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Kolář, Michal. "Degradation of organic pollutants employing various photocatalytic systems." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2008. http://tel.archives-ouvertes.fr/tel-00731166.
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La dégradation photoinduite du Monuron (herbicide) a été étudiée dans trois systèmes différents produisant des radicaux hydroxyle : en présence du complexe Fe(III)Cit, dans une suspension de TiO2 et dans un système combiné Fe(III)Cit / TiO2. Le but principal était d'améliorer l'efficacité photocatalytique. La spéciation et la photoactivité du complexe ont été déterminées en fonction du pH. La cinétique de dégradation du Monuron photoinduite par le complexe se fait en deux étapes avec deux sources successives de radicaux °OH : 1) photolyse du complexe ; 2) cycle photoredox du fer. La présence de TiO2 améliore l'efficacité du système Fe(III)Cit à pH acide alors qu'à pH neutre l'efficacité du système est complètement inhibée. La concentration en oxygène et le pH sont les facteurs clés en présence du complexe Fe(III)Cit. De plus, dans un système pilote utilisant du TiO2, l'influence d'un solvant organique lors de la dégradation du 4-chlorophénol en milieu aquatique a été examinée.
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Kolar, Michal. "Degradation of organic pollutants employing various photocatalytic systems." Clermont-Ferrand 2, 2008. http://www.theses.fr/2008CLF21885.
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La dégradation photoinduite du Monuron (herbicide) a été étudiée dans trois systèmes différents produisant des radicaux hydroxyle : en présence du complexe Fe(III)Cit, dans une suspension de TiO2 et dans un système combiné Fe(III)Cit / TiO2. Le but principal était d'améliorer l'efficacité photocatalytique. La spéciation et la photoactivité du complexe ont été déterminées en fonction du pH. La cinétique de dégradation du Monuron photoinduite par le complexe se fait en deux étapes avec deux sources successives de radicaux °OH : 1) photolyse du complexe ; 2) cycle photoredox du fer. La présence de TiO2 améliore l'efficacité du système Fe(III)Cit à pH acide alors qu'à pH neutre l'efficacité du système est complètement inhibée. La concentration en oxygène et le pH sont les facteurs clés en présence du complexe Fe(III)Cit. De plus, dans un système pilote utilisant du TiO2, l'influence d'un solvant organique lors de la dégradation du 4-chlorophénol en milieu aquatique a été examinée
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Wang, Yi. "Metal-organic and organic photosensitizers for photocatalytic hydrogen generation and carbon dioxide reduction." HKBU Institutional Repository, 2017. https://repository.hkbu.edu.hk/etd_oa/414.
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This thesis is focused on developing metal-organic and organic molecules for photocatalytic water splitting and carbon dioxide reduction. In chapter 1, an overview of hydrogen production, dye-sensitized solar cells and carbon dioxide reduction are provided. The development history and reaction mechanisms of catalytic systems are introduced along with the typical examples in each field. The applications of both metal-organic and organic compounds are covered. In chapter 2, nine molecular organic photosensitizers were designed and synthesized. The nine molecules were employed as the photosensitizing reagent in the fabrication of dye-sensitized solar cells and applied in photocatalytic water reduction via coupling with TiO2 semiconductors and Pt co-catalyst. The highest turnover number (TON) of 10200 was achieved by organic photosensitizer 1g for hydrogen generation. The effect of alkyl chains and triarylamine donor moiety to the photocatalytic performance was investigated. A shorter alkyl chain was found to favor the reaction due to a lower hydrophobicity which in turn may block the interaction between the photocatalyst and water molecules. Besides, the triarylamine donor units facilitated high hydrogen generation rates by reducing the contact between catalytic active sites and the oxidized form of sacrificial reagents. In chapter 3, five earth-abundant metal complexes were synthesized to serve as the catalyst and CdS nanorods (NRs) were prepared to be the photosensitizer for the photocatalytic water reduction. A cobalt dithiolene complex (2a) achieved a TON of 30635 in 20 h under the blue light irradiation at a concentration of 10 µM. A new complex 2c also gave a high TON of 12375 under the same conditions and its TON was further improved to 115213 in 87 h by reducing the concentration of catalyst by ten times. The size effect of CdS NRs was investigated and larger nanoparticles exhibited higher hydrogen production rates. In chapter 4, ten iridium(III) complexes were synthesized and used as dual-functional molecules in photocatalytic carbon dioxide reduction by acting as both the photosensitizing reagent as well as the catalyst. The best performance was achieved by 3j, giving a TON of 230 under the irradiation of blue LED. A push-pull effect brought by trifluoromethyl and methoxy group sucessfully enhanced the carbon dioxide reduction efficiency. The hydrophobicity of n-butyl chain also provided effective protection to the active sites of reaction intermediate. Additional steric hindrance was found to extend the lifespan of photocatalytic systems but led to a drop in the overall conversion efficiency. Chapter 5 summarizes the specific synthetic procedures and characterization parameters of the molecules in chapters 2-4.
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Hamill, Noel Anthony. "Photocatalytic destruction of dichlorobutenes in waste water treatment." Thesis, Queen's University Belfast, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322954.
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Lim, Leonard Lik Pueh. "In-situ photocatalytic remediation of organic contaminants in groundwater." Thesis, University of Cambridge, 2010. https://www.repository.cam.ac.uk/handle/1810/238767.
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This research is about the development of a photocatalytic reactor design, Honeycomb, for in-situ groundwater remediation. Photocatalysis, typically a pseudo first order advanced oxidation process, is initiated via the illumination of UVA light on the catalyst, i.e. titanium dioxide (TiO2). In the presence of oxygen, highly reactive oxidising agents are generated such as superoxide (O2-), hydroxyl (OH.-) radicals, and holes (hvb+) on the catalyst surface which can oxidise a wide range of organic compounds. The target contaminant is methyl tert butyl ether (MTBE), a popular gasoline additive in the past three decades, which gives the water an unpleasant taste and odour at 20 μg L-1, making it undrinkable. This research consists of three major parts, i.e. (i) establishing a suitable catalyst immobilisation procedure, (ii) characterisation and evaluation of reactor models and (iii) scale up studies in a sand tank. TiO2 does not attach well onto many surfaces. Therefore, the first step was to determine a suitable immobilisation procedure by preparing TiO2 films using several potential procedures and testing them under the same conditions, at small scale. The coatings were evaluated in terms of photocatalytic activity and adhesion. The photocatalytic activity of the coatings was tested using methylene blue dye (MB), which is a photocatalytic indicator. A hybrid coating, which comprises a sol gel solution enriched with Aeroxide TiO2 P25 powder, on woven fibreglass exhibited the best adhesion and photocatalytic activity among samples evaluated. Thus, it was used to produce immobilised catalyst for this research. Consequently, the immobilisation procedure was scaled up to synthesize TiO2 coatings for the potential photocatalytic reactor design. The photocatalytic activity of the coatings produced from the scaled up immobilisation procedure were reasonably comparable to that produced at small scale. Due to the UVA irradiation and mass transfer limitations, photocatalytic reactors are typically compact in order to maximise their efficiency to accommodate high flows, particularly in water and wastewater treatment. In the case of groundwater, however, the treatment area can span up to meters in width and depth. Groundwater flow is significantly lower than that of water treatment, as the reactor design does not need to be compact. Considering both factors, a photocatalytic reactor design of hexagonal cross-section (Honeycomb) was proposed, in which the structures can be arranged adjacent to each other forming a honeycomb. A model was constructed and tested in a 4 L column (cylindrical) reactor, using the MB test to characterise the reactor performance and operating conditions. This was followed by a hydraulic performance study, which encompasses single and double pass flow studies. The single pass flow study involves the photocatalytic oxidation (PCO) of MB and MTBE, while the double pass flow study was focused on the PCO of MTBE only. The double pass can simulate two serially connected reactors. Single pass flow studies found that the critical hydraulic residence time (HRT) for the PCO of MB and MTBE is approximately 1 day, achieving up to 84 % MTBE removal. Critical HRT refers to the minimum average duration for a batch of contaminant remaining in the reactor in order to maintain the potential efficiency of the reactor. Double pass studies showed the reactor can achieve up to 95 % MTBE removal in 48 hours, and that reactor performance in the field of serially connected reactors can be estimated by sequential order of single pass removal efficiency. In groundwater, there are likely to be other impurities present and the effects of groundwater constituents on the reactor efficiency were studied. The MTBE PCO rate is affected by the presence of organic compounds and dissolved ions mainly due to the competition for hydroxyl radicals and the deactivation of catalyst surface via adsorption of the more strongly adsorbed organic molecules and ions. Despite the presence of organic compounds and dissolved ions, the reactor achieved about 80 % MTBE removal in 48 hours. A double pass flow study showed that the overall efficiency of the photocatalytic reactor in the field can be estimated via sequential order of its efficiency in a single pass flow study using the actual groundwater sample in the laboratory. A sand tank was designed for the simulation of the clean up of an MTBE plume from a point source leakage using the 200 mm i.d. Honeycomb I prototype. Honeycomb I achieved up to 88.1 % MTBE removal when the contaminated groundwater flowed through (single pass) at 14.6 cm d-1. The critical HRT for Honeycomb I was also approximately 1 day, similar to that in the column reactor. The response of MTBE removal efficiency towards flow obtained in the column reactor and sand tank was generic, indicating that the reactor efficiency can be obtained via testing of the model in the column reactor. The presence of toluene, ethylbenzene and o-xylene (TEo-X) decreased the MTBE removal efficiency in both the sand tank and column reactor. The same set of catalyst and 15 W Philips Cleo UVA fluorescent lamp was operated for a total of about 582 h (24 d) out of the cumulative 1039 h (43 d) sand tank experiments, achieving an overall MTBE removal efficiency of about 76.2 %. The experiments in the column reactor and sand tank exhibited the reliability of the immobilised catalyst produced in this research. This research demonstrates the potential of Honeycomb for in-situ groundwater remediation and also proposes its fabrication and installation options in the field.
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Sommers, Jacob. "Towards Photocatalytic Overall Water Splitting via Small Organic Shuttles." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34607.
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This thesis studies the development of a new method for photochemical overall water splitting using a small organic shuttle.
In Section 2, BiVO4, was studied to determine the CO2 reduction mechanism and how catalytic activity decays. BiVO4 catalysts were capable of producing a maximum of 200 μmol of methanol per gram of catalyst from CO2 in basic media, and later decomposed by BiVO4. The decay of BiVO4¬ was studied by x-ray diffraction and scanning electron microscopy, demonstrating reversible decomposition of BiVO4. BiVO4 is etched, leeching vanadium into solution, while nanoparticles of bismuth oxide are deposited on the surface of BiVO4.
In Section 3, ferrocyanide salts, an aqueous, cheap, and abundant photocatalyst was used for the first time to dehydrogenate aqueous formaldehyde selectively into formate and hydrogen. The catalyst is capable of record turnovers and turnover frequencies for formaldehyde dehydrogenation catalysts. A preliminary mechanism was proposed from experimental and computational data.
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Ngwang, Helen Chonde. "Heterogeneous photocatalytic degradation studies of organic compounds in water." Thesis, Brunel University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393175.
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Bouleghlimat, Emir. "Materials for the photocatalytic treatment of recalcitrant organic waste." Thesis, Cardiff University, 2017. http://orca.cf.ac.uk/107678/.
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The photocatalytic degradation of cinnamic acid, by TiO2, has been studied extensively in aerobic and anaerobic conditions and in the presence of common salts often found in industrial waste waters. Analysis of the intermediates formed found that molecular oxygen is central to forming the important radicals for the main benzaldehyde mechanism by which cinnamic acid initially degrades, as well as a key component required for the mineralisation to carbon dioxide. In the absence of molecular oxygen an alternate, but slower, pathway becomes the prevalent. The hydroxyl driven mechanism is capable of decarboxylation of the initial carboxyl group but further oxidation does not occur at a reasonable rate. By investigating the effect of salts in solution we found that sulfates and chlorides both interfere with degradation mechanisms and decrease the mineralisation efficiency of titania photocatalysis. Sulfates blocked important surface sites needed for substrate binding that inhibited the benzaldehyde pathway and slowed down the degradation pathway. Whilst chloride formed radical chlorine species (Cl∙) in the presence of TiO2 that resulted in the increase of cinnamic acid removal and the emergence of new reaction pathways. Cl∙ competed with the superoxide radical anion (O2∙-) to attack across the double bond of cinnamic acid, decarboxylate and form several new acetophenone-derived intermediates. A widening of the intermediate map, through the formation of new intermediates, is coupled with a significant slowing of total mineralisation which presents real issues for photocatalytic waste water treatment where chloride ions are present. Additionally, the chlorine radical induced pathways produce intermediates of a greater toxicity; bringing the implication that partial oxidative degradation could result in waste water with an increased toxicity. Anodic nanotubes were explored as an option for alternative materials to be used within photocatalytic reactors. Nanotubes anodised for 8 hours were found to be the most photoactive in the liquid phase, and in the surface degradation of contaminants, due to the wider pores that were structurally sound enough to not slope and reduce light penetration. The surface topography was identified as the key factor for promoting photocatalysis. It was also found that the materials had a cross-phase applicability, in that the most active liquid phase nanotubes were also the most efficient for surface degradation. The incorporation of tungsten into the anodisation process did not improve the photocatalytic activity. Photodeposition of palladium and gold resulted in a decrease in the degradative efficiency of the nanotube arrays. Pd/TiO2 and Au/TiO2 powders were found to reduce the degradation rate of cinnamic acid in oxygenated conditions, although both metals improved the oxidation of surface deposits of carbon. In deoxygenated conditions, Pd/TiO2 catalysts exhibited superior degradation of cinnamic acid in comparison to plain TiO2 and gold doped catalysts. Enhancements in the mineralisation rates, to CO2, were also found. The improvements were attributed to the presence of palladium improving charge separation and introducing new reaction sites capable of decarboxylating the alcohol and aldehyde functionalities, respectively. While the gold nanoparticles were poorly dispersed, they were found to increase the selectivity for phenylacetaldehyde, in deoxygenated conditions, by a factor of 5.
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DAVYDOV, LEV. "PHOTOCATALYTIC DEGRADATION OF ORGANIC CONTAMINANTS: NOVEL CATALYSTS AND PROCESS." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin995381776.
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Davydov, Lev. "Photocatalytic degradation of organic contaminants novel catalysts and process /." Cincinnati, Ohio : University of Cincinnati, 2001. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=ucin995381776.
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Kuna, Ewelina Magdalena <1989>. "Spectroscopic study on diverse photocatalytic systems for organic transformations." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amsdottorato.unibo.it/9279/1/Kuna%20Ewelina%20Magdalena_PhD%20Thesis.pdf.
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The present doctoral dissertation was dedicated to select and develop an integrated photocatalytic system, which can be applied in organic reactions performed at liquid-liquid (homogenous reaction system) or liquid-solid (heterogenous reaction system) interface inside the microfluidic channels. The scientific strategy included (i) examination of potential photocatalysts upon various reaction conditions, (ii) selection of stable photocatalytic system and (iii) its implementation towards flow photochemistry by design an exemplar prototype of microfluidic devices for chemical transformations. Demonstrated strategy consist of consecutive protocols precisely described in subsequent chapters of this thesis.
First part of the discussion is concentrated on the selection of photoactive organic molecule, which can act as photocatalyst for further organic transformation. The significant efforts have been made to understand all the factors which affect the formation of stable and efficient photocatalytic system. On that basis, benzothiadiazole derivative compound is proposed as an environmentally friendly photocatalyst applicable in a simple dehalogenation and C-C bond formation reactions of thiophene compounds, as well as in photo-controlled polymerization reaction of methacrylate monomers.
Subsequently, to expand the scope of the photoredox catalysis towards flow technologies, the extensive spectroscopic studies on selected photocatalytic system, forming at the liquid-liquid and the solid-liquid interfaces inside the microchannel, were performed. This study allowed to design an exemplar prototype of microfluidic device, which can work upon homogenous and heterogeneous reaction conditions.
At the end, the potential application of inorganic photocatalyst towards flow photochemistry is briefly discussed. The ruthenium (Ru(bpy)2CN2) complex with cyanide ligands (CN-) is consider as a potential molecular module that may provide desire architecture of photocatalytic systems, especially under microfluidic conditions due to its self-assembling properties.
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Miao, Jing. "Simulated solar light assisted photocatalytic degradation of organic matters." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2015. https://ro.ecu.edu.au/theses/1638.
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The increasing human population combined with overexploitation of water resources for domestic purposes, industry, and irrigation, has resulted in a shortage of freshwater supply in many parts of the world. Advanced oxidation processes (AOP) have been applied widely to water and wastewater treatment, especially heterogeneous and homogeneous photocatalysis. The photocatalytic reactions take place under ambient operating conditions, but the photoactivity is usually constrained by the narrow wavelength spectrum for photonic activation of catalysts. The higher-end of ultraviolet (UV) spectrum required for catalyst activation is usually accompanied by high operation costs. From the viewpoint of solar energy utilization, the development of photocatalysis under ultraviolet-visible (UV-Vis) light is emerging as an important research direction in this field, and would be perceived as an advantage offering an energy-cost reduction for the AOPs.
The main goal of this study was to enlarge the existing knowledge in heterogeneous and homogeneous photocatalysis under UV-Vis light application for water decontamination. Commercial dyes, especially azo dyes, were chosen as target compounds, to investigate the degradation and mineralization by nanosized semiconductors or sodium hyperchlorite (NaClO) under the irradiation of UV-Vis from the solar simulators.
Acid red 14, a type of azo dye containing sulfonic groups and being commonly used as a textile dye, was chosen as a target compound, to investigate the degradation by a nanosized commercial TiO2 under simulated solar light. The characteristics such as phase features, specific surface area, bandgap energy, etc., of the nanosized TiO2 were investigated. The color removal rate, decrease rate of total organic carbon (TOC), and production rate of sulfate ions in aqueous solution were determined. Acid red 14 could be decolorized and mineralized efficiently with this nanosized TiO2 under simulated solar light. Acidic or neutral conditions were beneficial to the decolorization of acid red 14 aqueous solutions. Acid red 14 was nearly 100% mineralized after 60-min irradiation by simulated solar light under certain experimental conditions. The photocatalytic degradation efficiency increased with increasing irradiation intensity of solar simulated light. TiO2 dosage, pH value of aqueous solution, and initial concentration of acid red 14, had significant effects on the decolorization efficiency. It is feasible to use photocatalysis with this nanosized TiO2 under simulated solar light to efficiently degrade and mineralize acid red 14. The high photocatalytic efficiency of this TiO2 under simulated solar light might be related to its lower bandgap energy (Eg) and the relatively higher fraction of anatase phase.
The photocatalytic degradation of mordant black 11 under UV–Vis light, was investigated using a type of commercial nanosized zinc oxide (ZnO) as photocatalyst in aqueous solutions. Nanosized ZnO was characterized by different methods, including UV–Vis diffuse reflectance spectrum (UV–Vis DRS), X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) method, etc. The effects of influential experimental parameters on decolorization rate, including catalyst dosage, initial dye concentration, initial pH value, irradiation intensity, etc., were studied in details. It was found that after 60-min irradiation, the decolorization rate was only 58.4% at pH 2, but above 98% at natural (pH ~ 4.27) and alkaline conditions. Mordant black 11 could be nearly 100% decolorized after 60 min irradiation by UV–Vis light at natural/alkaline pH and 0.3 g/L dosage. It was found that alkaline pH increased the decolorization rate; an increase in irradiation intensity of UV–Vis light enhanced the degradation rate of the dye significantly at low dosage, while little influence as 0.3 g/L dosage.
The homogeneous photocatalytic degradation of Cibacron Brilliant Red 3B-A (BR 3B-A) in aqueous solution was investigated using sodium hypochlorite (NaClO) as the photocatalyst under the irradiation by UV-Vis light, including simulated solar light and that stronger in UV region. Compared with hydrogen peroxide (H2O2) and Fenton’s reagent at pH 3, NaClO showed much better photocatalytic performances: the decolorization rate reached 97% as dye concentration 100 ppm at the 1.0 g/L NaClO dosage and natural pH. Acidic conditions were more beneficial to the decolorization of BR 3B-A aqueous solution.
Ball milling (BM) was performed by changing the milling time from 0 to 12 h, and revolution speed fixed at 200 rpm. Ball milled TiO2 (A) was used to photocatalytically degrade three commercial azo dyes with different chemical structures. Firstly, BR 3B-A was photocatalytically degraded with the TiO2 (A) ball milled for different time periods. It suggested that among the samples, TiO2 (A) ball milled for 2 h showed the best photocatalytic degradation of BR 3B-A: decolorization rate reached 94.4% at 30 min, compared with 30.0% of the original TiO2 (A). Then TiO2 (A) ball milled for 2 h (BM2 TiO2 (A) )were chosen to photcatalytically degrade and mineralize BR 3B-A, Cibacron Brilliant Yellow 3G-P (BY 3G-P), and Astron Pink FG, with Chloride (Cl) linking to different kinds of Carbon atoms. As known from the ion chromatography (IC) results, the Chlorides broke apart from the aliphitic carbon much more easily and quickly than those connecting with Benzene and Thiazine. Cl- production rates were 99.7%, 78.1%, and 73.2%, respectively, for Astron Pink FG, BY 3G-P, and BR 3B-A at the same interval, after 60-min irradiation. An increase in the amorphous phase in a certain degree was presumably responsible for the increase in photocatalytic performance of TiO2 (A) ball milled for 2 h.
As clearly shown from the results, it is flexible to employ heterogeneous/homogeneous photocatalysis under simulated solar light and UV-Vis light stronger in UV region to degrade and mineralize the organic matters. It will be beneficial for decreasing the energy requirements, the decontamination cost, and the secondary pollution due to the relatively higher mineralization degree. Future study should be emphasized on the photocatalytic degradation of emerging organic pollutants, such as natural organic matters (NOM) like humic acid, pharmaceuticals, pesticides, etc., and prospect the possible mechanisms
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Lamprianidis, Panagiotis. "Photoredox catalysis with 10-phenyl-10H- phenothiazine and synthesis of a photocatalytic chiral proline-based organocatalyst." Thesis, KTH, Organisk kemi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-293510.
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Photoredox catalysis applications for the purpose of new synthetic routes in organic and sustainable chemistry are hot topics in organic synthesis today. In the present study, the synthesis of a chiral proline-based organocatalyst functionalized with 10-phenyl-10H phenothiazine (PTH) photocatalytic moietiesis investigated and attempted for the first time. PTH, an organic photocatalyst, isstudied for its photocatalytic activity in different organic reactions, such as dehalogenation of aromatic halides and the pinacol coupling reaction between aromatic aldehydes. These transformations are otherwise difficult to achieve without a suitable catalyst and the reactions were performed with moderate to high yields.Applikationer av photoredox-katalys med syftet att generera nya syntetiska vägar inom organisk och hållbar kemi är populära ämnen i organisk syntes idag. I denna studien undersöktes för första gången syntesen av en kiral prolinbaserad organokatalysator som är funktionaliserad med fotokatalytiska enheter (10-fenyl-10H-fenotiazin (PTH)). Den fotokatalytiska aktiviteten av PTH studerades för olika organiska reaktioner, såsom t.ex. dehalogenering av aromatiska halider och pinacolkopplingar mellan aromatiska aldehyder. Dessa transformationer är annars svåra att uppnå utan en lämplig fotokatalysator och reaktionerna utfördes med måttliga till höga utbyten.
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Chen, Yi-Chuan. "Effect of Ultrasound on the Photocatalytic Degradation of Organic Compounds." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1029262093.
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Bayless, Lynette Vera. "Photocatalytic oxidation of volatile organic compounds for indoor air applications." Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/1496.
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Zhou, Guanliang. "Photocatalytic degradation of organic compounds using carbon based composite catalysts." Thesis, Curtin University, 2013. http://hdl.handle.net/20.500.11937/1328.
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In recent decades, the applications of advanced oxidation processes (AOPs) for organic pollutants treatment in wastewater have been thoroughly investigated. These techniques base on chemical destruction and give a complete solution to the problem of wastewater containing toxic organics. Among these processes, semiconductor-based photocatalytic process has been employed as a low-cost, environmentally friendly and sustainable technique to purify water/wastewater. Meanwhile, chemical oxidation process is also considered as an effective remediation technique to reduce the concentrations of targeted toxic organics in wastewater to acceptable levels.The aim of this work is emphasizing the role of new synthesized catalysts in advanced oxidation process for wastewater treatment. The key conclusion of this thesis is that novel photocatalysts being capable to degrade organics in aqueous phase at room temperature were successfully synthesized and the investigation of “green cobalt based catalysts” for degradation of organic pollutants via advanced oxidation processes was achieved. Various types of catalysts were synthesized with hydrothermal carbonization method or wet impregnation method, and used for degradation of phenol in aqueous phase with UV-vis and visible light irradiation. Titanates: ZnTiO3, FeTiO3 and Bi4Ti3O12 were modified by coating cobalt (Co) to prepare photocatalysts. Microcarbon spheres were also synthesized by hydrothermal method, and used to support TiO2 (C-TiO2), nanoscaled zerovalent iron (nano-Fe0@CS), cobalt (micro-CS@Co) and graphitic carbon nitride (C-g-CN). All of these catalyst materials were tested for phenol degradation. Some of these synthesized catalysts were also examined for activating peroxymonosulfate (PMS, Oxone) for the decomposition of phenol.
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DIONYSIOU, DIONYSIOS D. "ENGINEERED PROCESS FOR THE PHOTOCATALYTIC TREATMENT OF ORGANIC CONTAMINANTS IN WATER." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin981726931.
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Mohamed, Elham Farouk. "Removal of organic compounds from water by adsorption and photocatalytic oxidation." Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0036/document.
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Les effluents industriels sont constitués de molécules de natures très diverses, plus ou moins réfractaires aux classiques traitements biologiques. Les normes de rejets évoluant régulièrement vers des contraintes de plus en plus sévères, il semble aujourd'hui nécessaire de proposer des solutions complémentaires pour atteindre de hauts rendements d'épuration. Le premier procédé mis en oeuvre dans ce travail est l'adsorption sur charbon actif. Le caractère novateur de cette technique se situe dans l'utilisation de charbons actifs fabriqués à partir de boues de stations d'épuration d'eaux usées. La seconde méthode est un procédé hybride innovant combinant adsorption et photocatalyse avec TiO2. Les eaux industrielles ciblées sont les effluents colorés, représentés par la tartrazine, et les effluents phénolés représentés par le phénol, l'acide p-hydroxybenzoïque, le p-chlorophénol er le p-nitrophénol. Pour traiter par adsorption les eaux chargées en phénols, plusieurs charbons actifs commerciaux et six charbons de boues ont été utilisés. Il ressort de cette première étude que, malgré leurs faibles surfaces spécifiques, certains charbons de boues présentent des performances très satisfaisantes. Le procédé séquentiel combinant adsorption et photocatalyse a été réalisé avec plusieurs matériaux: un tissu Ahlstrom contenant du charbon et du TiO2, un charbon actif avec dépôt de TiO2 par MOCVD puis un mélange de charbon actif et TiO2 en poudre. Des résultats prometteurs ont été obtenus pour dégrader la tartrazine, en particulier avec le TiO2 déposé sur charbon actif montrant que la proximité de sites d'adsorption et photocatalytique améliore les performances de l'oxydationIn order to explore a new sequential process for water treatment its two steps, adsorption on activated carbon and in situ photocatalytic oxidative regeneration, were investigated successively. Several commercial activated carbons (AC) and sewage sludge based activated carbons (SBAC) were tested with several phenols and one dye as pollutants. Despite low BET surface SBAC exhibits convenient adsorption properties. Photocatalysis on TiO2 was carried out with several materials to achieve activated carbon adsorption- egeneration process: a multilayer tissue with fixed granular AC and TiO2 on a sheet, a composite with TiO2, CVD deposited on AC, and AC-TiO2 powder mixture for comparison. Promising results were obtained especially with TiO2 deposited on AC proving the vicinity of adsorption and photocatalytic sites to be beneficial
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He, Xiang. "Metal-Organic Framework (MOF)-Based Materials: Aerosol Synthesis and Photocatalytic Applications." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5736.
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Metal-organic frameworks (MOFs) have been attracting great attention in the past several decades mainly because of their amazing properties, including tunable surface chemistry, flexible structure, large surface area, and huge porosity. Endorsed by those merits, MOFs have been applied in a wide range of applications, such as catalysis, gas separation, drug delivery, and sensing. Typically, MOFs are synthesized via the hydrothermal method, which, however, is difficult to scale up and requires long reaction durations (e.g., from hours to days). To achieve the full potentials of MOFs, the exploration of a novel strategy is necessary for the facile and fast synthesis of MOFs. Here in this dissertation, the aerosol route was presented as a facile route to synthesize MOFs and MOF-based composites. The aerosol route not only enabled fast crystallization of MOFs (i.e., within seconds), but also allowed continuous tuning of MOF’s properties by simply adjusting the operating parameters (e.g., temperature, pressure, and precursor conditions). To map out the formation mechanism of MOFs inside the microdroplets, systematic experimental and simulation work were carried out, which demonstrated that the fast heat and mass transfer during the aerosol route played a vital role in the rapid synthesis of MOFs.
Beyond the synthesis of MOFs, the photocatalytic applications of MOF-based materials for energy and environmental sustainability were also studied in detail. More specifically, several efficient MOF-based composite photocatalysts were designed, including HKUST-1/TiO2, HKUST-1/TiO2/Cu2O, ZIF-8/ZnO, and MIL-100(Fe)/TiO2. The composite photocatalysts exhibited remarkable efficiencies towards either CO2 photoreduction or water remediation. In-depth exploration of the photocatalytic mechanism was carried out with the aid of several advanced techniques, such as in situ diffuse reflectance infrared Fourier spectroscopy (DRIFTS), photoluminescence spectroscopy, grazing-incidence wide-angle X-ray scattering, and ultrafast transient absorption spectroscopy. Meanwhile, the density functional theory (DFT) calculation was also applied to provide further mechanistic insights. The results demonstrated that MOFs acted as excellent co-catalysts, which not only facilitated molecule adsorption and activation, but also promoted the separation of the photo-induced charge carriers, leading to increased charge carrier densities in the photocatalytic systems for significantly enhanced efficiencies.
The work from this dissertation is expected to broaden the synthesis strategies for the synthesis of MOF-based materials and advance the fundamental understanding of MOFs’ roles in photocatalytic applications, which should have a great impact on the rational design of MOF-based composite photocatalysts for energy and environmental sustainability.
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Xiao, Qi. "Visible light photocatalytic synthesis of fine organic chemicals with new photocatalysts." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/84078/14/Qi_Xiao_Thesis.pdf.
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This project was a step forward in developing new recyclable photocatalysts for chemical reactions. These new photocatalysts can facilitate reactions by using visible light under moderate reaction conditions which is suitable for a sustainable, green and eco-friendly modern chemical industry. The outcome of the study greatly extended our understanding in metal nanoparticle photocatalysis, which reveals new photocatalytic mechanisms for the controlled transformation of chemical reactions. The prospect of sunlight irradiation driving chemical reactions may provide opportunity for the organic synthesis via a more controlled, simplified, and greener process in the future.
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Riboni, F. "PHOTOCATALYTIC REACTIONS FOR ENERGY CONVERSION." Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/244319.
Full textAbstract:
General upward trends in fossil fuel consumption and CO2 emissions, along with the accepted belief that global chemistry substantially influences climate, require that scientific research provides efficient remedies and/or alternatives to the present scenario. Photocatalysis is often proposed as one of the most promising technique to achieve these purposes.
This PhD thesis is mainly focused on the investigation of TiO2-based systems for the photocatalytic oxidation of formic acid in aqueous suspension, as well as for H2 production by methanol photo steam reforming in the gas phase. Two different approaches were adopted to minimize the drawbacks usually characterizing TiO2 photocatalysts: i) TiO2-WO3 mixed oxide photocatalysts were prepared with the aim of reducing the recombination rate of photopromoted electron/hole pairs. The superior photocatalytic performance of the mixed oxide system was mainly attributed to the positive effect induced by W in efficiently trapping the photopromoted electron from the conduction band of TiO2, ensuring extended charge carriers separation. Even better results were obtained upon the surface modification with Pt nanoparticles which, by virtue of the metal high work function, further enhanced e-/h+ separation. ii) surface modification of TiO2 with Au nanoparticles, possessing a Localized Surface Plasmon Resonance (LSPR) at λ = 530 nm was proved to be an efficient way to promote TiO2 photoactivity under visible light irradiation. By selecting three titania samples (i.e., a stoichiometric, nearly non defective TiO2, a N-doped TiO2 and a oxygen vacancy-rich TiO2), evidence of two different plasmonic photoactivity mechanisms was provided, with the so-called hot electron transfer promoting plasmonic photoactivity in the stoichiometric TiO2 and Plasmon Resonance Energy Transfer accounting for the observed plasmonic visible light photoactivity of doped samples.
Being the abatement of CO2 through (photo)electrochemical reduction very challenging (E0(CO2/CO2-* = -2.14 V)), an alternative way has been studied: pyridinyl radicals (1-PyH*), photogenerated by irradiating a pyridine (Py) solution, were found to efficiently react with CO2 yielding a carbamic species (HPy-1-COOH), triggered by a stepwise mechanism where electron transfer from 1-PyH* precedes proton transfer. Formate (HCOO-) was also obtained, demonstrating that photoexcited pyridine does catalyze the 2e—reduction of CO2.
Finally, Fenton oxidation of gaseous isoprene on the surface of aqueous Fe2+ droplets, yielding carboxylic acids, polyols and carbonyl compounds, detected in situ through ElectroSpray Ionization Mass Spectrometry, accounted for alternative routes for the conversion of organic gases into secondary organic aerosol, occurring under tropospheric conditions, and may be incorporated into present atmospheric chemistry models.
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Sass, Danielle. "Nano silver-Iron-reduced graphene oxide modified titanium dioxide photocatalyst for the remediation of Organic dye in water systems." University of the Western Cape, 2018. http://hdl.handle.net/11394/6274.
Full textAbstract:
Magister Scientiae - MSc (Chemistry)Drinking water with high concentrations of inorganic and organic contaminants can cause adverse health defects. Specifically methyl orange dye is an organic water contaminant that has been known (along with others like methyl blue etc.) to have an increase in our water systems over the past few years due to increasing demand in industrial processes. It is therefore of utmost importance to remediate organic contaminants and ultimately enable prevention. The contaminants can be removed by photocatalysis. Anatase TiO2 is known for its photocatalytic degradation of environmental pollutants and photoelectro-chemical conversion of solar energy. However its application is limited since it is a wide band gap semiconductor, (Eg = 3.2 eV). The following study deals with the enhancement of the photocatalytic properties of TiO2 for remediation of organic water contaminants. The study was carried out to produce the two nanocomposites AgFe-TiO2 and AgFe-TiO2-rGO photocatalyst which purpose is to be cheap and easy to apply, with improved (fast and effective) photocatalytic degradation of methyl orange. The main objective was to decrease the band gap and to introduce intra-band gap states to absorb visible light. Modification of the TiO2 with small bandgap semiconductor, graphene and Ag- Fe nanoalloy reduced the bandgap energy for visible light absorption and photocatalytic degradation of methyl orange dye. The two composites were synthesised using sonication and chemical synthesis methods. A photocatalytic study (degradation of methyl orange dye) was carried out using a system incorporating an UV lamp source to determine the degradation of methyl orange catalysed by the synthesised photocatalysts AgFe-TiO2-rGO and AgFe-TiO2 along with UV-vis Spectroscopy. Morphological studies were carried out using HRSEM and HRTEM which determined the spherical agglomerated nature of AgFe-TiO2 and the sheet-like nature of AgFe-TiO2-rGO containing spherical agglomerants but that also contained pockets formed by the sheets of the rGO. XRD served as confirmation of the phase of TiO2 in both composites to be anatase. Analysis confirmed the formation and elemental determination of both composites. It was observed that the Band gap of TiO2 degussa decreased from 2.94 eV to 2.77 eV in the composite AgFe-TiO2. The photocatalytic reactivity of AgFe- TiO2 was an improvement from TiO2 and AgFe-TiO2-rGO based on the photocatalytic study. Therefore concluding that AgFe-TiO2 was the best catalyst to convert the dye (Orange II) into free radicals and ultimately remove the contaminant from the water compared to AgFe-TiO2-rGO.
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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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Noganta, Siyasanga. "Photocatalytic degradation of organic pollutants using Ag-Fe₃O₄/SiO₂/TiO₂ nanocomposite." Thesis, University of the Western Cape, 2015. http://hdl.handle.net/11394/5208.
Full textAbstract:
>Magister Scientiae - MScThe global lack of clean water for human sanitation and other purposes has become an emerging dilemma for human beings. The presence of organic pollutants in wastewater produced by textile industries, leather manufacturing and chemical industries is an alarming matter for a safe environment and human health. For the last decades, conventional methods have been applied for the purification of water but due to industrialization these methods fall short. Advanced oxidation processes and their reliable application in degradation of many contaminants have been reported as a potential method to reduce and/or alleviate this problem. Lately, it has been assumed that incorporation of some metal nanoparticles such as magnetite nanoparticles as photocatalyst for Fenton reaction could improve the degradation efficiency of contaminants. Core/shell nanoparticles, are extensively studied because of their wide applications in the biomedical, drug delivery, electronics fields and water treatment. The current study is centred on the synthesis of silver-doped Fe₃O₄/SiO₂/TiO₂ photocatalyst. Magnetically separable Fe₃O₄/SiO₂/TiO₂ composite with core–shell structure were synthesized by the deposition of uniform anatase TiO₂ NPs on Fe₃O₄/SiO₂ by using titanium butoxide (TBOT) as titanium source. Then, the silver is doped on TiO₂ layer by hydrothermal method. Integration of magnetic nanoparticles was suggested to avoid the post separation difficulties associated with the powder form of the TiO₂ catalyst, increase of the surface area and adsorption properties. Lastly and most importantly magnetic nanoparticles upsurge the production of hydroxyl groups or reduced charge recombination. The a synthesized catalysts were characterized using Transmission Electron Microscopy, X-ray Diffraction; Infra-red Spectroscopy, Scanning Electron Microscope and Energy Dispersive Spectroscopy. Other characterization techniques includeVibrating Sample Magnetometry, Brunauer Emmett Teller analysis and Thermogravimetric analysis. The average size of the particles size is 72 nm. Furthermore the photocatalytic performances of the magnetic catalysts were assessed in comparison with that commercial titanium dioxide for the degradation of methylene blue using photochemical reactor under ultra violet light. The results showed that the photocatalytic activity was enhanced using Fe₃O₄/SiO₂/TiO₂ and Ag-Fe₃O₄/SiO₂/TiO₂ compared with that for Fe₃O₄, commercial titanium dioxide powder.
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Meredith, Sylvia. "Synthesis of a Zinc Dipyrrin Complex for Photocatalytic Reduction of CO2." Digital Commons @ East Tennessee State University, 2021. https://dc.etsu.edu/honors/645.
Full textAbstract:
Zinc dipyrrin complexes have the potential to act as cheap, effective photosensitizers. Synthesizing and studying different types could lead to more efficient solar energy harvesting processes, especially the production of solar fuel. Here, two attempts to synthesize 1,3,7,9-tetraphenyl-5-mesityldipyrromethene are reported and discussed. According to 1H NMR, the first synthesis attempt was not successful. The second synthesis attempt was not purified effectively, so 1H NMR produced inconclusive results. Further purification strategies or alternate synthesis methods are required.
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Hakki, Amer [Verfasser]. "Novel photocatalytic organic synthesis : cyclization and N-alkylation of nitroaromatic compounds / Amer Hakki." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2013. http://d-nb.info/1049226887/34.
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Balayeva, Narmina Oktay [Verfasser]. "Visible-light-driven photocatalytic organic synthesis with surface modified TiO2-composites / Narmina Balayeva." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2020. http://d-nb.info/1216240957/34.
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Balayeva, Narmina [Verfasser]. "Visible-light-driven photocatalytic organic synthesis with surface modified TiO2-composites / Narmina Balayeva." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2020. http://d-nb.info/1216240957/34.
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BOSCHETTI, MICOL. "Water decontamination from organic micropollutants via photocatalytic solar systems based on WO3 photoanodes." Doctoral thesis, Università degli studi di Ferrara, 2020. http://hdl.handle.net/11392/2488195.
Full textAbstract:
The development of new materials and processes with a sustainable approach to allow an efficient removal from water sources of emergent contaminants, such as drugs and antibiotics, currently represents the next challenging task in water decontamination field. Photocatalysis and photoelectrocatalysis processes triggered via sunlight are among the most efficient Advanced Oxidation Processes for water decontamination. These methods are based on the interaction in water of natural light with oxide semiconductors, which generate high-reactive chemical species able to oxidize the organic micropollutants.
Here, the realization of two solar devices is presented, namely a parabolic concentrator and a modular stand-alone reactor. Their working principle is based on the photocatalysis and photoelectrocatalysis processes. As active material integrated within the solar devices, nanostructured tungsten trioxide was investigated via several realization techniques (solvothermal, electrochemical oxidation, and sol-gel) on glass and metal substrates. WO3-based electrodes attained photocurrents in the range of 1-5 mA/cm2, consistent with literature, and an activation in the visible part of the solar spectrum, up to 470 nm. Photodegradation tests, carried out on several specific drugs, showed outstanding results with an almost complete abatement in case of some pollutants, and a COD (Chemical Oxygen Demand) decrease of more than 60% in 1 h.
Both the solar devices could be scaled up in the next future for industrial scopes within the tertiary water treatment. Most importantly, they use a sustainable process, without additional energy costs, and with a possible hydrogen production as added value to the decontamination process.Nell'ambito del trattamento delle acque è emersa la necessità di sviluppare nuovi materiali e processi al fine di consentire un'efficiente rimozione di contaminanti emergenti, quali droghe e antibiotici, attualmente presenti nei bacini idrici, sfruttando un approccio sostenibile. I metodi di fotocatalisi e di fotoelettrocatalisi innescati da luce solare sono tra i processi di ossidazione avanzata più efficaci per la decontaminazione delle acque. Tali metodi sono basati sull'interazione in acqua di luce solare con ossidi semiconduttori; questa interazione genera specie chimiche altamente reattive, capaci di ossidare i microinquinanti organici, quindi purificando l'acqua. In questo lavoro sono presentati due dispositivi solari, ossia un concentratore solare e un reattore autonomo modulare, il cui principio di funzionamento si basa sui processi di fotocatalisi e fotoelettrocatalisi. Come materiale attivo integrato all'interno dei dispositivi solari è stato studiato il triossido di tungsteno nanostrutturato. In particolare, diverse tecniche di realizzazione (solvotermale, anodizzazione elettrochimica, e sol-gel) sono state caratterizzate sfruttando substrati in vetro e metallo. Gli elettrodi basati su WO3 hanno raggiunto fotocorrenti di 1-5 mA/cm2, consistenti con quelle riportate in letteratura, e un'attivazione nella parte visibile dello spettro solare fino a 470 nm. I test di fotodegradazione, effettuati su alcuni specifici medicinali, hanno mostrato notevoli risultati, con un abbattimento pressoché totale di alcuni inquinanti, e una diminuzione di oltre il 60% del COD (Domanda Chimica di Ossigeno) in 1 ora. Entrambi i dispositivi solari possono essere ampliati in un prossimo futuro a scopi industriali per il trattamento terziario delle acque, sfruttando un processo sostenibile, senza costi energetici aggiuntivi e con una possibile produzione di idrogeno come valore aggiunto al processo di decontaminazione.
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Weymouth-Wilson, Alexander Charles. "The photocatalytic addition of alcohols to 5-substituted furan-2(5H)-ones : scope and utility." Thesis, University of Reading, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320550.
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Calder, Raymond Michael. "An investigation into the photocatalytic activity of titanium dioxide." Thesis, University of St Andrews, 1990. http://hdl.handle.net/10023/2680.
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Ho, Po Yu. "New molecular materials for organic and dye-sensitized solar cells and photocatalytic hydrogen generation." HKBU Institutional Repository, 2016. https://repository.hkbu.edu.hk/etd_oa/280.
Full textAbstract:
Emerging solar energy technology, including photovoltaics, solar fuels generation and solar thermal systems, is considered as one of the most potential renewable energy resources because of the tremendous and free radiant energy supply by our sun. Unlike burning of fossil fuels, carbon dioxide emission-free energy conversion process is definitely another key feature and attracting scientists to explore these research areas. Besides, this implies a giant business market to compete with traditional fossil fuel companies. Nevertheless, it is too early to realize commercial application since the technologies are in the early development stage and there is still much room to explore and improve. Simply speaking, energy conversion efficiency, robustness, environmental impacts and cost are the major factors the community should deeply concentrate on at this moment. This provides many research opportunities on the creation of novel molecular functional materials and investigates the relationship between the molecular design and functional properties, and they obviously take up significant roles in the technology evolution. The basic concepts and conspectuses regarding organic photovoltaics and light-driven hydrogen generation are collected in Chapter 1. In Chapter 2, a series of new thiophene-based small molecules is presented and the discussion is focused on its application in the bulk-heterojunction organic solar cells. Importantly, the structure-property relationship is elucidated by varying the terminal electron withdrawing group and elongating the central electron donating unit. The highest power conversion efficiency (η) of 2.6% is attained by the device with compound M3 as the active material with traditional device configuration (without any annealing process and additives addition) under AM 1.5G irradiation. In Chapter 3, a series of DπA organic dyes is introduced and the discussion concentrates on its application in the dye-sensitized solar cells. Briefly, a case study on alkyl chain effects is investigated while a new starburst triarylamine donor and uncommon selenophene-containing π-linker are studied separately. The highest power conversion efficiency (η) of 6.7% is achieved by D11 under AM 1.5G irradiation with a high open-circuit voltage of 0.825 V. In Chapter 4, three new platinum(II) diimine complexes are synthesized and they are utilized as photosensitizers with platinized titanium dioxide as catalyst site in the context of light-driven hydrogen generation. Comparison between platinum(II) diimine dithiolate complex and platinum(II) diimine bis(acetylide) complex is accomplished, and the importance of photosensitization using an organic chromophore with a desirable energy transfer consideration is accounted. Finally, Chapter 5 puts forward the concluding remarks and possible future works while Chapter 6 includes all the experimental details of the studied compounds presented in Chapter 24.
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BALASUBRAMANIAN, GANESH. "EVALUATING THE EFFECT OF SELECTED PROCESS PARAMETERS ON THE PHOTOCATALYTIC DEGRADATION OF ORGANIC POLLUTANTS." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1012410668.
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Sass, Danielle Thandi. "Nano silver-iron-reduced graphene oxide modified titanium dioxide photocatalyst for the remediation of organic dye in water systems." University of the Western Cape, 2018. http://hdl.handle.net/11394/6410.
Full textAbstract:
Magister Scientiae - MSc (Chemistry)Drinking water with high concentrations of inorganic and organic contaminants can cause adverse health defects. Specifically methyl orange dye is an organic water contaminant that has been known (along with others like methyl blue etc.) to have an increase in our water systems over the past few years due to increasing demand in industrial processes. It is therefore of utmost importance to remediate organic contaminants and ultimately enable prevention. The contaminants can be removed by photocatalysis. Anatase TiO2 is known for its photocatalytic degradation of environmental pollutants and photoelectro-chemical conversion of solar energy. However its application is limited since it is a wide band gap semiconductor, (Eg = 3.2 eV). The following study deals with the enhancement of the photocatalytic properties of TiO2 for remediation of organic water contaminants.
2021-12-31
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James, Derak J. "Synthesis and photocatalytic activity of the MoS₂ and WS₂ nanoparticles in degradation of organic compounds." Muncie, Ind. : Ball State University, 2009. http://cardinalscholar.bsu.edu/653.
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Rezaei, Reza. "The impact of natural organic matter (NOM) on photocatalytic process for the degradation of micropollutants." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/60814.
Full textAbstract:
Photocatalytic oxidation process has been demonstrated as an effective technology for the removal of micropollutants in water. This process, however, is greatly affected by the presence of natural organic matter (NOM) in natural water, which interferes with treatment process by absorbing UV radiation and scavenging oxidant species. This research focused on investigating the effect of NOM on the photocatalytic oxidation of 2,4-dichlorophenoxy acetic acid (2,4-D), as target contaminant at different pH. Experiments were performed in fluidized photocatalytic reactor using template free photocatalyst spheres.
Changes in solution pH were used to decouple the effects of NOM on adsorption and major oxidative mechanisms, e.g., reactions on the surface of the photocatalytic spheres via positive hole mediation and in the solution via hydroxyl radicals (●OH) reaction. At pH 3, due to electrostatic attraction between solutes (2,4-D and NOM) and photocatalyst surface, photocatalytic oxidation mostly occurred via charge transfer on the surface of the photocatalyst. At pH 7, on the other hand, electrostatic repulsion between solutes and photocatalyst surface reduced adsorption and the process was primarily driven by hydroxyl radical reactions. The removal of 2,4-D reduced from 49% in the absence of NOM to 7% in the presence of 5 mgL-1 TOC NOM in neutral pH. At pH 3, this reduction was from 88% to 58%. It was observed that at neutral pH, due to higher aromatic moieties concentration and lower NOM adsorption, the effect of NOM on scavenging ●OH was considerable. This effect substantially decreased at low pH due to high adsorption of NOM.
Higher 2,4-D removal at low pH was also due to the effect of pH on the kinetic of photocatalytic oxidation. Photocatalytic oxidation at pH 7 followed first order kinetic model. At pH 3, on the other hand, the rate of oxidation was a combination of first order and L-H models. Furthermore, the dependence of rate constants on UV intensity changed with pH; the rate constant was directly proportional to UV intensity at pH 3; whereas it is proportional to the square root of intensity at pH 7.Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
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James, Derak J. "Synthesis and photocatalytic activity of the MoS2 and WS2 nanoparticles in degradation of organic compounds." CardinalScholar 1.0, 2009. http://liblink.bsu.edu/uhtbin/catkey/1503981.
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Nanoparticles of MoS2 and WS2 were synthesized by decomposing the
appropriate metal hexacarbonyl in the presence of sulfur dissolved in decalin at 140°C.
A significant fraction of the nanoparticles was ≤ 15 nm in diameter as verified by
Transmission Electron Microscopy. The process was repeated in the presence of silica
and then titania to produce supported metal sulfides. The unsupported nanoparticles were
found to exhibit a size-dependent shift in their threshold UV-visible absorption due to
quantum confinement. Photocatalytic properties of each sulfide from synthesis in decalin
were explored by using each as a catalyst in the photodegradation of methylene blue by
visible light. These sulfides were also used to catalyze the photodegradation of acetone.
Unsupported MoS2 and WS2 nanoparticles catalyzed the photodegradation of
acetone under visible light of ≥ 400 nm wavelength. This is the first study reporting the
photocatalytic properties of the unsupported WS2 nanoparticles. Photodegradation of
methylene blue under ≥ 435 nm irradiation was detected using unsupported WS2 but not
unsupported MoS2, likely because activity was masked by the likely photobleaching of
the dye. When deposited on silica or titania, the nanosized MoS2 and WS2 could be
uniformly distributed in aqueous solutions to maximize the photocatalytic efficiency. Correcting the absorbance measurements for light scattering by solids proved to be beneficial for extracting kinetic information. Both silica deposited sulfides were found to significantly increase the rate of methylene blue photodegradation, and deposited WS2 increased this rate significantly more than deposited MoS2. Similarly, both titania deposited sulfides significantly increased the rate of methylene blue photodegradation, and the deposited WS2 increased this rate significantly more than the deposited MoS2Synthesis of the sulfide photocatalysts -- Characterization of synthesized nanoparticles -- Photocatalytic degradation tests : setup and protocols -- Photocatalytic degradation tests : results.
Department of Chemistry
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AlSalka, Yamen [Verfasser]. "Photocatalytic Water Splitting for Solar Hydrogen Production and Simultaneous Decontamination of Organic Pollutants / Yamen AlSalka." Hannover : Gottfried Wilhelm Leibniz Universität, 2020. http://d-nb.info/1213445957/34.
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Ngo, Thuhuong T. "Photocatalytic Reduction of CO2 with Tunable Bandgap and Bandedge Materials." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6551.
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Solar energy is a sustainable resource which has substantial potential to meet the increasing demand for renewable energy. Though there has been some success in harvesting solar energy for electricity production, converting solar energy to chemical energy as fuels is still a challenge due to low efficiency.
Since the discovery of TiO2 photocatalysts for splitting water (4) and reducing CO2 (5) to form useful chemical feedstock such as H2, CO and CH4, much research has been done to increase the efficiency of photocatalysts. However, the current conversion efficiency of photocatalysts remains low (~5%) (6, 7). Issues being addressed include the wide bandgap and mismatched band edge for reactions (thermodynamic energy for reaction), poor quantum efficiency of the photon collector systems, high recombination of e-/h+ pairs and limitation in the rate of charge transfer from photocatalyst to reactants.
This work focuses on improving efficiency of photocatalysts for fuel production through several approaches: (1) engineering a metal-organic-framework (MOF) to have proper band gaps and band edges for targeted reactions and for enhancing photoadsorption in the visible light range, (2) tuning an ABO3-type perovskite for desired bandgaps and thermodynamically favored bandedges for CO2 reduction with water in visible light range.
A porphyrin-based Ti-MOF is studied for CO2 photoreduction to gaseous chemical fuels such as CH4 and CO. The porphyrin linkers allow porphyrin-based MOF-525 to achieve narrow bandgap (Eg = ~1.7eV) to absorb visible light, indicating its ability to harvest more solar energy than conventional TiO2. Ti/Zr-MOF-525 also exhibited the appropriate energy level alignment for CO2 and H2O redox reaction for CO and CH4 production. Its CO2 photoreactivity under visible light was demonstrated in a photoreaction, illuminated by 150W Xenon solar simulator. Interestingly, Ti/Zr-MOF-525 demonstrates a selectivity toward CH4, a more valuable fuels than CO. The gas phase reaction condition is an advance over liquid photoreaction. The catalyst stability was also studied and presented. After 3 cycles of reactions, Ti/Zr-MOF-525 is relatively stable for CO2 photoreduction and able to maintain its photoreactivity at about 60-65% of fresh catalyst. The reduction of reactivity is due to a less stable fresh catalyst.
When investigating LaCr1-xFexO3 perovskite oxides for photocatalyst, it was found that when replacing Cr ions at the B sites of LaCrO3 by Fe ions, the bandgap does not follow a linear trend in regards to metal ratio composition but rather reflects the smaller bandgap of LaFeO3. Bandedges were successfully measured for the new synthesized materials. At x = 0.25, the conduction band potential remains similar with x = 0. However, at x = 0.75, the conduction band potential was more negative than either perovskites at x = 0 or x = 1. Future simulation of density of state could address this interesting observation. CO2 reduction relativities of each perovskites were predicted well by their measured bandgaps and bandedges. Among five studied perovskites, synthesized LaCr0.25Fe0.75O3 (x = 0.75) is the most active for CO2 photoreduction under visible illumination at room temperature thanks to its small bandgap (2.0 eV) and its suitable bandedges for CO2 photoreduction.
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Mapukata, Sivuyisiwe. "Photocatalytic treatment of organic and inorganic water pollutants using zinc phthalocyanine-cobalt ferrite magnetic nanoparticle conjugates." Thesis, Rhodes University, 2019. http://hdl.handle.net/10962/67603.
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This work explores the synthesis and photophysicochemical properties of zinc phthalocyanines when conjugated to cobalt ferrite magnetic nanoparticles. Phthalocyanines with amine and carboxylic acid functional groups were synthesised so as to covalently link them via amide bonds to cobalt ferrite magnetic nanoparticles with carboxylic acid and amine groups, respectively. Spectroscopic and microscopic studies confirmed the formation and purity of the phthalocyanine-cobalt ferrite magnetic nanoparticle conjugates which exhibited enhanced triplet and singlet quantum yields compared to the phthalocyanines alone. The studies showed that the presence of cobalt ferrite nanoparticles significantly lowered fluorescence quantum yields and lifetimes. The conjugates not only showed much higher singlet oxygen quantum yields compared to the phthalocyanines alone but were also attractive because of their magnetic regeneration and hence reusability properties, making them appealing for photocatalytic applications. The photocatalytic ability of some of the phthalocyanines and their conjugates were then tested based on their photooxidation and photoreduction abilities on Methyl Orange and hexavalent chromium, respectively. For catalyst support, some of the zinc phthalocyanines, cobalt ferrite magnetic nanoparticles and their respective conjugates were successfully incorporated into electrospun polystyrene and polyamide-6 fibers. Spectral characteristics of the functionalized electrospun fibers confirmed the incorporation of the photocatalysts and indicated that the phthalocyanines and their respective conjuagates remained intact with their integrity maintained within the polymeric fiber matrices. The photochemical properties of the complexes were equally maintained within the electrospun fibers hence they were applied in the photooxidation of azo dyes using Orange G and Methyl Orange as model organic compounds.
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Liao, Longfei [Verfasser], Regina [Akademischer Betreuer] Palkovits, and Marcel [Akademischer Betreuer] Liauw. "Photocatalytic selective oxidation of alcohols over triazine-based organic polymers / Longfei Liao ; Regina Palkovits, Marcel Liauw." Aachen : Universitätsbibliothek der RWTH Aachen, 2021. http://d-nb.info/1235221792/34.
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Vildozo, Daniel. "Performance study of photocatalytic oxidation for the abatement of volatile organic compounds from indoor air environments." Thesis, Lyon 1, 2010. http://www.theses.fr/2010LYO10110.
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Ces derniers temps, des procédés commerciaux basés sur la technologie photocatalytique, sont arrivés sur le marché, afin de satisfaire la demande croissante du traitement de l’air intérieur. L’objectif de ce présent travail est de développer une nouvelle méthodologie pour évaluer l’efficacité de ce nouveau procédé. Pour l’étude de l’application de la photocatalyse au traitement de l’air intérieur, un dispositif expérimental a été mis au point et deux méthodes analytiques ont été développées (ATD-GCMS et GC-PDHID). La performance de la dégradation photocatalytique du 2-propanol et du toluène à faibles concentrations (ppbv) a été étudiée. L’influence des différents paramètres (humidité relative, débit, concentration initiale, etc.) et leurs interactions sur la conversion, la formation des intermédiaires et la minéralisation au CO2 a été établieMany commercial systems based in the photocatalytic technology have reached the market recently in order to address the growing demand for improve poor indoor air qualities. The present work deals with the development of a new methodology in order to evaluate the efficiency of this process. For the study of photocatalytic oxidation for indoor air applications, an experimental set-up was designed and two analytical tools (ATD-GC-MS and GC-PDHID) were developed. The performance of the photocatalytic treatment of 2-propanol and toluene at indoor air concentrations levels (ppbv) were realised. The influence of several parameters and their interactions effects on the conversion, by-product formation and mineralization to CO2 were established
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Huang, Yan. "Synthesis, Kinetic and Photocatalytic Studies of Porphyrin-Ruthenium-Oxo Complexes." TopSCHOLAR®, 2010. http://digitalcommons.wku.edu/theses/182.
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Macrocyclic ligand-complexed transition metal-oxo intermediates are the active oxidizing species in a variety of important biological and catalytic oxidation reactions. Many transition metal catalysts have been designed to mimic the predominant oxidation catalysts in Nature, namely the cytochrome P450 enzymes. Ruthenium porphyrin complexes have been the center of the research and have successfully been utilized, as catalysts, in major oxidation reactions such as the hydroxylation of alkanes. This study focuses on kinetic and photocatalytic studies of oxidation reactions with wellcharacterized high-valent ruthenium-oxo porphyrin complexes. The trans-dioxoruthenium(VI) porphyrins have been among the best characterized metal-oxo intermediates and their involvement as the active oxidant in the hydrocarbon oxidation have been extensively studied. Following the literature known methods, a series of trans-dioxoruthenium(VI) porphyrin complexes (3a-b) were synthesized and spectroscopically characterized by UV-vis, IR and lH-NMR. In addition to the well-known chemical methods, we developed a novel photochemical approach for generation of trans-dioxoruthenium(VI) porphyrins with visible light. The fast kinetic study of two-electron oxidations of para-substituted phenyl methyl sulfides by these dioxoruthenium(VI) species was conducted by using stopped-flow spectroscopy. Results showed that the decay of trans--dioxoruthenium(VI) porphyrins in the presence of reactive sulfides follows a biexponential process. The reactivity order in the series of dioxoruthenium complexes follows TPFPP> TPP> TMP, consistent with expectations based on the electrophilic nature of high-valent metal-oxo species. Moreover, the sulfoxidation reactions are 3 to 4 orders of magnitude faster than the well-known epoxidation reactions. In addition, several ruthenium porphyrins were used as the catalysts in the competitive oxidation reactions to identify the kinetically competent oxidants during catalytic turnover conditions. The photocatalytic studies of aerobic oxidation reactions of hydrocarbons catalyzed by a bis-porphyrin-ruthenium(lV) fl-OXO dimer using atmospheric oxygen as oxygen source in the absence of co-reductants were investigated as well. The ruthenium(lV) fl-OXO bisporphyrin (6a) was found to catalyze aerobic oxidation of a variety of organic substrates efficiently. By comparison, 6a was found to be more efficient photocatalyst than the well-known 3a under identical conditions. A KIE at 298K was found to be larger than those observed in autoxidation processes, suggesting a nonradical mechanism that involved the intermediacy of ruthenium(V)-oxo species as postulated.
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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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Gao, Yao. "A Novel Multifunctional Photocatalytic Oxidation (PCO) Gel Preventing Mold/Mildew Growth and Volatile Organic Compound (VOC) Emission." Scholarly Repository, 2011. http://scholarlyrepository.miami.edu/oa_dissertations/623.
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With the increasing time people spend indoors, the indoor environment quality draws more and more attention. The concentration of indoor pollutants is usually much higher than outdoors, in which volatile organic compounds (VOCs) and mold/mildew are both major pollutants and cause many health problems to residents. Efforts devoted from academy and industry to protecting people from indoor environment problems are apparently not sufficient. Photocatalysts, such as TiO2, WO and ZnO, can absorb light photons and react with O2 and H2O to generate highly oxidative radicals, which can oxidize VOCs and disinfect microorganisms. Recently, this photocatalytic oxidation (PCO) technology has been intensively studied to reduce VOCs and disinfect bacteria in the indoor environment. Few papers address the indoor mold/mildew problem, and this research therefore endeavors to do so. The objectives are to evaluate the effectiveness of PCO technology to resist mold/mildew growth and prevent VOC emission from building materials under either UV or visible light irradiation. The models, including linear regression, logistic regression, and numerical model, are also built for interpreting experimental results and for predicting performance in application. The mold/mildew resistance of different PCO gels was examined using accelerated mold/mildew growth agar plate tests. These gels included TiO2 only and TiO2 in combination with H2O2 and with Ag. Without the application of PCO gels, no mold/mildew inhibition was observed from UV (365 nm) or visible light. Under UV light irradiation, the TiO2 gel achieved complete mold/mildew inhibition. Without light, a 12-day delay of mold growth was obtained using the Ag-TiO2/H2O2 gel. Under visible light irradiation, the Ag-TiO2/H2O2 gel was also the most effective PCO gel with a 8-day delay of mold growth, which, however, was shorter than the same gel in the condition of no light with a 10-day delay due to the light-induced deterioration of the Ag-TiO2. The reduction of VOC emission from PCO gel (TiO2 gel and Ag-TiO2/H2O2 gel) coated building materials under UV or visible light irradiation was also confirmed by small chamber tests (the Ag-TiO2/H2O2 gel with above 50% reduction of total VOC emission). A linear model was obtained for the Ag-TiO2/H2O2 gel in the condition of no light, with respect to the correlation between the delay of mold growth and the gel ingredients. A logistic model was created for predicting the probability of mold growth on different TiO2 gels with different UV light exposure time at different intensities. A numerical model was developed with better accuracy than the previous one for VOC emission from PCO gel coated building materials. This study showed that the PCO gel might be a promising multifunctional material in resisting mold/mildew growth and preventing VOC emission in the indoor environment (The TiO2 gel for complete mold/mildew inhibition and the Ag-TiO2/H2O2 gel for delay of mold growth in emergency situations and reduction of VOC emission from building materials). More stable Ag-TiO2 or other visible-light-driven photocatalysts are needed in future research because of the deterioration of the current one.
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Atitar, Mohamed Faycal [Verfasser]. "Surface interactions and kinetics of TiO2 photocatalytic oxidation of organic pollutants in aqueous solution / Mohamed Faycal Atitar." Hannover : Technische Informationsbibliothek (TIB), 2018. http://d-nb.info/1166088022/34.
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Kralik, Antonin [Verfasser], and Burkhard [Akademischer Betreuer] König. "Heterogeneous photocatalytic water splitting as a source of redox equivalents for organic synthesis / Antonin Kralik ; Betreuer: Burkhard König." Regensburg : Universitätsbibliothek Regensburg, 2019. http://d-nb.info/1196873445/34.
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Tilgner, Dominic [Verfasser], and Rhett [Akademischer Betreuer] Kempe. "The Modification of Porous Coordination Polymers or Metal-Organic Frameworks for Photocatalytic Applications / Dominic Tilgner ; Betreuer: Rhett Kempe." Bayreuth : Universität Bayreuth, 2018. http://d-nb.info/1163319139/34.
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Akly, Christina. "Counter flow silica-titania photocatalytic reactor for the simultaneous treatment of air and water contaminated with volatile organic compounds." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0024998.
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Zhai, Yuxin. "Spectroscopic Studies of Adsorbed CO2 on Polyamines and Photo-generated Electrons in Photocatalytic Synthesis." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1538145926835136.
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