Hani Gnayem

Development of Hybrid BiOClxBr1−x‐Embedded Alumina Films and Their Application as Highly Efficient Visible‐Light‐Driven Photocatalytic Reactors

A highly stable 75 wt % BiOClx Br1-x -loaded alumina composite film has been developed for the fabrication of glass-based photoreactors. A very simple approach has been adopted that does not involve the use of a special instrument and can be applied to all types of substrates irrespective to their size and shape. The structure and morphology of the films were well characterized by XRD, SEM, TEM, N2 -sorption, IR, Raman, and UV/Vis diffuse reflectance spectroscopy. BiOClx Br1-x microspheres (1-3 μm) with closely packed thin nanoplates (width ≈10 nm) were integrated within alumina to develop a hybrid film. The photocatalytic capacity of the films was evaluated for the decomposition of Rhodamine B (RhB) and naphthalene under visible-light irradiation. The composite films showed a remarkable photocatalytic activity and stability and have been reused for several cycles without any deterioration of their original activity.

Disinfection and Mechanistic Insights of Escherichia coli in Water by Bismuth Oxyhalide Photocatalysis

This study demonstrates the potential of a new BiOCl0.875Br0.125 photocatalyst to disinfect Escherichia coli in water under simulated solar irradiation. Photocatalytic efficiency was examined for different photocatalyst loadings, solar wavelengths, exposure times, photocatalyst concentration × contact time (Ct) concept and with the use of scavengers. To elucidate the inactivation mechanism, we examined DNA damage, membrane damage, lipid peroxidation and protein release. Both photolysis and photocatalysis were negligible under visible irradiation, but enhanced photocatalytic activity was observed under solar UVA (λ > 320 nm) and UVB (λ > 280 nm), with 1.5 and 3.6 log inactivation, respectively, after 40 min of irradiation. The log inactivation vs Ct curve for E. coli by UVA/BiOCl0.875Br0.125 was fairly linear, with Ct = 10 g L−1 × min, resulting in 2 log inactivation. Photocatalytic treatment led to membrane damage, but without lipid peroxidation. Accordingly, protein was released from the cells after UVA or UVA/BiOCl0.875Br0.125 treatment. Photocatalysis also increased endonuclease‐sensitive sites vs photolysis alone, by an unknown mechanism. Finally, E. coli inactivation was not influenced by the addition of tert‐butanol or l‐histidine, implying that neither hydroxyl radicals nor singlet oxygen reactive species are involved in the inactivation process.

Hybrid bismuth oxyhalides@gypsum as self-cleaning composites: novel aspects of a sustainable photocatalytic technology for solar environmental cleanup

Herein we report the fabrication of a novel heterojunctioned BiOClxBr1−x@gypsum composite and its application as a self-cleaning surface for the straightforward use in construction and building materials. The morphology, chemical composition and crystal structure of the hybrid material were characterized using X-ray diffraction and scanning electron microscopy. The photocatalytic activity of the new composite was investigated for the degradation of naphthalene and rhodamine B (RhB) under visible light (λ ≥ 420 nm) irradiation. Our results show rapid and complete destruction of the RhB dye after only 4 minutes under Xe visible light irradiation (422–740 nm) and 2.5 minutes under mild sunlight illumination. Total organic carbon measurements could verify the absolute mineralization of the recalcitrant naphthalene contamination, as a state of the art example, within 20 minutes of visible light illumination.

Solar Photocatalytic Degradation of Trace Organic Pollutants in Water by Bi(0)-Doped Bismuth Oxyhalide Thin Films

Herein, we demonstrate the fabrication of Bi(0)-doped bismuth oxyhalide solid solution films for the removal of trace organic pollutants (TrOPs) in water. With the advantage of a viscous AlOOH sol, very high loadings (75 wt %) of bismuth oxyhalides were embedded within the thin films and calcined at 500 °C to develop porous alumina composite coatings. Various concentrations of Bi(0) doping were tested for their photocatalytic activity. Seven TrOPs including iopromide (IPRM), iohexol (IHX), iopamidol (IPMD), sulfamethoxazole (SMX), carbamazepine, venlafaxine, and bezafibrate (BZF) were selected for this study based on their occurrence and detection in effluents and surface waters worldwide. In all tests, with the exception of IPRM, 3% Bi(0)-doped BiOCl0.875Br0.125 showed highest activity, which can be attributed to its unique, highly organized, and compact morphology besides its well-matched energy band positions. Although IPMD, IHX, IPRM, and SMX are susceptible to photolysis, still the photocatalytic activity significantly augmented the removal of all tested compounds. In addition, analysis of the surface charge excluded electrostatic interactions and confirmed the ion-exchange adsorption mechanism for the high degradation rate of BZF in the presence of bismuth oxyhalides.