Inactivation of fungal spores from clinical environment by silver bio-nanoparticles; optimization, artificial neural network model and mechanism

Use of ozonation technology to combat viruses and bacteria in aquatic environments: problems and application perspectives for SARS-CoV-2

COVID-19 is a global health threat with a large number of confirmed cases and deaths worldwide. Person-to-person transmission through respiratory droplets and contact with aerosol-infected surfaces are the main ways in which the virus spreads. However, according to the updated literature, the new coronavirus (SARS-CoV-2) has also been detected in aqueous matrices, with the main route of transmission being feces and masks from patients diagnosed with the disease. Given the emergence of public health and environmental protection from the presence of lethal viruses and bacteria, this review article aims to report the major challenges associated with the application of ozonation in water contaminated with viruses and bacteria, in order to clarify whether these communities can survive or infect after the disinfection process and if it is efficient. Available data suggest that ozonation is able to increase the inactivation effect of microorganisms by about 50% in the logarithmic range, reducing infectivity. In addition, the evidence-based knowledge reported in this article is useful to support water and sanitation safety planning and to protect human health from exposure to cited contaminants through water.

Challenges and opportunities in the application of bioinspired engineered nanomaterials for the recovery of metal ions from mining industry wastewater

Heavy-metal-bearing wastewater is among the most formidable challenges the mining industry currently faces in maintaining its social license to operate. Amongst the technologies available for metal ion adsorption, bioinspired engineering nanomaterials have emerged as one which exhibits great promise. However, current processes used for the preparation of adsorbents (including nanoscale activated carbon and biochar) represent a source of adverse impacts on the environment. In contrast, the application of biogenic-nanoparticles, i.e., those derived from processes catalysed by microbiota, has received significant attention in the last few years. Coupled with this, the use of naturally occurring reagents is of major importance for the sustainability of this emerging industry. This paper analyses the life cycle assessment (LCA) of the synthesis of adsorbents derived from agricultural wastes. Moreover, rather than simply recovering the ecotoxic metals from wastewater, the potential to valorise dissolved metals into high-value metallic nanoparticle products is discussed. LCA analysis revealed that the adsorbent had some adverse impact on the environment. The agricultural wastes contributed 27.86% to global warming, 54.64% to ozone formation, 33.06% to fine particles, and 98.24% to marine eutrophication. Mining wastewater is an important, and largely currently unexploited, source of metal value. However, the often-low concentration of such metals dictates that their conversion into high-value products (such as engineered nanoparticles) is an important new research frontier. Within this the use of biosynthesis methods has emerged as having great potential due to a range of beneficial attributes, including low cost, high efficacy and/or environmental compatibility.

Evaluation of Antifungal Properties of Titania P25

Commercial titania photocatalyst—P25 was chosen for an antifungal property examination due to it exhibiting one of the highest photocatalytic activities among titania photocatalysts. Titania P25 was homogenized first (HomoP25) and then annealed at different temperatures. Additionally, HomoP25 was modified with 0.5 wt% or 2.0 wt% of platinum by a photodeposition method. The obtained samples were characterized by diffuse-reflectance spectroscopy (DRS), X-ray photoabsorption spectroscopy (XPS), X-ray diffraction (XRD) and Raman spectroscopy. Moreover, photocatalytic activity was tested for methanol dehydrogenation under UV/vis irradiation. The spore-destroying effect of photocatalysts was investigated against two mold fungal species, i.e., Aspergillus fumigatus and Aspergillus niger. Both the mycelium growth and API ZYM (estimation of enzymatic activity) tests were applied for the assessment of antifungal effect. It was found that annealing caused a change of surface properties of the titania samples, i.e., an increase in the noncrystalline part, a growth of particles and enhanced oxygen adsorption on its surface, which resulted in an increase in both the hydrogen evolution rate and the antifungal effect. Titania samples annealed at 300−500 °C were highly active during 60-min UV/vis irradiation, inhibiting the germination of both fungal spores, whereas titania modification with platinum (0.5 and 2.0 wt%) had negligible effect, despite being highly active for hydrogen evolution. The control experiments revealed the lack of titania activity in the dark, as well as high resistance of fungi for applied UV/vis irradiation in the absence of photocatalysts. Moreover, the complete inhibition of 19 hydrolases, secreted by both tested fungi, was noted under UV/vis irradiation on the annealed P25 sample. It is proposed that titania photocatalysts of large particle sizes (>150 nm) and enriched surface with oxygen might efficiently destroy fungal structures under mild irradiation conditions and, thus, be highly promising as covering materials for daily products.