Photocatalytic properties of TiO2 for the degradation of O3: Examined by environmental parameters

2021 ◽  
Vol 02 ◽  
Author(s):  
Magnus Christoffer Skov ◽  
Steffen Enggaard Kristensen ◽  
Teis Nørgaard Mikkelsen
Keyword(s):  
Relative Humidity ◽  
Light Intensity ◽  
Uv Light ◽  
Light Exposure ◽  
Environmental Parameters ◽  
Photocatalytic Properties ◽  
Uptake Coefficient ◽  
Ambient Conditions ◽  
Natural Sunlight ◽  
Photocatalytic Effect

Background: This paper describes how environmentally relevant parameters affect titanium dioxide's photocatalytic properties (TiO2) to decompose ozone (O3). Methods: Thus, experiments have been carried out in a box chamber with TiO2 coated roofing membrane samples to determine the significance of light intensity, temperature, initial O3 concentration, and relative humidity. Furthermore, an outdoor experiment has been conducted where the roofing membrane was subjected to natural sunlight. Results: The results show a significant photocatalytic effect of TiO2. The half-life of the O3 decay curve is 5.8 min in near-ambient UV-light exposure compared with 7.1 min in dark conditions. Experiments conducted at higher light intensity show a more extensive degradation of O3, where the value of the reactive uptake coefficient increases from 0.044 to 0.051. Also, the measurements carried out under natural sunlight show a photocatalytic effect where the uptake coefficient value is 0.046. A larger photocatalytic effect is detected for the experiments conducted at 283 K and 303 K temperatures compared with experiments under standard conditions. Conclusion: Experiments carried out with a very high initial concentration of O3 show that 28.1 μg of O3 is decomposed than ambient conditions, where 2.3 μg is destroyed. This demonstrates that light intensity, temperature, ozone concentration, and relative humidity significantly impact TiO2's degradation of O3.

scholarly journals Production of HONO from NO<sub>2</sub> uptake on illuminated TiO<sub>2</sub> aerosol particles and following the illumination of mixed TiO<sub>2</sub>∕ammonium nitrate particles

2021 ◽  
Vol 21 (7) ◽  
pp. 5755-5775
Author(s):  
Joanna E. Dyson ◽  
Graham A. Boustead ◽  
Lauren T. Fleming ◽  
Mark Blitz ◽  
Daniel Stone ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Relative Humidity ◽  
Marine Boundary Layer ◽  
Separate Experiment ◽  
Photon Flux ◽  
No Production ◽  
Uptake Coefficient ◽  
Ambient Conditions ◽  
Mixing Ratios ◽  
Reactive Uptake Coefficient

Abstract. The rate of production of HONO from illuminated TiO2 aerosols in the presence of NO2 was measured using an aerosol flow tube system coupled to a photo-fragmentation laser-induced fluorescence detection apparatus. The reactive uptake coefficient of NO2 to form HONO, γNO2→HONO, was determined for NO2 mixing ratios in the range 34–400 ppb, with γNO2→HONO spanning the range (9.97 ± 3.52) × 10−6 to (1.26 ± 0.17) × 10−4 at a relative humidity of 15 ± 1 % and for a lamp photon flux of (1.63 ± 0.09) ×1016 photons cm−2 s−1 (integrated between 290 and 400 nm), which is similar to midday ambient actinic flux values. γNO2→HONO increased as a function of NO2 mixing ratio at low NO2 before peaking at (1.26 ± 0.17) ×10-4 at ∼ 51 ppb NO2 and then sharply decreasing at higher NO2 mixing ratios rather than levelling off, which would be indicative of surface saturation. The dependence of HONO production on relative humidity was also investigated, with a peak in production of HONO from TiO2 aerosol surfaces found at ∼ 25 % RH. Possible mechanisms consistent with the observed trends in both the HONO production and reactive uptake coefficient were investigated using a zero-dimensional kinetic box model. The modelling studies supported a mechanism for HONO production on the aerosol surface involving two molecules of NO2, as well as a surface HONO loss mechanism which is dependent upon NO2. In a separate experiment, significant production of HONO was observed from illumination of mixed nitrate/TiO2 aerosols in the absence of NO2. However, no production of HONO was seen from the illumination of nitrate aerosols alone. The rate of production of HONO observed from mixed nitrate/TiO2 aerosols was scaled to ambient conditions found at the Cape Verde Atmospheric Observatory (CVAO) in the remote tropical marine boundary layer. The rate of HONO production from aerosol particulate nitrate photolysis containing a photocatalyst was found to be similar to the missing HONO production rate necessary to reproduce observed concentrations of HONO at CVAO. These results provide evidence that particulate nitrate photolysis may have a significant impact on the production of HONO and hence NOx in the marine boundary layer where mixed aerosols containing nitrate and a photocatalytic species such as TiO2, as found in dust, are present.

V2O5-Photocatalyzed Oxidation of Diphenylamine

2014 ◽  
Vol 807 ◽  
pp. 81-90
Author(s):  
C. Karunakaran ◽  
S. Karuthapandian
Keyword(s):  
Kinetic Model ◽  
Light Intensity ◽  
Uv Light ◽  
Product Formation ◽  
Airflow Rate ◽  
Natural Sunlight

V2O5 catalyzes the oxidation of diphenylamine (DPA) to N-phenyl-p-benzoquinonimine (PBQ) in ethanol under UV light as well as under natural sunlight. The formation of PBQ was studied as a function of [DPA], V2O5-loading, airflow rate, light intensity, etc. Formation of PBQ is larger on illumination at 254 nm than at 365 nm and the catalyst is reusable. The mechanism of photocatalysis is discussed and the product formation analyzed using a kinetic model. ZnO and CdO enhance the V2O5-photocatalyzed formation of PBQ and the results are rationalized.

Characterization and identification of a plastic-like off-odor in mineral water

2009 ◽  
Vol 9 (3) ◽  
pp. 299-309 ◽  
Author(s):  
A. Strube ◽  
A. Buettner ◽  
Carola Groetzinger
Keyword(s):  
Carbonyl Compounds ◽  
Mineral Water ◽  
Uv Light ◽  
Light Exposure ◽  
Stir Bar Sorptive Extraction ◽  
Compound Formation ◽  
Natural Sunlight ◽  
Sorptive Extraction ◽  
Artificial Uv ◽  
First Time

A specific mineral water off-odor, the so-called “sunlight” flavor produced after UV light exposure, was characterized by sensory analysis in different mineral water samples and ranked according to overall odor intensity. The odorants were isolated by means of solvent extraction and stir bar sorptive extraction (SBSE) techniques, respectively. Analyses were performed with two-dimensional (2D) high resolution gas chromatographic (HRGC) separation and parallel mass spectrometric (MS) and olfactometric (O) detection. Additionally, analyses of off-odor-free samples exposed to natural sunlight or to “artificial” UV radiation (replicating natural sunlight) were analyzed to assess off-odor compound formation. 14 common characteristic odorants in commercial off-odor and irradiated samples were identified. These were predominantly saturated and mono or di-unsaturated carbonyl compounds, with several substances exhibiting the characteristic fatty and plastic-like odor impressions. Eight of the compounds identified were detected for the first time as off-odor “sunlight” flavor contributors to mineral water and had amongst the highest flavor dilution (FD) factors in the extracted samples.

scholarly journals Stability and ocular biodistribution of topically administered PLGA nanoparticles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sean Swetledge ◽  
Renee Carter ◽  
Rhett Stout ◽  
Carlos E. Astete ◽  
Jangwook P. Jung ◽  
...  
Keyword(s):  
Uv Light ◽  
Light Exposure ◽  
Polymeric Nanoparticles ◽  
Plga Nanoparticles ◽  
Eye Disease ◽  
Control Group ◽  
Eye Tissues ◽  
Nanoparticle Morphology ◽  
The Stability

AbstractPolymeric nanoparticles have been investigated as potential delivery systems for therapeutic compounds to address many ailments including eye disease. The stability and spatiotemporal distribution of polymeric nanoparticles in the eye are important regarding the practical applicability and efficacy of the delivery system in treating eye disease. We selected poly(lactic-co-glycolic acid) (PLGA) nanoparticles loaded with lutein, a carotenoid antioxidant associated with eye health, as our model ophthalmic nanodelivery system and evaluated its stability when suspended in various conditions involving temperature and light exposure. We also assessed the ocular biodistribution of the fluorescently labeled nanoparticle vehicle when administered topically. Lutein-loaded nanoparticles were stable in suspension when stored at 4 °C with only 26% lutein release and no significant lutein decay or changes in nanoparticle morphology. When stored at 25 °C and 37 °C, these NPs showed signs of bulk degradation, had significant lutein decay compared to 4 °C, and released over 40% lutein after 5 weeks in suspension. Lutein-loaded nanoparticles were also more resistant to photodegradation compared to free lutein when exposed to ultraviolet (UV) light, decaying approximately 5 times slower. When applied topically in vivo, Cy5-labled nanoparticles showed high uptake in exterior eye tissues including the cornea, episcleral tissue, and sclera. The choroid was the only inner eye tissue that was significantly higher than the control group. Decreased fluorescence in all exterior eye tissues and the choroid at 1 h compared to 30 min indicated rapid elimination of nanoparticles from the eye.

scholarly journals Thermal and Photocatalytic Performance of Unsaturated Polyester Resins Modified with TiO2 Nanoparticles as Panel Bodies for Vehicles

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2036
Author(s):  
Miren Blanco ◽  
Cristina Monteserín ◽  
Nerea Uranga ◽  
Estíbaliz Gómez ◽  
Estíbaliz Aranzabe ◽  
...  
Keyword(s):  
Tio2 Nanoparticles ◽  
Energy Use ◽  
Near Infrared ◽  
Uv Light ◽  
Unsaturated Polyester ◽  
Curing Kinetics ◽  
Pollutant Emissions ◽  
Transport Sector ◽  
Scanning Calorimetry ◽  
Photocatalytic Effect

The transport sector is the fastest growing contributor to climate emissions and experiences the highest growth in energy use. This study explores the use of TiO2 nanoparticles for obtaining photocatalytic nanocomposites with improved infrared reflectance properties. The nanocomposites were prepared by dispersing 0–20 wt% of TiO2 nanoparticles in an unsaturated polyester resin. The effect of TiO2 on the curing kinetics was studied by differential scanning calorimetry, showing a significant delay of the curing reactions. The thermal reflectance of the modified resins was characterized by UV-Vis-NIR spectrophotometry, measuring total solar reflectance (TSR). The TiO2 greatly increased the TSR of the resin, due to the reflectance properties of the nanoparticles and the change in color of the modified resin. These nanocomposites reflect a significant part of near-infrared radiation, which can contribute to a reduction of the use of heating, ventilation, and air conditioning. Moreover, the photocatalytic effect of the TiO2 modified nanocomposites was studied by monitoring the degradation of an organic model contaminant in an aqueous medium under UV light, and the reusability of the nanocomposites was studied with 5 cycles. The developed nanocomposites are proposed as a solution for reducing global warming and pollutant emissions.

scholarly journals Optimizing Planting Density and Impact of Panicle Types on Grain Yield and Microclimatic Response Index of Hybrid Rice (Oryza sativa L.)

2021 ◽  
Author(s):  
Guotao Yang ◽  
Xuechun Wang ◽  
Farhan Nabi ◽  
Hongni Wang ◽  
Changkun Zhao ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Light Intensity ◽  
Grain Yield ◽  
Hybrid Rice ◽  
Plant Density ◽  
Oryza Sativa L ◽  
Planting Density ◽  
Response Index ◽  
Lower Position ◽  
High Plant Density

AbstractThe architecture of rice plant represents important and complex agronomic traits, such as panicles morphology, which directly influence the microclimate of rice population and consequently grain yield. To enhance yield, modification of plant architecture to create new hybrid cultivars is considered a sustainable approach. The current study includes an investigation of yield and microclimate response index under low to high plant density of two indica hybrid rice R498 (curved panicles) and R499 (erect panicles), from 2017 to 2018. The split-plot design included planting densities of 11.9–36.2 plant/m2. The results showed that compared with R498, R499 produced a higher grain yield of 8.02–8.83 t/ha at a higher planting density of 26.5–36.2 plant/m2. The response index of light intensity and relative humidity to the planting density of R499 was higher than that of R498 at the lower position of the rice population. However, the response index of temperature to the planting density of R499 was higher at the upper position (0.2–1.4%) than at the lower position. Compared with R498, R499 at a high planting density developed lower relative humidity (78–88%) and higher light intensity (9900–15,916 lx) at the lower position of the rice population. Our finding suggests that erect panicles are highly related to grain yield microclimatic contributors under a highly dense rice population, such as light intensity utilization, humidity, and temperature. The application of erect panicle rice type provides a potential strategy for yield improvement by increasing microclimatic conditions in rice.

795 A multicenter phase II trial (SWOG S1609, cohort 51) of ipilimumab and nivolumab in metastatic or unresectable angiosarcoma: a substudy of dual anti-CTLA-4 and anti-PD-1 blockade in rare tumors (DART)

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A843-A843
Author(s):  
Michael Wagner ◽  
Megan Othus ◽  
Sandip Patel ◽  
Christopher Ryan ◽  
Ashish Sangal ◽  
...  
Keyword(s):  
Phase Ii ◽  
Immune Checkpoint ◽  
Uv Light ◽  
Light Exposure ◽  
Case Reports ◽  
Objective Response ◽  
Open Label ◽  
Primary Tumors ◽  
Multicenter Phase ◽  
Grade 3

BackgroundAngiosarcoma is a rare cancer of endothelial cells that can be aggressive and carries a high mortality. A subset of angiosarcomas are characterized by high tumor mutational burden (TMB) and UV light exposure DNA mutational signature. Isolated case reports have suggested clinical efficacy of immune checkpoint blockade in angiosarcoma; no prospective studies of immune checkpoint inhibition in angiosarcoma have been reported. We report efficacy analysis results for patients with advanced or unresectable angiosarcoma treated with ipilimumab and nivolumab as a cohort of an ongoing phase II study for rare cancers (NCT02834013).MethodsThis is a prospective, open-label, multicenter phase II clinical trial of ipilimumab (1mg/kg IV q6weeks) plus nivolumab (240mg IV q2weeks) for patients with metastatic or unresectable angiosarcoma. Primary endpoint is objective response rate as assessed by RECIST v1.1, including measurable cutaneous disease that can be followed by photography. Secondary endpoints include PFS, OS, stable disease at six months, and toxicity. A two-stage design is used with six patients in the first stage and an additional ten patients in the second stage.ResultsAt data cutoff, 16 patients with angiosarcoma were enrolled. Median age was 68 years (25-81 years). Median number of prior lines of therapy was 2 (0-5). 9 patients had cutaneous primary tumors of any cutaneous site, 7 had non-cutaneous primary tumors. ORR for all patients was 25% (4/16, table 1, figure 1). Subgroup analysis revealed that 60% (3/5) of patients with primary cutaneous tumors of the scalp or face had a confirmed objective response. 6-month PFS was 38%. 75% of patients experienced an adverse event (AE), and 25% experienced a grade 3-4 AE. 68.8% experienced an immune related AE (irAE), and 2 (12.5%) developed grade 3 or 4 irAEs. Grade 3-4 irAEs were ALT and AST increase and diarrhea. There were no grade 5 toxicities.ConclusionsThe combination of ipilimumab and nivolumab was well tolerated and had an ORR of 25% in angiosarcoma regardless of primary site, with 3 of 5 patients with cutaneous tumors of the scalp or face responding. Ipilimumab and nivolumab warrant further investigation in angiosarcoma.AcknowledgementsFunding: National Institutes of Health/National Cancer Institute grant awards CA180888, CA180819, CA180868; and in part by Bristol-Myers Squibb CompanyTrial RegistrationNCT02834013Ethics ApprovalThis study was approved by the NCI CIRB.

scholarly journals Prioritizing and Analyzing the Role of Climate and Urban Parameters in the Confirmed Cases of COVID-19 Based on Artificial Intelligence Applications

2020 ◽  
Vol 17 (10) ◽  
pp. 3730 ◽  
Author(s):  
Sina Shaffiee Haghshenas ◽  
Behrouz Pirouz ◽  
Sami Shaffiee Haghshenas ◽  
Behzad Pirouz ◽  
Patrizia Piro ◽  
...  
Keyword(s):  
Artificial Intelligence ◽  
Infectious Disease ◽  
Relative Humidity ◽  
Cost Function ◽  
Selection Process ◽  
Environmental Parameters ◽  
Pso Algorithm ◽  
Data Set ◽  
De Algorithm

Nowadays, an infectious disease outbreak is considered one of the most destructive effects in the sustainable development process. The outbreak of new coronavirus (COVID-19) as an infectious disease showed that it has undesirable social, environmental, and economic impacts, and leads to serious challenges and threats. Additionally, investigating the prioritization parameters is of vital importance to reducing the negative impacts of this global crisis. Hence, the main aim of this study is to prioritize and analyze the role of certain environmental parameters. For this purpose, four cities in Italy were selected as a case study and some notable climate parameters—such as daily average temperature, relative humidity, wind speed—and an urban parameter, population density, were considered as input data set, with confirmed cases of COVID-19 being the output dataset. In this paper, two artificial intelligence techniques, including an artificial neural network (ANN) based on particle swarm optimization (PSO) algorithm and differential evolution (DE) algorithm, were used for prioritizing climate and urban parameters. The analysis is based on the feature selection process and then the obtained results from the proposed models compared to select the best one. Finally, the difference in cost function was about 0.0001 between the performances of the two models, hence, the two methods were not different in cost function, however, ANN-PSO was found to be better, because it reached to the desired precision level in lesser iterations than ANN-DE. In addition, the priority of two variables, urban parameter, and relative humidity, were the highest to predict the confirmed cases of COVID-19.

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