Enhanced adsorptive removal of the organic dye Vat Red FBB using Algerian desert soil: Equilibrium, kinetic, and thermodynamic studies

This study investigates the potential of Algerian Desert Soil as an adsorbent for the removal of Vat Red FBB dye from textile wastewater. The effects of operational parameters, including temperature, adsorbent dosage, initial dye concentration, contact time, and pH, were systematically examined. The highest removal efficiency of 100% was obtained at pH 3, with a significant reduction occurring within the first 5 min ( approx. 70%). Adsorption isotherm analysis indicated that the Langmuir model provided the best fit to the experimental data (R² = 0.99958), describing monolayer adsorption with a maximum capacity of 746.27 mg/g. Kinetic studies revealed that the process followed a pseudo-second-order model. Thermodynamic parameters confirmed that the adsorption was physical (ΔH° = +13.22 kJ/mol), spontaneous (-2.06 to -5.72 kJ mol⁻¹) as the temperature increased from 293 K to 313 K, and endothermic ( ΔS° = +51.75 J mol -1 K -1 ). These findings highlight Algerian Desert Soil as a promising, low-cost, and efficient material for treating dye-contaminated industrial wastewater, providing a practical solution to mitigate environmental pollution and support sustainable water management.