonite (Ben), chitosan (CS), sodium alginate (SA) and sodium sulphate (SS). The synthesised beads were characterised using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy and a digital microscope, which indicated successful crosslinking between the components. The batch adsorption method was employed to investigate the adsorptive capabilities of CS/SA/SS/Ben-300 mg using methylene blue (MB) as a dye model. The highest adsorption of MB (50 mg/L) (88%) followed the pseudo-second-order kinetic model with a rate constant of 0.9195 g mg-1 min-1 and a linear regression coefficient (R2) of 0.98 at 323 K and pH 12. This suggests that the MB adsorption followed a chemisorption mechanism. Furthermore, the Langmuir model was found to better describe the adsorption process compared to the Freundlich model. According to the Langmuir isotherm, the maximum monolayer adsorption capacity ("q" _"max" ) of the organobentonite beads was observed to be 48.94 mg/g under the optimum conditions. The reusability of CS/SA/SS-Ben-300 mg demonstrated no significant decrease in MB removal efficiency.