The COVID-19 pandemic has severely impacted public health worldwide. Evidence of SARS-CoV-2 transmission via aerosols and surfaces has highlighted the need for efficient indoor disinfection methods. For instance, the use of ozone gas as a safe and potent disinfectant against SARS-CoV-2 virus is of particular interest. Here we tested the use of pseudoviruses as a model for evaluating ozone disinfection of the coronavirus at ozone concentrations of 30, 100, and 1000 ppmv. Results show that ozone disinfection rate of pseudoviruses was similar to that of coronavirus 229E (HuCoV-229E) at short contact times, below 30 min. Viral infection decreased by 95% following ozone exposure for 20 min at 1000 ppmv, 30 min at 100 ppmv and about 40 min at 30 ppmv. This findings mean that ozone is a powerful disinfectant toward the enveloped pseudovirus even at low ozone exposure. We also showed that viral disinfection occurs on various contaminated surfaces, with a positive association between disinfection and surface hydrophilicity. Infected surfaces made of aluminum alloy, for example, were better disinfected with ozone as compared to brass, copper, and nickel surfaces. Lastly, we demonstrate the advantage of ozone over liquid disinfectants by showing similar viral disinfection on top, side, bottom, and interior surfaces. Overall, our study demonstrates the potential use of ozone gas disinfection to combat the COVID-19 outbreak.

No abstract

Many of polybrominated organic compounds, used as flame retardant additives, belong to the group of persistent organic pollutants. Compound-specific isotope analysis is one of the potential analytical tools for investigating their fate in the environment. However, the isotope effects associated with transformations of brominated organic compounds are still poorly explored. In the present study, we investigated carbon and bromine isotope fractionation during degradation of tribromoneopentyl alcohol (TBNPA), one of the widely used flame retardant additives, in three different chemical processes: transformation in aqueous alkaline solution (pH 8); reductive dehalogenation by zero-valent iron nanoparticles (nZVI) in anoxic conditions; oxidative degradation by H2O2 in the presence of CuO nanoparticles (nCuO). Two-dimensional carbon-bromine isotope plots (δ(13)C/Δ(81)Br) for each reaction gave different process-dependent isotope slopes (Λ(C/Br)): 25.2 ± 2.5 for alkaline hydrolysis (pH 8); 3.8 ± 0.5 for debromination in the presence of nZVI in anoxic conditions; ∞ in the case of catalytic oxidation by H2O2 with nCuO. The obtained isotope effects for both elements were generally in agreement with the values expected for the suggested reaction mechanisms. The results of the present study support further applications of dual carbon-bromine isotope analysis as a tool for identification of reaction pathway during transformations of brominated organic compounds in the environment.

Transport of Ag-NPs in partially saturated soil exhibits different patterns comparing sand and soil under saturated and partially saturated, conditions.

No abstract

In situ chemical ozonation (ISCO 3 ), in which gaseous ozone is being injected into the subsurface, is a common method for remediating contaminated groundwater that is largely affected by the inevitable consumption of ozone by soil itself (rather than the target contaminants). In this study, ozone consumption by two main soil types of Israeli coastline aquifer was examined. Iron-rich soil showed considerably higher reactivity than did calcareous soil. We further investigated the effect of both physical and chemical soil characteristics on finite and catalytic ozone decay, hydroxyl-radical formation, and ozone transport behavior. Ozone consumption increased by >90% in the presence of fine soil particles (<100 μm), resulting from the large number of reactive sites and the higher content of ozone consumers compared to coarse soil particles. Soil organic matter consumed ozone twice as fast as iron components, promoted radical formation at higher rates, and mainly acted as a finite ozone consumer. In continuously fed column experiments, the reactions with iron components dominate catalytic ozone consumption during transport in porous media. Overall, this study demonstrates that the characterization of ozone reactions in soil can be helpful in evaluating the feasibility and efficiency of ISCO 3 and inform the design of ISCO 3 treatment, e.g., the need to inject additional radical promoters.

In this work, we examine an alternative ozone delivery method for groundwater remediation using permeable membranes. A cylindrical polydimethylsiloxane (PDMS) membrane was used for passive ozone injection in a two-dimensional system simulating in situ groundwater treatment. Liquid velocity and presence of ozone consumers (e.g., nitrite) were found to regulate the ozone diffusion rate through the membrane and the resultant dissolved ozone concentration. A higher liquid velocity (examined in a 340–920 cm day–1 range) resulted in an increase in ozone diffusion rates (up to 2 μmol s–1 m–2) and a decrease in dissolved ozone concentration due to a dilution effect. Similarly, increasing the nitrite concentration from 0.5 to 25 mM enhanced the ozone diffusion rate by up to 5.64 μmol s–1 m–2. To examine the membrane performance, carbamazepine was used as a fast-reacting model pollutant. Up to 80% carbamazepine removal was obtained for the lowest liquid velocity examined, which is also relevant for typical groundwater velocities. However, a low ratio of carbamazepine-removed to ozone-delivered was obtained, which was associated with reactions occurring close to the membrane surface that may enable additional reactions of ozone with carbamazepine transformation products. Overall, this study provides new insights to support planning and design of groundwater applications using permeable membranes in reactive permeable barrier mode.

The understanding of engineered nanoparticle (ENP) fate and transport in soil–water environments is important for the evaluation of potential risks of ENPs to the ecosystem and human health. The effects of pyrite grains and three types of oxyanionssulfate, phosphate, and arsenateon the retention of citrate-coated gold nanoparticles (citrate–Au–NPs) were studied in partially saturated soil column experiments. The mobility of Au–NP was found to be in the order: Au–NP–sulfide (originating from pyrite) > Au–NP–sulfate > citrate–Au–NP > Au–NP–arsenate > Au–NP–phosphate. Chemical retention mechanisms, including hydrogen bonding and calcium bridging, are proposed and discussed. The retention of Au–NPs in soil columns increases with the increased ability of transformed Au–NP surfaces to create strong hydrogen bonding through adsorbed oxyanions with soil surfaces. Oxyanions were also found to reduce aggregation and aggregate size of Au–NPs upon interaction with Ca2+ solution. While the effects of cationic substances on ENP transport and stability have been studied frequently, the results here demonstrate that anionic substances have a substantial effect on Au–NP transport and stability. Furthermore, this study highlights the importance of examining ENPs under environmentally relevant condition, and the significant effect of ENP transformations on their mobility in soils.