ABSTRACT
Several drugs have sparked interest as potential COVID-19 treatment options. Doxycycline (DOX) has been widely used with other potential agents to reduce COVID-19-induced inflammation. DOX and OFLX, both well-known antimicrobial and anti-inflammatory drugs, were chosen as model pollutants. Fe, Cu-codoped TiO2-SiO2 was synthesised as a novel photocatalyst active under sunlight irradiation to treat model pollutants. The synthesised catalyst samples were meticulously characterised using various techniques to evaluate their morphological, optical, and structural properties. The results of BET analysis showed that the TSFC1 sample has a large specific surface area of 288 m(2)g(-1). Maximum degradation of DOX and OFLX (about 98%) was achieved with the TSFC1 catalyst. The photocatalytic reusability was investigated for up to seven successive cycles, and the composite particles maintained their high photodegradation activity for DOX and OFLX. TFSC1 composite, in particular, demonstrated high catalytic activity as well as excellent recovery potential, and its combination with solar light, silica, and dopants can be introduced as a promising strategy for efficiently destroying both DOX and OFLX antibiotics. This study highlights the feasibility of hybridising doped dual semiconductor nanostructures in implementing solar light-powered pharmaceutical wastewater degradation.
ABSTRACT
Modern life-style is creating an indoor generation: human beings spend approximately 90% of their time indoors, almost 70% of which is at home – this trend is now exacerbated by the lockdowns/restrictions imposed due to the COVID-19 pandemic. That large amount of time spent indoors may have negative consequences on health and well-being. Indeed, poor indoor air quality is linked to a condition known as sick building syndrome. Therefore, breathing the freshest air possible is of outmost importance. Still, due to reduced ventilation rates, indoor air quality can be considerably worse than outdoor. Heating, ventilation, and air conditioning (HVAC), air filtration systems and a well-ventilated space are a partial answer. However, these approaches involve only a physical removal. The photocatalytic mineralization of pollutants into non-hazardous, or at least less dangerous compounds, is a more viable solution for their removal. Titanium dioxide, the archetype photocatalytic material, needs UVA light to be ‘activated’. However, modern household light emitting diode lamps irradiate only in the visible region of the solar spectrum. We show that the surface of titanium dioxide nanoparticles modified with copper oxide(s) and graphene has promise as a viable way to remove gaseous pollutants (benzene and nitrogen oxides) using a common light emitting diode bulb, mimicking real indoor lighting conditions. Titanium dioxide, modified with 1 mol% CuxO and 1 wt% graphene, proved to have a stable photocatalytic degradation rate, three times higher than that of unmodified titania. Materials produced in this research work are thus strong candidates for offering a safer indoor environment. © 2022 Elsevier Ltd
ABSTRACT
In this work, Cu-Sn-TiO2 composite coatings were electrochemically obtained from a sulfate bath containing 0-10 g/L of TiO2 nanoparticles. The effect of TiO2 particles on kinetics of cathodic electrodeposition has been studied by linear sweep voltammetry and chronopotentiometry. As compared to the Cu-Sn alloy, the Cu-Sn-TiO2 composite coatings show rougher surfaces with TiO2 agglomerates embedded in the metal matrix. The highest average amount of included TiO2 is 1.7 wt.%, in the case of the bath containing 5 g/L thereof. Composite coatings showed significantly improved antibacterial properties towards E. coli ATCC 8739 bacteria as compared to the Cu-Sn coatings of the same composition. Such improvement has been connected with the corrosion resistance of the composites studied by linear polarization and electrochemical impedance spectroscopy. In the bacterial media and 3% NaCl solutions, Cu-Sn-TiO2 composite coatings have lower corrosion resistance as compared to Cu-Sn alloys, which is caused by the nonuniformity of the surface.
ABSTRACT
A practical scale photocatalytic air purifier equipped with a TiO2/H-ZSM-5 composite bead filter was demonstrated to be able to effectively remove indoor volatile organic compounds (VOCs) and viruses with sustainable performances under UVA-LED illumination. TiO2 hybridized with 5 wt% H-ZSM-5 zeolite significantly enhanced its photocatalytic activity for degrading VOCs including formaldehyde, acetaldehyde, and toluene, than bare TiO2. H-ZSM-5 provided strong adsorption sites for these compounds, thus accelerating their photocatalytic conversion into CO2 by adjacent TiO2 photocatalyst. Moreover, owing to its superior adsorption capacity, the composite bead filter completely prevented the emission of formaldehyde produced by photocatalytic oxidation of toluene. The sustainability of this composite bead filter for VOC removal was confirmed by regeneration and accelerated durability tests. In addition, the photocatalytic air purifier was effective in removing aerosolized viral particles of bacteriophage Phi-X 174. It was confirmed that the viruses on filter surfaces were completely inactivated by photocatalytic oxidation. TiO2/H-ZSM-5 composite beads also exhibited excellent efficacies for inactivation of pathogenic coronaviruses including SARS-CoV-2. The photocatalytic process degraded viral RNAs of SARS-CoV-2 by more than 99.999% in 1 h, eliminating the viral infectivity. Results of this study suggest that the air purifier equipped with the composite bead filter is ready for practical applications for home and hospital uses.