Synthesis, Characterization and Photocatalytic Activity of Iron(II) and Iron(III) Coordination Polymers Derived from Terephthalic Acid

The growing demand for disinfection of polluted waters from different sources has led to the development of new and more effective water purification technologies. Photocatalysis holds great promise as an efficient and sustainable oxidation technology for application in wastewater treatment. Coordination polymers CPs have attracted ever growing research interest as a new kind of potential photocatalyst because of their unique properties of designable structure. New coordination polymers have been prepared by condensation of terephthalic acid with iron(II) and iron(III) ions. The corresponding structures have been described by infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy, X-ray powder diffraction and thermogravimetric analysis. The obtained data revealed that the Iron(II) polymer exhibits an infinite one-dimensional chain structure; while, Iron(III) polymer exhibits a three-dimensional metal–organic framework structure. The FTIR results suggested that the terephthalic acid was coordinated to the metal center as a dibasic tetradentate manner. The behavior of thermal decomposition for the prepared polymers was discussed. The kinetic and thermodynamic parameters have been evaluated using the Coats–Redfern method. The photocatalytic performances of the polymers for decomposition of methyl orange under UV irradiation were studied. The effect of parameters such as addition of H₂O₂ and pH of the dye solutions on the removal efficiency of methyl orange was also investigated. The prepared polymers promising photocatalytic activities for the degradation of methylene orange in water at room temperature.