Search results for "MICI"
showing 10 items of 1671 documents
Bubble formation at variously inclined nozzles
2014
Bubble formation at variously inclined submerged nozzles, fed with a continuous gas flow rate, is investigated. Results confirm previous findings, such as a substantial independence of bubble size of nozzle diameter and its dependence on the cubic root of gas flow rate at sufficiently high values of this parameter. Nozzle inclination in the range between 0 and 135° from the vertical upward orientation is found to have a negligible effect on bubble size. Observed bubble rise velocities lead to an estimation of the average liquid velocity induced by bubbles motion, leading in turn to a very simple correlation for the estimation of the liquid velocities induced by the repeated passage of bubbl…
Free surface oxygen transfer in large aspect ratio unbaffled bio-reactors, with or without draft-tube
2015
Abstract It is widely accepted that animal cell damage in aerated bioreactors is mainly related to the bursting of bubbles at the air–liquid interface. A viable alternative to sparged bioreactors may be represented by uncovered unbaffled stirred tanks, which have been recently found to be able to provide sufficient mass transfer through the deep free surface vortex which takes place under agitation conditions. As a matter of fact, if the vortex is not allowed to reach impeller blades, no bubble formation and subsequent bursting at the free-surface, along with relevant cells damage, occurs. In this work oxygen transfer performance of large aspect ratio unbaffled stirred bioreactors, either e…
Biological effects and photodegradation by TiO(2) of terpenes present in industrial wastewater.
2010
Abstract The aim of this work was to study the biological effects of four monoterpenes, i.e. α-pinene, β-pinene, 3-carene and d -limonene present in the wastewater of a citrus transformation factory. The study was carried out by exposing V79 Chinese hamster cells to single terpene or to the mixture of four terpenes at concentrations corresponding to those in the wastewater evaluated by head space solid phase micro extraction and gas chromatography (HS-SPME-GC) analyses. Treatments with single or combined terpenes similarly affected cell vitality, but only the combined treatments induced the 6-thioguanine resistant mutants. Moreover the photocatalytic degradation of the four terpenes was suc…
Spatial pattern analysis using hybrid models: an application to the Hellenic seismicity
2016
Earthquakes are one of the most destructive natural disasters and the spatial distribution of their epi- centres generally shows diverse interaction structures at different spatial scales. In this paper, we use a multi-scale point pattern model to describe the main seismicity in the Hellenic area over the last 10 years. We analyze the interaction between events and the relationship with geo- logical information of the study area, using hybrid models as proposed by Baddeley et al. ( 2013 ). In our analysis, we find two competing suitable hybrid models, one with a full parametric structure and the other one based on nonpara- metric kernel estimators for the spatial inhomogeneity.
A survey of photocatalytic materials for environmental remediation
2012
Abstract Heterogeneous photocatalysis is an advanced oxidation process which has been the subject of a huge amount of studies related to air cleaning and water purification. All these processes have been carried out mainly by using TiO 2 -based materials as the photocatalysts and ca. 75% of the articles published in the last 3 years is related to them. This review illustrates the efforts in the search of alternative photocatalysts that are not based on TiO 2 , with some exceptions concerning particularly innovative modifications as nanoassembled TiO 2 or TiO 2 composites with active carbon, graphite and fullerene. Papers reporting preparation, characterization and testing of binary, ternary…
Sequential biological and photocatalysis based treatments for shipboard slop purification: A pilot plant investigation
2019
This study investigated the treatment of a shipboard slop containing commercial gasoline in a pilot plant scale consisting of a membrane biological reactor (MBR) and photocatalytic reactor (PCR) acting in series. The MBR contributed for approximately 70% to the overall slop purification. More precisely, the biological process was able to remove approximately 40%, on average, of the organic pollution in the slop. Nevertheless, the membrane was capable to retain a large amount of organic molecules within the system, amounting for a further 30% of the influent total organic content removal. However, this affected the membrane fouling, thus resulting in the increase of the pore blocking mechani…
Photocatalytic activity of TiO2/SiO2 systems
2009
Silica-supported TiO(2) powders were synthesized by a wet method under mild conditions. The aim of the work was the preparation of TiO(2)/SiO(2) additives for photocatalytic cements. Three types of commercial SiO(2) were used as supports: Cabot, Axim and Fly Ash. Cabot silica was ultra-pure whereas the other two silica contained different percentages of various oxides. The TiO(2)/SiO(2) samples, denoted TiO(2)/Cabot, TiO(2)/Axim and TiO(2)/Fly Ash, were prepared by boiling suspensions obtained by addition of silica to a solution of TiCl(4) in water (volume ratio 1:10). The photocatalytic activity was evaluated in a gas-solid system both in batch and in continuous reactors using 2-propanol a…
Experimental P-T-ro Measurements of Supercritical Mixtures of Carbon Dioxide, Carbon Monoxide, and Hydrogen and Semiquantitative Estimation of Their …
2007
The P-T-ρ behavior of the CO2-CO-H2 system was studied in the supercritical region under operative conditions close to those adopted to perform hydrogenation and hydroformylation reactions in dense CO 2, thus providing new interesting information on this fluid mixture. Experiments were performed in a fixed volume reactor in the temperature range from 298 K to 343 K changing the density and the composition of the fluid phase. The one-component (Hildebrand) solubility parameter of the mixture was estimated from experimentally measured P vs T profiles, and its dependence on the density and composition of the system was analyzed to study the antisolvent effect of the permanent gases. We have fo…
Photochemical and photocatalytic isomerization of trans -caffeic acid and cyclization of cis -caffeic acid to esculetin
2016
Abstract The photoisomerization of trans-caffeic acid to cis-caffeic acid has been studied in the presence of N2 in homogeneous aqueous solutions and in suspensions of various TiO2 catalysts. The results supported the hypothesis of an energy transfer process from TiO2 to the substrate due to the recombination of the photogenerated electron–hole pairs. The differences among the measured photostationary [cis]/[trans] ratios have been attributed to the different physico-chemical properties of the catalysts. In particular, the lowest ratio measured in the presence of Merck TiO2 was ascribed to the very low adsorption of trans-caffeic acid onto the surface of this sample. In the presence of O2 a…
Attività catalitica e fotocatalitica di eteropoliacidi Wells-Dawson e Keggin per la disidratazione del 2-propanolo in regime gas-solido
2016
Tra i più studiati poliossometallati (nanoagglomerati di ossigeno con metalli transizionali), figurano gli eteropoliacidi (EPA) che sono degli acidi inorganici forti con ben defin ite strutture molecolari. In funzione della loro geometria, essi vengono classificati come Keggin e Wells-Dawson. Gli (EPA) sono usati in catalisi omogenea ed eterogenea e funzionano anche come fotocatalizzatori, essenzialmente in sistemi omogenei. Questi materiali sono, inoltre, economici e non tossici.