Peripherally tetra-substituted zinc (II) phthalocyanine sensitized TiO 2 composite: Monitoring with tandem LC/MS and photocatalytic degradation of amoxicillin

Abstract

The presence of pharmaceutically active compounds, including antibiotics, in various waters is of concern worldwide. The global handicap is that antibiotics derivatives, even when present in low concentrations in the environment, can lead to the development of antibiotic-resistant bacteria. The main purpose of this research was to degrade amoxicillin (AMX), which rapidly transforms into various degradation products (DPs) that can prove resistant to removal from water sources. To this end, the use of TiO2 nanocomposites with modified zinc phthalocyanine (ZnPc)/TiO2 was considered to both degrade the AMX compound and remove its possible DPs. The (ZnPc)/TiO2 nanocomposites are firstly synthesized by sol-gel method using titanium isopropoxide and ZnPc as Ti source, and dye pigments, respectively. The (ZnPc)/TiO2 samples were characterized by scanning electron microscopy / energy dispersive X-ray analyzer (SEM/EDX), X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), and Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV-DRS). To estimate the DPs formed during the photocatalytic cleavage of AMX, a triple quadrupole LC/MS/MS (Tandem MS2) was performed. It was proposed possible DPs empirical structures as structural by paying attention to the literature information in identifying possible DPs. Mineralization of AMX was also investigated by total organic carbon (TOC) analysis, suggesting that either amoxicillin itself or its resistant metabolites are still in solution and mineralization did not occur in the an expected manner.