Adsorption, equilibrium, and kinetic studies on enhanced Acid Blue 113 dye removal from aqueous solutions using Chitosan/Silica/Zinc Oxide nanocomposites

The study focuses on the synthesis of a Chitosan/Silica/Zinc Oxide Nanocomposite (CSZN) via sol-gel method for Acid Blue 113 (AB113) adsorption from aqueous solutions. The synthesised nanocomposite was characterised using SEM with EDS, FTIR, and XRD analyses to confirm its structure and composition. Adsorption experiments assessed parameters including contact time, pH, CSZN dosage, and temperature, identifying optimal conditions as 60 min contact time, pH 4, 0.3 g/L dosage, 25 degrees C, achieving 66.18% removal efficiency at 20 mg/L AB113 concentration. Adsorption kinetics followed pseudo-second order, while equilibrium data fitted the Langmuir isotherm, with a maximum capacity of 61.35 mg/g. Desorption efficiency using 0.1 N NaOH was 59.62%, enabling CSZN reuse. Thermodynamic analysis revealed spontaneous and endothermic adsorption, with positive Delta So indicating increased system entropy due to reduced hydration around dye molecules. Adsorption increased linearly with temperature (293-308 K), aligning with chemisorption characteristics. Reusability studies showed that CSZN maintained removal efficiency >45% after 10 cycles, demonstrating its sustainability and cost effectiveness, for water treatment and environmental remediation.