Adsorption of Organic Dye on ZnFeAl-LDH and Derived Mixed Metal Oxide

The ZnFeAl-LDH was synthesized via the well-known co-precipitation method. The obtained solid was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR). Taguchi orthogonal design with five factors, namely adsorbent type and dosage, pH, dye concentration, and time was performed to optimize and model the dye removal efficiency and the percentage by LDH and derived MMO. The proposed model was in accordance with the experimental results with a correlation coefficient of 95.2% and 98.7% for removal efficiency and percentage, respectively. The desirability approach was adopted in order to maximize the adsorption capacity (q) and adsorption percentage (R %). Under optimum conditions, the maximum adsorption capacity of 151.48 mg/g and the removal percentage of 99.7% were obtained. Isotherm modeling and kinetic investigations showed that Langmuir and pseudo-second-order models describe both the adsorption equilibrium and kinetic behavior well.