Search

Heterogeneous photocatalysis is highlighted to treat volatile organic compound (VOC) emission. Then, this work analysed the influence of palladium (Pd) content loaded in TiO2 on n-octane and iso-octane photodegradation. For this, TiO2 was loaded with Pd in different contents: 0.4%, 0.7%, and 1.0%. The samples were characterized, and the photodegradation experiments were conducted by Pd/TiO2/UV process. The characterization analyses showed that the metal presence did not change the catalyst structure or its surface area; however, it reduced the bandgap energy. The photocatalytic results proved that palladium improved n-octane degradation from 62% (pure TiO2) to 92.6% (0.4%Pd/TiO2) and, iso-octane degradation enhanced from 59% (pure TiO2) to 90.6% (0.7%Pd/TiO2); all results were obtained in the space time of 39 s. Therefore, 0.4%Pd/TiO2 and 0.7%Pd/TiO2 showed better oxidation results to degradation n-octane and iso-octane, respectively. The kinetic model of pseudo-first order showed a good fit for the data of both VOCs. Heterogeneous photocatalysis with Pd/TiO2 showed to be an adequate technique to reduce VOCs emission.

Heterogeneous photocatalysis with TiO2 have been studied for VOCs degradation; however, aromatic VOCs degradation lead TiO2 deactivation. The objective of this study was to degrade aromatic VOCs by heterogeneous photocatalysis avoiding TiO2 deactivation. The experiments were conducted using a UV-C lamp (254 nm), relatively humidity (RH – 26–60 %), and ozone (O3 – 2.38 to 5.35 %). Due to O3 addition, it was necessary to have uncoated regions in the quartz tube around the lamp to allow UV photons to reach the gas bulk and generate radicals from O3. Different quartz tube coating fractions were tested to analyze its influence on VOCs degradation. The highest toluene degradation was 99.2 % for the reactor with 90 % of coating, 3.4 % of O3, space time of 123 s, and RH of 26 %. It was observed RH greater than 26 % affected the degradation achieved. Ozone addition allowed TiO2 use for 77 h avoiding early catalyst deactivation. Besides that, the requirement of uncoated regions indicated that VOC oxidative reactions occur both on solid and gas phases. This suggested that the addition of O3 combined with the reactor configuration is a promising alternative for aromatic compound degradation by heterogeneous photocatalysis.

Pyrolysis and combustion kinetics of sugarcane bagasse and straw was analyzed using thermogravimetric measurements and applying the DAEM. The kinetic parameters of pyrolysis and combustion reaction...

Heterogeneous photocatalysis is highlighted to treat volatile organic compound (VOC) emission. Then, this work analysed the influence of palladium (Pd) content loaded in TiO

Volatile organic compounds (VOCs) are atmospheric pollutants that can affect human healthy and intensify some environmental problems. Among different techniques to degrade VOCs, heterogeneous photocatalysis has been highlighted. The aim of this research was to obtain high toluene degradation using heterogeneous photocatalysis in the ozone presence (TiO2/O3/UV) and analyze VOC degradation over the reactor length comparing with ozone concentration also over the reactor length. Ozone concentration has influence on toluene degradation; 75% of VOC degradation was reached with 69.0 mgL−1 of O3 meanwhile a degradation of 91% was obtained with 96.2 mgL−1 of O3. Toluene degradation reached a plateau over reactor length at flowrate of 565 mL min−1, which indicates the reactor was oversized in this case. However, it was not observed at 1425 mL min−1. In addition, it was evaluated that O3 concentration and toluene reaction rate decreased over the reactor length.

Volatile organic compounds (VOC) are air pollutants usually found in urban and industrial areas. Heterogeneous photocatalysis is an interesting technique used to degrade these compounds. Several approaches may enhance this process; some studies have shown higher VOC conversions by adding ozone to the experimental system, once ozone increases the number of reactive radicals in the reaction. In this context, this work studied the conversion of cyclohexane and toluene by heterogeneous photocatalysis in gas phase, in the presence of titanium dioxide (TiO2), UV light, and different concentrations of ozone. For fixed space times from 13.1 to 48.8 s, an average increase of 9% was reached in cyclohexane conversion when comparing the system with maximum concentration of ozone (0.8%) and the system without it. In addition, difference of less than 2% in the conversion of cyclohexane with different moisture fractions was observed. Toluene photodegradation was also analyzed in the presence of ozone and although the conversion was only about 40% for the space time of 25 s, this result was maintained during 4 h of experiment, with no catalyst deactivation as usually reported in the literature for aromatic compounds. Based on the results, ozone addition is an advantageous technique to improve the photodegradation of VOC.

Orange juice industries produce essential oils ( d -limonene) and citrus pulp. The citrus pulp corresponds to 49 kg per 100 kg of orange processed and it is the bagasse of processed fruit after pressing, milling, pelleting and drying operations. However, bagasse drying process causes emission of volatile organic compounds (VOCs) because albedo and flavedo are present in the bagasse containing a residual amount of d -limonene and volatile oils unrecovered in other process steps. These compounds are a primary source of air pollution and it cause problems related to tropospheric ozone formation, photochemical pollution and human health problems, when being into the atmosphere. In this context, the emission of VOCs was studied, exposing particles of albedo and flavedo (Citrus sinensis L. Osbeck) to airflows with constant velocity at different exposure times and at seven temperatures. The experiments were conducted in an experimental module, where gas samples at the airflow outlet were collected for the quantification of furfural, α-pinene, β-pinene, 3-carene, p-cymene and d -limonene by gas chromatography with detector of flame ionization (GC-FID). The results showed that the main compounds emitted were d -limonene, 3-carene and α-pinene from the flavedo with a tendency to increase the emission with the increase of the temperature. The emission of VOCs occurred by steam distillation process predominating between room temperature and 160 °C, and by steam distillation followed by evaporation by thermal degradation effect due to the exposure time at temperatures between 160 and 250 °C.

Agricultural residues have been pointed out as an important source to energy conversion by direct burning. Nevertheless, their use still faces operational problems, such as slagging and fouling, mainly related to the inorganic fraction of their composition. The objectives of this work were to understand the fusion behavior of sugarcane biomass ash formed during thermal conversion and the tendency of slag and fouling to occur, in addition to propose possible solutions to minimize these problems using a mixture of biomass species and/or additive minerals. To that end, experimental measurements and thermodynamic simulations were employed to relate the chemical composition to the fusibility. The ashes chemical composition was characterized by EDS and XRD, while the ash fusion temperatures AFTs (DT, ST, HT and FT) were measured by AF700 equipment and estimated using FactSage modeling. Statistical analysis helped to derive the relationship between chemical composition and AFTs. The ashes were rich in SiO2, Al2O3 and Fe2O3 and revealed that for bagasse the element that most contributes to increase DT is Si, whereas for straw the presence of Al has a stronger effect to increase DT. Fe was found to act as flux element. XRD results showed the phases differences, finding more amorphous components in straw ash than in bagasse, which may lead to a different ash fusion behavior. Straw 2015 ash presented a DT of 733 °C while for bagasse 2015 and 2016 ashes the values of DT were 777 and 917 °C, respectively. In contrast, the DT of straw ash increased when mixed with bagasse 2015 and 2016 to values of 841 and 885 °C, respectively, and also when 1% of Al2O3 was added, obtaining a DT of 930 °C. For bagasse samples, the additives showed a minor effect on ash melting behavior.

Over decades heterogeneous photocatalysis has been successfully applied to degrade a wide range of pollutants. Despite it, when aromatic volatile organic compounds (VOCs) are treated, generally, challenges such as low efficiency and photocatalyst deactivation are faced. In this scenario, the association between heterogeneous photocatalysis and ozone (TiO2/UV/O3) has emerged as an alternative to overcome such issues, although it has not yet been applied to ethylbenzene removal from gaseous streams. In this work, gas-phase ethylbenzene degradation (73 ppmv) by UV radiation, O3, UV/O3, TiO2, TiO2/UV, TiO2/O3, and TiO2/UV/O3 processes was evaluated. The influence of parameters such as relative humidity (26–80%), space-time (130, 74, 52, and 29 s), ozone concentration (3.6, 4.2, and 5.5%), and percentage of catalytic coating area (50, 70, 90, and 100%) on ethylbenzene removal was investigated. Relative humidity from 26 to 50% did not affect ethylbenzene degradation significantly and TiO2/UV/O3 enhanced its removal up to 87.7% and 22% when compared to the TiO2/UV and the UV/O3 processes, respectively. A maximum ethylbenzene conversion of 98% was also reached at 130 s, 70% of TiO2 coating area, and 5.5% of ozone. We found that, in the TiO2/UV/O3 system, reactions on the catalyst surface and in the gas bulk were both important, thus a 70% of TiO2 coating area was obtained as the best configuration. Furthermore, catalyst stability was assessed by a time-on-stream experiment and TiO2/UV/O3 maintained the average ethylbenzene conversion at 75% during 50 h. TGA/DTGA and FTIR analyses allowed the identification of possible compounds adsorbed on the catalyst surface after reactions.

Heterogeneous photocatalytic oxidation systems using titanium dioxide (TiO2) have been extensively studied for the removal of several volatile organic compounds (VOCs). The addition of noble metals such as palladium on TiO2 may improve photocatalytic activity by increasing charge separation efficiency. In this work, palladium was impregnated on TiO2 and the efficiency of the new catalyst was tested and compared with that of pure TiO2. Pd was impregnated on TiO2 by the reduction method, using NaBH4, and was characterized by XRD, XPS, UV–Vis, and H2 chemisorption. The photocatalytic tests were performed in an annular coated-wall reactor using octane, isooctane, n-hexane, and cyclohexane at inlet concentrations varying from 100 to 120 ppmv. Compared with pure TiO2 film, the photocatalytic activity of TiO2 impregnated with 1 wt% of palladium was improved. All the aforementioned analytical techniques confirmed the presence of Pd incorporated into the structure of TiO2, and the conversion rates were studied in a broad range of residence times, yielding up to 90 % or higher rates in 40 s of residence time, thus underscoring the relevant contribution of the technology Fechado

Agradecimentos: This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001. This work was also supported by Fundação de Desenvolvimento da Unicamp (FUNCAMP). The authors are thankful to Espaço da Escrita - Pró-Reitoria de Pesquisa - UNICAMP - for the language services provided Abstract: Volatile organic compounds (VOCs) are responsible for environmental problems and may affect human health. Several treatment technologies minimize VOCs emissions; among those, catalytic oxidation appears as a promising alternative. In this study, a pilot-scale catalytic reactor was developed and the influence of process parameters on toluene degradation were investigated. Inlet gases were heated by electrical resistances and the catalyst employed was a honeycomb shape commercial automotive catalyst (Umicore, model AFT). Toluene degradation higher than 99% was achieved for several conditions and temperature showed to be the most important process variable for it. For all concentrations, it was observed that when increasing temperature led to a decrease on the space time. At 800?ppmv, varying from 543?K to 633?K, the space time decreased from 0.121?s to 0.08?s, respectively. At 1600?ppmv for the same temperature range, space time was reduced from 0.098?s to 0.040?s, respectively. At 2400?ppmv, varying from 543?K to 633?K, space time decreased from 0.081?s to 0.048?s. The catalytic reactor developed proved to be efficient for VOCs treatment, showing a high potential of application at industrial emission sources COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES Fechado

Volatile organic compounds (VOC) are air pollutants usually found in urban and industrial areas. Heterogeneous photocatalysis is an interesting technique used to degrade these compounds. Several approaches may enhance this process; some studies have shown higher VOC conversions by adding ozone to the experimental system, once ozone increases the number of reactive radicals in the reaction. In this context, this work studied the conversion of cyclohexane and toluene by heterogeneous photocatalysis in gas phase, in the presence of titanium dioxide (TiO

El objetivo del presente estudio fue evaluar la interacción entre el ozono y el material de la tubería usada para su transporte, usualmente polimérica, a fin de determinar las pérdidas de ozono durante el proceso. Para este propósito, una mezcla gaseosa de ozono-oxígeno se hizo fluir a través de dos tipos de tubería, PVC y silicona, desde el generador de ozono hasta el punto de recolección. La concentración de ozono en la mezcla gaseosa y el flujo volumétrico de la corriente gaseosa fueron variadas para cada experimento. El flujo másico de ozono fue medido en el punto de recolección, aplicando el método yodométrico por titulación indirecta. La pérdida de ozono fue observada en ambas tuberías. Estas pérdidas están asociadas a la reacción química entre el ozono y el material de la tubería, como también a la auto descomposición del ozono.

The degradation of air quality in great urban centers is noted by frequent critical episodes of air pollution and public health issues, and vehicles are a great source of pollutant emissions, mainly derived from combustion processes. A database is needed to direct mitigation of emissions. The main objective of this work is to present it as an emissions inventory. The results show that vehicular sources of CO, HC and NOx represent over 75% of total emissions in the MRC. Besides, the proposed methodology presented results consistent with the literature

This paper proposes a methodology to predict benzene uptake rate in ambient air, using passive samplers with Tenax TA. Variations in the uptake rate were found to occur as a function of the sampling time; and were greater at the beginning of sampling. An empirical model was obtained and values for uptake rate agree with literature. Concentration prediction errors can be minimized by using sampling times of 4 to 14 days, thus avoiding the influence of excessive uptake rates in the initial days and the influence of back diffusion at the end of the sampling period.

This work presents a three-dimensional model for the dispersion of effluents in rivers using Computational Fluid Dynamics (CFD) techniques. There are several models in the literature, some of which even analyze complex flows. They are however restricted to small river sections. The main contribution of this work is that it proposes a new software capable of predicting the dispersion of effluents in very large open channels. The model is very fast, an unusual feature of CFD models. Due to this, it is possible to predict the dispersion of substances in long sections of rivers with some kilometers in extension. Moreover, multiple emissions can be analyzed by the model, allowing its use as a predictive tool to analyze and guide management decisions on future industrial installations near rivers. Results for the dispersion of an inert emission in a river near Campinas (Brazil) were used to validate the model.

A quantitative study was performed in Campinas, Brazil. Measurements were taken on an avenue with intense vehicle traffic in the city's downtown area from August 2003 to August 2004. A dichotomous sampler was employed for PM 2.5 and PM 10 . Samples were collected for 24 h at 3-day intervals. In addition, seasonal variations were investigated, using a MOUDI cascade impactor and VOC adsorption tubes, during a specific 5-day period in the summer of 2003 (December) and the winter of 2004 (August). The polycarbonate filters were analyzed by gravimetry, Particle Induced X-ray Emission (PIXE), ion chromatography and reflectance, to identify the mass concentration, elemental composition, ions and elemental carbon mass, respectively. The quartz filters were analyzed by gravimetry and thermal combustion carbon analysis to identify the mass concentration and carbon mass. Results showed an annual mean of 20.85, 10.68 and 10.17 μg m − 3 for PM 10 , PM 2.5 and PM 2.5–10 , respectively. The cascade impactor provided mass distribution and revealed differences between the two seasons. The size distribution for chemical elements indicated soil-derived elements in the coarse fraction. PM winter concentrations were expected to be higher than those in summer, but that was not the case during the days of this study, when summer and winter concentrations were almost identical The PIXE analysis revealed metals and metal compounds, soil-derived elements, sulfates, carbonates, chlorides and other anthropogenic air-borne particles, supposing molecules in their usual composition. An analysis of the VOCs revealed benzene, toluene, m, p -xylene, n -hexane, 2-metilhexane and n -nonane. A mass balance analysis indicated different classes, among which elemental carbon was the most abundant, followed by organic carbon, soil elements and industrial sources.

This study aimed to compare the performance of an internal combustion engine fed with blends of biodiesel produced from soybean and diesel, and blends of biodiesel produced from beef tallow and diesel. Performance was evaluated in terms of power generated at low loading conditions (0.5, 1.0 and 1.5 kW) and emission of organic and inorganic pollutants. In order to analyse inorganic gases (CO, SO2 and NOx), an automatic analyser was used and the organic emissions (benzene, toluene, ethylbenzene and xylene – BTEX) were carried out using a gas chromatograph. The results indicate that the introduction of the two biodiesels in the fuel caused a reduction in CO, SO2 and BTEX emissions. In addition, the reduction was proportional to the increase in loading regime. Beef tallow biodiesels presented better results regarding emission than soybean biodiesels. The use of pure biodiesels also presented a net reduction in pollutant gas emissions without hindering the engine generator performance.

Heterogeneous photocatalytic oxidation systems using titanium dioxide (TiO

A complexa dinâmica envolvida na poluicao atmosferica promove a necessidade de metodologias de analise que representem, com maior fidelidade, suas caracteristicas fisicas. Nas ultimas decadas, diversas pesquisas demonstraram os efeitos nocivos dos contaminantes atmosfericos a saude humana, fauna e flora, desta forma explicitando a urgencia do conhecimento das causas, padroes e mecanismos deste fenomeno. Os metodos classicos empregados para este fim, frequentemente, negligenciam as interacoes nao lineares presentes na evolucao temporal dos poluentes. Nesta vanguarda, o presente trabalho aplica a teoria caotica determinista no estudo de series temporais de concentracao de material particulado inalavel (PM10) e monoxido de carbono fornecidas pela estacao de monitoramento do Parque do Ibirapuera (Sao Paulo) pertencente a Companhia Ambiental do Estado de Sao Paulo (CETESB). Foram obtidos os atratores no espaco de fases e, a partir de sua topografia, determinou-se os valores dos invariantes dimensao de correlacao (D2) e entropia de Kolmogorov (K). Com base nessas grandezas, observou-se a natureza nao linear, aperiodica e deterministica dos dados avaliados, demonstrando que a teoria do caos e uma alternativa viavel no estudo de poluicao atmosferica.

This work presents an overview over heterogeneous photocatalysis performed in gas phase towards the degradation of o-xylene, n-hexane, n-octane, n-decane, methylcyclohexane and 2,2,4-trimethylpentane. The experimental set-up composed by a titanium plug flow reactor vessel contained a quartz tube with a 100 W UV lamp placed at center position from 1.7 cm to the quartz wall. A titanium dioxide film was immobilized on the internal walls of the reactor and used as catalyst. All measurements were taken after reaching steady state condition and evaluated at the inlet and outlet of the system. Conversion rates were studied in a wide range of residence times yielding to a 90% or above conversion as from 20 seconds of residence time. During experiments the temperature of reactor's wall was monitored and remained between 52 and 62 °C. Temperature influence over degradation rates was negligible once a control experiment performed at 15 °C did not modify outgoing results. Humidity effect was also evaluated showing an ideal working range of 10-80% with abrupt conversion decay outside the range. By varying inlet concentration between 60 and 110 ppmv the VOC degradation curves remained unchanged. Loss over catalytic activity was only observed for o-xylene after 30 minutes of reaction, the catalyst was reactivated with a solution of hydrogen peroxide and UV light followed by additional deposition of the catalytic layer. The kinetic study suggests a first order reaction rate.The study of effective and economically viable techniques on the treatment of volatile organic compounds (VOCs) has being highlighted as an important parameter on the environmental research. The heterogeneous photocatalysis in gas phase was proved to be an effective process for the degradation of the nonaromatic VOCs tested, yielding high conversion values for the optimized systems.

The objective of this study was to improve the vehicular emissions inventory for the light- and heavy-duty fleet in the metropolitan area of São Paulo (MASP), Brazil. To that end, we measured vehicle emissions in road tunnels located in the MASP. On March 22-26, 2004 and May 04-07, 2004, respectively, CO, CO2, NOx, SO2, and volatile organic compounds (VOCs) emissions were measured in two tunnels: the Janio Quadros, which carries light-dutyvehicles; and the Maria Maluf, which carries light-duty vehicles and heavy-duty diesel trucks. Pollutant concentrations were measured inside the tunnels, and background pollutant concentrations were measured outside of the tunnels. The mean CO and NOx emission factors (in g km(-1)) were, respectively, 14.6 +/- 2.3 and 1.6 +/- 0.3 for light-duty vehicles, compared with 20.6 +/- 4.7 and 22.3 +/- 9.8 for heavy-duty vehicles. The total VOCs emission factor for the Maria Maluf tunnel was 1.4 +/- 1.3 g km(-1). The main VOCs classes identified were aromatic, alkane, and aldehyde compounds. For the heavy-duty fleet, NOx emission factors were approximately 14 times higher than those found for the light-duty fleet. This was attributed to the high levels of NOx emissions from diesel vehicles.

RESUMO – A operacao de secagem para obtencao de farelo de polpa citrica em industrias de suco de laranja emite compostos orgânicos volateis (COVs) para a atmosfera causando problemas relacionados a poluicao do ar. Desta forma, estudou-se a emissao de COVs durante a exposicao de conjuntos de particulas de albedo e flavedo de laranja-pera a fluxo de ar seco com velocidade constante em diferentes tempos de exposicao e a sete temperaturas. Coletaram-se amostras de gas na saida do fluxo de ar e quantificou-se por cromatografia gasosa com detector de ionizacao por chama (CGDIC): furfural, α-pineno, β-pineno, 3-careno, p-cimeno e d-limoneno. Os principais compostos emitidos foram o d-limoneno, 3-careno e α-pineno a partir do flavedo com tendencia ao aumento da emissao com a temperatura e diminuicao com o tempo de exposicao. Emissao de COVs por arraste a vapor pode ter ocorrido associada a volatilizacao por efeito do fluxo de ar e da temperatura deste e, alem disto, pode-se notar que a secagem conduzida com fluxo de ar dentro de uma faixa de temperatura pode proporcionar uma secagem eficiente e com moderadas emissoes de volateis.

A model based on one-dimensional approach which considers the radiation within each zone and between immediately adjacent zones as well as conduction and convection is proposed in this work. The zone modeling and jet or flame, annular gas and solid flowing streams approach is adopted. The kiln and afterburner are splitted of axially into equal width zones, where each stream is considered well stirred. The heat capacities, thermal condutivities and viscosities are calculated taking into account the dependence on temperature and compositions. The influences of the several parameters, flame geometry approximation, as well as, the mass loss rate specification on flame and exit temperature are analyzed.

Benzene, toluene, ethylbenzene and xylenes (BTEX) are hydrocarbons present in fossil fuels and, consequently, are also present in fuel combustion emissions, as toxic organic volatile compounds. Concentrations of these compounds found in the atmosphere of urban regions are indicative of vehicular pollution. In this work were studied BTEX atmospheric concentrations from five sites of metropolitan area of Campinas (Sao Paulo, Brazil), which have different characteristics: (1) suburban site; (2) downtown site; (3) urban site A; (4) urban site B; (5) industrial. The most abundant compound found in all sites was toluene (2.4 – 10 μg m -3 ). B/T ratio was used to study predominance of vehicular emissions and X/E indicates the distance from the site to the sources due to different photochemical reactivity of the compounds. It was possible to observe that sites away from the urban region and located in the predominant wind direction have lower concentration of BTEX as well as lower X/E ratios, indicating that pollution is due to transport emissions.

The air quality in the industrial area and surroundings of the city of Paulinia (state of Sao Paulo, Brazil) has been investigated by analysing the concentration of air pollutants (SO2, PM10, NO, NO2, CO and ozone) and identifying the main sources of air pollution. A mobile pollutant monitoring unit was used to collect the data at five different sites from November 2000 to July 2002. Critical pollutants were determined based on air quality standards, and sources were identified by principal component analysis. Photochemical reactions play an important role in Paulinia's air pollution: three out of five monitored sites showed levels exceeding the standard air quality of ozone. SO2 and PM10 appeared as pollutants deserving special attention. All the monitored sites showed vehicles and industrial plants (which release SO2) to be significant sources of pollution. Depending on the location, ozone was related mainly with vehicular or industrial sources.

In order to characterize the composition of the main urban air organic compounds in the megacity of Sao Paulo, analysis of samples collected during the winter of 2003 downtown was carried out. The samplings were performed on the roof of a building in the commercial center of São Paulo. Hydrocarbons and carbonyls compounds were collected on August 4, 5 and 6. Comparing to previous data, the concentration of hydrocarbons presented no decrease in the concentration, except for the aldehydes, which decreased when compared to previous data. Among the HCs species analyzed, the highest concentrations observed were those of toluene (7.5 ± 3.4 ppbv), n-decane (3.2 ± 2.0 ppbv), benzene (2.7 ± 1.4 ppbv) and 1,3,5-trimethylbenzene (2.2 ± 1.5 ppbv).

Este estudo apresenta o desenvolvimento de um reator de leito fluidizado em escala laboratorial para a degradação fotoquímica de compostos orgânicos voláteis, desde seu projeto até a construção de um modelo fluidodinâmico para posterior estudo de scale-up e otimização. O processo de tratamento baseia-se na foto-oxidação catalítica dos contaminantes em contato com dióxido de titânio (TiO2) e radiação ultravioleta. Para a construção da unidade laboratorial, o projeto contou com o financiamento do projeto PIPE - Fase 1 financiado pela FAPESP (No.00953/2016). Um dos resultados deste projeto foi uma pesquisa de mercado com diversos clientes que mostrou a necessidade de desenvolvimento de novas tecnologias para tratamento de gases contaminados com compostos orgânicos voláteis (COV). A unidade laboratorial foi montada e instalada, sendo realizados dois tipos de experimentos no reator fotocatalítico. O primeiro foi para tratamento de aromáticos (BTX) utilizando-se como catalisador TiO2, impregnado em sílica, sintetizado em laboratório. Como resultado desta etapa, observou-se que reator foi capaz de remover os contaminantes estudados. No entanto, nas condições investigadas, o processo não foi capaz de reduzir significativamente as concentrações de contaminante no ar tratado e o catalisador foi desativado pelos poluentes, requerendo um processo de regeneração. Para uma melhor avaliação do reator e a sua modelagem, optou-se por utilizar um poluente modelo, n-hexano, de forma a não degradar o catalisador. Para estes experimentos, o catalisador utilizado também foi trocado para TiO2 comercial tipo anatase. Resultados quantitativos relacionaram o aumento da conversão no reator com o aumento de massa de catalisador e diminuição com um aumento na vazão volumétrica. A partir destes experimentos, pode-se obter um modelo cinético baseado na determinação dos parâmetros cinéticos em um reator fotocatalítico usando a abordagem Langmuir-Hinshelwood para a degradação do n-hexano com sucesso. Por fim, a modelagem fluidodinâmica deste reator foi realizada utilizando-se o software comercial Fluent. Desenvolveu-se um modelo que considera a fluidodinâmica e cinética da reação obtida experimentalmente. Algumas simplificações foram feitas para otimizar os tempos de simulação e os principais resultados do CFD foram os campos de pressão, velocidade, fração volumétrica de sólidos e velocidade da reação de decomposição do n-hexano. This study presents the development of a fluidized bed photoreactor in laboratorial scale for volatile organic compounds (VOC) photochemical degradation, since the reactor project until a fluid dynamics model construction for future scale-up study and optimization. The treatment process is based on contaminants catalytic photo-oxidation in contact with titanium dioxide (TiO2) and ultraviolet radiation. For laboratorial unit construction, this project was beneficed by PIPE project - Phase 1 of the project financed by FAPESP (No. 00953/2016). One of the results of this project was a market research with several clients. It showed a development need of new technologies for contaminated gas treatment with VOC. The laboratorial unit was installed and two experiments types were carried out in the photoreactor. The first type was to aromatic (BTX) treatment using as catalyst TiO2, impregnated in silica and synthesized in laboratory. As result of this phase, the photoreactor was able to remove the contaminants. However, in investigated conditions, the process was not able to eliminate completely the contaminants and the catalyst was inactivated by intermediate products, requiring a regeneration process. To get a better reactor evaluation and modeling, a model pollutant, nhexane, was chosen in order not to degrading the catalyst. For these experiments, the chosen catalyst was commercial TiO2 in anatase type. The results showed that reactor conversion rises with higher catalyst loads and decreases with higher volumetric flow rate. Therefore, a kinetic model was successfully obtained, based on kinetic parameters determination in a photoreactor using Langmuir-Hinshelwood approach to n-hexane degradation. Lastly, a fluid dynamics (CFD) photoreactor modeling was developed using the commercial software Fluent. A model was built considering fluid dynamics and reaction kinetic obtained experimentally. Some model simplifications were done in order to optimize the simulation time and the main CFD results were pressure, velocity, solid volumetric fraction fields and n-hexane decomposition reaction velocity.

O presente estudo visa à análise comparativa do desempenho dos modelos de estatística multivariada Multi-layer Perceptron Neural Networks, Random Forests e Support Vector Machine na previsão de máxima concentração diária de ozônio na baixa atmosfera na Região Metropolitana de São Paulo (RMSP), caracterizada pela alta concentração de habitantes e intensa atividade econômica, onde a qualidade do ar é afetada principalmente por episódios de altos níveis de ozônio. Foram aplicados tanto modelos de regressão quanto de classificação. Nos casos de classificação, estudou-se também o desempenho de dois modelos de análise de discriminantes: Linear Discriminant Analysis e Fisher Discriminant Analysis. Para a construção dos modelos utilizou-se uma base de dados com medições de variáveis meteorológicas, além da concentração de ozônio, fornecida pela Companhia Ambiental do Estado de São Paulo (CETESB). Dada a grande importância e a complexidade do processo de formação de ozônio na baixa atmosfera, a Universidade de São Paulo (USP) e a CETESB têm desenvolvido estudos no tema desde 1999, através dos quais produziram-se modelos de previsão baseados em redes neurais, implementados pela equipe da CETESB. O presente estudo é uma continuação do desenvolvimento anterior e contém as seguintes inovações quanto à metodologia e resultados esperados: (1) ajuste de novos modelos com novas estruturas, incluindo-se técnicas de Support Vector Machine, Random Forests e Discriminação; (2) uso de uma base de dados mais ampla e atualizada, de modo a melhorar a representatividade dos modelos; (3) ajuste dos modelos à nova legislação, Decreto Estadual 59.113 de 23/04/2013, que estabelece novos padrões de qualidade do ar para os poluentes atmosféricos, dentre os quais o ozônio. Embora nos casos de classificação nenhum dos modelos tenha apresentado bons resultados, nos casos de regressão foi possível obter resultados melhores do que os esperados. O modelo de Multi-layer Perceptron foi o que mostrou melhor desempenho para prever concentrações máximas de ozônio, tanto para a previsão de máximas concentrações baseadas em médias horárias quanto em médias móveis de 8 horas, que resultaram em coeficientes de correlação 0,867 e 0,891, respectivamente. The present study aims to compare the performance of the multivariate statistical models Multi-layer Perceptron Neural Networks, Random Forests and Support Vector Machine applied to the prediction of daily maximum concentrations of groundlevel ozone in the Metropolitan Area of São Paulo (MASP), characterized by the high population density and the intense economic activity, where the air quality is mostly affected by high ozone levels. Both regression and classification models were applied. In the classification cases, two more models were applied: Linear Discriminant Analysis and Fisher Discriminant Analysis. The models were constructed using a database containing meteorological variables and daily maximum ozone concentration values, which were provided by the Environmental Agency of São Paulo State (CETESB). Given the great importance and complexity of the process of ozone formation in the troposphere, the University of São Paulo (USP) and CETESB have made studies in this area since 1999 and developed a prediction model based on neural networks, which was implemented by CETESB. The present study is a continuation of the previous one and contains the following innovations regarding the methodology and expected results: (1) comparison with other models such as support vector machines, random forests and discriminant analysis; (2) use of a wider and up-to-date database, which improves the representativeness of the models; (3) the models took into acount the new legislation, State decree 59113 of 04/23/2013, that establishes new air quality standards for ozone. Although none of the classification models had a good performance, the regression models yielded better than expected results. The multi-layer perceptron model was the one with higher performance in the prediction of daily maximum ozone concentrations based both on hourly averages and on eight-hour moving averages, which yielded correlation coefficients of 0.867 and 0.891 respectively.