Removal of Acid Red 33 from Aqueous Solution Using Nanoscale Zero-Valent Iron Supported on Activated Carbon: Kinetic, Isotherm, Thermodynamic Studies

In this study, zero-valent iron nanoparticles immobilized on activated carbon (nZVI-AC) were synthesized to rapidly remove Acid Red 33 (AR 33) as an azo dye from an aqueous medium. This novel nanocomposite was characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-Ray Diffraction (XRD), and Fourier Transform InfraRed (FT-IR)spectroscopy. The effect of experimental variables, including adsorbent dosage, pH, initial concentration of AR 33, and the temperature was studied to select the optimum conditions for maximum removal efficiency. The optimal conditions were achieved at an adsorbent dosage of 0.2 g/L, pH=3, initial dye concentration of 10 mg/L, and a temperature of 313 K. Isotherms and kinetics studies indicated that Langmuir isotherm with regression determination (R²) of 0.9914 and pseudo-first-order model with R2=0.9922 fitted well to the experimental data. The calculated thermodynamic parameters such as ΔG°, ΔH°, and ΔS° revealed that the adsorption process was spontaneous and endothermic. The reusability of the nZVI-AC was investigated and it found that this adsorbent had a potential ability to remove AR 33 dye.