Dissertations / Theses on the topic 'Magnetic photocatalyst'

A aplicação de semicondutores no tratamento de água e efluentes líquidos é uma tecnologia de remediação ambiental promissora, em especial para poluentes orgânicos. Entre os vários semicondutores que também são fotocatalisadores, o TiO2 é amplamente usado em aplicações ambientais, por ser inerte biológica e quimicamente, ter elevado potencial de oxidação, baixo custo e estabilidade frente à corrosão. Entretanto, o TiO2 também tem algumas desvantagens, tais como: ele é excitado apenas por luz UV e requer uma operação unitária adicional (por exemplo, filtração ou centrifugação) para o reuso do catalisador. Para contornar estas limitações, usou-se um procedimento simples para a síntese de um fotocatalisador magnético (Fe3O4/TiO2) com alta área superficial específica e atividade catalítica, quando comparado com o TiO2 P25 da Evonik. O fotocatalisador foi sintetizado através de um procedimento em três etapas: (1) Partículas α-Fe2O3 foram obtidas por precipitação de uma solução de FeCl3.6H2O 0.01 mol L-1, que foi submetida a uma hidrólise forçada à 100°C por 48 h; (2) Partículas de α-Fe2O3/TiO2 foram obtidas por heterocoagulação de oxi-hidróxidos de Ti(IV) sobre as partículas de α-Fe2O3, as quais foram calcinada a 500°C por 2 h; e (3) As partículas \"casaca/caroço\" do fotocatalisador foram obtidas por calcinação a 400°C por 1 h sob atmosfera redutora (H2). A atividade fotocatalítica do material sintetizado foi avaliada aplicando-o no descoramento de uma solução do corante Azul Ácido 9 (C.I. 42090). Os efeitos do pH e da concentração de catalisador foram estimados por meio de um planejamento fatorial 22. Foi obtido um fotocatalisador com área superficial específica de 202 m2 g-1, facilmente separável do meio reacional em aproximadamente 2 min com o auxílio de um ímã. O fotocatalisador apresentou absorção em toda a região do visível. A maior remoção de cor (54%) foi obtida com pH 3,0, 1,0 g L-1 de catalisador e 2 horas de reação.
The use of semiconductors for treating polluted waters and wastewaters is a promising environmental remediation technology, especially for organic pollutants. Among the several semiconductors that are also photocatalysts, TiO2 is extensively used for environmental application, due to its biological and chemical inertness, high oxidation power, low cost, and stability regarding corrosion. However, TiO2 also has some disadvantages, such as: it is only UV-excited and requires an additional unit operation (e.g. filtration or centrifugation) for reuse purposes. In order to work around those limitations, a simple procedure for synthesizing a magnetic photocatalyst (Fe3O4/TiO2), with high specific surface area and good photocatalytic activity when compared to Evonik\'s TiO2 P25, was used. The photocatalyst was synthesized in a three-step procedure: (1) α-Fe2O3 particles were obtained, by precipitation, from FeCl3.6H2O 0.01 mol L-1, which underwent a forced acid hydrolysis at 100°C for 48 h; (2) α-Fe2O3/TiO2 particles were obtained, by heterocoagulation, of Ti(IV) oxide species on the α-Fe2O3, followed by calcination at 500°C for 2 h; and (3) The core/shell photocatalyst particles were obtained by calcination the α-Fe2O3/TiO2 particles at 400°C for 1 h under reducing atmosphere (H2). The photocatalytic activity of the synthesized material was assessed by the color removal of an Acid Blue 9 (C.I. 42090) dye solution. pH and catalyst dosage effects were estimated by a 22 factorial design. Fe3O4/TiO2 core/shell particles with specific surface area of 202 m2 g-1were obtained. They were easily separated from the reaction medium, in approximately 2 min, with the aid of a magnet. The photocatalyst absorbed radiation throughout the visible spectrum. The greatest color removal (54%) was achieved with pH 3.0, 1.0 g L-1 of photocatalyst, and 2 h of reaction.

Magnetic photocatalysts were synthesised by coating a magnetic core with a layer of photoactive titanium dioxide. This magnetic photocatalyst is for use in slurry-type reactors in which the catalyst can be easily recovered by the application of an external magnetic field. The first attempt at producing this magnetic photocatalyst involved the direct deposition of titanium dioxide onto the surface of magnetic iron oxide particles. The photoactivity of these Fe3O4/TiO2 was lower than that of single-phase TiO2 and was found to decrease with an increase in the heat treatment. These observations were explained in terms of an unfavourable heterojunction between the titanium dioxide and the iron oxide core. Fe ion diffusion from the iron oxide core into the titanium dioxide matrix upon heat treatment, leading to a highly doped TiO2 lattice, was also contributing to the observed low activities of these samples. These Fe3O4/TiO2 particles were found to be unstable, with photodissolution of the iron oxide phase being encountered. This photodissolution was dependent on the heat treatment applied, the greater the extent of the heat treatment, the lower the incidence of photodissolution. This was explained in terms of the stability of the iron oxide phases present, as well as the lower photoactivity of the titanium dioxide matrix. In fact, the observed photodissolution was found to be induced-photodissolution. That is, the photogenerated electrons in the titanium dioxide phase were being injected into the lower lying conduction band of the iron oxide core, leading to its reduction and then dissolution. Thus, the approach of directly depositing TiO2 onto the surface of a magnetic iron oxide core proved ineffective in producing a stable magnetic photocatalyst. The introduction of an intermediate passive SiO2 layer between the titanium dioxide phase and the iron oxide phase inhibited the direct electrical contact and hence prevented the photodissolution of the iron oxide phase. Improvements in the photoactivity were seen to be due to the inhibition of both the electronic and chemical interactions between the iron oxide and titanium dioxide phases. Preliminary optimisation experiments revealed that a thin SiO2 layer is sufficient for inhibiting the photodissolution. The thickness of the TiO2 coating was found not to have a significant effect on the photocatalytic performance of the coated particles. Finally, heat treating for 20 minutes at 450??C was sufficient for converting the titanium dioxide into a photoactive phase, longer heating times had no beneficial effect on the photoactivity.

Treatment of wastewater using magnetic technology is a rising field. In this thesis, the latest research on the subject is reviewed and several adsorbents with different coatings, which impart them unique properties, are discussed. Separation of particles from aqueous solution using magnetic technology is more convenient compared to conventional techniques, such as filtration and centrifugation. The adsorbents described in this thesis are effective for adsorption of several types of contaminants, such as heavy metals and different types of dyes.    Magnetic microspheres were synthesised using porous polystyrene microspheres as template. The microspheres were first sulfonated using chlorosulfonic acid followed by stirring in the presence of ferrous chloride which then was oxidised and magnetic nanoparticles were formed on the surface.    The sulfonated microspheres had a surface area of 420 m2/g and the magnetic 175 m2/g, indicative of Fe3O4 nanoparticles were successfully formed in the pores. The weight fraction of the Fe3O4 nanoparticles in the magnetic microspheres was 33 %.    Adsorption and desorption studies of the cationic dye, methylene blue, using mesoporous magnetic microspheres were performed. The results show that the mesoporous magnetic microspheres have good ability to adsorb methylene blue at low concentrations. In a cycle study the adsorption efficiency were nearly 100 % throughout the study. Using a 6/4 EtOH/H2O with saturated KCl solution the desorption efficiency in the cycle study were about 95 %.      The microspheres were used as carriers for TiO2 in order to overcome the problem with the separation of TiO2 from solution. The TGA results show that the microspheres contained about 12 % of TiO2. The TiO2 coated microspheres were used for the photocatalytic degradation of phenol. However, the TiO2 microspheres did not work. This was a result from that the phenol had too little contact with the TiO2. A possible way of solving this problem could be to decrease the size of the microspheres, thus increase the surface area.    Lysozyme was adsorbed and separated using the porous microspheres. The lysozyme adsorption worked best at pH 9.6, which is the pI for lysozyme. The lysozyme could be extracted from the microspheres by using a pH 13 buffer. Also, by using MeOH/H2O and EtOH/H2O solutions with saturated KCl the lysozyme could be desorbed. An adsorption and desorption mechanism was also presented.
Vattenrening med magnetisk teknologi är en ny och alltmer uppmärksammad teknik. Magnetisk separation är ett enkelt och snabbt sätt att separera något från en lösning. Magnetisk separation är mer lätthanterligt jämfört med traditionell separationsteknik såsom centrifugering och filtrering.  Med porösa polystyren mikrosfärer som mall, syntetiserades magnetiska mikrosfärer. Först så sulfonerades mikrosfärerna med klorosulfonisk syra, följt av att de rördes om i en järnkloridlösning. Magnetiska nanopartiklar bildades i porerna och på ytan av mikrosfärerna.    Sulfonerade mikrosfärerna hade en specifik ytarea på 420 m2/g och de magnetiska 175　m2/g, detta indikerar att Fe3O4-nanopartiklar bildades på ytan och i porerna. Massfraktionen av Fe3O4 var 33 %.    Adsorption- och desorptionsstudier på de magnetiska mikrosfärerna utfördes. Färgämnet metylblått användes i studien. Resultaten visade att magnetiska mikrosfärerna hade en bra adsorptionsförmåga vid låga koncentrationer av metylblått. Cykelstudier visade att adsorptionsverkningsgraden var nära 100 % under flera adsorptionscykler. Desorptionsförsök med olika lösningsmedel visade att en mättad KCl 6/4 EtOH/H2O lösning gav en desorptions-verkningsgrad på ca 95 %.   Mikrosfärerna användes som mall och kärna för att syntetisera en TiO2-fotokatalysator, detta för att överkomma problemet som finns med separation av rent TiO2 pulver från lösning. TGA resultaten visade att mikrosfärerna innehöll ca 12 % TiO2. De syntetiserade TiO2-mikrosfärerna användes till att bryta ner fenol fotokatalytiskt. Dock fungerade inte detta experiment. En anledning var att fenolen hade för lite kontakt med TiO2. En lösning på detta problem är att använda mikrosfärer med högre specifik ytarea.    Proteinet lysozym användes som modellprotein för försök att separera proteiner från lösning genom att använda porösa mikrosfärer. Resultatet visade att lysozym kunde adsorberas vid pH 9.6. Med en pH 13 buffer kunde lysozymet sedan extraheras från mikrosfärerna. En mekanism för adsorptionen och desorptionen på mikrosfärerna presenterades.

This thesis describes the synthesis and characterisation of titania photocatalysts for incorporation into a polyethylene film. Monodisperse, anatase-phase titania nanoparticles are prepared and the synthesis conditions necessary for attraction to a laponite clay support are determined. Methods of preventing agglomeration of the laponite system such as the use of a polyethylene oxide surfactant or chemical modification of the laponite plate edges with a dimethyloctyl methoxysilane are also explored. Finally, photocatalytic studies on the laponite-supported titania nanoparticles are performed, and the compatibility and photoactivity of these materials in the polyethylene film are examined.

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This work aimed to investigate the adsorption and photocatalysis of solutions containing nimesulide and 17β-estradiol with a composite formed of active charcoal decorated with NiFe2O4 nanoparticles. The composite was prepared by the hydrothermal method using Ni (NO3)2 6H2O and Fe(NO3)3 9H2O as precursors solubilized in basic aqueous medium. The solution was sealed in a Teflon reactor and heated 463.15 K for 10 h. The composite was characterized by X-ray diffraction, the morphology was observed by scanning electron microscopy and the with the vibrating sample magnetometer. Nimesulide and 17β-estradiol adsorb according to a pseudo-second order kinetics. The calculation of the thermodynamic parameters of adsorption indicated that the adsorption of nimesulide occurs in an endothermic, spontaneous and favorable manner in all temperatures investigated. The adsorption enthalpy magnitude between the nimesulide and the active charcoal decorated with ferrite is 90.2 kJ mol-1 which indicates that the adsorption is endothermic and occurs through chemisorption. The initial concentration of nimesulide decays by 70% and the concentration of 17β-estradiol decays by 99% after 60 min of UV light irradiation.
Este trabalho teve como objetivo investigar a adsorção e a fotocatálise de soluções contendo a nimesulida e o 17 -estradiol com um compósito formado por carvão ativo decorado com nanopartículas de NiFe2O4. O compósito foi preparado pelo método hidrotermal utilizando o Ni(NO3)2 6 H2O e o Fe(NO3)3 9 H2O como precursores solubilizados em meio aquoso básico. A solução foi selada em um reator de Teflon e aquecida 463,15 K durante 10 h. O compósito foi caracterizado por difração de raios X, a morfologia foi observada por microscopia eletrônica de varredura e a com o magnetômetro de amostra vibrante. A nimesulida e o 17 -estradiol adsorvem segundo uma cinética de pseudo-segunda ordem. O cálculo dos parâmetros termodinâmicos de adsorção indicou que a adsorção da nimesulida ocorre de forma endotérmica, espontânea e favorável em todas as temperaturas investigadas. A magnitude da entalpia de adsorção entre a nimesulida e o carvão ativo decorado com ferrita é 90,2 kJ mol-1 o que indica que a adsorção é endotérmica e ocorre através de quimissorção. A concentração inicial da nimesulida decai 70% e a concentração do 17 -estradiol decai de 99% após 60 min de irradiação com luz UV.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
Nanotechnology has received great prominence in recent years due to the versatility of new materials and its applications at the various sectors of society. The functionalized magnetic nanoparticles have been the focus of intense research because of the ability to use on different systems, with emphasis on the catalytic processes of environmental decontamination. In particular, we have seen a growing demand for hybrid catalysts capable of utilizing sunlight, constructed from TiO2 particles by photosensitised dyes. Thus, this study aimed to develop a new magnetic nanosystem, based on use of meso-porphyrins derived from Cashew Nut Shell Liquid (CNSL), coated with TiO2, with potential application in heterogeneous photocatalysis. Moreover, produce a new ferrofluid derived biomass from the anacardic acid (AA MAG). To this end, were synthesized Fe3O4 nanoparticles with an average size of 11nm, coated with a 1st layer of oleic acid and a 2nd layer of meso-porphyrin (3-n-PDPP). This nanosystem also was covered with a layer of TiO2. This procedure produced a new magnetic nanosystem of porphyrin (NMP). The new ferrofluid AA-MAG and magnetic nanosystems were characterized by Transmission Electron Microscopy (TEM), infrared spectroscopy, Thermal analysis (TG) and magnetization curves. The results showed that NMP showed good thermal stability, superparamagnetic behavior and dimension nanometric (≈ 14nm). The fluorescent properties were little affected, which enables its application in photocatalytic systems.
A nanotecnologia vem recebendo grande destaque nos Ãltimos anos graÃas à versatilidade dos novos materiais gerados e suas aplicaÃÃes nos diversos setores da sociedade. As nanopartÃculas magnÃticas funcionalizadas tÃm sido foco de intensas pesquisas devido à capacidade de utilizaÃÃo em diferentes sistemas, com destaque para os processos catalÃticos de descontaminaÃÃo ambiental. Em especial, tem-se observado uma crescente demanda por catalisadores hÃbridos capazes de utilizar a luz solar, construÃdos a partir de partÃculas de TiO2 fotossensibilizadas por corantes. Assim, o presente trabalho teve por objetivo desenvolver um novo nanosistema magnÃtico, baseado no emprego de meso-porfirinas derivadas do LÃquido da Casca da Castanha de Caju (LCC), recobertas com TiO2, com potencial aplicaÃÃo em fotocatÃlise heterogÃnea. AlÃm disso, produzir um novo ferrofluido derivado da biomassa, a partir do Ãcido anacÃrdico (AA-MAG). Para isso, foram sintetizadas nanopartÃculas de Fe3O4 com tamanho mÃdio de 11nm, revestidas por uma 1 camada de Ãcido oleico e uma 2 camada da meso-porfirina (3-n-PDPP). Esse nanosistema tambÃm foi recoberto por uma camada de TiO2. Este procedimento produziu um segundo novo nanosistema magnÃtico de porfirina (NMP). O novo ferrofluido AA-MAG e os nanosistemas magnÃticos foram caracterizados por Microscopia eletrÃnica de trasmissÃo (MET), Espectroscopia no Infravermelho, AnÃlise tÃrmica (TG) e curvas de magnetizaÃÃo. Os resultados mostraram que o NMP apresentou uma boa estabilidade tÃrmica, comportamento superparamagnÃtico e dimensÃes nanomÃtricas (≈ 14nm). As propriedades fluorescentes foram pouco afetadas, o que possibilita sua aplicaÃÃo em sistemas fotocatalÃticos.

O presente trabalho descreve a preparação de catalisadores magnéticos para aplicação nos processos de fotocatálise heterogênea e ozonização catalítica heterogênea, visando a degradação de poluentes emergentes. Primeiramente buscou-se preparar nanopartículas magnéticas para posterior aplicação no preparo de catalisadores magnéticos de TiO2. Diversas variáveis experimentais foram avaliadas na preparação das nanopartículas magnéticas, tais como: temperatura de reação, tempo de agitação, tempo no ultrasom, velocidade de agitação, velocidade de agitação da base, tempo de agitação do estabilizante, concentração da base e do estabilizante. A influência destes parâmetros de preparação no diâmetro hidrodinâmico e distribuição de tamanho das partículas foi avaliada por meio de um planejamento estatístico. Dependendo das condições experimentais, obteve-se materiais com um tamanho médio variando entre 11 e 36 nm e entre 23% e 77% de distribuição de tamanho. Na condição otimizada, obteve-se partículas com um tamanho médio, obtido pela técnica de espalhamento de luz dinâmico, de 18 nm e 21% de distribuição. O nanomaterial magnético foi utilizado para preparar os catalisadores híbridos Fe3O2@TiO2 e Fe3O4@SiO2@TiO2. Os materiais foram caracterizados por difratoemtria de raios-X (XRD), microscopia de varredura (MEV) e transmissão (TEM), espectroscopia no infravermelho (FT-IR), análise térmica (TG e DTA), espectrometria de emissão óptica (ICP-OES), medidas de área superficial (BET) e espalhamento dinâmico de luz (DLS). Os catalisadores magnéticos foram empregados na degradação dos poluentes emergentes paracetamol; 4-metilaminoantipirina (4-MAA); ibuprofeno; 17 β-estradiol; 17 α-etinilestradiol, e do fenol. Nos processos de degradação também variou-se o efeito do pH nas respostas dos sistemas. De maneira geral, o material Fe3O4@TiO2 apresentou atividade catalítica nos processos de degradação fotoquímica e de ozonização, com desempenho similar ou, em alguns casos, superior ao TiO2. Em relação a 4-MAA, obteve-se, em 60 minutos de tratamento, 25% de mineralização para o processo de fotólise e 66% para o processo de fotocatálise empregando Fe3O4@TiO2. Para o processo de ozonização em pH 3, obteve-se, em 180 minutos de tratamento, 40 e 60% de mineralização para o processo não catalítico e o processo catalítico empregando Fe3O4@TiO2, respectivamente. Os resultados utilizando-se TiO2 foram semelhantes à ozonização não catalítica, o que demonstra o efeito positivo do núcleo magnético para a atividade do material. Assim, o material híbrido multifuncional Fe3O4@TiO2 mostrou-se eficiente para a degradação de poluentes emergentes empregando-se os processos de fotocatálise e de ozonização catalítica heterogênea, possibilitando uma adicional praticidade de separação do meio de tratamento.
The present work describes the preparation of magnetic catalysts for application in heterogeneous photocatalysis and heterogeneous catalytic ozonation processes, aiming the degradation of emerging pollutants. Magnetic nanoparticles were prepered as substratum of magnetic TiO2 catalysts. Several experimental variables were evaluated in the preparation of the magnetic nanoparticles, such as temperature, stirring time, sonication time, precipitation reaction stirring speed, base addition rate, dispersion stirring time, base concentration and stabilizer percentage. The influence of these parameters on particle hydrodynamic diameter and size distribution were measured by a statistical design. Depending on the experimental conditions, materials with an average size ranging between 11 nm and 35 nm and distribution between 23% and 77% were obtained. In the optimum preparation conditions, Fe3O4 magnetic particles with a hydrodynamic diameter of 18 nm and 21% distribution were obtained. The magnetic nanomaterial was used to prepare the hybrid catalysts Fe3O4@TiO2 and Fe3O4@SiO2@TiO2. The prepared materials were characterized by X-ray diffraction (XRD), field-emiss ion scanning electron microscopy (FEG-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric (TG), differential thermal analysis (DTA), inductively coupled plasma optical emission spectrometry (ICP-OES), BET specific surface area and dynamic light scattering (DLS). The magnetic catalysts were employed in the degradation of the emerging pollutants paracetamol; 4-methylaminoantipyrin (4-MAA); ibuprofen; 17 β-estradiol; 17 α-ethinyl estradiol, and phenol. In the treatment processes the effect pH on the systems was also varied. In general, the material Fe3O4@TiO2 showed catalytic activity in the processes of photochemical degradation and ozonation, with performance similar or, in some cases, superior to TiO2. For example, the 4-MAA mineralization, after 60 minutes of treatment, by the photolysis process reached a m aximum value of 25%. In the same treatment time by the photocatalytic process using Fe3O4@TiO2 it was obtained 66% of 4-MAA mineralization. For the ozonation process, in pH 3, after 180 minutes of treatment, 40% of 4-MAA mineralization was achieved by non-catalytic method. On the other hand, in the same treatment time employing Fe3O4@TiO2, 60% of 4-MAA mineralization was obtained. In addition, for the ozonation process using TiO2 similar results to non-catalytic ozonation were observed, which demonstrates the positive effect of the magnetic core for the activity of the catalyst. Thus, the hybrid material Fe3O4@TiO2 was efficient for the degradation of emerging pollutants employing the photocatalysis and heterogeneous catalytic ozonation processes, allowing an additional practicality for separating the catalyst from the treatment medium.

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The need to control textile effluents due to contamination of rivers has led CONAMA to regulate and require a more efficient treatment process. Among the methods of treatment, heterogeneous catalysis stands out due to its high efficiency. The most used photocatalyst is TiO2. The combination of this material with other ones has been employed to improve its activity and/or its performance. Several systems have been tested, including the core-shell that constitutes a complete coverage of one material by another. In this work, TiO2@CoFe2O4 was synthesized by the modified-Pechini method with the addition of CoFe2O4 nanoparticles into the polymeric resin containing titanium. A magnetic material was obtained, which was characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), ultraviolet - visible spectroscopy (UV-Vis), specific surface area by the BET method. The materials were applied in the photodiscoloration of an azo dye. The pure TiO2 calcined at 700 °C showed a mixture of phases anatase / rutile in the proportions 77/23%, which was the calcination temperature which led to the highest photocatalytic activity in the discoloration of the solution yellow gold remazol (RNL). A discoloration of 81% in color of the solution was attained after 6 h of exposure to UV light, while 94% was reached after 2 h of irradiation with sunlight. With the core@shell system CoFe2O4@TiO2 synthesized with 90 % of TiO2, a mixture of anatase and rutile of 92 : 8% was obtained for a calcination temperature of 500 °C. This material showed 76% discoloration after 16 h of exposure to UV light under the same conditions used for the test with pure TiO2
A necessidade do controle de efluentes têxteis devido à contaminação de águas fluviais tem levado órgãos como o CONAMA a regulamentar e exigir um processo de tratamento mais eficiente. Dentre os métodos de tratamento estudados, os Processos Oxidativos Avançados (POA) têm demonstrado grande eficiência, como na fotocatálise heterogênea utilizando materiais semicondutores, sendo o TiO2 um dos mais empregados. A combinação deste material com outros tem sido estudada com o objetivo de melhorar a atividade e/ou performance do mesmo. Para isso vários sistemas têm sido utilizados, dentre eles o core@shell, que consiste na completa cobertura de um material por outro. Neste trabalho o CoFe2O4@TiO2 foi sintetizado pelo método Pechini modificado, com a adição do CoFe2O4 nanoparticulado à uma resina polimérica de titânio, sendo obtido um material magnético, o qual foi caracterizado por difração de raios X (DRX), espectroscopia infravermelho (IV), espectroscopia na região ultravioleta e visível (UV-Vis), análise de área superficial específica pelo método de BET. Os materiais foram testados na fotodegradação de um corante azo. O TiO2 puro calcinado a 700 ºC, apresentou mistura de fases anatase / rutilo com proporção 77 / 23 %, sendo a temperatura de calcinação que levou à maior atividade fotocatalítica na descoloração da solução de amarelo ouro remazol (RNL). Foi obtida 81 % de redução da cor da solução em 6 h de exposição a luz UV e 94 % após 2 h com irradiação de luz solar. Com o sistema core@shell CoFe2O4@TiO2 sintetizado com 90 % de TiO2 foi obtida uma mistura de 92 % de anatase e 8 % de rutilo, para uma temperatura de calcinação de 500 ºC. Este material levou a 76 % de descoloração em 16 h de exposição à luz UV com as mesmas condições utilizadas para o teste com o TiO2 puro

The crisis of freshwater has been a big concern worldwide. Water contamination that occurs through the discharge of toxic pollutants from different natural and anthropogenic sources have worsened the situation. Adsorption has emerged as a simple and economical water treatment procedure although the challenge is to find the right adsorbent that can efficiently remove the target contaminant followed by their easy recovery from the reaction vessel. In this dissertation, I have focused on the synthesis, characterizations and applications of environmentally compatible and magnetic humic acid coated magnetite nanoparticles (HA-MNP) as a potential adsorbent for water purification. Phosphate is an essential nutrient for many plants and organisms in the environment. However, it can also cause water pollution when present in excess amounts. The adsorption experiments showed that the laboratory synthesized nanoparticles (HA-MNP) can remove more than 90% of phosphate from water mainly through the mechanism of chemisorption. The overall removal process is spontaneous, endothermic and favorable. Water contamination by arsenic is considered one of the biggest natural disasters in human history. In the study, HA-MNP has been applied for the successful trapping and separation of two highly toxic inorganic As species, As(III) and As(V) from water. The removal of As(V) was faster than As(III) for the same initial arsenic concentration and HA-MNP loading. The binding of As species is mainly attributed to three different phases, rapid surface association, intraparticle diffusion and equilibrium adsorption. Selenium is a micronutrient for humans that can be toxic at modest concentrations. The remediation of toxic selenium species, Se(IV) and Se(VI) by using HA-MNP has been found effective under a variety of environmental conditions except at highly alkaline pH and the presence of sulfate and phosphate in aqueous solution. Selenite or Se(IV) forms strong inner sphere complexes while Se(VI) forms relatively weaker outer sphere complexes with the adsorbent sites. The oxidation and adsorption of As(III) is explored by using the photocatalytic and adsorptive behavior of HA-MNP. The higher removal efficiency is attained through the reactive oxygen species mediated photo-conversion As(III) to As(V). Combination of oxygen and 350 nm light provides the best results.

Orientador: Gustavo Rocha de Castro
Banca: Raquel Fernandes Pupo Nogueira
Banca: Marcelo Organachi Orlandi
Banca: Katia Jorge Ciuffi
Banca: Silvana Ruella de Oliveira
Resumo: A contaminação de corpos d'água e águas subterrâneas por substâncias tóxicas ocasiona a redução da qualidade da água e até mesmo sua inapropriação para consumo. Atualmente as técnicas convencionais de tratamento de águas e resíduos aquosos não são capazes de descontaminá-los totalmente, pois substâncias recalcitrantes e substâncias parcialmente removidas/degradadas - como alguns clorofenóis (CPs) e substâncias desreguladoras endócrinas (SDEs) - permanecem na água mesmo após submetida aos tratamentos convencionais, reforçando a necessidade do desenvolvimento de procedimentos mais completos, sustentáveis e que também sejam economicamente viáveis. A exemplo, a fotocatálise heterogênea utilizando materiais semicondutores ativados pela radiação UV para produção, principalmente, de radicais hidroxilos pode ser aplicada para se degradar contaminantes em meio aquoso, sendo o óxido de titânio o material mais empregado devido àelevada atividade, baixo custo, estabilidade, disponibilidade e propriedades químicas, físicas e biológicas adequadas. Apesar de diversas vantagens associadas ao seu uso em fotocatálise heterogênea, sua aplicação na forma de suspensões (a fim de fazer melhor proveito da área superficial das partículas) ainda é restrita devido principalmente a dificuldades de separação/remoção destas após o processo de degradação. Neste trabalho, fotocatalisadores híbridos a base de titânia foram produzidos para realizar fotocatálise heterogênea de compostos orgânicos em meio aquo... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The contamination of waters and groundwaters by toxic substances reduces the quality of water and can even make it inadequate for consumption. Currently, the conventional techniques for treatment of waters and wastewaters are not able to completely decontaminate them. This is attributed to the presence of partially removed/degraded andrecalcitrant substances such as chlorophenols (CPs) and endocrine-disrupting chemicals (EDCs), since they persist in water even after the conventional treatment. This emphasizes the need for the development of more complete and sustainable processes that are also economically viable. For instance, heterogeneous photocatalysis utilizing UV-activated semiconductors for the production, mainly, of hydroxyl radicals is applied in the degradation of contaminants in aqueous medium. In this aspect, titanium oxide is the most used material in virtue of its high activity, low cost, stability, availability and suitable chemical, physical and biological properties. Despite so many advantages for the application of titanium oxide in heterogeneous photocatalysis, its application as slurries (to make better use of the surface area of particles) is still restrained by drawbacks related to separation/extraction steps. In this work, titania-based photocatalist hybrids were produced to perform heterogeneous photocatalysis of organic compounds in aqueous medium.As an alternative to implement particle separation from slurries, titania and mesoporous silica were depo... (Complete abstract click electronic access below)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
A contaminação de corpos d’água e águas subterrâneas por substâncias tóxicas ocasiona a redução da qualidade da água e até mesmo sua inapropriação para consumo. Atualmente as técnicas convencionais de tratamento de águas e resíduos aquosos não são capazes de descontaminá-los totalmente, pois substâncias recalcitrantes e substâncias parcialmente removidas/degradadas – como alguns clorofenóis (CPs) e substâncias desreguladoras endócrinas (SDEs) – permanecem na água mesmo após submetida aos tratamentos convencionais, reforçando a necessidade do desenvolvimento de procedimentos mais completos, sustentáveis e que também sejam economicamente viáveis. A exemplo, a fotocatálise heterogênea utilizando materiais semicondutores ativados pela radiação UV para produção, principalmente, de radicais hidroxilos pode ser aplicada para se degradar contaminantes em meio aquoso, sendo o óxido de titânio o material mais empregado devido àelevada atividade, baixo custo, estabilidade, disponibilidade e propriedades químicas, físicas e biológicas adequadas. Apesar de diversas vantagens associadas ao seu uso em fotocatálise heterogênea, sua aplicação na forma de suspensões (a fim de fazer melhor proveito da área superficial das partículas) ainda é restrita devido principalmente a dificuldades de separação/remoção destas após o processo de degradação. Neste trabalho, fotocatalisadores híbridos a base de titânia foram produzidos para realizar fotocatálise heterogênea de compostos orgânicos em meio aquoso. Como abordagem alternativa para implementação da separação de suspensões, realizou-se a deposição de sílica mesoporosa e titânia sobre núcleos de magnetita, sendo a magnetita responsável por possibilitar a separação magnética do material híbridode suspensões, enquanto que a sílica mesoporosa incrementaria a atividade da titânia por meio do aumento de sua área superficial. No caso do recobrimento por titânia, uma nova rota por meio de ebulição de etanol foi desenvolvida. Análises de difração de raios X indicaram que o recobrimento de sílica preveniu a conversão dos núcleos de magnetita à hematita após calcinação. Foi notado também a formação da fase anatase de titânia nos materiais híbridos para composições de titânia iguais ou maiores que 43 % em massa. Análises de espectroscopia de infravermelho reforçaram a presença de titânia juntamente à sílica, e também apontou para um limite de deposição para a titânia, que foi posteriormente verificado também por espectrofotometria de fluorescência de raios X. Através de microscopia eletrônica de varredura, observou-se a formação e crescimento da fase anatase sobre partículas de sílica e magnetita para composições de 53 % de titânia ou maiores, e análises de espectroscopia de energia dispersiva de raios X demonstraram os elementos Si e Ti se encontrarem bem-distribuídos ao redor das partículas de magnetita, sílica e titânia. O material híbrido produzido apresentou estrutura mesoporosa como o da sílica MCM-41, no entanto de área superficial específica menor, atingindo em torno de 248 m2 g-1. Análises de ressonância magnética nuclear de 29Si indicaram haver ligação química entre as fases sólidas de sílica e titânia. Experimentos de fotodegradação demonstraram que os híbridos de magnetita, sílica e titânia consistem de adsorventes ineficientes de 4-clorofenol. A atividade fotocatalítica destes materiais apresentou relação com o crescimento da textura de titânia, sendo os materiais fotoativos aqueles com composições de 53 % ou maiores. Cinéticas de degradação de ordem zero foram observadas para todos os materiais. Os materiais fotoativos também se demonstraram indiferentes ao pH do meio, com eficiências similares em pH 3,0 e 7,2. Ao se comparar as eficiências dos materiais híbridos, em termos de suas taxas iniciais de degradação, com as de materiais comerciais Hombikat 100 UV e Aeroxide® TiO2 P25 estabeleceu-se que a ordem decrescente de eficiência sob concentrações de catalisador otimizadas foi Aeroxide® TiO2 P25 > Hombikat 100 UV >híbrido de sílica e titânia >híbrido de magnetita, sílica e titânia. Concluiu-se dos experimentos de degradação que a incorporação de sílica e magnetita aos fotocatalisadores de titânia compromete a eficiência degradativa destes; em contrapartida, no caso dos materiais contendo núcleos de magnetita, sua recuperação magnética pode consistir de uma propriedade compensatória em termos de aplicação. A fim de se incrementar a atividade fotocatalítica dos materiais, estes foram sujeitos a etapas de modificação superficial por meio da incorporação de ácido rubeânico (AR) por silanização ou adsorção direta e/ou também por complexação de íons Fe3+ em meio aquoso, com a finalidade de se sensitizar os fotocatalisadores. A imobilização do AR por meio de silanização demonstrou-se mais eficiente, enquanto sua dessorção foi verificada para o material modificado por adsorção direta. No caso dos materiais modificados com Fe3+, constatou-se que a complexação destes íons sobre os materiais híbridos implicou na redução da fotoatividade destes, enquanto nenhum efeito foi notado em pH 6 para a fotoatividade de Hombikat 100 UV modificado. Mais experimentos seriam necessários para se determinar as taxas de degradação iniciais dos materiais estudados. Nos experimentos sob luz visível apenas Hombikat 100 UV e sua respectiva versão modificada apresentaram atividade. Ao se aplicar o material Hombikat 100 UV modificado com Fe3+ em pH 3,0, notou-se evidência de aumento de eficiência sob iluminação UV.
The contamination of waters and groundwaters by toxic substances reduces the quality of water and can even make it inadequate for consumption. Currently, the conventional techniques for treatment of waters and wastewaters are not able to completely decontaminate them. This is attributed to the presence of partially removed/degraded andrecalcitrant substances such as chlorophenols (CPs) and endocrine-disrupting chemicals (EDCs), since they persist in water even after the conventional treatment. This emphasizes the need for the development of more complete and sustainable processes that are also economically viable. For instance, heterogeneous photocatalysis utilizing UV-activated semiconductors for the production, mainly, of hydroxyl radicals is applied in the degradation of contaminants in aqueous medium. In this aspect, titanium oxide is the most used material in virtue of its high activity, low cost, stability, availability and suitable chemical, physical and biological properties. Despite so many advantages for the application of titanium oxide in heterogeneous photocatalysis, its application as slurries (to make better use of the surface area of particles) is still restrained by drawbacks related to separation/extraction steps. In this work, titania-based photocatalist hybrids were produced to perform heterogeneous photocatalysis of organic compounds in aqueous medium.As an alternative to implement particle separation from slurries, titania and mesoporous silica were deposited on the surface of magnetite cores. The incorporation of magnetite to the hybrid aimed to enable its magnetic separation from slurries whereas the incorporation of silica had the purpose of incrementing its activity by increasing the surface area of the hybrid material. A new route has been developed to perform the titania coating, which was based on the boiling of ethanolic medium. X-ray diffraction analyses indicated that the silica layer prevented phase conversion of magnetite cores to hematite after calcination. The formation of titania anatase phase was also observed for the hybrid materials for the mass composition of 43 % or greater. Infrared spectroscopy supported the presence of titania along with silica, and also pointed to a deposition limit for the titania layer that was also verified posteriorly through x-ray fluorescence spectrophotometry. Scanning electron microscopy enabled the observation of the formation and growth of anatase phase over magnetite-silica particles for compositions of 53 % or greater. Energy-dispersive x-ray spectroscopy demonstrated that Si and Ti were well- distributed over the magnetite-silica-titania particles. The hybrid material presented mesoporous structure likewise MCM-41, but with a smaller specific surface area of approximately 248 m2 g 1.29Si nuclear magnetic resonance provided evidence that silica and titania phases were chemically bonded. Photodegradation experiments demonstrated that magnetite-silica-titania hybrids are inefficient 4-chlorophenol adsorbents. The photocatalytic activity of the hybrids demonstrated to have relation with the growth of the titania texture, being the photoactive materials those with mass compositions of 53 % or greater. The kinetic behavior of the materials was found to have zero order and was pH-independent, having similar performances at pH 3.0 and 7.2. As the efficiencies of the hybrids are compared with those of commercial materials Hombikat 100 UV and Aeroxide® TiO2 P25, the decreasing order of efficiency could be obtained as Aeroxide® TiO2 P25 > Hombikat 100 UV >silica-titania hybrid > magnetite-silica-titania hybrid. Degradation experiments allowed to conclude that the incorporation of silica and magnetite to the titania photocatalists compromise their efficiencies; on the other hand, in the case of the materials containing magnetite cores, the possibility of magnetic retrieval may consist of a compensatory property with regard to practical application. To increment the photocatalytic activity of the materials, they underwent surface modification steps to have immobilized rubeanic acid (RA) either through sinalization or through direct adsorption. The complexation of Fe3+ to the surface of the hybrids was also tested in combination with rubeanic acid or without it to perform the sensitization of the photocatalysts. The immobilization of RA via silanization demonstrated to be more efficient, whereas its desorption could be verified for the material modified with RA by direct adsorption. In the case of hybrid materials modified with Fe3+ ions, the complexation of the ions led to a decay in their performance whereas no effect was observed at pH 6 for the material Hombikat 100 UV modified with Fe3+.More experiments are necessary to determine the initial degradation rates of the studied materials. In the experiments under visible light, only Hombikat 100 UV and its modified version presented photoactivity. When Fe3+-modified Hombikat 100 UV was tested at pH 3.0, evidence of increase in activity was noted under UV illumination.
Fapesp 2013/22955-2 e 2015/05224-0

The potentially most important challenges today are related to energy and the environment. New materials and methods are needed in order to, in a sustainable way, convert and store energy, reduce pollution, and clean the air and water from contaminations. In this, nanomaterials and nanocomposites play a key role, and hence knowledge about the relation between synthesis, structure, and properties of nanosystems is paramount. This thesis demonstrates that solution-chemical synthesis, using amine-modified acetates and nitrates, can be used to prepare widely different nanostructured films. By adjusting the synthesis parameters, metals, oxides, and metal–oxide or oxide–oxide nanocomposites were prepared for two systems based on Co and Zn:Fe, respectively, and the films were characterised using diffraction, spectroscopy, and microscopy techniques, and SQUID magnetometry. A variety of crystalline cobalt films—Co metal, CoO, Co3O4, and composites with different metal:oxide ratios—were synthesised. Heat-treatment parameters and control of the film thickness enabled tuning of the phase ratios. Random and layered Co–CoO composites were prepared by utilising different heating rates and gas flow rates together with a morphology effect associated with the furnace tube. The Co–CoO films exhibited exchange bias due to the ferromagnetic–antiferromagnetic interaction between the Co and CoO, whereas variations in e.g. coercivity and exchange bias field were attributed to differences in the structure and phase distribution. Ordered structures of wurtzite ZnO surrounded by amorphous ZnxFeyO were prepared through controlled phase segregation during the heating, which after multiple coating and heating cycles yielded ZnO–ZnxFeyO superlattices. The amorphous ZnxFeyO was a prerequisite for superlattice formation, and it profoundly affected the ZnO phase, inhibiting grain growth and texture, already from 1% Fe. In addition, ZnO–ZnxFeyO exhibited a photocatalytic activity for the oxidation of water that was higher than results reported for pure ZnO, and comparable to recent results reported for graphene-modified ZnO.

碩士
國立高雄應用科技大學
化學工程系碩士班
96
The object of this paper will improve the magnetic photocatalyst by CTAB or PVA, because according the journal of magnetic photocatalyst indicate, the non-magnetic free type TiO2 particles could be produced during the process, the separation and recovery of non-magnetic free type TiO2 particles from water are difficult. The researches mainly restrain the non-magnetic free style TiO2 particles produce and also enhance the effect of TiO2 photocatalytic activities. The synthesized sample was characterized by XRD, FTIR, TGA, XRF, BET, SQUID, SEM, TEM. The photocatalytic activity of the synthesized composite particles was tested by photodegradation of Methyl Orange (MO) and Methylene Blue (MB) under UV illumination (250 nm) and compared with that of commerce photocatalyst P-25. The result shows, the first part, adopt CTAB to become liquid crystal template to improve magnetic photocatalyst, successful restrain the non-magnetic free type TiO2 particle produce and the surface area have obvious increase. The prepared photocatalysts own the excellent photocatalytic activities and magnetic. Repeated cycles of decomposition of methylene blue in aqueous solution were experimentally confirmed. The second part, carbon coating of magnetic photocatalyst was successfully carried out by heating a powder mixture of poly(vinyl alcohol) and TiO2/SiO2/Fe3O4 under N2 gas flow at temperatures above 700 °C. Carbon coating of magnetic photocatalyst was found to give different merits for photoactive performance, quick adsorption of MO and MB into the carbon layer, decomposition of adsorbed MO and MB by TiO2 and prevention of the interaction of TiO2 with binder resin. Repeated cycles of adsorption and decomposition of methylene blue in aqueous solution were experimentally confirmed.

碩士
國立高雄應用科技大學
化學工程系碩士班
95
Recyclable photocatalysts were successfully prepared to solve the problem of hard recovery of the used TiO2 powder. The Fe3O4 nanoparticle was preliminarily prepared by a co-precipitation, and then the core shell material of SiO2/Fe3O4 was synthesized using Fe3O4 nanoparticle as the core. Consequently, the magnetic mesoporous photocatalyst of TiO2/SiO2/Fe3O4 hybrid were successfully prepared by a sol-gel method. The synthesized products were characterized by X-ray diffraction (XRD), electron spectroscopy for chemical analysis (ESCA), and small angle X-ray scattering system (SAXS). The morphology of synthesized products was observed by scanning electron microscope (SEM) and transmission electron microscope (TEM). The specific surface area was measured with BET instrument. The magnetic properties were detected by superconducting quantum interference device (SQUID). The photo-activity of synthesized products was performance by using methyl orange as a material for photodecomposition analysis, by UV-VIS absorption spectroscopy. The results showed that the mesoporous photocatalyst of TiO2/SiO2/Fe3O4 hybrid could be easily separated and recycled by the magnetic force. Meanwhile, the photocatalytic activity of those hybrids did not decline markedly after being used second time.

碩士
元智大學
化學工程與材料科學學系
105
In this research carbon nanodots (C-dots) were attached on commercial Fe3O4 particles surface to be Fe3O4/C-dots composite material which will be a new type magnetic nanomaterial for photocatalyst. The as-prepared samples were characterized by VSM, XRD, FTIR, TEM, PL, UV-visible. The heating temperature was fixed at 140 and 180oC and the heating time was changed to fabricate Fe3O4/C-dotswhich were used as photocatalyst to decompose organic compounds in wastewater. In VSM results, either heating temperature 140oC or 180oC, saturation magnetization (Ms) decreased with increasing heating time. In XRD results, there was a board reflection on at 2 theta = 20o which was contributed by C-dots. The decreasing of Ms was attributed to C-dots attached on Fe3O4 surface resulting in the weight of uni Fe3O4 nanoparticle increased. The TEM images of Fe3O4/C-dots revealed that the amount of C-dots was on Fe3O4 surface increased with increasing heating time. Fe3O4/C-dots were successfully fabricated in this study. In order to measure Fe3O4/C-dots photodegradation, as-prepared sample were added into methylene blue (MB) under visible light. A great reduction of MB (80%) was observed by Fe3O4/C-dots under 140oC with 18 hour in 30 min. Fe3O4/C-dots under 180oC with 4 hour also present good photodegradation ability with 50% in 30 min.

博士
中原大學
化學研究所
95
In this research, the following subjects were investigated： (1) Synthesis of Fe3O4 nanoparticles by hydrothermal method. (2) Synthesis of Ag nanoparticles. (3) Deposition of silver on magnetic Fe3O4 nanoparticles. (4) Formation of Fe3O4 nanowire by electrophoresis deposition. (5) Synthesis of Fe3O4 nanorod arrays via AAO template precipitation and subsequent microwave hydrothermal process. (6) Synthesis and photocatalysis of Ag nanoparticle-modified mesoporous TiO2 powders. The study disclosed following facts: (1) various phases such as Fe3O4 、α-Fe2O3 were obtained and found to be dependent on the temperature, time, and precursors used in hydrothermal process. The hydrothermal process may form single spinel phase only when all precursors were dissolved in a basic solution (pH≥9). In addition, the selection of iron salts and the exact ratio of Fe2+ and Fe3+ are important for the formation of Fe3O4 phase. The size of nanoparticles obtained in this study was about 30 nm. (2) The silver nanoparticles from 3 to 20 nm were obtained by varying the concentrations of AgClO4 solution. Silver nitrate AgNO3、Poly(vinylpyrrolidone) (PVP) and the reducing agent NaBH4 were employed for the synthesis. Reduction of AgNO3 by D-glucose in the presence of starch gave a stable aqueous of silver nanoparticles. The Ag nanoparticles solution are stable over 6 momths at pH=12. (3) Synthesis of nano-composites materials Ag - Fe3O4 was carried out. Chemical reduction and oxidation was utilized such as： Ag+ + Fe+2 → Ag0 + Fe+3. Silver ions were used as oxidation agent to oxidize ions of Fe(II) to form a solution containing both Fe(II) and Fe(III) ions. After precipitation with ammonia hydroxide, magnetic nanoparticles containing silver metals were obtained. Our modifications of the magnetic nanoparticles were much easier than literature methods and the procedure to produce magnetic nanoparticles was also simplified. (4) Template-growth of Fe3O4 nanowires via electrophoretic deposition (EPD) was accomplished. Uniform Fe3O4 nanowires with length more than 20 mm and diameter around 130-150 nm are successfully synthesized. (5) Template-growth of Fe3O4 nanowires via precipitation and subsequent microwave hydrothermal process was investigated. Fe3O4 precipitates were obtained in a ferrous chloride and ferric chloride mixture (pH>9) followed by microwave hydrothermal process at 150 °C for 30 min. The nanowires have a polycrystalline spinel structure and very smooth surface and extreme parallel rod-shape. (6) Deposition of Ag nanoparticles on mesoporous anatase TiO2 powders as well as on commercial TiO2 powders via reduction of Ag+ solution was performed and their photocatalytic activities were investigated. Photocatalytic activities of Ag/TiO2 were evaluated by UV-visible test on degrading of methylene blue aqueous solution. For the synthesized mesoporous TiO2 powders, the catalytic activity increased as the amount of Ag nanoparticles increased. However, for the commercial TiO2 powders, the catalytic activity decreased as the amount of Ag increased. It is inferred that the Ag nanoparticles reduce the recombination of electron-hole pairs and therefore enhance the photocatalytic activity of the synthesized mesoporous TiO2 powders. However, the Ag nanoparticles retard the photocatalytic activity of commercial TiO2 powders by shielding their effective surface area for the accessing of light.

碩士
明新科技大學
化學工程與材料科技系碩士班
104
To separate the valued components from the spent dry batteries, steel plant acid washing waste liquid, and IC lead frame scraps. The spent dry batteries contain manganese dioxide, iron, zinc shell and copper. The steel plant acid washing waste liquid contains large amounts of divalent iron. The IC lead frame scraps contain about18% tin, 34% nickel, and 48% iron. Nickel, copper, zinc, and iron can be separated from the above three wastes to prepare Ni Cu Zn ferrite (Ni0.3Cu0.1Zn0.6Fe2O4) powder. First, the metal portions of the disassembled waste batteries are added into the steel plant acid washing liquid. The liquid is heated to 80℃ until the metal dissolved and becomes a Zn/Fe solution. The nitric acid is added slowly into the IC lead frame scarps to do the hydrolysis completely. Then, separate Sn(OH)4 solid by filtration and obtain a Ni/Fe solution. The above two solutions are mixed together followed by analyzing components using AA. After that, the Cu, Zn, and Fe are added into the mixed solution to adjust and makeup the proportion ratios according to the quantity of Ni as basis. Finally, the pH value of the solution is adjusted by alkali to turn the metal ions into their hydroxides’ precipitates. After filtration, washing, drying, and calcination processes, the NiCuZn ferrite powder can be obtained. Titanium dioxide photocatalyst has considerable degree of treatment effect in wastewater treatment and with at causing secondary pollution problems. But , a great difficulty of recovering the titanium dioxide particles occured. Therefore, this study uses the NiCuZn ferrite powder coupled with titanium sulfate and urea to make an improved TiO2 photocatalyst. Through the processes of filtration, drying, grinding, and calcination, the magnetic photocatalyst powder is formed. It remains the characteristics of TiO2 photocatalyst and can be recovered using a magnetic field to achieve the purpose of solid-liquid separation. A series of measurements and analyses using the equipment of ICP, XRF, XRD, SEM, TOC, and ADMI have been performed for the magnetic photocatalyst. The feasibility study of the advanced oxidation procedures (AOP) by using UVA / NiCuZn-Ferrite-TiO2 for simulated dye wastewater treatment is also conducted. The NiCuZn ferrite powder is prepared from the wastes of spent dry batteries, steel plant acid washing liquid, and IC lead frame scarps successfully. A magnetic photocatalyst is prepared by combining the powder with titanium sulfate and urea by coprecipitation method. The catalyst can be recycled by magnetic field after photo redox reaction. The developed technology in this study can be used in the field of waste treatment and recovery. It is an important issue in our environment.

碩士
國立成功大學
資源工程學系
104
Titanium dioxide nanoparticles have good dispersion and high surface area,but they are difficult to recover from water. The experiment of this study applies sol-gel method to synthesize NiFe2O4-SiO2-TiO2 magnetic photocatalyst. Nickel ferrite nanoparticles, has good magnetism, good thermal stability, and can easily be recovered when using an outer magnetic field using as magnetic core. NiFe2O4 was coated with a SiO2 passivation layer, which increases the surface area of the particles, and the passivation layer high energy gap helps avoiding photodissolution. Magenetic photocatalyst is retrievable and reusable, displaying environmental friendliness and economic effectiveness.

碩士
明新科技大學
化學工程與材料科技系碩士班
101
Ni-Zn ferrite with a composition of Ni1-x-yZnxFe2O4, are indispensable components in electrical circuit. More than ten thousand tons are needed in the whole world annually. Traditionally the ferrites are prepared by solid-state reaction method from oxides such as NiO, ZnO, Fe2O3 as raw materials. The materials’ cost is more then NT$100/kg, in which more than 85% is nickel’s cost. If cheaper nickel can be found, it will extensively reduce the raw materials’ cost. In this research project a waste nickel containing catalyst will be used in producing Ni-Zn ferrite. The nickel containing filtrate obtained accompanying with iron containing spent pickling acid, and zinc nitrate, as nickel, iron, and zinc sources, and alkali as neutralizing agent, Ni-Zn ferrite powders were produced by chemical co-precipitation method. In this process not only raw materials were much cheaper, but also processing fee may be collected from government for the waste materials. The quantity of these waste materials are very large. It is enough for producing Ni-Zn ferrites. Therefore it is very meaningful from the view points of material reutilization, earth’s resources saving, and environmental pollution reduction. Experimental process by using acid or ammonia process was used. The nickel ions in nickel-containing waste catalyst were dissolved from the solid waste into the acid solution. Then by using Ni as the basis in the nickel-containing solution, adjust the calculated composition and make up the deficiency of zinc and iron. Later, adding alkali into the solutions and heating the solutions to weak alkali, nickel、iron and zinc ions were precipitated out from the solution as amorphous hydroxides and slowly transform to crystalline spinel Ni-Zn ferrite powders. The powders were filtered, dried , ground and calcined to obtain magnetic Ni-Zn ferrite powders. Experimental treatment by using photocatalyst-TiO2 alone for dye wastewater is proven to be very efficient. Besides, the secondary pollution by the application of other advanced treatment methods can be eliminated. But, the difficulty of solids (TiO2 ) and liquid (wastewater) separation problems exists and hard to solve. Therefore, this study will use titanium sulfate、urea and Ni-Zn ferrite powder to produce modified titanium dioxide photocatalyst by coprecipitation mothod. Finally by filtration , drying , grinding and calcinations, magnetic photocatalyst powder was obtained. These magnetic photocatalysts can be recovered by the application of the magnetic field. The characterization of the prepared Ni-Zn ferrite power and modified magnetic photocatalysts with their application in the dye wastewater treatment under UVA irradiation was investigated by using AA﹐XRF﹐XRD﹐SEM﹐DLS﹐SQUID﹐TOC and colorimeter. The Langmuir adsorption isotherm and Langmuir-Hinshelwood kinetic model were proven to be applicable to the FBL dye wastewater treatment by using these photo magnetic Ni-Zn ferrite/TiO2 catalysts under UVA irradiation.

Xia, Dehua.
Thesis Ph.D. Chinese University of Hong Kong 2014.
Includes bibliographical references (leaves 142-172).
Abstracts also in Chinese.
Title from PDF title page (viewed on 16, November, 2016).

博士
國立臺灣大學
環境工程學研究所
99
The objective of this research was using Sol-Gel method to improve the conventional TiO2 catalysts. In order to increase the utility of visible light, ferroferric oxide and ammonium vanadate were composite of TiO2-Fe3O4 and V-TiO2 to provide the Rutile type structure, respectively. Both TiO2-Fe3O4 and V-TiO2 catalysts treated by grinding and sieving, their average particle sizes were near 20 nm by SEM analysis. As shown in XRD results, Anatase type and Rutile type structures appeared in both TiO2-Fe3O4 and V-TiO2 catalysts before MTBE decomposition. Otherwise, the major 2θ values of TiO2-Fe3O4 appeared in 25.4（Anatase）, 36.2（Rutile）and 48.2（Anatase）, so it means Anatase type and Rutile type structures still existed after MTBE decomposition. Oppositely, one 2θ peak in 27.5 of V-TiO2 disappeared after MTBE decomposition, owing to Rutile type structures broken. Observed the continuous discoloration experiments by composite TiO2-Fe3O4, the results of discoloration seemed to be not different in spite of three time reuses. Whether photocatalysts irradiated by Visible light or UV light, the performance of composite TiO2-Fe3O4 was rather than pure TiO2, and this also meant the durability of composite catalysts. In the optimum doses experiment, it showed adding 5 g TiO2-Fe3O4 could achieve 91 % MTBE removals, and followed by the 10 g, 2 g and 1 g. Besides, V-TiO2 catalysts has 82 % MTBE removals, which atomic ratio of vanadium to TiO2 was 0.1 (0.10VT-I). Continuous and close photoreactor systems were designed to degrade MTBE in this research. Under continuous system, pH10 was helpful for TiO2-Fe3O4 catalysts to gain better MTBE removals, but V-TiO2 photocatalytic degradation has better results under neutral pH 7. However, both V-TiO2 and TiO2-Fe3O4 have similar photocatalytic degradation results under close system whatever the pH value was pH 7 or pH 10. Considered the material cost difference between Fe3O4 and NH4VO3, it should be adopted lower price first if their removals were very similar. Moreover, the Fe3O4 material has magnetism, so TiO2-Fe3O4 could be reused by external magnetic field while TiO2-Fe3O4 has more potential value in real.

博士
國立東華大學
材料科學與工程學系
104
The work focuses on the two kinds of research direction of the dye degradation. First, we synthesized iron-doped TiO2 photocatalysts. The aim of the work is to study the effects of oxygen vacancy and surface hydroxyl group density on the photocatalytic activity of Fe3+-doped TiO2, and to investigate how the titanium dioxide doped with different concentration of the Fe3+ influenced their physical and chemical characterizations. The photocatalysts were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), electron spin resonance (ESR), X-ray photoelectron spectroscope (XPS) and Fourier transform infrared (FTIR) spectroscopy. The results revealed that adsorbed hydroxyl group density significantly influenced in photocatalytic activity, and a small amount of Fe3+ can act as a photo-generated hole and a photo-generated electron trap and inhibit the electron–hole recombination. The 0.10%- Fe3+-TiO2 with the highest surface hydroxyl group density revealed the maximum rate constant of 0.716 and the optimal photocatalytic degradation of methylene blue (MB). As Fe3+ doping levels are larger than 0.10%, the cluster of generated gradually. This implied that an excessive amount of Fe3+ doped into TiO2 is detrimental to the photocatalytic activity due to the formation of clusters and enhances the recombination of photogenerated electrons and holes. The second study proposed visible light of the recyclable magnetic photocatalytic degradation of the organic dye solution. If confirmed by studies with its feasibility, it will be applied to organic wastewater treatment program. We are studying for using this magnetic photocatalyst to treat dye wastewater as the following: (1) We prepared the TiO2/Mn-Zn ferrite composite powder for magnetic photocatalyst. The core Mn-Zn ferrite powder was synthesized by using steel pickling liquor and used alkaline batteries as the starting materials. The shell TiO2 nanocrystal was prepared by sol–gel hydrolysis precipitation of titanium isopropoxide (Ti(OC3H7)4) on the Mn-Zn ferrite powder. The thickness of the titania shell was found to be approximately 2 nm. The core of Mn-Zn ferrite is of spherical or elliptical shape and the particle size of the core is in the range of 20-40 nm. The magnetic Mn-Zn ferrite nanopowder is uniformly encapsulated in a titania layer forming the core–shell structure of TiO2/Mn-Zn ferrite powder. The magnetic photocatalyst can be successfully used to treat dye waste waters. (2) The TiO2/SiO2/Ni-Cu-Zn ferrite composite for magnetic photocatalysts with high photocatalytic activity is successfully prepared in this study. The composite are composed of spherical or elliptical Ni-Cu-Zn ferrite nanoparticles about 20-60 nm as magnetic cores, silica as barrier layers with thickness of 15 nm between the magnetic cores and titania shells with thickness approximately 1.5 nm. Photodegradation examination of TiO2/SiO2/Ni-Cu-Zn ferrite composite was carried out in methylene blue (MB) solutions illuminated under a Xe arc lamp with 35 W and color temperature of 6000 K. The results indicated that about 47.1% of MB molecules adsorbed on the TiO2/SiO2/Ni-Cu-Zn ferrite ferrite composite within 30 min mixing due to it higher pore volume of 0.034 cm3/g, and after 6 h Xe lamp irradiation, 83.9% of MB was photodegraded. Compared with the TiO2/Ni-Cu-Zn ferrite composite, the TiO2/SiO2/Ni-Cu-Zn ferrite ferrite composite with silica barrier layer prohibited the photodissolution and enhanced the photocatalytic ability. The magnetic photocatalyst shows high photocatalytic efficiency that the apparent first-order rate constant kobs is 0.18427 h-1, and good magnetic property that the saturation magnetization (Ms) of 37.45 emu/g, suggesting the magnetic photocatalyst can be easily recovered by the application of an external magnetic field. (3) Silver nanoparticles with different weight percentage immobilized on TiO2/SiO2/Ni-Cu-Zn ferrite nanoparticles were successfully prepared via coprecipitation and sol-gel hydrolysis precipitation method. The synthesized product was characterized using various techniques. Room temperature magnetic hysteresis curves shows that as synthesized 0.4wt% Ag immobilized TiO2/SiO2/Ni-Cu-Zn ferrite display superparamagnetic behavior with saturation magnetization of 39.93 emu g-1. XPS characterization confirmed the presence of Ag nanoparticles on the surface of magnetic semiconductor photocatalyst. Surface morphology was analyzed using TEM, which shows a non-uniform shaped core-shell structure with an average particle size of 18-40 nm of Ag nanoparticles deposited on the surface. The effect of immobilization of Ag nanoparticles on structural, optical and photocatalytic properties of TiO2/SiO2/Ni-Cu-Zn ferrite was investigated by X-ray diffraction (XRD), UV-Visible spectrophotometer, Photoluminescence (PL) spectroscopy and electrochemical measurements. Photocatalytic dye degradation of Ag-TiO2/SiO2/Ni-Cu-Zn ferrite composite was carried out in methylene blue (MB) solutions. The results indicated 87.75% of MB was photodegraded under Xe lamp irradiation for 0.4 wt% of Ag immobilized TiO2/SiO2/Ni-Cu-Zn ferrite. Moreover, it can be easily separated and recycled without significant loss of photocatalytic activity after being used five times. Therefore, compared to the conventional photocatalysts, this magnetic core–shell photocatalyst is green, cheap and more suitable for large scale applications.

碩士
國立高雄應用科技大學
化學工程與材料工程系博碩士班
104
Photocatalysis can be effectively applied in removing the pollutants in the water, and it has the significant problem that need to be solved. As a result, this research mainly focused on synthesizing magnetic photocatalysts which can effectively remove organic pollutants in the water under visible light. The organic pollutants (Methyl orange, MO) can be transformed into CO2¬ and H2O, etc. The used photocatalysts can be recycled by magnetic process. The octahedron, hollow sphere, and dodecahedron Cu-2O/graphene were synthesized via sol-gel and solvothermal methods. Then dope Cu2O onto high electron conductivity of graphene oxide (rGO) to reduce recombination electrons and electron holes. As a result, it has the most effective degradation efficiency when combine with 1% graphene oxide. Besides, the results demonstrate that Cu2O dodecahedra with exposed {110} facets with more dagling “Cu” atoms possesses higher activity than those with hollow sphere {110} & {111} facets and Octahedral {111} facets. We synthesized magnetic core-shell materials (Fe3O4@SiO2), follow by adding Cu2O and graphene oxide that can produce high saturation magnetization and photocatalysis performance of magnetic photocatalysts. Magnetic photocatalysts, dodecahedron Cu¬2O/rGO have removal efficiency of 98% MO in two hours under visible light, after several cycles still retains 85.17%.

碩士
淡江大學
化學工程與材料工程學系碩士班
103
ZnO/Ni/C magnetic photocatalytic particles were prepared using a hydrothermal technique. The aqueous solutions, having the molar ratios of Zn(CH3COO)2‧2H2O：Ni(NO3)2‧6H2O：C3H4OH(COOH)3 = 6：1：4 and the molar concentration of the total metallic ions (Zn2+ and Ni2+) = 0.1 M, were prepared. The pH of the solution was adjusted using 2 M NH4OH(aq). The solutions were then hydrothermally treated at 180 ℃ for 2 h. After centrifugally filtering and freeze-drying, the dried solid precursors were obtained and then thermally analyzed to investigate their thermal behavior, followed by calcining the solid precursors in N2 atmosphere at different temperatures. The calcined specimens were characterized using x-ray diffractometer (XRD), fourier transform infrared spectroscope (FTIR), scanning electron microscope (SEM) and photoluminescence spectroscope (PL). The photocatalytic performance of the prepared ZnO/Ni/C particles was evaluated by monitoring the ability to photocatalytically decompose the methylene blue in water under the irradiation of 365 nm UV light. Effects of pH values of the aqueous solution and calcination temperatures on the degree of crystallinity of ZnO and the weight ratio of ZnO to Ni in the ZnO/Ni/C magnetic photocatalytic particles were studied. The results indicated that the ZnO/Ni/C magnetic photocatalytic particles prepared by calcining the solid precursor obtained from the solution of pH = 4 (without NH4OH additions) in the nitrogen atmosphere at 600 ℃ possessed the best photocatalytic ability to decompose methylene, having a specific reaction rate, based on the mass of the photocatalyst used, 0.017 m3/(kg．s).

碩士
國立中正大學
應用地球物理研究所
102
In the present study three different magnetically separable ZnO catalysts (Fe3O4/ZnO: M1, Fe3O4/SiO2/ZnO: M2, Fe3O4/SiO2-APTS/ZnO: M3) were synthesized, characterized and tested for their photocatalysis in the degradation of methylene blue (MB) under sunlight irradiation. ZnO particles were precipitated on their respective magnetic counterpart using tetramethyl ammonium hydroxide (TMAH) as a coprecipitant, followed by a solvothermal synthesis. Results indicate that the photocatalytic activities of both M2 and M3 were superior to that of M1. The presence of silica coating in these catalysts enhanced efficient transport of the MB dye to the ZnO site thus enhancing the photocatalysis. The order of reactivity of photocatalysis in degradation of MB was found to be M2 > M3 > M1. Photocatalytic reactivity was related to the defects present in the samples under the synthesized conditions. Photoluminescence studies indicated the order of the defects in ZnO catalyst as M2>M3>M1. The presence of ZnO defects in the samples of M2 and M3 slowed electron recombination time, as a result the formation rate of hydroxyl radical increased and hence faster degradation of MB. The recycle experiments using magnetic separation in photocatalysis experiment showed good activity and repeatability thus demonstrating as stable and efficient magnetic catalysts.

碩士
明新科技大學
化學工程研究所
98
Experimental treatment by using photocatalyst-TiO2 alone for dye wastewater is very efficient, especially for decolorization. Besides, the secondary pollution by the application of TiO2 can be eliminated. But, the difficulty of solids (TiO2 ) and liquid (wastewater) separation problems exists and hard to solve.Therefore this project will focus on the preparation of magnetic photocatalysts, which has the characters and advantages for solving separation problems. The magnetic field can be applied in recycling and solid-liquid separation. Chemical co-precipitation process was used for the preparation of magnetic Ni-Cu-Zn ferrite. It was then mixed and treated with titanium sulfate, NH4OH or urea to form Ni-Cu-Zn ferrite/TiO2. The prepared magnetic TiO2 was used as photocatalysts to treat dye wastewater by solar irradiation. Langmuir-Hinshelwood kinetic model was also studied. In the result, magnetic photocatalysts was examined by XRD. It was found that TiO2 is anatase structure. In FBL dye wastewater, the treatment by TiO2(Ferrite：TiO2=1：1) by ammonia method is the most effective. When COD of FBL dye is 100ppm, the removal of TOC is 92.66% and the removal of ADMI is 99.42%. When COD of FBL dye is 400ppm, the removal of TOC is 86.58% and the removal of ADMI is 97.05%. It is evident that the prepared NiZnCu Ferrite/TiO2 photocatalysts exist both magnetic and photocatalytic properties. Langmuir adsorption isotherm and Langmuir-Hinshelwood kinetic model can all be applied to the dye wastewater treatment.

碩士
東海大學
環境科學與工程學系
98
Abstract Photocatalysts of high surface area (SA) possess superiority for photocatalytic reaction. Therefore, nano-size materials of high SA have been attracting extensive attention for decades due to the novel characteristics and high activity. Nano-sized photocatalysts are mostly used in slurry or immobilized systems, in which the latter does need the further separation equipments. Although the slurry system demands special separation process, the high photocatalytic ability makes it popularly adapted. However, the simple separation of nano-particles from liquid phases is still a difficult task up to now. Another task for traditional photocatalysts is to broaden the application of photocatalysts and make them effective under the visible-light irradiation. In order to overcome these two tasks, this study, therefore, investigated the synthesis of magnetically visible-light-active photocatalysts and their applications on the degradation of the endocrine disrupting chemical of dimethy phthalate (DMP). A series of magnetic S-doped (sulfide doped) TiO2 photocatalysts were synthesized by means of TTIP and thiourea with sol-gel routes. The synthetic parameters (e.g., water concentration of admixture and calcination temperature) were designed with response surface methodology (RSM). Prior to synthesis of S-TiO2, the magnetic carrier (SiO2/Fe3O4, M) was firstly prepared by precipitation (Fe3O4) and sol-gel (SiO2) routes. Sequentially, S-doped TiO2 was coated on magnetic carrier to obtain magnetic visible-light-active photocatalysts (SM-TiO2). The obtained photocatalysts have been characterized by TEM, SQUID, ESCA, FTIR, XRD, PL, UV-VIS-NIR spectrometer and Electrophoresis. The results showed that the optimal condition for SM-TiO2 synthesis is at sulfide loading ratio of 1.3-1.88 at.% and calcination temperature of 514-550oC, judged by the photocatalytic degradation of DMP. The obtained SM-TiO2 was at an average diameter smaller than 20 nm. The UV-VIS-NIR spectrometry showed that the red shift existed in the samples of SM-TiO2. The PL indicated that recombination rates of electron–hole pairs were the slowest for the SM-TiO2 synthesized at the optimal condition. The peaks at around 529.6, 530.4 and 531.6 eV of XPS spectra can be attributed to the oxygen in Ti–O–Ti, Ti–O–S and S–O–S linkages, respectively. The peaks corresponding to 1050 and 1131 cm-1 of FITR spectra confirmed the existence of SO42-. XRD spectra showed that the main crystal of SM-TiO2 was anatase phase. However, as the calcination temperature was as high as 750oC, the rutile phase occurred and was inhibited by the existence of sulfide. With respect to the adsorption and photodegradation of DMP with SM-TiO2, Langmuir and Freundlich isotherms and Langmuir-Hinshelwood model can well describe adsorption and photocatalytic behavior, respectively. In addition, the SM-TiO2 of 6.88 emu g-1 can be easily recovered from the heterogeneous system. After 6 run experiments (e.g., photo-degradation and then recovery for one run), the reaction rate of k was between 0.0185 to 0.0147 mg L-1 min-1 g-1, indicating that the stable physicochemical property. This study demonstrated that novel visible-light-active titania photocatalysts of magnetic core-shell type were successfully synthesized and applied on the degradation of DMP. Keywords: magnetic, photodegradation, visible-light-active, sulfide, Langmuir-Hishelwood model, Dimethy phthalate, Titania

碩士
東海大學
環境科學與工程學系
98
Photocatalysis is one of the most popular advance oxidation methods to degrade environmental pollutants due to the possession of effectiveness and rapid reaction. Therefore, it has been widely applied to the wastewater and air pollution treatments. However, the conventionally commercial catalysts face some problems, which are not visible-light-active and difficult to recover from the liquid/solid heterogeneous system. To overcome these shortcomings, this study has been carried out the synthesis of novel magnetic visible-light-active photocatalysts. Furthermore, dimethy phthalate (DMP), which belongs to endocrine disrupting chemicals, was used as an indicator to test the performance of the photocatalytic degradation. The magnetic photocatalyst of core-shell type (M-TiO2) was synthesized by chemical coprecipitation for magnetite and silica and sol-gel process for TiO2. The experimental parameters such as water concentration and calcination temperature were investigated to obtain the optimal synthesizing condition. The M-TiO2 prepared under the optimal condition was further coated with various weight loadings (wt.%) of copper phthalocyanine (Cupc) to obtain visible-light-active photocatalyst (CM-TiO2). The optimal condition for M-TiO2 synthesis is at water concentration of 0.4 M and calcination temperature of 550oC. And the optimal Cupc loading ratio was 1.92 wt.%. The adsorption and degradation behavior were well described with Langmuir and Freundlich isotherms, and the Langmuir-Hishelwood model, respectively. The crystal phases of M-TiO2 and CM-TiO2 were both anatase and magnetite: The optimal operating parameters for M-TiO2 at pH value of 3 and the dosage is 1.2 g L-1: For the CM-TiO2, the investigation on photocatalytic reactivity for the same photocatalyst showed that the parameter (k) of Langmuir-Hsinshelwood model kept almost the same value of 0.093 mgL-1 g-1 even after 9 reaction cycles, indicating the stable physicochemical property. This study demonstrated that novel hybrid magnetic materials were successfully synthesized and applied on the degradation of DMP. Keywords: Environmental hormone, Dimethy phthalate (DMP), photodegradation, magnetic photocatalyst, organic inorganic hybrid materials, copper phthalocyanine (Cupc), visible-light-active, Langmuir-Hishelwood model

碩士
國立東華大學
光電工程學系
105
Hydrogen, with its high energy density and storability and also only clean water as its main by-product after burning, is regarded ideal as a renewable energy sources. In recent years, hydrogen production by solar photocatalytic reforming has become one of the most popular research topics, especially in development of recyclable photocatalysts for visible-light. Here in this study, TiO2 doped Fe2O3 were synthesized and used as the photocatalyst to improve the drawback of low activity by using only TiO2. In the first part of this study, Fe2O3 and TiO2 powders were prepared to produce magnetic photocatalyst powder via the solid state reaction. In the X-ray diffraction (XRD) analysis, it shows that when the sintering temperature rose from 850oC to above 900oC, a new diffraction peak of Fe2TiO5 phase occurred at the 2θ = 25.6° position on the major diffraction plane (101). Through X-ray photo-electronic spectroscopy (XPS) analysis, because Fe3+ acted as a capture agent for both electrons and holes, the carriers captured by the traps could be easily released, thus prolonging the life of the photo-induced carriers and enhancing the photocatalytic activity. Also, after the heat treatment, oxygen vacancies found in the TiO2 crystals effectively increased the electron conductivity as well as the activity of the photocatalysts. In the photocatalytic hydrogen production experiment, it is found that the Fe2O3-TiO2 photocatalysts sintered at 900°C yielded the most cumulative production of hydrogen (975.00 μmol). According to the result of hysteresis loop, it is observed that the Fe2O3-TiO2 photocatalyst prepared, was weak magnetic,and it may be possibilities for magnetic recovery. The second part of the study was to prepare the photocatalyst powder by the sol-gel method. The XRD study indicated that the photocatalyst phase prepared by such method would be rich Fe2TiO5 with the major diffraction plane (101) at the 2θ = 27.07° position. Through the UV-vis measurement together with the Tauc model, the bandgap of the Fe2TiO5 photocatalyst prepared was about 1.9 eV. Finally, the photocatalytic hydrogen production experiment was carried out to measure the hydrogen production efficiency with the Fe2TiO5 photocatalyst. The result was that the soft magnetic Fe2TiO5 photocatalyst sintered at 700°C yielded the highest cumulative production of hydrogen (1072.90 μmol), which was better than the Fe2O3-TiO2 photocatalyst synthesized by the solid state reaction in the first part of the study.

碩士
國立東華大學
材料科學與工程學系
92
The aims of this study were to prepare and characterize the TiO2-WOx-N photocatalytic film by RF magnetron sputter system. The target of sputtering system was manufactured by TiO2 mixed 5mole%WO3 and prepare by hot press system. Then, the sputter process parameters were controlled under：variety the sputter working distance between the target and substrate(4cm~8cm), the reaction plasma was under different nitrogen and argon flux fraction (40%~100%) in fixed the sputter distance 4cm. The single crystal silicon wafer (100) and quartz were used as substrate. The reaction working pressure was 8 mtorr in the chamber. And the base pressure was 2×10-5 torr. The microstructures and phases analysis of the TiO2-WOx-N film were investigated by XRD and Raman spectrum. XPS, SEM&EDS were used to observed the surface morphology and composition. The photocatalytic activity of TiO2-Wox-N thin films were illuminated the fluorescent lamp and those induced photocatalytic properties were characterized by the water contact-angle measure and degradation of methylene blue. When the compositions of thin film were variety, the photocatalytic properties were varied with the crystallinity of the TiO2-WOx-N photocatalytic film. It was found that the photocatalyst thin film with well-crystallize and anatase phase was exhibited the best photocatalytic performance. The first part of our works was to the parameter of change the working distance. The sputter power is 250W, working pressure is 8mtorr and reaction gas flux is 100% N2 (10sccm). When the distance of substrate and target is 5cm that the thin film was revealed the well anatase crystal structure and the absorbance wavelength about 450nm and well photocatalystic properties by visible illumination. The degradation rate of methylene blue was K=0.05327hr-1. The water contact angle test of films was illuminated by fluorescent lamp from 65∘decreased to 11∘in 40min. But, when the working distance is 4cm, the concentration of nitrogen was too high and decreasing the phtocatalystic properties. The second part of our work was change the N2 flux ratio (40%~100%), fixed the working distance on 4cm, and working pressure 8 mtorr. When the reaction was 50% N2 flux ratio and 190W sputter power, the deposited TiO2-WOx-N thin film revealed very well-crystallize anatase phase. The absorption wavelength was shifted to 480nm, the degradation rate of methylene blue was K：0.1214hr-1, and the hydrophilic properties was contact angle decreased from 58∘to 4∘in 20min illuminated fluorescent lamp.

In recent years, pulp and paper mills have faced challenges on wastewater treatment management, due to the increase of effluents production and the environmental concerns, related with the need to meet progressively rigorous discharge limits imposed by new legislation. The effluents generated in pulp bleaching contain, among other organic pollutants, adsorbable organic halides (AOX) that can be photo-oxidized using ultraviolet radiation. There are strong evidences that confirm the efficiency of nanoparticles of titanium dioxide (TiO2) as photocatalyst in the photodegradation of AOX compounds. However, there is a need to develop supports for nano-TiO2, in order to allow its recovery and reutilization in consecutive photocatalytic tests, and this is the main aim of this thesis. Thus, this work investigated two independent strategies: (1) the preparation of nano-TiO2 with magnetic properties aiming easy and fast recovery by magnetic separation and (2) the use of geopolymer spheres containing TiO2, that were produced with a percentage of ash from residues of pulp and paper mills. All the materials were characterized using X-ray powder diffraction, spectroscopy (FTIR and UV-vis) and electron microscopy (SEM/TEM). The TiO2 nanoparticles with magnetic properties were prepared by in situ co-precipitation of magnetite (Fe3O4) in the presence of TiO2. The Fe3O4/TiO2 materials were prepared with variable TiO2 content (between 14.0 and 43.5wt%) and were composed of nanoparticles of magnetite and TiO2, in an irregular and non-homogeneous configuration. The highest TiO2 content was obtained for the sample Fe3O4/TiO2 (1:3) after centrifugation (43.5%). The geopolymer spheres containing TiO2 were around 3 mm average diameter, with porous surface. In terms of the chemical composition, the major crystalline compounds were TiO2 (24%), quartz (22%) and muscovite (20%). In a later stage, all materials were tested in the photodegradation of AOX present in real bleaching stream samples. The experiments were carried out for 1 hour in a laboratory photoreactor, with addition of H2O2 and using UV-light as radiation source. The percentage of AOX removal in all the supported photocatalysts was similar. The best results were attained with Fe3O4/TiO2 (1:3) centrifuged (73.3% AOX removal) and with the spheres (68.9% AOX removal). Comparing with TiO2 non-supported (76.6%), the removal efficiency on supported photocatalysts was slightly lower. In addition, it was also seen that the use of UV-light increases the performance of the photocatalysts, while the type of stirring (magnetic vs injection of compressed air) did not influence significantly the results. The percentage of catalyst magnetically recovered decreased with the increase of TiO2 content and with UV-light exposure, thus suggesting that these materials are sensitive to UV radiation and that they lose some of their magnetic force during the photocatalysis trials. Reusing the recovered photocatalysts in a second run, the AOX removal was relatively similar to the previous ones, with the best result obtained with Fe3O4/TiO2 (1:1), 75.8%, which proved their ability to be efficiently reused to remove AOX. The geopolymer spheres presented their surface and pores degraded after photocatalysis, but their chemical composition did not change significantly. These photocatalysts were also subjected to a second series of tests, which allowed to remove about 65.5% of AOX
Nos últimos anos, as fábricas da pasta de papel têm enfrentado desafios na gestão do tratamento de efluentes, devido ao aumento da produção dos mesmos e às preocupações ambientais, relacionadas com a necessidade de cumprir limites de descarga que são cada vez mais rigorosos e impostos por nova legislação. Os efluentes gerados na etapa de branqueamento contêm, entre outros poluentes orgânicos, compostos halogenados adsorvíveis (AOX) que podem ser foto-oxidados com radiação ultravioleta. Existem fortes evidências que confirmam a eficiência das nanopartículas de dióxido de titânio (TiO2) como fotocatalisador na degradação de compostos AOX. No entanto, há a necessidade de desenvolver suportes para o nano-TiO2, de modo a permitir a sua recuperação e reutilização em ensaios fotocatalíticos consecutivos, sendo este o principal objetivo desta tese. Assim, neste trabalho investigaram-se duas estratégias independentes: (1) a preparação de nano-TiO2 com propriedades magnéticas com vista a uma recuperação fácil e rápida por separação magnética e (2) o uso de esferas geopoliméricas contendo TiO2, que foram produzidas com uma percentagem de cinzas de resíduos da produção da pasta e papel. Todos os materiais preparados foram caracterizados por difração de raio X, espectroscopia (FTIR e UV-vis) e microscopia eletrónica (SEM e TEM). As nanopartículas de TiO2 com propriedades magnéticas foram preparadas por co-precipitação in situ de magnetite (Fe3O4) na presença de TiO2. Os materiais Fe3O4/TiO2 foram preparados com teores variáveis de TiO2 (entre 14.0 e 43.5%m/m), sendo compostos por nanopartículas de magnetite e TiO2, numa configuração irregular e não homogénea. O teor mais elevado de TiO2 foi obtido para a amostra Fe3O4/TiO2 (1:3) após centrifugação (43.5%). As esferas geopoliméricas contendo TiO2 tinham cerca de 3 mm de diâmetro médio e uma superfície porosa. Em termos de composição química, os compostos maioritários são TiO2 (24%), quartzo (22%) e muscovita (20%). Numa etapa seguinte, todos os materiais foram testados na degradação fotocatalítica de AOX em amostras reais provenientes do caudal de branqueamento. Os ensaios decorreram durante 1 hora, num fotoreator laboratorial, com adição de H2O2 e utilizando luz UV como fonte de radiação. A percentagem de remoção de AOX foi semelhante, independentemente do tipo de suporte utilizado. Os melhores resultados foram obtidos com Fe3O4/TiO2 (1:3) centrifugadas (remoção de 73.3% de AOX) e com as esferas (remoção de 68.9% de AOX). Comparando estes resultados com os de TiO2 não suportado (76.6%), a eficiência de remoção nos fotocatalisadores suportados foi ligeiramente menor. Além disso, também se observou que o uso de luz UV aumenta o desempenho dos fotocatalisadores, enquanto o tipo de agitação (agitação magnética vs. injeção de ar comprimido) não influenciou de forma significativa os resultados. A percentagem de catalisador recuperado magneticamente diminuiu com o aumento do teor de TiO2 e com a exposição à luz UV, sugerindo que estes materiais sejam sensíveis à radiação UV e que percam alguma da sua força magnética durante os ensaios de fotocatálise. Reutilizando os fotocatalisadores recuperados numa segunda série, a remoção de AOX foi relativamente similar às anteriores, com o melhor resultado a pertencer a Fe3O4/TiO2 (1:1), 75.8%, o que provou a sua capacidade de ser eficientemente reutilizado para remover AOX. As esferas geopoliméricas tiveram a sua superfície e poros degradados após os vários testes de fotocatálise, mas a sua composição química não se alterou significativamente. Estas também foram submetidas a uma segunda série de ensaios que permitiram remover cerca de 65.5% de AOX
Mestrado em Engenharia Química

碩士
國立中興大學
材料科學與工程學系所
105
Nitrogen-doped Fe3O4@Ag@TiO2-xNx composite particles have been successfully synthesized by solvothermal method using different kinds of dopant including methylamine (MA), diethylamine (DEA), ethyleneamine (EDA), urea (U), and ammonia (A). X-ray diffraction revealed that diffraction peaks pronouncedly broaden and their intensity reduce with the N-doping, indicating that reduced crystallinity and smaller crystalline size resulted. Based on XPS analysis, interstitial nitrogen-doping was found in the titanium dioxide layer of the composite particles. The Fe3O4@Ag@TiO2-xNx composite particles exhibited a high BET surface area of 251.3~431.9 m2/g and a BJH average pore diameter below 10 nm. By SQUID measurement at room temperature, the saturation magnetization (Ms) of the particles was 0.02 emu/g. From UV-vis spectroscopy and Tauc plot, the band gap was determined in the range of 2.4-2.8 eV for the Fe3O4@Ag@TiO2-xNx composite particles. We have also investigated dye degradation of organic dyes in water by dark adsorption and visible light irradiation. Among the nitrogen sources examined, the as-prepared powders show different adsorption ability to methylene blue (MB) and methyl orange (MO) as the solution pH was altered. The dye molecules must be adsorbed on the powder surface, before being photodegraded under the light irradiation. The methylamine-doped particles were found to have ~90% adsorption for the MB dye at pH=2, and ~30% adsorption followed then by ~20% photocatalytic activity for the MO dye. At pH=9, the methylamine-doped ones showed ~100% adsorption for the MB dye but there was no adsorption for the MO dye. The urea-doped ones showed ~40% adsorption followed then by ~30% after visible light irradiation at pH=2, but there was no significant effect for the MO degradation. In addition, the initial dye concentration was varied, and the methylamine-doped composite particles appeared to exhibit a multilayer adsorption behavior when the dye concentration was below 2.5x10-5 M. The methylamine-doped powders were recycled by an external magnetic field and were re-used for the dye removal. The particles showed a degradation rate nearly 95% after up to five times of use. Finally, Ag could be slowly released from the composite particles through the mesoporous shell structure. The release of Ag was found after immersion in water for 48 h, indicating long-lasting bactericidal ability.

碩士
國立臺中教育大學
科學教育與應用學系科學教育碩士班
103
The mixing and heating method and the hydrothermal method are applied to synthesizing two visible-light-driven (VLD) photocatalysts, SrFeO3-x/g-C3N4 and BiOBr/PbBiO2Br, respectively. X-ray diffractometer, Field Emission-Scanning Electron Microscopy-Energy Dispersive Spectroscopy, Field Emission-Transmission Electron Microscopy-Energy Dispersive Spectroscopy, Fourier Transform Infrared Spectroscopy, UV-vis diffuse reflectance spectra, Surface Area and Porosity Analyzer, and Ultraviolet Photoelectron Spectroscopy are utilized for distinguishing the synthesized samples. SrFeO3-x/g-C3N4 and BiOBr/PbBiO2Br degraded crystal violet dye and chloramphenicol solution are used for simulating the environmental target pollutants. From the reaction rate constant of the degraded crystal violet dye solution, the 4wt.% SrFeO3-x is added g-C3N4 for the calcination at 500℃ for 2 hours. The acquired SrFeO3-x/g-C3N4 0.0997h-1 is higher than g-C3N4 0.0209h-1 and SrFeO3-x 0.0014h-1, and the degradation efficiency constant of BiOBr/PbBiO2Br appears 0.0601h-1 which apparently enhances the photocatalytic efficiency in comparison to BiOBr 0.0207h-1 and PbBiO2Br 0.0017h-1. The distinguishing with reactive species and Electron Paramagnetic Resonance shows the important roles of free radicals, ․OH and․O2— , in the photocatalytic reaction. In order to understand the pathway of the crystal violet dye and chloramphenicol degradation, the reactive intermediate in the HPLC-PDA-ESI-MS separation process is used for predicting the possible photocatalytic degradation mechanism for the research basis of crystal violet dye and chloramphenicol degradation.

The research in the area of metal-organic frameworks (MOFs) continues to be interesting for their unique structures and tunable properties. In this thesis, the various aspects of metal-organic frameworks (MOFs) compounds are presented. As part of this study, preparation of MOFs of transition metals (Mn, Co, Ni, Zn), rare-earth metals (Y, La, Pr, Nd, Gd, Dy) and mixed metals (3d-4f) using aromatic carboxylates as linker ligands were accomplished. Structures of the synthesized compounds have been determined by single crystal X-ray diffraction technique. Magnetic properties of the transition metal based compounds have been studied by SQUID magnetometer and the magnetic behaviors have been correlated with their structures using suitable theoretical model. Photocatalytic properties on transition metal and mixed metal compounds have been investigated. Ligand-sensitized metal-center emission has been studied on the Eu3+ and Tb3+ doped MOF compounds of La and Y. Up-conversion luminescence properties of Nd based compounds have also been studied. To gain an insight into the possible mechanism of the formation of MOF compounds, a detailed study of the role of temperature and time during the synthesis has been undertaken. In addition, the transformations of low-dimensional structures to structures of higher dimensionality was also studied, both in the solid state as well as in the solution mediated processes. In Chapter 1 of the thesis an overview of framework compounds is presented. In Chapter 2, the synthesis, structure and magnetic properties of benzene tricaboxylate and 4,4’-oxybis(benzoate) compounds of 3d metals are presented. Some of these compounds show unusual structure and interesting magnetic properties. For example, three-dimensional MOF with -Mn-O-Mn- Kagome layer exhibits canted antiferromagntic behavior. Three-dimensional MOF based on body centered arrangement of Co4 clusters shows two-dimensional ferromagnetic behavior. In Chapter 3, the role of temperature and time of reaction in the formation of MOF compounds and the transformation studies are presented. These studies give a clue regarding the mechanism for the synthesis of MOF compound. In chapter 4, synthesis, structure and luminescent properties of rare-earth and 3d-4f mixed metal compounds are presented. The thermal decomposition of Gd-Co-pyridine carboxylate indicates the formation of nano-sized perovskite oxide at temperature ~ 700 °C. In chapter 5, the photocatalytic behavior for the decomposition of organic dyes using MOF compounds are presented.