Coordination Polymers Derived from Hydrazine as Photocatalysts for Degradation of Metronidazole from Pharmaceutical Wastewater

Metronidazole (MNZ) is a common brand of nitroimidazole antibiotic, which is widely used to treat infectious diseases caused by anaerobic bacteria and protozoa. The aim of this work was to degrade MNZ from the pharmaceutical wastewater. The degradation of the antibiotic metronidazole (MNZ) from aqueous solutions was evaluated by newly synthesized coordination polymers using a photocatalytic process. Zn(II), Cu(II), Fe(II), Co(II), and Ni(II) polymers with hydrazine, namely, [ZnSO₄(H₂O)(NH₂NH₂)]_<i>n</i>·0.5H₂O, [CuSO₄(H₂O)(NH₂NH₂)]_<i>n</i>·0.5H₂O, [FeSO₄(H₂O)₂(NH₂NH₂)]_<i>n</i>·H₂O, [Co(NO₃)₂(NH₂NH₂)]_<i>n</i>, and [Ni(NO₃)₂(NH₂NH₂)]_<i>n</i>, were synthesized. The prepared coordination polymers were characterized by elemental analysis, Fourier transformation infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), UV-visible, and VSM and thermogravimetric analysis (TGA/DTG). The removal studies were performed under the effect of UV radiation. The influences of various operational parameters such as catalyst dose, addition of hydrogen peroxide, and time of exposure on percentage photodegradation of metronidazole were evaluated. According to the experimental findings, metronidazole photodegradation increased with catalyst dose and exposure duration time. The [CuSO₄(H₂O)(NH₂NH₂)]_<i>n</i>·0.5H₂O polymer had the best photocatalytic activity under UV light among the polymers under study, reaching the maximum degradation efficiency of 92.10% following 150 min of irradiation. Finally, coordination polymers derived from hydrazine were shown to be a potential class of photocatalysts for the highly effective elimination of metronidazole from aqueous solutions.