Micro-sized TiO2 as photoactive catalyst coated on industrial porcelain grès tiles to photodegrade drugs in water

Oxidative Inactivation of SARS-CoV-2 on Photoactive AgNPs@TiO2 Ceramic Tiles

The current SARS-CoV-2 pandemic causes serious public health, social, and economic issues all over the globe. Surface transmission has been claimed as a possible SARS-CoV-2 infection route, especially in heavy contaminated environmental surfaces, including hospitals and crowded public places. Herein, we studied the deactivation of SARS-CoV-2 on photoactive AgNPs@TiO₂ coated on industrial ceramic tiles under dark, UVA, and LED light irradiations. SARS-CoV-2 inactivation is effective under any light/dark conditions. The presence of AgNPs has an important key to limit the survival of SARS-CoV-2 in the dark; moreover, there is a synergistic action when TiO₂ is decorated with Ag to enhance the virus photocatalytic inactivation even under LED. The radical oxidation was confirmed as the the central mechanism behind SARS-CoV-2 damage/inactivation by ESR analysis under LED light. Therefore, photoactive AgNPs@TiO₂ ceramic tiles could be exploited to fight surface infections, especially during viral severe pandemics.

COVID-19 and Healthcare Facilities: a Decalogue of Design Strategies for Resilient Hospitals

BACKGROUND AND AIM

The COVID-19 pandemic has upended the global healthcare systems. The surge in infections and sick critically ill patients has tested the resilience of healthcare infrastructures and facilities forcing organizations to quickly adapt and embrace emergency solutions. The paper proposes a decalogue of design strategies applicable both to new hospitals and to the refurbishment of existing hospitals.

METHODS

The authors conducted observations at hospitals, during public health webinars and through experts working groups from March to May 2020.

RESULTS

In this commentary, the authors present a list of strategies for creating critical care surge capacity and exploring design strategies for healthcare design for resilient hospital facilities. The strategies are organized into two tiers: I) design and II) operations. The (I) Design phase strategies are: 1) Strategic Site Location; 2) Typology Configuration; 3) Flexibility; 4) Functional program; 5) User-centerdness. The (II) Operation phase strategies are: 6) Healthcare network on the territory; 7) Patient safety; 8) HVAC and indoor air quality; 9) Innovative finishing materials and furniture; 10) Healthcare digital innovation.

CONCLUSIONS

Hospitals, health care systems, and institutions urgently need to assess their resources, identify potential bottlenecks, and create strategies for increasing critical care surge capacity. The COVID-19 pandemic disrupted healthcare operations and accelerated the processes of innovation and transformation. The design and operational strategies can enable the achievement of resilient hospital facilities. Further multidisciplinary researches is needed  to validate the strategies empirically.

Design of Multifunctional Titania-Based Photocatalysts by Controlled Redox Reactions

This work aims at the preparation of multifunctional titania-based photocatalysts with inherent capabilities for thermal co-activation and stabilisation of anatase polymorph, by designing the phase composition and microstructure of rutile-silicon carbide mixture. The processing involved a conventional solid state route, including partial pre-reduction of rutile by SiC in inert Ar atmosphere, followed by post-oxidation in air. The impacts of processing conditions on the phase composition and photocatalytic activity were evaluated using Taguchi planning. The XRD studies confirmed the presence of rutile/anatase mixtures in the post-oxidised samples. The results emphasise that pre-reduction and post-oxidation temperatures are critical in defining the phase composition, while post-oxidation time is relevant for the photocatalytic performance. Microstructural studies revealed the formation of core-shell particles, which can suppress the photocatalytic activity. The highest apparent reaction rate of the photodegradation of methylene blue was observed for the sample pre-reduced in Ar at 1300 °C for 5 h and then calcined in air at 400 °C for 25 h. Though its performance was ~1.6-times lower than that for the same amount of nanostructured industrial P25 photocatalyst, it was achieved in the material possessing 2–3 times lower surface area and containing ~50 mol% of SiO₂ and SiC, thus demonstrating excellent prospects for further improvements.

Digitally Printed AgNPs Doped TiO2 on Commercial Porcelain-Grès Tiles: Synergistic Effects and Continuous Photocatalytic Antibacterial Activity

In the present study, we use commercial digitally printed ceramic tiles, functionnalized by AgNPs doped micro–TiO2, to investigate the mechanism of Ag in the continouos photocatalytic antibacterial activity. The novelty of the research lies in the attempt to understand the mechanism of Ag, supported on TiO2, able to exhibit the same antibacterial activity of a standard system containing Ag species, but here, totally embedded on the tile surface, and thus not free to move and damage the bacteria cell. UV/vis diffuse reflectance spectroscopy (DRS) of AgNPs–TiO2 tiles indicated an enhanced visible light response, wherein a new absorption band was produced around 18,000–20,000 cm−1 (i.e., in the 400–600 nm range) owing to the surface plasmon resonance (SPR) of AgNPs. The antibacterial photocatalytic experiments were conducted towards the inactivation of E. coli under solar light and indoor light. It was found that the degradation speed of E. coli in the presence of AgNPs–TiO2 tiles is solar light-intensity depending. This justifies the semiconductor behavior of the material. Furthermore, the AgNPs–TiO2 tiles exhibit a high ability for the inactivation of E. coli at a high load (104–107 colony-forming unit (CFU)/mL). Additionally, AgNPs–TiO2 tiles showed a remarkable antibacterial activity under indoor light, which confirms the good photocatalytic ability of such tiles. On the basis of the reactive oxygen species (ROS) quenching experiments, O2•− species and h+ were more reactive for the inactivation of E. coli rather than •OH species. This is because of the different lifetime (bacteria are more likely oxidized by ROS with longer lifetime); in fact, O2•− and h+ exhibit a longer lifetime compared with •OH species. The generation of H2O2 as the most stable ROS molecule was also suggested.

Wastewater chemical contaminants: remediation by advanced oxidation processes

Approximately 70% of the terrestrial area is covered with water, but only a small water fraction is compatible with terrestrial life forms. Due to the increment in human consumption, the need for water resources is increasing, and it is estimated that more than 40% of the population worldwide will face water stress/scarcity within the next few decades. Water recycling and reuse may offer the opportunity to expand water resources. For that, the wastewater treatment paradigm should be changed and adequately treated wastewater should be seen as a valuable resource instead of a waste product. It is easily understandable that the exact composition and constituent concentration of wastewater vary according to its different sources (industrial, agricultural, urban usage of water). Consequently, a variety of known and emerging pollutants like heavy metals, antibiotics, pesticides, phthalates, polyaromatic hydrocarbons, halogenated compounds and endocrine disruptors have been found in natural water reservoirs, due to the limited effectiveness of conventional wastewater treatment. The conventional approach consists of a combination of physical, chemical and biological processes, aiming at the removal of large sediments such as heavier solids, scum and grease and of organic content in order to avoid the growth of microorganisms and eutrophication of the receiving water bodies. However, this approach is not sufficient to reduce the chemical pollutants and much less the emerging chemical pollutants. In this review, after some considerations concerning chemical pollutants and the problematic efficiency of their removal by conventional methods, an update is presented on the successes and challenges of novel approaches for wastewater remediation based on advanced oxidation processes. An insight into wastewater remediation involving the photodynamic approach mediated by tetrapyrrolic derivatives will be underlined.

TiO2 as Photosensitizer and Photoinitiator for Synthesis of Photoactive TiO2-PEGDA Hydrogel Without Organic Photoinitiator

The replacement of potentially toxic photoinitiators is of increasing interest regarding the synthesis of biomaterials by photopolymerization. Therefore, we present a new method for the preparation of UV polymerized hydrogels with TiO2 as a photoinitiator. Titania is known to be an excellent photoactive compound which is non-toxic, inert, and cheap. The so-formed hydrogels possess excellent mechanical properties, a high swelling ratio, and high thermal stability. Furthermore, no TiO2 is released from the hydrogels. Thus, the material is highly suitable for medical applications. Additionally, the present TiO2 in the hydrogels remains photoactive as demonstrated by degradation of methylene blue. This enables the application of TiO2-hydrogels in photodynamic therapy.

Mechanical Characterization of Gres Porcelain and Low-Velocity Impact Numerical Modeling

The current investigation was conducted on gres porcelain stoneware, a robust, impermeable and aesthetically pleasing type of ceramic mainly used for flooring, characterizing its resistance to bending and low-velocity impact, both representative efforts to which flooring tiles are constantly subjected as a consequence of the fall of objects and microsubsidences. The mechanical characterization was made through experimental tests following an adapted low-velocity impact testing routine, and the model was by validated numerical simulation through the explicit code software LS-DYNA based on the Johnson–Holmquist constitutive material model. Specimens were tested before and after an annealing cycle industrially used to allow porcelain folding. The thermal treatment demonstrated to infer a decrease in mechanical resistance on the material, understood as a consequence of its elevated maximum temperature and fast cooling rate. The numerical model calibrated successfully allows predicting the behavior of gres porcelain before and after annealing against low-velocity impact.