Kinetic and Thermodynamic Study of Methyl Orange Dye Adsorption on Zinc Carbonyldiphthalate, an Organometallic-Based Material Prepared with a Montmorillonite Clay

Our work is related to the use of adsorption as an effective physical method for water treatment contaminated with toxic dyes generated by various industries. We focused on the adsorption/removal of Methyl Orange (MO) dye from an aqueous solution using a new hybrid organometallic-based material constructed via In-Situ polymerization of Zinc-building units connected by coordination bonds to 4,4'-Carbonyldiphthalic acid (H4CDPA) as a flexible multidentate organic ligand under solvothermal conditions with an amount of Maghnite-H+, an acid-exchanged montmorillonite clay to obtain Zn-CDP/Mag-H+ extremely stable thermally with an onset temperature of degradation upper to 460°C as shown by ThermoGravimetric Analysis (TGA). The structure of this material is confirmed by Fourier Transform InfraRed (FT-IR) spectroscopy and X-Ray Diffraction (XRD). The effect of different parameters such as adsorbent mass, initial dye concentration, contact time, and pH of solution on the adsorption capacity of this material is investigated using UV-Visible spectroscopy. The kinetic study shows that the adsorption process of MO is very fast and well described by the pseudo-second-order model. The adsorption isotherms of the adsorbent/adsorbate systems are in agreement with the Langmuir equation showing an adsorption capacity of 147.05 mg/g for this material. The thermodynamic parameters calculated at various temperatures indicate that MO adsorption on Zn-CDP/Mag-H+ is an endothermic reaction (∆H° > 0) and spontaneous (∆G° < 0) process.