Photoelectrochemical properties of magnetic amine-based MIL-101(Cr) hybrid material and its application in the degradation of acebutolol in water

Rapid advances in industries and agricultural practices have recently released various toxic pollutants into aquatic systems. Among other pollutants, pharmaceuticals, have been detected in environmental aquatic systems at levels that have negative health impacts on both humans and animals. This study employed an <i>in situ</i> chemical co-precipitation method to fabricate a magnetic amine-based metal organic framework nanocomposite. This nanocomposite was successfully synthesised and applied as a photocatalytic material for the mineralization of acebutolol (ACE) in water. The prepared materials, including the nanocomposite (Fe₃O₄@NH₂-MIL-101(Cr)) were characterised using transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis, Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). The optoelectronic properties were determined using photoluminescence (PL), electrochemical impedance spectroscopy, diffuse reflectance spectroscopy (UV-Vis DRS) and ultraviolet-visible spectroscopy. The photocatalytic efficacy of the nanocomposite was assessed <i>via</i> the degradation of acebutolol under visible light illumination. The results indicate that adsorption-desorption equilibrium was attained after 60 min in the dark, and 98.3% degradation efficiency was achieved after 180 min with the light on. According to scavenging experiments, superoxide radicals (·O₂ ^-) were the main reactive oxygen species (ROS) during photodegradation. The Nyquist plot obtained from electrochemical impedance spectroscopy (EIS) showed that the Fe₃O₄@NH₂-MIL-101(Cr) nanocomposite had a reduced charge transfer resistance (<i>R</i> _ct), indicating separation and accelerated transfer of charges at the interface. The obtained electron lifespan (<i>τ</i> _e) supported the results, and was found to be higher for Fe₃O₄@NH₂-MIL-101(Cr) compared to NH₂-MIL-101(Cr) and pure Fe₃O₄. The photocatalytic mechanism revealed that the formed heterojunction followed a Z-scheme mechanism.