Removal of Methylene Blue by Low-Cost Adsorbent Prepared from Jujube Stones: Kinetic and Thermodynamic Studies

Abstract

Agricultural residue emerges as a cost-effective and readily available option for the adsorption of dyes, owing to its affordability and efficacy. The purpose of our study focuses on the methylene blue dye (MB) removal using chemically modified jujube stone (MJS) as an adsorbent. The MJS underwent characterization through multiple methodologies including scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The research system - atically investigated contact time, PH, temperature, initial dye concentration, and adsorbent dosage impact to optimize the removal efficiency. Experimental findings demonstrated that the MJS adsorbent achieved a dye removal efficiency of approximately 94% under batch mode and room temperature conditions. Kinetic analysis revealed an equilibrium time of around 70 minutes. Remarkably, this study unveils the novel application of chemically customized jujube stone a highly effective adsorbent for removing methylene blue dye. Applying the pseudo-second-order model provides the most precise description for methylene blue (MB) adsorption onto MJS. The modeling of adsorption isotherms indicated conformity to the Langmuir model. The thermodynamic study shows a negative value of ΔG, which demonstrates spontaneous MB adsorption into MJS, while a positive value of ΔH implies an endothermic adsorption process.