Synthesis of a novel adsorbent-photocatalytic material using a low energy route and its application to the remediation of water from contamination of 17-α ethinyl estradiol

Abstract

Endocrine-disrupting compounds such as 17α-ethinylestradiol (EE2) pose significant risks to aquatic ecosystems and human health, necessitating the development of advanced water purification materials. This thesis presents the synthesis and characterization of a novel composite coating of hydroxyapatite (HAP) and titanium dioxide (TiO₂) applied to hollow glass microspheres (HGMs) for the efficient removal of EE2 from aqueous systems. The composite was fabricated via a sol-gel assisted deposition method, leveraging the high surface area of HGMs and the complementary adsorption–photocatalytic properties of HAP and TiO₂. Comprehensive material characterization was performed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and atomic force microscopy (AFM) to confirm morphological, structural, and functional properties of the composite. Surface area and porosity were evaluated through BET N₂ adsorption isotherms. EE2 degradation and residual concentrations were quantified through high-performance liquid chromatography (HPLC) and liquid chromatography–mass spectrometry (LC-MS). The composite coatings demonstrated superior adsorption–photocatalytic performance compared to individual HAP and TiO₂ coatings, attributed to synergistic interactions that enhanced EE2 binding and photodegradation efficiency. Kinetic analysis revealed rapid removal rates, while repeated use confirmed the composite’s structural stability and reusability. Notably, the composite materials outperformed the current industry standard – activated carbon – in both removal efficiency and overall cost-effectiveness under comparable experimental conditions. These findings underscore the potential of hydroxyapatite–TiO₂ composites as next-generation materials for sustainable water purification, offering a promising strategy to mitigate emerging contaminants in aquatic environments.