SYNTHESIS OF METAL ORGANIC FRAMEWORKS FOR DYE REMOVAL FROM SYNTHETIC WASTEWATER

Abstract

Metal-organic frameworks (MOF) were synthesized to absorb methyl orange dyes in synthetic wastewater by synthesizing MOF materials, including MOF-Ni-DMF and MOF-Ni-DI, were synthesized using nickel (II) chloride hexahydrate and benzene-1,3,5-tricarboxylic acid (BTC) as precursors. In the synthesis, dimethylformamide (DMF) was used as the solvent for MOF-Ni-DMF, whereas water was used as the solvent for MOF-Ni-DI. Both materials were synthesized under hydrothermal conditions at 120 °C for 24 hours. Both synthesized MOF materials appeared as light green powders. The synthesized materials were characterized by their physical and chemical properties. Functional groups were identified using Fourier Transform Infrared Spectroscopy (FTIR), FTIR spectra of MOF-Ni-DMF and MOF-Ni-DI exhibited characteristic peak of Ni–O at approximately 720 cm⁻¹, carboxylate groups (–COO⁻) coordinated with nickel in the range of 1650–1350 cm⁻¹, carbonyl groups (C=O) around 1720 cm⁻¹, and hydroxyl groups (–OH) near 3400 cm⁻¹. These findings indicate the formation of coordination bonds between the metal ions and the organic ligand, with both nickel and BTC present in the structure of the materials. crystallinity was examined using X-ray Diffraction (XRD) MOF-Ni-DMF showed sharp and well-defined peaks, indicative of a crystalline structure, whereas MOF-Ni-DI exhibited broader and less intense peaks, suggesting an amorphous structure. The zeta potential was –12.7 mV for MOF-Ni-DMF and –15.2 mV for MOF-Ni-DI, respectively. the adsorption performance of MOF-Ni-DMF and MOF-Ni-DI was investigated using synthetic wastewater containing methyl orange at concentrations of 20, 50, and 100 mg/L (30 mL each). A 10 mg quantity of each MOF was used at pH 5.6 and a temperature of 25 °C. Adsorption tests were conducted at contact times of 20, 40, 60, and 80 minutes. The adsorption performance for methyl orange revealed that equilibrium was reached at 40 minutes. MOF-Ni-DMF demonstrated a higher adsorption capacity than MOF-Ni-DI at all tested concentrations of methyl orange. At 20 mg/L, MOF-Ni-DMF and MOF-Ni-DI adsorption capacity are 141.73 and 98.67 mg/g, respectively. And adsorption efficiency is 99.52% and 69.28% respectively. Both MOF-Ni-DMF and MOF-Ni-DI exhibited adsorption behavior consistent with the Freundlich isotherm model, with correlation coefficients (R²) of 0.99937 and 0.62949, respectively.