Academic literature on the topic 'Photocalyse'

The paper reports a work done on photocatalytic degradation of an Industrial dye Sulphur Black 1 with the help of Strontium Chromate photocatalyst. The experiment was controlled by photocalayst, visible light and air. And also studied the effect of hydrogen ion concentration, dye concentration and quantity of catalyst on the photodegradation. The experiment observed by spectrophotometrically at definite time gape

We discuss recent applications of first principles electronic structure calculations and molecular dynamics simulations to understand materials properties and reaction mechanisms in TiO2-based photocalysis. We focus on the structure of the TiO2-water interface, the behavior of photoexcited electrons at this interface, and the formation and structure of so-called black TiO2, a promising functional material capable to absorb the whole spectrum of visible light.

ZnO/TiO2 nanocomposites with several ratio of the components were prepared by sol-gel method using titanium isopropoxide and titanium butoxide as titania precursors. Phase formation and photocatalytic activity of ZnO/TiO2 nanocomposites depend on ratio of the components and calcination temperature. The photocatalytic activity in dependence on calcination temperasture, phase composition was determined by degradation of methylene blue solution under Hg lamp and solar light imitating illumination. The highest photocatalytic activity showed ZnO/TiO2 nanocomposites containing 99 mol.% ZnO and 50 mol% ZnO when hexagonal ZnTiO3 phase was formed. ZnO/TiO2 nanocomposites exhibited enhanced photoactivity under solar light with respect to Hg lamp irradiation.

Antibiotics have played a positive role in human health and. But underutilized antibiotics can’t be removed by normal treatment. The paper study the impact of fiber optical reactor catalytic degradation of oxytetracycline and step to examine the degradation effect. The results show that: temperature increases within a certain range contribute to the degradation of the oxytetracycline. Effects of pH on the photocatalytic reaction were significant, and alkaline conditions is more conducive to oxytetracycline photocatalytic degradation. In the concentration range of the experimental study, oxytetracycline photocatalytic degradation was inhibited by the higher initial concentration. Catalyst promoted oxytetracycline degradation, its addition amount on photocatalytic reaction influence is relatively large, when the pH is 7, with the increase of nano-TiO2 dosage, removal rate was gradually increased. The degradation rate of oxytetracycline in different reaction process can be shown as: photocalysis＞photolysis＞hydrolysis in this research.

Forming nanomaterials junctions and using plasmons represent two important, promising strategies for realizing broadband photocalysis in strategically important applications such as solar fuels and photocatalytic degradation of pollutants. In this talk, I will present some of our recent work on the rational design of nanohybrids and their applications in solar fuels and photocatalysis. One example is about the in situ synthesis of plasmonic Ag nanoparticles (AgNPs) and Ag-MOF. The intimate and stable interface between the AgNPs and Ag-MOF and hot electron transfer from the plasmonic AgNPs to MOF led to highly efficient visible-light photocatalytic H2 generation in aqueous solution, which surpasses most of reported MOF-based photocatalytic systems. This work sheds light on effective electronic and energy bridging between plasmonic NPs and MOF. References: [1] Nature communications, 12: 1231 (2021); [2] Nature communications, 2023, in press; [3] Chemistry of Materials, 2021, 33, 695-705; [4] Adv. Funct. Mater. 2019, 1902486.

Ce travail a été effectué dans le domaine de la dépollution des eaux par les procédés d'oxydation avancés, en particulier la photocatalyse en milieux homogène (Réaction de Fenton et photo-Fenton) et hétérogène (photocatalyse à base de TiO2). En milieu homogène, le mécanisme de dégradation d'un polluant, l'acide 2,4 dihydroxybenzoïque par les réactions de Fenton et photo-Fenton a été étudié précisément grâce à différentes techniques analytiques (spectrophotome��trie UV-visible, HPLC, HPLC couplée à la masse, chromatographie ionique, mesures de COT). L'étude des différents paramètres a permis de mettre en évidence que les premières étapes de la réaction d'oxydation du polluant sont communes aux deux procédés. Cependant, l'énergie photonique apportée dans le cas du procédé photo-Fenton est cruciale pendant l'étape de minéralisation et l'importance de paramètres tels que les conditions d'oxygénation du milieu réactionnel lors de cette étape a été prouvée. L'étude de la complexation du Fe(III) et des ses conséquences lors de l'oxydation d'une série de dérivés de l'acide benzoïque par les procédés de type-Fenton et photo-Fenton a été réalisée. La comparaison de la réactivité photochimique des complexes [acides aromatiques-Fe(III)] pour la formation de Fe(II) à celles des complexes ferriaqueux et ferrioxalate a montré la relative stabilité photochimique des complexes [acides aromatiques-Fe(III)] sous irradiation UV-visible. L'identification d'espèces réductrices (type hydroquinone) à des moments clés de la réaction a permis d'expliquer les profils cinétiques autocatalytiques observés lors de l'oxydation des acides aromatiques étudiés par les procédés de type Fenton et photo-Fenton. Dans le domaine de la photocatalyse en milieu hétérogène, de nouveaux photocatalyseurs à base de TiO2 dopé (par S, Ce(III), Fe(III)) ont été synthétisés par la méthode sol-gel. Ils ont été caractérisés par diffraction des rayons X, BET et spectrophotométrie UV-visible. L'efficacité photocatalytique a été testée par oxydation du 2,4-DHBA. Les photocatalyseurs à base de TiO2 dopés par S et Ce(III) possèdent une efficacité photocatalytique dans la région du visible supérieure à celle obtenue en utilisant le TiO2 commercial (P25, Degussa) traditionnellement utilisé en photocatalyse
This work was carried out in the field of water treatment using advanced oxidation processes (AOPs), especially Fenton and photo-Fenton processes and heterogeneous TiO2 photocatalysis. The mechanism of the oxidative degradation of a model pollutant, 2. 4 dihydroxybenzoicacid (2,4-DHBA) by the Fenton and photo-Fenton processes was investigated in detail using several analytical techniques (UV-visible spectrophotometry, HPLC, LC-MS, ion chromatography, TOC measurements). The results show that the early stage of oxidation of the pollutant is common to both processes. However, mineralization could only be achieved under irradiation (photo-Fenton) and the importance of parameters such as oxygenation conditions at this stage of the reaction was demonstrated. The complexation of Fe(III) and its consequences during the oxidation of benzoic acid derivatives by the Fenton and photo-Fenton-like processes were investigated. The comparison of the photochemical reactivity of [aromatic acid-Fe(III)] complexes for the production of Fe(II) with that of others iron(III)-complexes (such as ferriaquo complexes and ferrioxalate) showed the relative photochemical stability of [aromatic acid-Fe(III)] complexes under UV-visible irradiation. The identification of reducing species (e. G. , hydroquinone) at key reaction times provided an explanation for the observed autocatalytic kinetic profiles during the oxidation of aromatic acids by Fenton and photo-Fenton like processes. In the field of heterogeneous photocatalysis, new doped (sulfur, cerium(III), iron(III))-TiO2 photocatalysts were synthesized by a sol-gel method. They were characterized by X-ray diffraction, BET and UV-visible spectrophotometry. All of them absorb visible light (400-800nm). Their photocatalytic efficiency was tested on the oxidation of 2,4-DHBA. Under our conditions, iron(III) doping was detrimental for photocalytic efficiency under UV-irradiation and no improvement was observed under visible-irradiation. The new S and Ce(III) doped TiO2 showed a higher photocatalytic efficiency in the visible region than that obtained using commercial TiO2 (P25, Degussa), traditionally employed in photocatalysis

O processo de liquefação hidrotermal (HTL) pode converter diversos tipos de biomassa em óleo bruto. Além do produto principal, é gerado um efluente (PHWW) com elevada carga orgânica, quantidades altas de nutrientes e compostos tóxicos. Para lidar com este tipo efluente tem-se sugerido a combinação de tratamentos físico-químicos e biológicos. O objetivo deste estudo foi avaliar a aplicação de processos oxidativos (por H2O2 e fotocatálise com TiO2) e digestão anaeróbia no tratamento do efluente da liquefação hidrotermal de Spirulina. Inicialmente caracterizou-se o efluente em termos de carga orgânica, nutrientes e compostos nitrogenados cíclicos (CNC). Posteriormente, avaliou-se a concentração de oxidante e o tempo de reação no processo de oxidação com H2O2. O tratamento fotocatalítico foi então avaliada no tratamento do efluente em questão, isoladamente, em sequência e combinada ao processo de oxidação por ação de H2O2. Finalmente combinaram-se os processos de oxidação por ação de H2O2 e digestão anaeróbia no tratamento de efluente de PHWW. O efluente da liquefação hidrotermal de Spirulina apresentou elevada carga orgânica, pH alcalino e concentrações altas de nutrientes (nitrogênio e fósforo). Verificou-se também a presença de CNC como pirazinas, δ-valerolactama, caprolactama e butirolactama. A aplicação do processo oxidativo por H2O2 no tratamento de PHWW apresentou efeitos positivos, principalmente para a descoloração que atingiu 93,8 %. A eficiência máxima de remoção de DQO foi de 15,3%. Foi percebida também redução nas concentrações dos CNC. A eficiência do processo de oxidação avançada por fotocatálise e H2O2 foi maior do que obtida quando estes processos foram aplicados separadamente. A aplicação dos processos combinados apresentou eficiência de remoção de cor e DQO semelhante às obtidas quando os processos foram aplicados em sequência, propiciando economia de tempo de reação. Por fim, verificou-se que a digestão anaeróbia do efluente pré-tratado com H2O2 apresentou maior produção de CH4 e remoção de matéria orgânica quando comparada com a digestão anaeróbia que o efluente in natura. Assim, conclui-se a utlização de processos oxidativos avançados ou a combinação da oxidação por H2O2 com a digestão anaeróbia são alternativas promissoras para o tratamento da PHWW.
The hydrothermal liquefaction process (HTL) can convert various types of biomass into bio-crude oil. In addition to the main product, wastewater (PHWW) is generated with high organic content, high amounts of nutrients and toxic compounds. To cope with this type of wastewater the combination of physicochemical and biological treatments has been suggested. The aim of this study was to evaluate the application of oxidative processes (using H2O2 and photocatalysis with TiO2) and anaerobic digestion in the treatment of hydrothermal liquefaction of Spirulina wastewater. Firstly, PHWW was characterized in terms of organic matter, nutrients and nitrogen heterocyclic compounds (CNC) concentrations. Secondly, the oxidant concentration and the reaction time in the oxidation process using H2O2 was evaluated. Photocatalytic treatment was then tested isolated, in sequence and combinated with the oxidation processo using H2O2. Finally, oxidation with H2O2 and anaerobic digestion were combinated and evaluated. The PHWW showed high organic load, alkaline pH and high concentrations of nutrients (nitrogen and phosphorus). The presence of CNC as pyrazines, δ-valerolactam, caprolactam and butyrolactam was also verified. The application of the oxidative process using H2O2 showed positive effects mainly for color removal, which reached 93.8%. The maximum efficiency of COD removal was 15.3%. Reduction in CNC concentrations was also observed . The efficiency of the advanced oxidation process (by combining photocatalysis and H2O2) was greater than that obtained when these processes were applied separately. The application of the combined process presented color and COD removal efficiencies similar to those obtained when the processes were applied in sequence, allowing reaction time savings. Finally, the anaerobic digestion of pre-treated (with H2O2) PHWW showed a greater CH4 production and higher organic matter removal, compared to anaerobic digestion of in natura PHWW. Thus it is possible to conclude that the utlization of advanced oxidation processes or the combination of oxidation with H2O2 and anaerobic digestion are promising alternatives for the treatment of PHWW.

碩士
樹德科技大學
經營管理研究所
94
In this thesis, the application of design of experiment at the research and development stage is investigated. The process parameters and the hydrophilic properties of sputter deposited TiO2 thin films have been studied as an example by design of experiment approach. The TiO2 thin films were deposited on glass substrates using a UBM (Unbalanced Magnetron Sputtering) system. Wetting angle of the TiO2 thin films under ultraviolet ray was chosen as the indicator for the hydrophilic property. The coating parameters evaluated are sputtering atmosphere, target current, bias voltage, and ion bombard condition on specimen surfaces. The Taguchi optimization methodology, Response Surface Methods (RSM), Genetic Algorithm (GA), and Back-Propagation Network (BPN) method are employed to analyze the effect of these coating parameters. Analysis of the result shows that the bias of substrate is key parameter for the hydrophilic performance of TiO2 thin films。 The study shows satisfied results could be expected by the approach of design of experiments.

碩士
國立雲林科技大學
工業化學與災害防治研究所
93
In this study, nano-composite Ag/TiO2 phototcatalyst has been prepared by sol-gel method with addition of silver. The effect of different Ag/TiO2 molar ratios and annealed temperature on the properties of nano-composite photocatalyst material has been discussed. The samples were characterized by various analytical techniques, such as Thermogravimetric Analysis(TGA), UV-Visible Diffuse Reflectance Spectroscopy(UV-Visible), X-Ray Diffraction(XRD), low temperature N2 adsorption(BET), Transmission Electron Microscope(TEM) and Scanning Electron Microscope(SEM). The photocatalytic activity of the prepared sample was evaluated by photolysis solid–liquid phase of methylene blue and the solid-gas phase of aldehyde and anti-bacterial activity. The result of TGA reveals that the steady state temperature is 500℃ for titania, but the nano-composite Ag/TiO2 improves the steady state temperature up to 600℃. The result of XRD reveals that nano-composite Ag/TiO2 shows a significance of phase transition from anatase to rutile in comparison with pure titania. The temperature change for phase transition from 600℃(TiO2) to 700℃(Ag/TiO2) indicates that silver loading is capable of inhibiting phase transition. Moreover, the result of UV visible analysis shows that the addition of silver cause no change on the band gap energy of TiO2. From TEM and SEM micrographs, the grain size of TiO2 at 500℃ is approximately 15~20nm. however, the grain size of Ag/TiO2 at the same temperature is approximately 10~15nm. Therefore, it is understood that silver loading inhibits the growth of TiO2 crystal size. The specific surface area of 44.714m2/g for TiO2 was determined from the BET analysis, the result reveals that an applicable amount of silver loading will increase specific surface area, but in excess it will decrease specific surface area. Thus 2%Ag/TiO2 is preferred which gives the best specific surface areas of 63.24m2/g. The solid-liquid phase photocatalytic reaction of nano-composite 2%Ag/TiO2 photocatalyst under UV light exposure for 420 min demonstrated nearly 90% degradation of methyl blue. Under a similar condition the solid-gas phase photocatalytic reaction of nano-composite 2%Ag/TiO2 photocatalyst was exposed for 240 min and demonstrated nearly 92% degradation of acetaldehyde. On anti-bacterial test it was found that 2%Ag/TiO2 nano-composite material have good anti-bacterial properties. From all of the test results, it is clear that the silver loading TiO2 is able to increase the photocatalytic activity and have good anti-bacterial properties.