Search results for "DIOXIDE"
showing 10 items of 1250 documents
Hydrothermal growth mechanism of SnO2 nanorods in aqueous HCl
2018
Abstract Rutile-type nanorods of SnO2 were obtained in a one-pot hydrothermal synthesis starting from SnCl4·5H2O and HCl in a temperature range between 200 and 240°C. Although the nanorods are polydisperse, the average length of the nanorods could be adjusted from 13 to 65 nm by varying of the reaction temperature. The resulting anisotropic nanocrystals were characterized using powder X-ray diffraction (PXRD), (high resolution-) transmission electron microscopy (HR-TEM), and selected area electron diffraction (SAED). The particle growth proceeds via a dissolution-recrystallization process with soluble [SnCl5(H2O)]− intermediates, as confirmed by PXRD, Raman spectroscopy, and magic angle spi…
Photocatalytic Oxidation of Cyanides in Aqueous Titanium Dioxide Suspensions
1997
The photocatalytic oxidation of free cyanides in aqueous suspensions containing polycrystalline TiO2(anatase) powders irradiated in the near-UV region has been investigated. The rate of cyanide photooxidation has been studied by varying the following operative parameters: (i) initial cyanide concentration; (ii) catalyst concentration; (iii) initial pH; (iv) power of irradiation; and (v) chloride ion concentration in the reacting mixture. Under the used experimental conditions the photoreaction proceeded at a measurable rate until the complete disappearance of cyanides. The kinetics of cyanide photooxidation is affected by the catalyst concentration, the chloride ion concentration, and the p…
Effect of temperature on the growth of alfa-PbO2 nanostructures
2010
Abstract Ordered arrays of α-PbO 2 nanostructures were grown by galvanostatic anodic deposition into the channels of alumina templates. Electrodepositions were performed in an aqueous solution containing lead acetate and sodium acetate at pH 5.4. Bath temperature and electrodeposition time were varied to check their effect on the growth of nanostructures. It has been found that filling of alumina pores is independent of the time and electrodeposition temperature, whilst height and growth kinetics of nanostructures vary with both parameters. Temperature greatly influences morphology: wires grown at room temperature consisted of clusters of particles, leading to poorly compact structures, whi…
Removal of drugs in aqueous systens by photoassisted degradation
2005
Aqueous solutions of tetracycline, lincomycin and ranitidine were irradiated with UV light in homogeneous and heterogeneous systems. Two commercial polycrystalline TiO2 powders (Degussa P25 and Merck) were used as photocatalysts. After 5A h, an appreciable photolytic degradation of tetracycline and ranitidine was observed while the degradation of lincomycin was noticeably lower. As far as the mineralization is concerned, a small decrease of the TOC values was measured in the case of tetracycline whereas negligible variations were found for lincomycin or ranitidine. The presence of the photocatalysts greatly enhanced the degradation rates of the drugs with respect to those observed during th…
Reaction pathways of glucose oxidation by ozone under acidic conditions.
2009
The ozonation of d-glucose-1-(13)C, 2-(13)C, and 6-(13)C was carried out at pH 2.5 in a semi-batch reactor at room temperature. The products present in the liquid phase were analyzed by GC-MS, HPAEC-PAD, and (13)C NMR spectroscopy. Common oxidation products of glucose have also been submitted to identical ozonation conditions. For the first time, a pentaric acid was identified and its formation quantitatively correlated to the loss of C-6 of glucose in the form of carbon dioxide. Potential mechanisms for the formation of this pentaric acid are discussed. The well-accepted pathway involving the anomeric position in glucose, gluconic acid, arabinose, and carbon dioxide is reinvestigated. The …
Superficial defects induced by argon and oxygen bombardments on (110) TiO2 surfaces
1998
Abstract Compositional and chemical changes of titanium dioxide monocrystalline surfaces induced by bombardment with 4 keV argon and oxygen ions have been studied by AES, XPS and AFM. Argon ion bombardment induced strong changes in the composition and chemical state of the surface: loss of oxygen due to preferential sputtering occurred, and, related to this, Ti4+ species were reduced to Ti3+ and Ti2+. During oxygen bombardment, competition between preferential sputtering of oxygen ions of the oxide surface and oxygen implantation was observed. This phenomenon was found to be strongly dependent upon the incidence angle of the oxygen ions. Moreover, an oxygen bombardment with normal incidence…
Development of Eco-Friendly and Self-Cleaning Lime-Pozzolan Plasters for Bio-Construction and Cultural Heritage
2020
Summarization: Nowadays, the design and use of multi-functional mortars has increased significantly, with interesting applications in the green building and cultural heritage conservation sectors. A key point for a correct adoption of these innovative materials is their behavior along time and their resistance to the weathering. The objective of this project was to define the performance and durability of innovative mortars, in order to use them correctly and to avoid irreparable damage over time. For the development of this project, lime–metakaolin and hydraulic lime–metakaolin based mortars (hereinafter called A, B), as well as A and B with the addition of nano-TiO2 and perlite (hereinaft…
Artificial ventilation for basic life support leads to hyperventilation in first aid providers.
2003
The 'Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care - International Consensus on Science' recommend an artificial ventilation volume of 10 ml/kg bodyweight (equivalent to a tidal volume of 700-1000 ml) without the use of supplemental oxygen in adults with respiratory arrest. For first aid providers using the mouth-to-mouth or mouth-to-nose-ventilation technique, respectively, a ventilation volume of approximately 9.6 l/min results. Additionally, a deep breath is recommended before each ventilation to increase the end-expiratory oxygen concentration of the air exhaled by the first aid provider. To investigate the effects of these recommendations in health…
CO2 and H2S concentrations in the atmosphere at the Solfatara of Pozzuoli
1984
The CO2 and H2S concentration in the Solfatara atmosphere has been measured. The concentrations of both gases are higher neraby the more active areas and decrease away from them. A sharp horizontal and vertical gradient of the CO2 content has been recognized.
The Effect of the Covid-19 Lockdown on Air Quality in Three Italian Medium-Sized Cities
2020
Despite the societal and economic impacts of the COVID-19 pandemic, the lockdown measures put in place by the Italian government provided an unprecedented opportunity to increase our knowledge of the effect transportation and industry-related emissions have on the air quality in our cities. This study assessed the effect of reduced emissions during the lockdown period, due to COVID-19, on air quality in three Italian cities, Florence, Pisa, and Lucca. For this study, we compared the concentration of particulate matter PM10, PM2.5, NO2, and O3 measured during the lockdown period, with values obtained in the same period of 2019. Our results show no evidence of a direct relationship between th…