GO-Based Membranes for the Removal of Pharmaceuticals from Wastewater
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The increasing occurrence of pharmaceutical contaminants in wastewater has become a significant environmental concern due to their persistence and potential adverse effects on aquatic ecosystems and human health. The aim of this thesis, Graphene Oxide (GO)-Based Membranes for Removal of Pharmaceuticals from Wastewater, was to investigate the potential of graphene oxide-based membranes for the removal of selected pharmaceutical contaminants from aqueous solutions.
GO was synthesized from graphite flakes using a modified Hummers’ method and GO membranes fabricated using the vacuum filtration technique onto a polyvinylidene fluoride (PVDF) support membrane. Self-standing GO/PVA composite membrane was also prepared to assess the influence of polymer incorporation on GO membrane modification, as well as its effect on the removal of pharmaceuticals residues and the membrane properties. The synthesized materials and fabricated membranes were characterized using UV–Visible spectroscopy, Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Diffraction (XRD). Aqueous solutions of citalopram, diclofenac, amisulpride, carbamazepine, and metoprolol were filtered through the fabricated membranes using a syringe filtration system. The concentrations of the pharmaceuticals before and after filtration were determined using UV–Vis spectroscopy. In addition, forward osmosis (FO) experiments were conducted using GO/PVDF and GO/PVA membranes to evaluate water transport and reverse salt flux across the membranes.
The characterization results confirmed the successful synthesis of GO and the formation of GO-based membranes. Filtration experiments demonstrated that the GO/PVDF membrane selectively retained positively charged pharmaceuticals, while neutral and negatively charged pharmaceuticals exhibited lower retention. The incorporation of PVA altered the filtration behaviour of the pristine GO membrane and resulted in improved retention of neutral pharmaceutical compounds. FO experiments showed that the GO/PVA membrane exhibited enhanced water transport and lower reverse salt flux compared with the pristine GO/PVDF membrane, indicating improved membrane selectivity and structural stability due to the modification with PVA.
The study concludes that GO-based membranes are promising materials for the removal of pharmaceutical contaminants from wastewater. The membrane performance was strongly influenced by the physicochemical properties of the pharmaceutical compounds and the membrane composition. Furthermore, the incorporation of PVA improved membrane performance, especially in FO applications.