Eco-Friendly Crystal Violet Dye Adsorption Using Natural Date Stem Powder: Mechanism, Kinetics, and Thermodynamics

This study investigates the efficacy of natural date stem powder (NDSP) as an economical and environmentally sustainable adsorbent for the removal of crystal violet dye from wastewater. Thorough characterization using SEM, FTIR, and XRD elucidated NDSP's structural and functional attributes favorable for dye adsorption. A systematic evaluation of critical parameters such as initial dye concentration (1-10 mg/L), adsorbent dosage (0.5-3 g/L), contact period (0-120 min), stirring speed (0-700 rpm), and ionic additives was investigated to determine optimal conditions for maximum removal efficiency. The equilibrium values conform most closely to the Langmuir isotherm model (R² = 0.78), signifying monolayer adsorption with a maximum capacity of 9.47 mg/g. Kinetic analyses demonstrated a strong connection with the Elovich model (R² = 0.982), affirming chemisorption as the primary process. Thermodynamic analysis indicated a spontaneous process (ΔG° = -5.72 to -6.83 kJ/mol) and an endothermic reaction (ΔH° = 7.36 kJ/mol). These findings establish NDSP as a viable, sustainable option for wastewater treatment, integrating agricultural waste valorization with efficient dye elimination.