Enhanced Removal of Oxytetracycline from Wastewater by Fe/Ni Integrated Zif-8 Nanocomposites

Here, a nanosized Fe/Ni functionalized zeolitic imidazolate framework-8 (ZIF-8-Fe/Ni) was fabricated and evaluated for removing oxytetracycline (OTC) from wastewater. The OTC removal efficiency of ZIF-8-Fe/Ni was 18.5% better than an iron functionalized zeolitic imidazolate framework-8 (ZIF-8-Fe) and 34.6% better than an unfunctionalized zeolitic imidazolate framework-8 (ZIF-8). This confirmed that the inclusion of Ni into the composite enhanced OTC removal efficiency. The function of both Fe/Ni and ZIF-8 was confirmed by Cyclic Voltammetry (CV) and amperometric I-t measurements, indicating that OTC was reduced by ZIF-8-Fe/Ni. Transmission electron microscopy (TEM) mapping and X-ray photoelectron spectroscopy (XPS) indicated that Fe/Ni was evenly dispersed throughout ZIF-8 and partially oxidized. The OTC adsorption isotherm best-fitted Langmuir isotherm . OTC adsorption kinetics followed a pseudo-second-order reaction , while OTC degradation followed pseudo-first-order reduction kinetics . Thus overall, the removal of OTC involved a combination of both adsorption and catalytic reduction. Degradation products identified by high-performance liquid chromatography-mass spectrometry (HPLC-MS) supported a catalytic reduction mechanism. Finally, the removal efficiency of OTC in real wastewater was assessed and reached 92.6%, where even after 5 reuse cycles, the removal efficiency of the material still attained a noteworthy 74.9%, indicating that ZIF-8-Fe/Ni exhibited high removal efficiency and good recyclability