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Artykuły w czasopismach na temat "Photocatalytic oxidation process"
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Witkowski, Hubert, Wioletta Jackiewicz-Rek, Janusz Jarosławski, Karol Chilmon i Artur Szkop. "Ozone Formation during Photocatalytic Oxidation of Nitric Oxides under UV Irradiation with the Use of Commercial TiO2 Photocatalytic Powders". Materials 15, nr 17 (26.08.2022): 5905. http://dx.doi.org/10.3390/ma15175905.
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The application of photocatalytic materials has been intensively researched in recent decades. The process of nitric oxide (NO) oxidation during photocatalysis has been observed to result in the formation of nitric dioxide (NO2). This is a significant factor of the photocatalysis process, as NO2 is more toxic than NO. However, it has been reported that ozone (O3) is also formed during the photocatalytic reaction. This study analyzed the formation and oxidationof O3 during the photocatalytic oxidation of NO under ultraviolet irradiation using commercial photocatalytic powders: AEROXIDE® TiO2 P25 by Evonik, KRONOClean® 7050 by KRONOS®, and KRONOClean® 7000 by KRONOS®. An NO concentration of 100 ppb was assumed in laboratory tests based on the average nitric oxide concentrations recorded by the monitoring station in Warsaw. A mix flow-type reactor was applied in the study, and the appropriateness of its application was verified using a numerical model. The developed model assumed an empty reactor without a photocatalytic material, as well as a reactor with a photocatalytic material at its bottom to verify the gas flow in the chamber. The analysis of the air purification performance of photocatalytic powders indicated a significant reduction of NO and NOx and typical NO2 formation. However, no significant formation of O3 was observed. This observation was verified by the oxidation of pure ozone in the process of photocatalysis. The results indicated the oxidation of ozone concentration during the photocatalytic reaction, but self-decomposition of a significant amount of the gas.
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Khuzwayo, Z., i E. M. N. Chirwa. "Evaluation of flow-rate dynamics in the simultaneous photocatalytic treatment of multichlorinated substituted phenols in continuous-flow systems". Water Science and Technology 74, nr 9 (30.08.2016): 2211–24. http://dx.doi.org/10.2166/wst.2016.411.
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The project investigated the simultaneous degradation of chlorophenols dissolved in aqueous systems. The photocatalysis advanced oxidation process was the technology applied to achieve treatment. Chemical behavioural tracking was performed using the chloride dehalogenation sequence dynamics. The study recorded reductive dehalogenation chemical transformation kinetics of multi-substituted chlorinated phenolics in continuous flow reactor systems. This was performed by manipulation of liquid flow-rates in the photocatalytic oxidations process using suspended and immobilised catalyst applications. A modified Langmuir-Hinshelwood kinetic model was proposed that explained the oxidation transformational behaviour of the dehalogenation process derived intermediates. Complementary photocatalytic performance matrices were established for each flow regime; model parameters were calculated and estimated for behavioural profiles of all compounds under scrutiny.
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Kuliesiene, Neringa, Sandra Sakalauskaite, Simona Tuckute, Marius Urbonavicius, Sarunas Varnagiris, Rimantas Daugelavicius i Martynas Lelis. "TiO2 Application for the Photocatalytical Inactivation of S. enterica, E. coli and M. luteus Bacteria Mixtures". Environmental and Climate Technologies 24, nr 3 (1.11.2020): 418–29. http://dx.doi.org/10.2478/rtuect-2020-0113.
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Abstract Water contamination by various bacteria, viruses and other pathogens is a great threat to human health. Amongst other Advanced Oxidation Processes TiO2 photocatalysis is considered as one of the most efficient treatment for the polluted wastewater disinfection. Usually, the wastewater produced by higher risk objects, such as hospitals, implicates diverse contaminants, but efficiency of most of the Advanced Oxidation Processes is tested by using only single pathogens and information on inactivation of bacteria mixtures is still limited. In this study, photocatalytical inactivation of three commonly found bacterial pathogens (gram-positive (Micrococcus luteus) and gram-negative (Salmonella enterica, Escherichia coli)) was investigated. Efficiency of traditional photocatalytic disinfection process using single bacterial pathogens was compared to the one observed for their mixtures. The impact of photocatalytical process parameters and treatment time on bacteria disinfection efficiency was studied. Photocatalytic disinfection efficiency testing with bacteria mixtures revealed, that in the presence of TiO2 photocatalyst and UV irradiation tested gram-positive cells were inactivated slower than gram-negative cells. Another important finding was that an overall photocatalytic disinfection efficiency of bacteria mixtures is not a straight forward sum of inactivation rates of individually tested pathogens but has a strong relationship to the properties of their competitive growth.
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Kuliesiene, Neringa, Sandra Sakalauskaite, Simona Tuckute, Marius Urbonavicius, Sarunas Varnagiris, Rimantas Daugelavicius i Martynas Lelis. "TiO2 Application for the Photocatalytical Inactivation of S. enterica, E. coli and M. luteus Bacteria Mixtures". Environmental and Climate Technologies 24, nr 3 (1.11.2020): 418–29. http://dx.doi.org/10.2478/rtuect-2020-0113.
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AbstractWater contamination by various bacteria, viruses and other pathogens is a great threat to human health. Amongst other Advanced Oxidation Processes TiO2 photocatalysis is considered as one of the most efficient treatment for the polluted wastewater disinfection. Usually, the wastewater produced by higher risk objects, such as hospitals, implicates diverse contaminants, but efficiency of most of the Advanced Oxidation Processes is tested by using only single pathogens and information on inactivation of bacteria mixtures is still limited. In this study, photocatalytical inactivation of three commonly found bacterial pathogens (gram-positive (Micrococcus luteus) and gram-negative (Salmonella enterica, Escherichia coli)) was investigated. Efficiency of traditional photocatalytic disinfection process using single bacterial pathogens was compared to the one observed for their mixtures. The impact of photocatalytical process parameters and treatment time on bacteria disinfection efficiency was studied. Photocatalytic disinfection efficiency testing with bacteria mixtures revealed, that in the presence of TiO2 photocatalyst and UV irradiation tested gram-positive cells were inactivated slower than gram-negative cells. Another important finding was that an overall photocatalytic disinfection efficiency of bacteria mixtures is not a straight forward sum of inactivation rates of individually tested pathogens but has a strong relationship to the properties of their competitive growth.
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Tytgat, Tom, Birger Hauchecorne, Artem M. Abakumov, Marianne Smits, Sammy W. Verbruggen i Silvia Lenaerts. "Photocatalytic process optimisation for ethylene oxidation". Chemical Engineering Journal 209 (październik 2012): 494–500. http://dx.doi.org/10.1016/j.cej.2012.08.032.
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Nikolenko, Anastasiya, i Boris Melnykov. "Photocatalytic Oxidation of Formaldehyde Vapour Using Amorphous Titanium Dioxide". Chemistry & Chemical Technology 4, nr 4 (15.12.2010): 311–15. http://dx.doi.org/10.23939/chcht04.04.311.
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The gas-phase photocatalytic oxidation of formaldehyde over illuminated amorphous titanium dioxide was investigated using a model flow reactor with the following experimental conditions: 0.1–0.5 l/min flow rate and an organic compound concentration range of 0.006–0.082 mol/m3. Mathematical model of the process which includes two sequential stages: formation of formic acid and its subsequent oxidation to CO2 was offered. It was found that when the amount of TiO2 on carrying agent (anodized titanium) is 3.6 mg/cm2, the intensity of UV lamp is 18 W and the catalyst temperature is 293 K, values of observed rate constants are equal to 6.5.10−3 s−1 for the first stage and 1.10−2 s−1 for the second stage of oxidation. The apparent activation energy of photocatalytic oxidation process of formaldehyde vapour for temperature interval 293 – 323 K is 20.2 kJ/mol.
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Quan, Yu Lian, Bi Qing Shi, Li Jing Yang i Ren Zhi Zhang. "Pretreatment of Seawater by PAC/PAM Coagulation-Photocatalytic Oxidation Process". Advanced Materials Research 779-780 (wrzesień 2013): 1518–21. http://dx.doi.org/10.4028/www.scientific.net/amr.779-780.1518.
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Coagulation-photocatalytic oxidation process was used for pretreatment of simulated seawater, which had moderate turbidity and more organics. The optimal conditions of PAC/PAM coagulation and TiO2 photocatalytic oxidation were investigated by simple variable method, coagulation and photocatalytic oxidation were combinated under optimal conditions finally. Results showed that when the dosage of polyacrylamide (PAM) and polyaluminium chloride (PAC) was 20mg/L and 0.5 mg/L respectively, the pH of simulated seawater was 8.0, the amount of TiO2 photocatalyst was 1.8g/L and UV radiation time was 1h, the removal ratio of the turbidity and CODMn in simulated seawater was 97.5% and 72% respectively. Synergistic effect between coagulation and photocatalytic oxidation eventually made turbidity and organics in the effluent water meet the requirements of reverse osmosis system.
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Coronel, Stalin, Diana Endara, Ana Belén Lozada, Lucía E. Manangón-Perugachi i Ernesto de la Torre. "Photocatalytic Study of Cyanide Oxidation Using Titanium Dioxide (TiO2)-Activated Carbon Composites in a Continuous Flow Photo-Reactor". Catalysts 11, nr 8 (30.07.2021): 924. http://dx.doi.org/10.3390/catal11080924.
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The photocatalytic oxidation of cyanide by titanium dioxide (TiO2) supported on activated carbon (AC) was evaluated in a continuous flow UV photo-reactor. The continuous photo-reactor was made of glass and covered with a wood box to isolate the fluid of external conditions. The TiO2-AC synthesized by the impregnation of TiO2 on granular AC composites was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), Scanning Electron Microscopy (SEM), and nitrogen adsorption-desorption isotherms. Photocatalytic and adsorption tests were conducted separately and simultaneously. The results showed that 97% of CN− was degraded within 24 h due to combined photocatalytic oxidation and adsorption. To estimate the contribution of only adsorption, two-stage tests were performed. First, 74% cyanide ion degradation was reached in 24 h under dark conditions. This result was attributed to CN− adsorption and oxidation due to the generation of H2O2 on the surface of AC. Then, 99% degradation of cyanide ion was obtained through photocatalysis during 24 h. These results showed that photocatalysis and the continuous photo-reactor’s design enhanced the photocatalytic cyanide oxidation performance compared to an agitated batch system. Therefore, the use of TiO2-AC composites in a continuous flow photo-reactor is a promising process for the photocatalytic degradation of cyanide in aqueous solutions.
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Shi, Laishun, Xiaomei Wang, Na Li, Chunlei Huai i Jie Liu. "UV Irradiation Chlorine Dioxide Photocatalytic Oxidation of Simulated Fuchsine Wastewater by UV-Vis and Online FTIR Spectrophotometric Method". ISRN Analytical Chemistry 2012 (11.04.2012): 1–7. http://dx.doi.org/10.5402/2012/951465.
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The photocatalyst TiO2/SiO2 was prepared and used for chlorine dioxide photocatalytic oxidation of simulated fuchsine wastewater under UV irradiation. The removal efficiency of fuchsine treated by photocatalytic oxidation process is higher than that of chemical oxidation process. By using UV-Vis and online FTIR analysis technique, the intermediates during the degradation process were obtained. The benzene ring in fuchsine was degraded into quinone and carboxylic acid and finally changed into carbon dioxide and water during the photocatalytic oxidation. The degradation reaction mechanism of fuchsine by UV irradiation chlorine dioxide photocatalytic oxidation was proposed based upon the experiment evidence.
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Lu, Ming-Chun, i Jong-Nan Chen. "Pretreatment of pesticide wastewater by photocatalytic oxidation". Water Science and Technology 36, nr 2-3 (1.07.1997): 117–22. http://dx.doi.org/10.2166/wst.1997.0497.
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The toxic chemicals, 2,4-D (a herbicide) and propoxur (an insecticide), were used as the model compounds in these experiments. Total organic carbon analyzer was used to assess the efficiency of photocatalytic mineralization. Microtox bioassay was employed in evaluating the toxicity of solutions treated by photocatalysis. Ultraviolet absorption spectra were also used for showing the different characteristics of the compounds undergoing photocatalytic oxidation. Results show that propoxur is less degradable than 2,4-D, and the photomineralization of these pesticides follows a behavior of first-order reaction. Products of 2,4-D and propoxur are more toxic than the parent compound after partial photodegradation. This shows that complete mineralization is necessary for total detoxification of these pesticides. In other words, toxicity is an important criteria in assessing the pretreatment process.
Rozprawy doktorskie na temat "Photocatalytic oxidation process"
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Harianto, Rina. "Design of a Novel Thin Film Reactor for Photocatalytic Water Treatment Process". Miami University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=miami1604335732713241.
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GHOSH, MONOJ. "Fabrication of Inorganic Oxide Nanofibers Using Gas Jet Fiber Spinning Process and Their Applications in Photocatalytic Oxidation". University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1478726324293037.
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Fendrich, Murilo Alexandre. "Solar concentration for the environment industry: photocatalytic materials and application technologies". Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/285695.
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This thesis presents the achievements pursued during the doctoral course. The work was carried out in the context of the project ERiCSol (Energia RInnovabile e Combustili SOLari), as part of the University of Trento strategic plan for the years 2017-2021. The project was conceived to establish an interdepartmental area to promote the challenge of developing scientific research and technological innovation to increase the competitiveness of Trento at national and international level in the areas of energy and environment. Among all the goals of the project, this work dedicates special attention to 1) development of novel materials for solar photocatalytic reactions and 2) use of renewable energy to push forward applications in water remediation. To accomplish these goals, the research brings a full collection of experimental activities regarding the employment of solar concentration for the environment industry and therefore this document is organized in 9 chapters. In chapter 1, it is presented the introduction outlining the overview of the environment industry, the employment of solar light as energy source and the general and specific objectives.
Chapter 2 presents a literature review regarding the last 30 years of applications correlating the use of solar light towards wastewater purification. The chapter reviews the engineering features of solar collectors, photocatalyst materials employed and the panorama of the pollutants investigated up to the present date in solar photocatalysis, presenting comparisons between models and real wastewater approaches. Chapter 3 details the experimental techniques and characterizations employed to sustain the investigation proposed in the thesis. The first part of the chapter explains the features of parabolic dish solar concentrator designed and manufactured by the IdEA group at the physics department of the university of Trento. After, it is presented the pulsed laser deposition, a thin films fabrication technique employed to produce the photocatalysts used on water purification experiments. The second part of the chapter presents the description of the characterization techniques used to reveal the fabricated photocatalyst materials properties. Based on the review on the fundamentals of solar photocatalysis and the experimental techniques, chapters 4 and 5 present a discussion in the field of novel photocatalytic materials capable to operate under concentrated sunlight irradiation. Chapter 4 in special presents the investigation regarding the fabrication of tungsten trioxide (WO3) thin film coatings, bringing the novelty of using pulsed laser deposition as the fabrication method and the evaluation of this material in photocatalysis for the degradation of methylene blue dye model pollutant. Chapter 5 instead, presents the development on Zinc Oxide (ZnO) nanoparticles, bringing an innovative point of view on a “green-synthesis” approach and the material immobilization in film for heterogeneous photocatalysis routes. Chapters 6 and 7 discuss solar photocatalysis aiming to shift applications from model pollutants to real wastewater remediation conditions. Important comparisons are performed and discussed regarding the advantages and existing drawbacks. To fulfill this purpose, chapter 6 presents an application case of solar photocatalysis to the degradation of a surfactant-rich industrial wastewater whereas chapter 7 presents the approach focused on the remediation of organic lead contaminants present on a local water well site in the city of Trento. The last experimental approach of concentrated solar light is presented on chapter 8, dedicated to the application of concentrated sunlight towards waste biomass valorization. Conversely to the application on water previously described, this chapter presents the activity on designing, fabricating and coupling a hydrothermal reactor with concentrated sunlight using it as the driving force to promote degradation of grape seeds evolving into hydrochars with possible valorization of the carbonized material. Lastly, chapter 9 presents the conclusions and suggestions, this item expresses the final considerations on the results of the experimental investigations, advantages and limitations observed, and suggests possible actions for future works.
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Tokode, Oluwatosin. "Photocatalytic destruction of volatile organic compounds from the oil and gas industry". Thesis, Robert Gordon University, 2014. http://hdl.handle.net/10059/1134.
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Heterogeneous photocatalysis is an advanced oxidation technology widely applied in environmental remediation processes. It is a relatively safe and affordable technology with a low impact on the environment and has found applications in a number of fields from chemical engineering, construction and microbiology to medicine. It is not catalysis in the real sense of the word as the photons which initiate the desired photocatalytic reaction are consumed in the process. The cost of these photons is by far the limiting economic factor in its application. From a technical standpoint, the inefficient use of the aforementioned photons during the photocatalytic reaction is responsible for the limited adoption of its application in industry. This inefficiency is characterised by low quantum yields or photonic efficiencies during its application. The mechanism of the technique of controlled periodic illumination which was previously proposed as a way of enhancing the low photonic efficiency of TiO2 photocatalysis has been investigated using a novel controlled experimental approach; the results showed no advantage of periodic illumination over continuous illumination at equivalent photon flux. When the technique of controlled periodic illumination is applied in a photocatalytic reaction where attraction between substrate molecules and catalyst surface is maximum and photo-oxidation by surface-trapped holes, {TiIVOH•}+ ads is predominant, photonic efficiency is significantly improved. For immobilized reactors which usually have a lower illuminated surface area per unit volume compared to suspended catalyst and mass transfer limitations, the photonic efficiency is even lower. A novel photocatalytic impeller reactor was designed to investigate photonic efficiency in gas–solid photocatalysis of aromatic volatile organic compounds. The results indicate photonic efficiency is a function of mass transfer and catalyst deactivation rate. The development of future reactors which can optimise the use of photons and maximize photonic efficiency is important for the widespread adoption of heterogeneous photocatalysis by industry.
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Rincon, Guillermo J. "Photocatalytic Mineralization of Phenol on Fluidized Titanium Oxide-Coated Silica Gel". ScholarWorks@UNO, 2015. http://scholarworks.uno.edu/td/2009.
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A bench-scale tubular reactor with recirculation was built in order to study the efficiency of the photocatalytic oxidation of phenol on fluidized titanium oxide-coated silica gel beads. A UV-C lamp placed along the central vertical axes of the reactor was used as source of photons. A bed of silica gel beads was fluidized by means of fluid recirculation and forced to follow upward helical flow around the lamp. Anatase was successfully synthetized on silica gel particles of average diameters 224, 357 and 461 µm, as confirmed by scanning electron micrographs, through a sol-gel technique using a titanium (iv)isopropoxide / hydrochloric acid / ethanol precursor.
Data was obtained from multiple 8-hours photocatalytic experiments using a determined mass of beads fluidized in an aqueous solution of known initial phenol concentration. Contaminant degradation with irradiation time was measured as COD. Beads that had been subjected to three consecutive coating procedures produced an 8-h removal efficiency 10% higher than beads with a single coat. 20 g L-1 of silica beads was found to be the optimum load for the experimental reactor configuration regardless of beads size, although efficiency increased with decreasing size of the latter.
Experimental results confirmed that the efficiency of phenol photocatalytic degradation decreases with increasing pollutant concentration. Also, the highest removal was achieved with initial pH 3, and it decreased with increasing pH. When NaCl was added to the solution, COD removal increased with increasing salinity. Additionally, it was found that dissolved oxygen is indispensable for photocatalysis to proceed, and that saturation of the treated mixture with oxygen was effectively achieved by keeping the liquid surface in contact with pure oxygen at 1 atm.
Finally, statistical analysis of the data showed that photocatalytic mineralization of phenol-derived COD under the experimental conditions follows exponential decay. Based on this finding, a correlation model was proposed for the accurate prediction (minimum R2 = 0.9840) of the COD removal efficiency of the reactor for any given initial COD.
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Tapia, Tlatelpa Tecilli. "Optoelectronic optimization of photocatalytic processes for wastewater treatment". Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/667685.
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Water pollution is an alarming problem that endangers the health of all living beings. The textile industry is listed as one of the most contaminating industries, since in order to carry out its dyeing and finishing processes, it requires a large amount of water resources; by decades, this industry has used Advanced Oxidation Processes (AOPs), since they have several advantages (e. g. destruction of toxic substances, reduction of heavy metals, allowing their use in conjunction with other processes, among others). Among the AOPs, heterogeneous photocatalysis stands out for its high efficiency for the removal of contaminants, including azo dyes.
In order to perform a photocatalytic process, it is necessary to have a photoreactor, which will require a photocatalyst and at least one light source that activates the catalyst. This type of photoreactors can present several problems, such as the use of high cost photocatalysts, the generation of toxic byproducts in some low photocatalysts, the high electrical consumption caused by the use of traditional lighting sources and even difficulties with the geometry of the photoreactors.
Hence the scientific community has tried to optimize the photocatalytic processes, some scientists have worked in the generation of new photocatalysts to be able to use them in wavelengths generated by low cost lighting sources (e. g. visible light), nevertheless, which in many times it increases the price of the photocatalyst. Another approach is to reduce electricity consumption by opting for the replacement of traditional lamps with low consumption lighting, for example, LED lighting; However, this substitution is currently done arbitrarily, so sometimes some authors doubt the ability to use these sources in this type of process. Moreover, when trying to improve the lighting sources, the photoreactor can be altered, so it is important to take into account its characteristics in order to achieve a significant improvement.
This thesis focuses on an optoelectronic optimization to improve the efficiency of the lighting sources used in photocatalytic reactors. For this, a methodology has been generated to calculate LED arrays using uniform irradiance models, this irradiance must be homogeneous, with enough energy to photoactivate the catalyst with the aim to replace the traditional lamps, avoiding the chemical alteration of the photocatalysts; Likewise, a photocatalytic reactor has been designed and implemented on a laboratory scale with ultraviolet illumination adjusted to its characteristics (i.e. geometry, dimensions, among others) to work with a low cost photocatalyst (TiO2) in the decolorization of wastewater with textile dyes. Finally, in-situ monitoring has been designed and implemented in order to analyze the decolorization of textile water, this type of monitoring avoids the collection of water samples during the process, without altering the geometry of the reactor or reducing the volume of treated water in the reactor.La contaminación del agua es un problema alarmante que pone en peligro la salud de todos los seres vivos. La industria textil está catalogada como una de las industrias más contaminantes, puesto que para realizar sus procesos de teñido y acabado requieren de una gran cantidad de recursos hídricos; desde hace décadas esta industria ha usado los Procesos de Oxidación Avanzada (AOPs) al presentar diversas ventajas (e. g. destrucción de sustancias tóxicas, reducción de metales pesados, permitir su uso en conjunto con otros procesos, entre otros). Entre los AOPs, sobresale la fotocatálisis heterogénea, por su alta eficiencia para la remoción de contaminantes, incluidos los colorantes azoicos. Para realizar un proceso fotocatalítico, es necesario tener un fotorreactor, el cual requerirá de un fotocatalizador y al menos una fuente de iluminación que active el catalizador. Este tipo de fotorreactores pueden presentar diversos problemas, tales como, el uso fotocatalizadores de alto costo, la generación de subproductos tóxicos en algunos fotocatalizadores de bajo, el alto consumo eléctrico causado por la utilización de fuentes tradicionales de iluminación e incluso dificultades con la geometría de los fotorreactores. Por lo tanto la comunidad científica ha intentado optimizar los procesos fotocatalíticos, algunos científicos han trabajado en la generación de nuevos fotocatalizadores para poder utilizarlos en longitudes de onda generada por fuentes de iluminación de bajo coste (e. g. luz visible), no obstante, lo que en muchas ocasiones incrementa el precio del fotocatalizador. Otro enfoque se encuentra en la reducción del consumo eléctrico optando por la sustitución de las lámparas tradicionales por iluminación de bajo consumo, por ejemplo, iluminación LED; sin embargo, actualmente esta sustitución se realiza de manera arbitraria, por lo que en ocasiones algunos autores dudan de la capacidad de utilizar estas fuentes en este tipo de procesos. Además al intentar mejorar las fuentes de iluminación puede alterarse el fotorreactor, por lo que es importante tomar en consideración sus características para lograr una mejora significativa. Esta tesis se enfoca en una optimización optoelectrónica para mejorar la eficiencia de las fuentes de iluminación utilizadas en reactores fotocatalíticos. Para ello se ha generado una metodología para calcular arreglos de LEDs utilizando modelos de irradiancia uniforme, esta irradiancia debe ser homogénea, con energía suficiente para fotoactivar el catalizador y sustituir las lámparas tradicionales, evitando la alteración química de los fotocatalizadores; asimismo, se ha diseñado e implementado un reactor fotocatalítico a escala de laboratorio con iluminación ultravioleta ajustada a sus características (geometría, dimensiones, entre otros) para trabajar con un fotocatalizador de bajo coste (TiO2) en la decoloración de agua con colorantes textiles. Para finalizar se ha diseñado e implementado un sistema de monitorización in-situ para la decoloración de aguas teñidas, este tipo de monitorización evita la toma de muestras de durante el proceso, sin alterar la geometría del reactor ni disminuir el volumen de agua tratada del reactor.
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Jiang, Dianlu, i n/a. "Studies of Photocatalytic Processes at Nanoporous TiO2 Film Electrodes by Photoelectrochemical Techniques and Development of a Novel Methodology for Rapid Determination of Chemical Oxygen Demand". Griffith University. School of Environmental and Applied Science, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20040723.155003.
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In this work, a series of simple, rapid and effective photoelectrochemical methodologies have been developed and successfully applied to the study of kinetic and thermodynamic characteristics of photocatalytic oxidation processes at TiO2 nanoparticulate films. As an application of the systematic studies of photocatalytic processes by photoelectrochemical techniques, a rapid, direct, absolute, environmental-friendly and accurate COD analysis method was successfully developed. In this work, the TiO2 nanoparticles colloid was prepared by the sol-gel method. The TiO2 nanoparticles were immobilized onto ITO conducting glass slides by dip-coating method. Thermal treatment was carried out to obtain nanoporous TiO2 films of different structures. At low calcination temperature (below 600°C), nanoporous TiO2 films of pure anatase phase were prepared. At high calcination temperature (above 600°C), nanoporous TiO2 films of mixed anatase and rutile phases were obtained. At these film electrodes, the work was carried out. By employing steady state photocurrent method and choosing phthalic acid as the model compound, the photocatalytic activity of the TiO2 nanoporous films calcined at various temperatures and for different lengths of time was evaluated. It was found that the films with mixed anatase and rutile phases calcined at high temperature exhibited high photocatalytic activity. Based on semiconductor band theory, a model was proposed, which explained well this finding. By employing linear sweep voltammetry (under illumination) and choosing glucose (an effective photohole scavenger) as a model compound, the characteristics of the photocatalytic processes at nanoparticulate semiconductor electrodes were investigated. Characteristics of the nanoporous semiconductor electrodes markedly different from bulk semiconductor electrodes were observed. That is, within a large range of electrode potentials above the flat band potential the electrodes behaved as a pure resistance instead of exhibiting variable resistance expected for bulk semiconductor electrodes. The magnitude of the resistance was dependent on the properties of the electrodes and the maximum photocatalytic oxidation rate at TiO2 surface determined by the light intensity and substrate concentration. A model was proposed, which explained well the special characteristics of particulate semiconductor electrodes (nanoporous semiconductor electrodes). This is the first clear description of the overall photocatalytic process at nanoparticulate semiconductor electrodes. The investigation set a theoretical foundation for employing photoelectrochemical techniques to study photocatalytic processes. By using the transient technique (illumination step method analogous to potential step method in conventional electrochemistry), the adsorption of a number of strong adsorbates on both low temperature and high temperature calcined TiO2 nanoporous films was investigated. Similar adsorption characteristics for different adsorbates on different films were observed. In all the cases, three different surface bound complexes were identified, which was attributed to the heterogeneity of TiO2 surface. The photocatalytic degradation kinetics of the pre-adsorbed organic compounds of different chemical nature was also studied by processing the photocurrent-time profiles. Two different photocatalytic processes, exhibiting different rate characteristics, were observed. This was, again, attributed to the heterogeneity of the TiO2 surface corresponding to heterogeneous adsorption characteristics. The catalytic first order rate constants of both fast and slow processes were obtained for different organic compounds. It was found that for different adsorbates of different chemical nature the magnitudes of rate constant for the slow kinetic process were very similar, while the magnitudes of rate constant for the fast process were significantly affected by the photohole demand characteristics of different adsorbates. Photohole demand distribution that depends on the size and structure of the adsorbed molecules was believed to be responsible for the difference. By employing steady state photocurrent method, the photocatalytic degradation kinetic characteristics of both strong adsorbates and weak adsorbates of different chemical structures were compared at pure anatase TiO2 nanoporous TiO2 films as well as at anatase/rutile mixed phase TiO2 nanoporous film electrodes. At the former electrodes for all the different organic compounds studied, the photocatalytic reaction rate increased linearly with concentration at low concentrations. Under such conditions, it was demonstrated that the overall photocatalytic process was controlled by diffusion and was independent of the chemical nature of organic compounds. However, the linear concentration range and the maximum photocatalytic reaction rate at high concentrations were significantly dependent on the chemical nature of the substrates. This was explained by the difference in the interaction of different organic compounds with TiO2 surface, the difference in their photohole demand distributions at the TiO2 surface and the difference in their nature of intermediates formed during their photocatalytic mineralization. In contrast, at the latter electrodes for the photocatalytic oxidation of different organic compounds the linear ranges (diffusion control concentration range) and the maximum reaction rates at high concentration were much larger than at the former electrodes and much less dependent on the chemical nature of the organic compounds. The spatial separation of photoelectrons and photoholes (due to the coexistence of rutile phase and anatase phase) and the increase in the lifetime of photoelectrons and photoholes are responsible for the excellent photocatalytic activity of the electrodes. By employing the thin-layer photoelectrochemical technique (analogous to the thin-layer exhaustive electrolytic technique), the photocatalytic oxidation of different organic compounds at the mixed phase TiO2 nanoporous electrodes were investigated in a thin layer photoelectrochemical cell. It was found that the charge derived from exhaustive oxidation agreed well with theoretical charge expected for the mineralisation of a specific organic compound. This finding was true for all the compounds investigated and was also true for mixtures of different organic compounds. The photocatalytic degradation kinetics of different organic compounds of different chemical identities in the thin layer cell was also investigated by the photoelectrochemical method. Two kinetic processes of different decay time constants were identified, which were attributed to the degradation of preadsorbed compounds and the degradation of compounds in solution. For the degradation of compounds in solution, a change in the overall control step from substrate diffusion to heterogeneous surface reaction was observed. For different organic compounds, the variation of the rate constant was determined by the photohole demand rather than by the chemical identities of substrates. The kinetics of the fast kinetic process, on the other hand, was greatly affected by the adsorption properties of the substrates. For the strong adsorbates, the rate was much larger than for weak adsorbates. However, the rate constant of the process was independent of the chemical identities of the substrates and the variation of the constant was also determined by the photohole demand. Based on the principles of exhaustive photoelectrocatalytic degradation of organic matter in a thin layer cell, a novel, rapid, direct, environmental-friendly and absolute COD analysis method was developed. The method was tested on synthetic samples as well as real wastewater samples from a variety of industries. For synthetic samples with given compositions the COD values measured by my method agree very well with theoretical COD value. For real samples and synthetic samples the COD values measured by my method correlated very well with those measured by standard dichromate COD analysis method.
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Jiang, Dianlu. "Studies of Photocatalytic Processes at Nanoporous TiO2 Film Electrodes by Photoelectrochemical Techniques and Development of a Novel Methodology for Rapid Determination of Chemical Oxygen Dphotocatalemand". Thesis, Griffith University, 2004. http://hdl.handle.net/10072/366458.
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In this work, a series of simple, rapid and effective photoelectrochemical methodologies have been developed and successfully applied to the study of kinetic and thermodynamic characteristics of photocatalytic oxidation processes at TiO2 nanoparticulate films. As an application of the systematic studies of photocatalytic processes by photoelectrochemical techniques, a rapid, direct, absolute, environmental-friendly and accurate COD analysis method was successfully developed. In this work, the TiO2 nanoparticles colloid was prepared by the sol-gel method. The TiO2 nanoparticles were immobilized onto ITO conducting glass slides by dip-coating method. Thermal treatment was carried out to obtain nanoporous TiO2 films of different structures. At low calcination temperature (below 600°C), nanoporous TiO2 films of pure anatase phase were prepared. At high calcination temperature (above 600°C), nanoporous TiO2 films of mixed anatase and rutile phases were obtained. At these film electrodes, the work was carried out. By employing steady state photocurrent method and choosing phthalic acid as the model compound, the photocatalytic activity of the TiO2 nanoporous films calcined at various temperatures and for different lengths of time was evaluated. It was found that the films with mixed anatase and rutile phases calcined at high temperature exhibited high photocatalytic activity. Based on semiconductor band theory, a model was proposed, which explained well this finding.
By employing linear sweep voltammetry (under illumination) and choosing glucose (an effective photohole scavenger) as a model compound, the characteristics of the photocatalytic processes at nanoparticulate semiconductor electrodes were investigated. Characteristics of the nanoporous semiconductor electrodes markedly different from bulk semiconductor electrodes were observed. That is, within a large range of electrode potentials above the flat band potential the electrodes behaved as a pure resistance instead of exhibiting variable resistance expected for bulk semiconductor electrodes. The magnitude of the resistance was dependent on the properties of the electrodes and the maximum photocatalytic oxidation rate at TiO2 surface determined by the light intensity and substrate concentration. A model was proposed, which explained well the special characteristics of particulate semiconductor electrodes (nanoporous semiconductor electrodes). This is the first clear description of the overall photocatalytic process at nanoparticulate semiconductor electrodes. The investigation set a theoretical foundation for employing photoelectrochemical techniques to study photocatalytic processes.
By using the transient technique (illumination step method analogous to potential step method in conventional electrochemistry), the adsorption of a number of strong adsorbates on both low temperature and high temperature calcined TiO2 nanoporous films was investigated. Similar adsorption characteristics for different adsorbates on different films were observed. In all the cases, three different surface bound complexes were identified, which was attributed to the heterogeneity of TiO2 surface. The photocatalytic degradation kinetics of the pre-adsorbed organic compounds of different chemical nature was also studied by processing the photocurrent-time profiles. Two different photocatalytic processes, exhibiting different rate characteristics, were observed. This was, again, attributed to the heterogeneity of the TiO2 surface corresponding to heterogeneous adsorption characteristics. The catalytic first order rate constants of both fast and slow processes were obtained for different organic compounds. It was found that for different adsorbates of different chemical nature the magnitudes of rate constant for the slow kinetic process were very similar, while the magnitudes of rate constant for the fast process were significantly affected by the photohole demand characteristics of different adsorbates. Photohole demand distribution that depends on the size and structure of the adsorbed molecules was believed to be responsible for the difference.
By employing steady state photocurrent method, the photocatalytic degradation kinetic characteristics of both strong adsorbates and weak adsorbates of different chemical structures were compared at pure anatase TiO2 nanoporous TiO2 films as well as at anatase/rutile mixed phase TiO2 nanoporous film electrodes. At the former electrodes for all the different organic compounds studied, the photocatalytic reaction rate increased linearly with concentration at low concentrations. Under such conditions, it was demonstrated that the overall photocatalytic process was controlled by diffusion and was independent of the chemical nature of organic compounds. However, the linear concentration range and the maximum photocatalytic reaction rate at high concentrations were significantly dependent on the chemical nature of the substrates. This was explained by the difference in the interaction of different organic compounds with TiO2 surface, the difference in their photohole demand distributions at the TiO2 surface and the difference in their nature of intermediates formed during their photocatalytic mineralization. In contrast, at the latter electrodes for the photocatalytic oxidation of different organic compounds the linear ranges (diffusion control concentration range) and the maximum reaction rates at high concentration were much larger than at the former electrodes and much less dependent on the chemical nature of the organic compounds. The spatial separation of photoelectrons and photoholes (due to the coexistence of rutile phase and anatase phase) and the increase in the lifetime of photoelectrons and photoholes are responsible for the excellent photocatalytic activity of the electrodes. By employing the thin-layer photoelectrochemical technique (analogous to the thin-layer exhaustive electrolytic technique), the photocatalytic oxidation of different organic compounds at the mixed phase TiO2 nanoporous electrodes were investigated in a thin layer photoelectrochemical cell. It was found that the charge derived from exhaustive oxidation agreed well with theoretical charge expected for the mineralisation of a specific organic compound. This finding was true for all the compounds investigated and was also true for mixtures of different organic compounds. The photocatalytic degradation kinetics of different organic compounds of different chemical identities in the thin layer cell was also investigated by the photoelectrochemical method. Two kinetic processes of different decay time constants were identified, which were attributed to the degradation of preadsorbed compounds and the degradation of compounds in solution. For the degradation of compounds in solution, a change in the overall control step from substrate diffusion to heterogeneous surface reaction was observed. For different organic compounds, the variation of the rate constant was determined by the photohole demand rather than by the chemical identities of substrates. The kinetics of the fast kinetic process, on the other hand, was greatly affected by the adsorption properties of the substrates. For the strong adsorbates, the rate was much larger than for weak adsorbates. However, the rate constant of the process was independent of the chemical identities of the substrates and the variation of the constant was also determined by the photohole demand.
Based on the principles of exhaustive photoelectrocatalytic degradation of organic matter in a thin layer cell, a novel, rapid, direct, environmental-friendly and absolute COD analysis method was developed. The method was tested on synthetic samples as well as real wastewater samples from a variety of industries. For synthetic samples with given compositions the COD values measured by my method agree very well with theoretical COD value. For real samples and synthetic samples the COD values measured by my method correlated very well with those measured by standard dichromate COD analysis method.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environmental and Applied Science
Full Text
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Okolongo, Gauthier Nganda. "Advanced oxidative water treatment process using an electrohydraulic discharge reactor and TiO2 immobilised on nanofibres". Thesis, University of Western Cape, 2013. http://hdl.handle.net/11394/3329.
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Philosophiae Doctor - PhDThe aim of this study was to design and build an electrohydraulic discharge reactor in such a way that the synthetic immobilized TiO2 nanophotocatalytic components could be integrated, for the production of active species such as OH radicals, ozone and hydrogen peroxide, as a cocktail to clean drinking water without the addition of chemicals. The research objectives include: • To design and construct the different AOP prototypes based on various electrode configurations and compare their operation. • To optimize the discharge parameters and conditions of the best AOP system. • To determine the effectiveness of the best prototype for the degradation of methylene blue as model pollutant. • To compare the designed AOP system with the Sodis method for the disinfection of contaminated river water. • To prepare supported TiO2 nanoparticles via electro spinning, followed by combustion and study the effect on the morphology of TiO2 nanoparticles. • To determine the stability and robustness of composite nano-crystalline TiO2 photocatalysts by sonication • To determine the enhanced effect of combining the composite TiO2 in the AOP system on degradation of methylene blue under the same conditions. • To detect the active species promoting disinfection.
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Samanamud, Gisella Rossana Lamas. "Estudo da aplicação de ZnO fotoirradiado com luz solar no tratamento de efluentes de laticínios". Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/97/97136/tde-27082013-101339/.
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Os produtos lácteos são tidos como os alimentos mais perfeitos para o homem devido ao seu alto valor nutritivo. Entretanto, esses produtos vêm refletidos na elevada carga orgânica de efluente gerado. Os Processos Oxidativos Avançados (POA) são métodos químicos baseados na geração de radicais hidroxilas, que promovem a oxidação de compostos orgânicos. O uso de semicondutores no tratamento de efluentes tem sido de grande interesse devido à sua alta eficiência, estabilidade fotoquímica, natureza não-tóxica e baixo custo, especialmente quando a luz do sol é usada como fonte de irradiação. O uso de Óxido de Zinco (ZnO), por exemplo, além de mais econômico, absorve uma fração maior de espectro UV e tem melhor desempenho em pH neutro. Este estudo consistiu em avaliar a aplicação e eficiência da fotocatálise heterogênea (POA) solar com ZnO em termos de percentual de degradação de Carga Orgânica Total (COT) para um posterior tratamento biológico aerado visando melhorar as condições de despejo do efluente de modo a preservar o ecossistema e economia dos recursos naturais. O sistema POA consistiu de um volume fixo de efluente de 3L, de uma chapa metálica 800 x 250 mm revestida com uma formulação de tinta contendo ZnO, um reservatório de vidro, uma bomba centrífuga e aberto para absorção de radiações UV solar. Os resultados foram obtidos e analisados a partir do método de planejamento de experimentos em termos de percentual de degradação de COT. O melhor resultado apresentou um percentual de degradação de COT de 31,5% onde os níves das variáveis estudadas ocorreram em pH 8,0 em chapa de ZnO com espessura de 100 micrômetros (?m), utilizando o efluente in natura e o tempo total de reação de 3 h (180min). O efluente tratado pelo POA solar com ZnO foi submetido ao tratamento biológico aerado. O pH ótimo e a concentração de lodo foram de 6,0 e 5,0 mg/L, respectivamente. O percentual de degradação de COT para os tratamentos combinados foi de 75,1 % para o efluente de laticínios utilizado neste estudo. Isto sugere que o tratamento por POA utilizando ZnO seguido de um Tratamento Biológico Aerado seria uma alternativa promissora no tratamento de efluentes de laticínios.Dairy products are the most perfect type of food for men due to its high nutritive value reflected on its high organic load of wastewater generated. The Advanced Oxidation Processes (AOP) are chemical methods based on the generation of hydroxyls radicals that promote the oxidation of organic compounds. The use of semiconductors in wastewater treatment has been of great interest owing to its high efficiency, photochemical stability, non-toxic nature and lower costs, especially when sunlight is used as source of irradiation. The use of Zinc Oxide (ZnO), for instance, besides being more economic, it also absorbs a greater range of UV spectrum and it has a better performance on neutral pH. This study consisted in evaluating the application and efficiency of solar photocatalytic oxidation (AOP) with ZnO in percentage terms of removal of Total Organic Carbon (TOC) prior to an aerobic biological treatment aiming to improve the conditions of the disposal of this wastewater in order to conserve the water environment and saving natural resources. The AOP system consisted of a working volume of 3 L, a sheet metal 800 x 250 mm covered with a paint formula containing ZnO, a glass vessel, a pump and an open system in order to collect solar UV radiation. The results were obtained and analyzed from design of experiments in terms of percentage of removal of TOC. The maximum percentage was found to be 31.5 % of removal of TOC and at pH 8.0, thickness of the sheet containing ZnO of 100 micrometers (?m), wastewater in natura and total time of reaction of 3 h (180 min). The solar AOP with ZnO treated wastewater was subjected to an aerobic biological treatment. The optimum pH and sludge loading were of 6.0 and 5.0 mg/L, respectively. The combination of both treatments resulted in 75.1 % of removal of TOC from the dairy wastewater used in this study. This suggests that the AOP using ZnO followed by an aerobic biological treatment would be a promising alternative for the treatment of dairy wastewater.
Książki na temat "Photocatalytic oxidation process"
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Bruce, Raupp Gregory, Turchi Craig i Superfund Innovative Technology Evaluation Program (U.S.), red. Integration of photocatalytic oxidation with air stripping of contaminated aquifers. [Washington, D.C.?]: U.S. Environmental Protection Agency, Superfund Innovative Technology Evaluation, 1999.
Znajdź pełny tekst źródłaCzęści książek na temat "Photocatalytic oxidation process"
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Gupta, Tejendra K., Sucheta Sengupta i Manoj Raula. "Optimization of Process, Mechanism and Kinetics Study for Photocatalytic Oxidation". W Green Chemistry and Sustainable Technology, 33–48. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-77371-7_2.
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Li, X. Z., B. L. Yuan i Nigel Graham. "Degradation of Dibutyl Phthalate in Aqueous Solution by a Combined Ferrate and Photocatalytic Oxidation Process". W Ferrates, 364–77. Washington, DC: American Chemical Society, 2008. http://dx.doi.org/10.1021/bk-2008-0985.ch022.
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Quimbayo, Jennyffer Martinez, Satu Ojala, Samuli Urpelainen, Mika Huuhtanen, Wei Cao, Marko Huttula i Riitta L. Keiski. "Nanostructured Photocatalytic Materials for Water Purification". W Advanced Oxidation Processes for Wastewater Treatment, 249–70. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003165958-21.
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Goveas, Jenice Jean, Naveen Praveen Mascarenhas i Richard Adolf Gonsalves. "Photocatalytic Degradation of Rhodamine-B by Advance Oxidative Process Using Electrochemically Synthesized ZnO–V2O5 Nanostructures". W Advanced Manufacturing and Materials Science, 255–63. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-76276-0_25.
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"Photocatalytic Oxidation of Organic Contaminants". W Process Engineering for Pollution Control and Waste Minimization, 391–418. CRC Press, 1994. http://dx.doi.org/10.1201/9781482277586-25.
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Saravanathamizhan, R., V. T. Perarasu i Balaji Dhandapani. "Advanced oxidation process for effluent treatment in textile, pharmaceutical, and tannery industries". W Photocatalytic Degradation of Dyes, 719–45. Elsevier, 2021. http://dx.doi.org/10.1016/b978-0-12-823876-9.00020-2.
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Luo, Jingpeng, Weiying Pang, Qingying Ye i Dong Fu. "Fe-Cu Bimetallic Oxide Quantum Dots Coupled with g-C3N4 Nanosheets for Efficient Photo-Fenton Degradation of Phenol". W Advances in Transdisciplinary Engineering. IOS Press, 2022. http://dx.doi.org/10.3233/atde220343.
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Graphitized carbon nitride (g-C3N4), as a simple and green photocatalytic material, has been widely used in photocatalytic degradation. However, the photocatalytic activity of g-C3N4 was inhibited by poor visible light absorption and high photocarrier recombination rate. Metal quantum dots (Qds)/g-C3N4 nanosheets coupled catalysts have attracted more and more attention in the Fenton advanced oxidation process due to their high charge mobility and more active sites. In this work, heterogeneous photocatalysts of Fe-Cu bimetallic oxide quantum coupled with g-C3N4 nanosheets were prepared. It shows high activity in Fenton and photocatalytic system. Under the optimal conditions, the removal efficiency of 50 ppm phenol reached 99% after 60 min. The removal efficiency of the catalyst for phenol did not decrease significantly after four cycles of experiments, and the catalyst had good stability. The experimental results show that the synergy between g-C3N4 semiconductor photocatalytic oxidation technology and heterogeneous Fenton advanced oxidation technology has great practical significance.
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Gebregiorgis, Teklit. "Photocatalytic and Biological Oxidation Treatment of Real Textile Wastewater". W Molecular Biotechnology. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.89587.
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With rapidly growing urbanization and industrialization in developing countries, a large volume of wastewater is produced from industries that contain chemicals generating high environmental risks, which could affect health and socio-economic activities if not treated properly. In this study, the discoloration of wastewater containing azo dyes by chemical oxidation process combined with a biological treatment was evaluated and applied on real textile wastewater generated from one Ethiopian industrial site. The use of TiO2 as a photocatalyst and the effect of the addition of H2O2 on color removal were investigated. Photocatalysis was followed by aerobic biological treatment and their combination resulted in 93.3 and 90.4% removal of color and chemical oxygen demand (COD), respectively. These results revealed that the combination of photocatalytic and biological treatment approach shows a promising potential for the removal of color from real textile wastewater.
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Davis, A. P., i C. P. Huang. "REMOVAL OF PHENOLS FROM WATER BY A PHOTOCATALYTIC OXIDATION PROCESS". W Water Pollution Research and Control Brighton, 455–64. Elsevier, 1988. http://dx.doi.org/10.1016/b978-1-4832-8439-2.50047-x.
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Srivastava, Ruchi, i Irfan Rashid Sofi. "Impact of Synthetic Dyes on Human Health and Environment". W Impact of Textile Dyes on Public Health and the Environment, 146–61. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-0311-9.ch007.
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Colour is the most important part to make any fabric attractive, but its use for dying has become a major environmental hazard. Colloidal particles present with color increases the turbidity, gives bad appearance, foul odour, and obstructs the penetration of sunlight into water bodies required for the photosynthesis process, which interferes with the oxygen flow mechanism and hence marine life. So, it is essential to remove such pollutants from the waste water before its final disposal into water bodies. Photocatalysis is one of the advance oxidation processes, mainly carried out in the presence of light and suitable photocatalytic materials for the degradation of dyes. This chapter outlines the background of dye chemistry, the application areas, and the impact of dyeing effluents in the environment and on living beings.
Streszczenia konferencji na temat "Photocatalytic oxidation process"
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Yu, Huili, Kaili Zhang i Carole Rossi. "Theoretical Investigation on Nano TiO2 Photocatalytic Oxidation of VOCs". W 2007 First International Conference on Integration and Commercialization of Micro and Nanosystems. ASMEDC, 2007. http://dx.doi.org/10.1115/mnc2007-21406.
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Controlling mechanisms for photocatalytic degradation of volatile organic compounds by nano TiO2 catalyst are found to be mass transfer, diffusion, adsorption and photochemistry. A mathematical model for the degradation process is developed by incorporating these mechanisms in a plane plate air purification physical model. Finite difference method is employed to solve the governing equation and boundary conditions. The computation results are validated using the data from experiments. The model is then used to investigate the effects of some key factors on the degradation of formaldehyde including UV light intensity, UV light attenuation coefficient, adsorption, catalyst thickness, and flow rate.
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Lepeytre, C., C. Lavaud i G. Serve. "Photocatalytic and Photochemical Degradation of Liquid Waste Containing EDTA". W ASME 2011 14th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2011. http://dx.doi.org/10.1115/icem2011-59144.
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The decontamination factor of liquid waste containing 60Co is generally weak. This is due to the presence of complexant molecules. For instance, complexation of EDTA with 60Co decreases efficiency of radioactive waste treatment. The aim of this study was to degrade EDTA in H2O and CO2 and to concentrate free 60Co in order to increase decontamination factor. A first test of radioactive waste treatment by photocatalysis was allowed to increase decontamination factor (60Co) from 16 to 196 with a device requiring to be improved. The present work concerns the first step of the degradation process development with a more powerful device. These first experiments were leaded to follow the only EDTA oxidation. EDTA degradation was carried out by the following Advanced Oxidation Processes (AOP): UV/H2O2 (photochemistry); UV/TiO2 (photocatalysis); UV/TiO2/H2O2. A specific reactor was achieved for this study. The wavelength used was 254 nm (UVC). The photocatalytic degradation of EDTA was carried out with Degussa P-25 titanium dioxide (TiO2), which is a semiconductor photocatalyst. The degradation degree of EDTA and the intermediate products were monitored by TOC and ionic chromatography methods. The effects of various parameters such as pH and the quantity of H2O2 were studied. This allows us to conclude that basic pH slows down EDTA degradation. The study showed that UV/H2O2 process was the most effective treatment process under acid conditions. The rate of EDTA degradation was very high and reached 95% in 120 minutes. The presence of glyoxilic, oxalic, glycolic and formic acids was detected as degradation products. Among the intermediates produced by photochemistry, NO3− ions presence informed of the amine degradations. These results highlighted faster EDTA degradation by photochemistry than photocatalysis.
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Wang Liping, Lu Lei, Xue Chunyang i Gao Naiyun. "Pretreatment of Micro-polluted Raw Water by Using TiO2/PP Photocatalytic Oxidation and Biofilms Combination Process". W 2011 International Conference on Measuring Technology and Mechatronics Automation (ICMTMA). IEEE, 2011. http://dx.doi.org/10.1109/icmtma.2011.511.
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Tota-Maharaj, Kiran, i Nichola Coleman. "Developing Novel Photocatalytic Cementitious Permeable Pavements for Depollution of Contaminants and Impurities in Urban Cities". W Environmental Engineering. VGTU Technika, 2017. http://dx.doi.org/10.3846/enviro.2017.053.
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Photocatalyst such as Titanium Dioxide (TiO2) has been recently introduced as a nanoparticle into cementitious permeable pavements. Combining photocatalytic compounds within concrete permeable pavements can aid with depollution of several contaminants found in urban water streams and air impurities. This paper presents research carried out at the University of Greenwich, UK using photocatalytic concrete with varying percentages of TiO2 (0 %, 1% and 5%) to assess the levels depollution which can be achieved. Concrete samples were testing against the degradation of 2, 4-Dichlorophenoxyacetic Acid, a harmful chemical found in herbicides. This advanced oxidation process can aid in the reduction of urban pollution from an air and water perspective, improving sustainability for urban cities. Self-cleaning benefits of photocatalytic concrete permeable pavements can be used to keep urban infrastructure cleaner and more aesthetically pleasing. Experimental tests were carried out on the characterisation of inorganics through X-Ray diffraction and Fourier Transform Infrared Spectroscopy to ensure that the structures of the concrete samples were not altered by addition of the nanoparticles (photocatalyst). Experimental results were compared to that found in previous literature and confirmed that the addition of 5% TiO2 did not affect the structure of the concrete samples and can be a viable option used in urban infrastructure such as permeable pavements.
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Elmakki, Tasneem, Fathima Sifani Zavahir, Mona Gulied, Norhan Ismail, Areeba Hameed i Dong Suk Han. "Advanced Degradation of Organic Substance in Water Using No-Ferric Fenton Reaction on Titania Nanotube". W Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0028.
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Highly reactive OH radicals facilitate advanced oxidation processes (AOPs). AOPs are irreplaceable in environmental remediation including but not limited to pollutant degradation. H2O2 leading to OH radicals in iron based fenton systems are well known and few other oxides of alumina and ceria in non-ferrous fenton systems. Majority of studied catalysts materials are in powder form, which limits the catalysts long term applicability in real systems due to separation and regeneration of the catalyst with required catalytic activity, which is costly. In this present work, we have studied anatase phased titania nanotube arrays (TNA) grown on Ti films prepared by an anodization approach for methyl orange (MO) dye degradation under photocatalytic conditions. Key findings reveal long stability of TNAs over fifty reaction cycles in batch process with higher degree of reproducible performance. Complete removal of MO was achieved after six hours of exposure in AM 1.5 G light (equivalent to 1 sun intensity), where hydrogen peroxide accounted for only 1/200th of the amount of initial dye concentration. This superior performance is ascribed to surface oxygen vacancies and Ti3+ sites promoting regeneration of peroxide in the ongoing reaction medium that is consequently transformed to OH radicals. This is further confirmed by the experiments conducted with formic acid, a known hydroxyl radical scavenger, where the dye degradation was observed to be minimal at a near zero rate even after six hours of reaction time, upon measurements with UV-visible spectroscopy. About 38% of the initial dye was oxidized after 1 h into the reaction under light irradiation in a typical system whereas activity was hugely promoted to over 55% when it was coupled with a Pt wire in an electroless process, without supply of additional power. In conclusion, this TNA based new material is highly regarded as environmentally sustainable, easily reusable, non-toxic and commercially viable candidate for real wastewater treatment plants where the treatment plants are usually large tanks constructed in the open space with access to freely available, energetically rich solar power.
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Vijayaraghavan, Sanjay, i D. Y. Goswami. "Photocatalytic Oxidation of Toluene in Water From an Algae Pond With High Dissolved Oxygen Content". W ASME Solar 2002: International Solar Energy Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/sed2002-1061.
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Water in well-mixed ponds containing photosynthetic algae has been observed to have an extremely high Dissolved Oxygen (DO) content. Up to four times saturation levels of DO have been recorded. Since DO is known to have an important role in the photocatalytic oxidation of organic contaminants in water, it was hypothesized that a faster rate of contaminant destruction would be observed in water drawn from algae ponds supersaturated with DO. In order to verify this hypothesis a bench scale, batch type photoreactor was constructed. Some baseline tests were performed to investigate the influence of UV intensity, water pH and DO content on the photocatalytic destruction of toluene in water. An array of ultraviolet “blacklight” lamps in a lamp box was used to simulate solar ultraviolet radiation. First-order reaction rate constants were calculated from the destruction data, using a kinetic model proposed earlier. The reaction was found to proceed forward equally fast at pH 4 and 10. A power law relation was derived for the reaction rate dependence on UV intensity. Presence of DO in the water was found to be required for the reaction to go forward. Water from an algae pond, supersaturated with dissolved oxygen was spiked with toluene and destruction tests were then conducted in the same reactor. These tests did not show the expected improvement in destruction rates.
Raporty organizacyjne na temat "Photocatalytic oxidation process"
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Blake, D. M., E. Wolfrum i J. Boulter. Photocatalytic oxidation and reduction chemistry and a new process for treatment of pink water and related contaminated water. Office of Scientific and Technical Information (OSTI), październik 1996. http://dx.doi.org/10.2172/395626.
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