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Novos adsorventes para aplica??o na remo??o de enxofre de combust?veis / Application of new adsorbents in sulfur removal from fuelsOliveira, Katherine Carrilho de 04 February 2015 (has links)
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Previous issue date: 2015-02-04 / Atualmente o mercado exige derivados de petr?leo cada vez mais puros e, com isso, surge a
necessidade de novos m?todos para obten??o desses produtos que sejam mais eficientes e
economicamente vi?veis. Considerando a remo??o do enxofre do diesel, a maioria das
refinarias utiliza o processo de hidrogena??o catal?tica, a hidrodessulfuriza??o. Esses
processos s?o de elevado conte?do energ?tico e alto custo de produ??o, al?m de baixa
efici?ncia na remo??o do enxofre a baixas concentra??es (abaixo de 500 ppm). A adsor??o
apresenta-se como uma alternativa eficiente e economicamente vi?vel em rela??o ?s t?cnicas
atualmente utilizadas. Com isso, o objetivo principal deste trabalho ? desenvolver e otimizar a
obten??o de novos adsorventes a base de diatomita, modificados com microemuls?es de dois
tensoativos n?o i?nicos, agregando efici?ncia ao material, visando a sua aplica??o na remo??o
do enxofre presente no diesel comercial. Para a modifica??o da diatomita, variou-se: os
pontos de microemuls?o para cada tensoativo (RNX 95 e UNTL 90), a fase aquosa da
microemuls?o atrav?s da utiliza??o ou n?o de sais (CaCl2 e BaCl2) , o tempo de contato
durante a modifica??o e a forma de contato. Foram realizadas an?lises de microscopia
eletr?nica de varredura, difra??o de raios X, fluoresc?ncia de raios X, termogravimetria e
adsor??o de N2 (BET) para a caracteriza??o dos novos materiais obtidos. No estudo da
capacidade de adsor??o dos materiais obtidos, foi realizada uma modelagem estat?stica para
avaliar a influ?ncia da concentra??o do sal na fase aquosa (20 ppm a 1500 ppm), da
temperatura do banho finito (25 a 60?C) e da concentra??o de enxofre do diesel. Observou-se
que a temperatura e a concentra??o de enxofre (300 a 1100 ppm) foram os par?metros mais
significativos, no qual aumentando-se seus valores aumenta-se a capacidade da argila
modificada de adsorver o enxofre presente no diesel. A capacidade de adsor??o aumentou de
0,43 mg/g para 1,34 mg/g com a otimiza??o do ponto de microemuls?o e com a adi??o de
sais. / Currently the market requires increasingly pure oil derivatives and, with that, comes the need
for new methods for obtaining those products that are more efficient and economically viable.
Considering the removal of sulfur from diesel, most refineries uses catalytic hydrogenation
process, the hydrodesulfurization. These processes needs high energy content and high cost of
production and has low efficiency in removing sulfur at low concentrations (below 500 ppm).
The adsorption presents itself as an efficient and economically viable alternative in relation to
the techniques currently used. With that, the main purpose of this work is to develop and
optimize the obtaining of new adsorbents based on diatomite, modified with two non ionic
surfactants microemulsions, adding efficiency to the material, to its application on removal of
sulfur present in commercial diesel. Analyses were undertaken of scanning electron
microscopy (SEM), x-ray diffraction (XRD), x-ray fluorescence (XRF), thermogravimetry
(TG) and N2 adsorption (BET) for characterization of new materials obtained. The variables
used for diatomite modification were: microemulsion points for each surfactant (RNX 95 and
UNTL 90), microemulsion aqueous phase through the use or non-use of salts (CaCl2 and
BaCl2), the contact time during the modification and the contact form. The study of
adsorption capacity of materials obtained was performed using a statistical modeling to
evaluate the influence of salt concentration in the aqueous phase (20 ppm to 1500 ppm), finite
bath temperature (25 to 60? C) and the concentration of sulphur in diesel. It was observed that
the temperature and the concentration of sulphur (300 to 1100 ppm) were the most significant
parameters, in which increasing their values increase the ability of modified clay to adsorb the
sulphur in diesel fuel. Adsorption capacity increased from 0.43 to mg/g 1.34 mg/g with
microemulsion point optimization and with the addition of salts.
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Remo??o de corantes utilizando tensoativos: extra??o por ponto de nuvem e flocula??o i?nicaMelo, Ricardo Paulo Fonseca 23 April 2015 (has links)
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Previous issue date: 2015-04-23 / O setor t?xtil ? um dos principais respons?veis pela gera??o de efluentes
industriais devido, principalmente, aos grandes volumes de ?gua, que apresentam
elevado teor de carga org?nica. Neste, observa-se a presen?a de corantes, tensoativos,
amido, alco?is, ?cido ac?tico e outros constituintes, provenientes das v?rias etapas de
processamento do material t?xtil. Diante disto, o tratamento destes efluentes ?
necess?rio antes de lan??-los nos corpos de ?gua, pois podem causar altera??es f?sicoqu?micas
desastrosas para o meio ambiente. Os tensoativos s?o subst?ncias muito
utilizadas nos processos de separa??o e, neste trabalho, foram utilizados no tratamento
de efluentes t?xteis, aplicando a extra??o por ponto de nuvem e a extra??o por
flocula??o i?nica. Na extra??o de corante reativo por ponto de nuvem foi utilizado o
tensoativo nonilfenol, com grau de etoxila??o 9,5. A avalia??o do processo foi
realizada em termos da temperatura, concentra??o de tensoativo e de corante. Neste
processo, a remo??o de corante alcan?ou 91%. A flocula??o i?nica ocorre devido ?
presen?a de c?lcio, que reage com tensoativo ani?nico e forma tensoativos insol?veis,
capazes de atrair a mat?ria org?nica atrav?s da adsor??o. Neste trabalho, a flocula??o
i?nica, utilizando sab?o base, foi aplicada ao tratamento de efluente sint?tico contendo
corantes pertencentes a tr?s classes: os diretos, reativos e dispersos. A avalia??o do
processo foi realizada pela influ?ncia dos seguintes par?metros: concentra??o de
tensoativo e de eletr?litos, velocidade de agita??o, tempo de repouso, temperatura e
pH. A flocula??o do tensoativo foi realizada de dois modos: formando o floco no
pr?prio efluente e formando o floco antes de mistur?-lo ao efluente. A remo??o do
corante direto e reativo, quando o floco ? formado dentro do efluente t?xtil, foi de 97%
e 87%, respectivamente. No caso em que o floco ? formado antes de adicion?-lo ao
efluente a remo??o de corante direto e disperso alcan?ou 92% e 87%, respectivamente.
Estes resultados mostram que os processos avaliados foram eficientes para remo??o de
corantes em efluentes t?xteis. / The textile sector is one of the main contributors to the generation of
industrial wastewaters due to the use of large volumes of water, which has a high
organic load content. In these, it is observed to the presence of dyes, surfactants, starch,
alcohols, acetic acid and other constituents, from the various processing steps of the
textiles. Hence, the treatment of textile wastewater becomes fundamental before
releasing it into water bodies, where they can cause disastrous physical-chemical
changes for the environment. Surfactants are substances widely used in separation
processes and their use for treating textile wastewaters was evaluated in this research
by applying the cloud point extraction and the ionic flocculation. In the cloud point
extraction was used as surfactant nonylphenol with 9.5 ethoxylation degree to remove
reactive dye. The process evaluation was performed in terms of temperature, surfactant
and dye concentrations. The dye removal reached 91%. The ionic flocculation occurs
due to the presence of calcium, which reacts with anionic surfactant to form insoluble
surfactants capable of attracting the organic matter by adsorption. In this work the ionic
flocculation using base soap was applied to the treatment of synthetic wastewater
containing dyes belonging to three classes: direct, reactive, and disperse. It was
evaluated by the influence of the following parameters: surfactant and electrolyte
concentrations, stirring speed, equilibrium time, temperature, and pH. The flocculation
of the surfactant was carried out in two ways: forming the floc in the effluent itself and
forming the floc before mixing it to the effluent. Removal of reactive and direct dye,
when the floc is formed into textile effluent was 97% and 87%, respectively. In the
case where the floc is formed prior to adding it to the effluent, the removal to direct and
disperse dye reached 92% and 87%, respectively. These results show the efficience of
the evaluated processes for dye removal from textile wastewaters.
|
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Tratamento de cascalho de perfura??o utilizando sistemas microemulsionadosSilva, Daniel Nobre Nunes da 04 February 2015 (has links)
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Previous issue date: 2015-02-04 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq / A ind?stria do petr?leo ? uma das atividades que mais gera res?duos ao meio
ambiente. O cascalho de perfura??o ? um res?duo gerado em grande quantidade no processo
de perfura??o de po?os e que pode provocar impactos ambientais, tais como a contamina??o
do solo e consequentemente a contamina??o de len??is fre?ticos, caso descartados sem
tratamento pr?vio. Surge ? necessidade de se desenvolver atividades cient?ficas e de pesquisar
maneiras de adequar esses res?duos as normas ambientais vigentes. No caso dos res?duos
s?lidos, a norma NBR 10004:2004 da Associa??o Brasileira de Normas T?cnicas (ABNT)
classifica-os em res?duos classe I (perigoso) e classe II (n?o perigoso), onde estabelece quais
os res?duos que podem ou n?o ser descartados no meio ambiente sem provocar impacto
ambiental. Este trabalho apresenta uma inovadora alternativa para tratar o cascalho de
perfura??o, que ? classificado como res?duo classe I (Abreu & Souza, 2005), removendo
principalmente a n-parafina presente no mesmo, uma vez que este ? originado quando se usa
fluidos de perfura??o base ?leo. Utilizando sistemas microemulsionados promove-se a
remo??o deste contaminante de amostras de cascalho de perfura??o provenientes de po?os
localizados em Alto do Rodrigues ? RN. Inicialmente, determinou-se a concentra??o de
parafina utilizando o m?todo de infravermelho, em amostras previamente extra?das com
ultrassom, obteve-se uma concentra??o de parafina na faixa de 36,59 a 43,52 g de parafina
por quilograma de cascalho. Utilizou-se dois sistemas microemulsionados contendo dois
tensoativos n?o i?nicos de diferentes classes, um ? um ?lcool etoxilado (UNTL-90) e o outro
um nonifenol etoxilado (RNX 110). Os resultados indicaram que o sistema com tensoativo
UNTL-90 possui melhor efici?ncia que o sistema com RNX 110. O estudo da influ?ncia do
tempo de contato na extra??o mostrou que para tempos maiores que 25 minutos tem-se uma
tend?ncia ao aumento do percentual de extra??o com o aumento do tempo de contato.
Observou-se tamb?m que a extra??o ? r?pida, pois em 1 minutos de contato tem-se 22,7 % de
extra??o. A reutiliza??o do sistema microemulsionado, sem a remo??o da parafina extra?da
em etapas anteriores, mostrou redu??o de 29,32 no percentual de extra??o comparando a
primeira e a terceira extra??o, mas comparando a primeira e segunda extra??es a redu??o ? de
8,5 no percentual de extra??o, logo a otimiza??o da reutiliza??o dos sistemas pode ser uma
op??o para viabilizar economicamente a remo??o de parafina de cascalho. A extra??o com
agita??o se mostrou mais eficaz no tratamento do cascalho, atingindo o percentual de extra??o
de 87,04 %, ou seja, se obt?m um cascalho de perfura??o com 0,551 % de parafina.
Utilizando o percentual de parafina empregado nos fluidos de perfura??o n?o aquosos e o
limite m?ximo de fluido no cascalho para descarte estabelecido pela Ag?ncia de Prote??o
Ambiental dos Estados Unidos (US Environmental Protection Agency - US EPA), chega-se ?
conclus?o que o teor de parafina no cascalho n?o pode ser superior a 3,93 %. Conclui-se que a
quantidade de parafina no cascalho tratado com o sistema microemulsionado e com agita??o
est? bem abaixo do estabelecido pelo ?rg?o americano (US EPA), mostrando que o sistema
microemulsionado utilizado foi eficiente na remo??o da parafina do cascalho de perfura??o. / The oil industry is one of the activities that generates more waste to the
environment. The drill cuttings is a waste generated in large quantities in the drilling process
and that may cause environmental damage such as soil contamination and consequently the
contamination of groundwater if disposed of without prior treatment. Arises the need to
develop scientific activities and research ways to adapt these wastes the current environmental
standards. In the case of solid wastes, the NBR 10004: 2004 of the Brazilian Association of
Technical Standards (ABNT) classifies them into class I waste (hazardous) and class II (not
dangerous), which determines which wastes may or may not be discarded in the environment
without causing environmental impact. This study presents a novel alternative for treating
drill cuttings, where this waste was classified as class I (Abreu & Souza, 2005), mainly by
removing the n-paraffin present in it, since this arises when using drilling fluids base oil.
Using microemulsion systems promotes the removal of this contaminant drill cuttings
samples from wells located in Alto do Rodrigues - RN. Initially, we determined the
concentration of paraffin using infrared method in samples were extracted with ultrasound, we
obtained a paraffin concentration in the range from 36.59 to 43.52 g of paraffin per kilogram
of cuttings. Used two microemulsion systems containing two nonionic surfactants from
different classes, one is an alcohol ethoxylated (UNTL-90) and the other an nonylphenol
ethoxylated (RNX 110). The results indicated that the system UNTL-90 surfactant has better
efficiency than the system with RNX 110. The study of the influence of contact time at the
extraction showed that for times greater than 25 minutes has a tendency to increase the
percentage extraction with increasing contact time. It was also observed that the extraction is
fast because at 1 minute contact has 22.7% extraction. The reuse of the microemulsion system
without removing the paraffin extracted in previous steps, showed reduction of 29.32 in
percentage of extraction by comparing the first and third extraction, but by comparing the first
and second extractions reduction is 8.5 in percentage extraction, so the systems reuse
optimization can be an option for economically viable removing paraffin from cuttings. The
extraction with shaking is more effective in the treatment of cuttings, reaching the extraction
percentage of 87.04%, that is, obtaining a drill cuttings with 0.551% paraffin. Using the
percentage of paraffin employed in non-aqueous drilling fluids and fluid maximum limit on
cuttings for disposal established by the Environmental Protection Agency of the United States
(US EPA), one arrives at the conclusion that the level of paraffin on gravel cannot exceed
3.93%. Conclude that the amount of paraffin in the treated cuttings with the microemulsion
system with shaking is below the established by US EPA, showing that the system used was
efficient in removing the paraffin from the drill cuttings.
|
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Polpa de jambol?o (Eugenia jambolana Lam.) fresca e desidratada: caracter?sticas f?sico-qu?micas, bioativas e funcionais, efeitos biol?gicos em Caenorhabditis elegans e uso para produ??o de frozen yogurt caprino probi?tico / Fresh and dried jambolan fruit pulp (Eugenia jambolana Lam.): physicochemical, bioactive and functional characteristics, biological effects in Caenorhabditis elegans and its use for the production of caprine frozen yogurtBezerra, Maria de F?tima 24 April 2015 (has links)
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Previous issue date: 2015-04-24 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / A presente tese avaliou a polpa de jambol?o (Eugenia jambolana Lam.) fresca e
desidratada mediante dois processos de secagem (liofiliza??o e atomiza??o com 10 % de goma
Ar?bica) quanto as caracter?sticas f?sico-qu?micas (pH, umidade, atividade de ?gua, di?metro
m?dio de part?culas, solubilidade dos p?s e cor instrumental), bioativas [compostos fen?licos
totais (CFT), antocianinas monom?ricas, proantocianidinas (PA), ?cido el?gico total (AET),
miricetina e cianidina] e estudo da funcionalidade in vitro (atividade antioxidante, antienzim?tica
e antimicrobiana). Em seguida, a funcionalidade in vivo da polpa de jambol?o foi avaliada, com
uso do modelo Caenorhabditis elegans, quanto ? via sinaliza??o de insulina, longevidade e
doen?as neurodegenerativas (doen?a de Alzheimer e Mal de Parkinson). A polpa de jambol?o
desidratada apresentou consider?vel reten??o de CFT (50 % a 75 %), PA (90 % a 98 %), AET
(31 % a 83 %), miricetina (40 % a 84 %), cianidina (72 % a 84 %) e atividade antioxidante (15
%). A polpa fresca, o p? liofilizado e o p? atomizado apresentaram elevada atividade inibit?ria
contra lipase pancre?tica (4,4 a 5,8 mg/mL), alfa-glicosidase (10,3 a 13,8 mg/mL) e alfa-amilase
(8,9 a 11,2 mg/mL). Esses grupos experimentais tamb?m se apresentaram inibidores ativos
contra o crescimento de S. aureus. Os p?s de jambol?o aumentaram a express?o de genes ligados
? via de sinaliza??o de insulina (SIR-2.1, PPTR-1, DAF-16, SOD-3, e CTL) e foram capazes de
estender o tempo m?dio de vida de C. elegans (18,07 % a 24,34 %), reduzir a paralisia induzida
pelo amiloide AB1-42 e os danos causados pela mol?cula neurot?xica 1-methyl-4-
phenylpyridinium (MPP+
). A partir disso, foi desenvolvido frozen yogurt com uso do leite
caprino adicionado de Bifidobacterium animalis subsp. lactis BI-07 com polpa ou p? atomizado
de jambol?o. O produto final foi avaliado quanto a suas caracter?sticas f?sico-qu?micas (pH,
acidez titul?vel, s?lidos totais, prote?na, a??cares redutores totais, gordura, cinzas, overrun e
teste de derretimento], bioativas (CFT e antocianinas monom?ricas), atividade antioxidante,
iii
viabilidade da cultura probi?tica e an?lise sensorial (teste de aceita??o). As amostras de frozen
yogurt caprino com cultura probi?tica apresentaram menor pH e maior acidez, CFT, antocianinas
e atividade antioxidante quando comparada com aquelas sem a presen?a da B. animalis. Foram
observados n?veis de overrun entre 14,2% e 22,6%. As amostras de frozen yogurt com cultura
probi?tica alcan?aram resultados inferiores para o atributo sabor. De maneira geral, a presente
pesquisa apresenta o jambol?o como um fruto rico em compostos bioativos, com elevada
capacidade funcional, com potencial para modular importantes vias biol?gicas, aumentar a
expectativa de vida e retardar risco de doen?as neurodegenerativas. Atualmente o jambol?o ? um
fruto ex?tico subaproveitado no Brasil com elevado poder corante e a presente tese mostra, pela
primeira vez na literatura, importantes achados tecnol?gicos, biol?gicos e cient?ficos sobre essa
fruta que podem ser usados para o desenvolvimento de produtos alimentares saud?veis. / This work evaluated the fresh, spray dried (with 10 % of Arabic Gum) and freeze dried
jambolan pulp (Eugenia jambolana Lam.) in regard to physicochemical (pH, moisture, water
activity, average particle diameter, solubility and color), bioactive [total phenolic content (TPC),
monomeric anthocyanin, pronathocyanidin (PA), total elagic acid (TEA), myricetin and
cyanidin] and in vitro functionality (antioxidant, antienzymatic and antimicrobial activities]. In
addition, the in vivo functionality of jambolan pulp was investigated using the Caenorhabditis
elegans model for insulin signaling, longevity and induced neurodegeneration (Alzheimer?s
disease and Parkinson?s disease related symptoms). The dried jambolan pulp presented TPC
retention (50% to 75%), PA (90% to 98%), TEA (31% to 83%), myricetin (40% to 84%),
cyanidin (72% to 84%) and antioxidant activity (15%). The fresh jambolan pulp, the freeze dried
pulp and the spray dried jambolan pulp presented high enzymatic inhibitory activity against
pancreatic lipase (4,4 to 5,8 mg/mL), alpha-glycosidase (10,3 to 13,8 mg/mL) and alpha-amylase
(8,9 to 11,2 mg/mL). They also were active inhibitors against the pathogen S. aureus. The dried
jambolan experimental samples were able to increase the expression of several genes linked to
the insulin signaling pathways (SIR-2.1, PPTR-1, DAF-16, SOD-3, e CTL) and increased the
lifespan in C. elegans (18,07 % - 24,34 %), besides decreasing the amyloid AB1-42 aggregation
induced paralysis and MPP+ (1-methyl-4-phenylpyridinium) induced neurodegeneration. Based
on that, the jambolan pulp and the spray dried jambolan pulp were further selected for the
production of caprine frozen yogurt with the addition of Bifidobacterium animalis subsp. lactis
BI-07. The final product were evaluated in regard to their physicochemical (pH, acidity, total
solids, protein, total reducing sugars, fat, ashes, overrun, melting test), bioactive (TPC and
monomeric anthocyanin, antioxidant activity, probiotic viability and sensory analysis (sensory
acceptance). The results showed that samples with probiotic had lowest pH and higher acidity,
TPC, anthocyanin and antioxidant activity. It was also observed low overrun (14.2% to 22.6%).
vi
Samples with probiotic had lower flavor scores. Overall, this research presents the jambolan as a
highly functional bioactive-rich fruit with the potential to modulate important biological
pathways, extend lifespan and retard the development of neurodegenerative diseases. Jambolan
is an underexploited exotic fruit with a high colorant potential and this thesis shows for the first
time in the literature important technological, biological and scientific data about this fruit that
could be used towards the development of health-oriented food products.
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Degrada??o fotocatal?tica oxidativa do fenol utilizando carv?o obtido da pir?lise de diferentes biomassasOliveira, Gislane Pinho de 25 June 2015 (has links)
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Previous issue date: 2015-06-25 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / O progresso industrial moderno vem incorporando compostos fen?licos entre as
impurezas encontradas na ?gua. Por se tratar de uma subst?ncia t?xica e cancer?gena, ?
imprescind?vel que a mesma seja reduzida ? concentra??es toler?veis, determinadas pelo
CONAMA. Neste contexto, este trabalho tem como objetivo o tratamento e caracteriza??o de
catalisadores oriundos do biocarv?o, subproduto da pir?lise de biomassa (avel?s e p? de
madeira), assim como sua avalia??o na degrada??o fotocatal?tica do fenol. Os ensaios foram
realizados em um reator leito de lama, com medi??es instant?neas da temperatura, pH e
oxig?nio dissolvido. Os experimentos foram realizados nas seguintes condi??es operacionais:
temperatura igual a 50 ?C, vaz?o de oxig?nio igual a 410 mL min-1
, volume de solu??o reagente
igual a 3,2 L, l?mpada UV de 400 W, press?o de 1 atm e tempo de rea??o de 2 horas. Os
par?metros avaliados foram o pH do meio reacional (3,0; 6,9 e 10,7), concentra??o inicial de
fenol comercial (250, 500 e 1000 ppm), concentra??o de catalisador (0, 1, 2 e 3 g L-1
) e natureza
do catalisador (carv?o do aveloz ativado e lavado com diclorometano, CAADCM, e carv?o da
madeira ativado e lavado com diclorometano, CMADCM). Os resultados de FRX, DRX e BET
comprovaram a presen?a de ferro e pot?ssio em quantidades satisfat?rias para o catalisador
CAADCM e em quantidades reduzidas no catalisador CMADCM, e o aumento da ?rea
superficial dos materiais ap?s a ativa??o qu?mica e f?sica. As curvas de degrada??o do fenol
indicam que o pH tem uma influ?ncia significativa na convers?o do fenol, apresentando
melhores resultados para os valores de pH mais reduzidos. A concentra??o ?tima de catalisador
observada foi de 1 g L-1
e o aumento da concentra??o inicial de fenol exerce uma influ?ncia
negativa na condu??o da rea??o. Tamb?m foi observado o efeito positivo da presen?a de ferro
e pot?ssio na estrutura do catalisador: obteve-se convers?es melhores para os ensaios realizados
com o catalisador CAADCM, quando comparado com o catalisador CMADCM nas mesmas
condi??es. A maior convers?o foi obtida para o ensaio realizado em pH ?cido (3,0), com uma
concentra??o inicial de fenol igual a 250 ppm na presen?a do catalisador CAADCM a 1 g L-1
.
As amostras l?quidas retiradas a cada 15 minutos foram analisadas por cromatografia l?quida
identificando e quantificando a hidroquinona, p-benzoquinona, catecol e ?cido maleico.
Finalmente um mecanismo do processo reacional foi proposto, considerando que o fenol ?
transformado em fase homog?nea e os demais reagem na superf?cie do catalisador. Aplicandose
o modelo de Langmuir-Hinshelwood juntamente com um balan?o de massa, obteve-se um
sistema de equa??es diferenciais que foi resolvido utilizando o m?todo de Runge-Kutta de 4?
ordem associado a uma rotina de otimiza??o SWARM (enxame de part?culas), visando
minimizar a fun??o objetivo de m?nimos quadrados para estima??o dos par?metros cin?ticos e
de adsor??o. Obteve-se constantes cin?ticas da ordem de grandeza de 10-3
para a degrada??o do
fenol, 10-4
? 10-2
para a forma??o de ?cidos, 10-6
? 10-9
para a mineraliza??o dos quin?nicos
(hidroquinona, p-benzoquinona e catecol), 10-3
? 102 para a mineraliza??o dos ?cidos. / The modern industrial progress has been contaminating water with phenolic
compounds. These are toxic and carcinogenic substances and it is essential to reduce its
concentration in water to a tolerable one, determined by CONAMA, in order to protect the
living organisms. In this context, this work focuses on the treatment and characterization of
catalysts derived from the bio-coal, by-product of biomass pyrolysis (avel?s and wood dust) as
well as its evaluation in the phenol photocatalytic degradation reaction. Assays were carried out
in a slurry bed reactor, which enables instantaneous measurements of temperature, pH and
dissolved oxygen. The experiments were performed in the following operating conditions:
temperature of 50 ?C, oxygen flow equals to 410 mL min-1
, volume of reagent solution equals
to 3.2 L, 400 W UV lamp, at 1 atm pressure, with a 2 hours run. The parameters evaluated were
the pH (3.0, 6.9 and 10.7), initial concentration of commercial phenol (250, 500 and 1000 ppm),
catalyst concentration (0, 1, 2, and 3 g L-1
), nature of the catalyst (activated avel?s carbon
washed with dichloromethane, CAADCM, and CMADCM, activated dust wood carbon washed
with dichloromethane). The results of XRF, XRD and BET confirmed the presence of iron and
potassium in satisfactory amounts to the CAADCM catalyst and on a reduced amount to
CMADCM catalyst, and also the surface area increase of the materials after a chemical and
physical activation. The phenol degradation curves indicate that pH has a significant effect on
the phenol conversion, showing better results for lowers pH. The optimum concentration of
catalyst is observed equals to 1 g L-1
, and the increase of the initial phenol concentration exerts
a negative influence in the reaction execution. It was also observed positive effect of the
presence of iron and potassium in the catalyst structure: betters conversions were observed for
tests conducted with the catalyst CAADCM compared to CMADCM catalyst under the same
conditions. The higher conversion was achieved for the test carried out at acid pH (3.0) with an
initial concentration of phenol at 250 ppm catalyst in the presence of CAADCM at 1 g L-1
. The
liquid samples taken every 15 minutes were analyzed by liquid chromatography identifying and
quantifying hydroquinone, p-benzoquinone, catechol and maleic acid. Finally, a reaction
mechanism is proposed, cogitating the phenol is transformed into the homogeneous phase and
the others react on the catalyst surface. Applying the model of Langmuir-Hinshelwood along
with a mass balance it was obtained a system of differential equations that were solved using
the Runge-Kutta 4th order method associated with a optimization routine called SWARM
(particle swarm) aiming to minimize the least square objective function for obtaining the
kinetic and adsorption parameters. Related to the kinetic rate constant, it was obtained a
magnitude of 10-3
for the phenol degradation, 10-4
to 10-2
for forming the acids, 10-6
to 10-9
for
the mineralization of quinones (hydroquinone, p-benzoquinone and catechol), 10-3
to 10-2
for
the mineralization of acids.
|
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Extra??o, caracteriza??o e avalia??o bioativa do extrato de Arrabidaea chicaSantos, Rog?rio Pitanga 15 June 2015 (has links)
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Previous issue date: 2015-06-15 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq / A utiliza??o de plantas com finalidades medicinais ? milenar, sendo bastante
difundida sua aplica??o em medicamentos. Apesar das plantas serem fontes promissoras para
a descoberta de novas mol?culas de interesse farmacol?gico, estimativas revelam que apenas
17% delas foram estudadas quanto a sua possibilidade de uso na medicina. Assim, a
biodiversidade da flora brasileira representa um imenso potencial de utiliza??o econ?mica
pela ind?stria farmac?utica. A planta Arrabidaea chica, popularmente conhecida como
?pariri?, ? comum na regi?o Amaz?nica, e a ela s?o atribu?das v?rias propriedades medicinais.
As folhas desta planta s?o ricas em antocianinas, que s?o compostos fen?licos com alto poder
antioxidante. Os compostos antioxidantes desempenham um papel vital na preven??o de
doen?as neurol?gicas e cardiovasculares, c?ncer e diabetes, entre outras. Dentre as
antocianinas encontradas na Arrabidaea chica, destaca-se a Carajurina (6,7-dihidroxi-5,4?-
dimetoxi-flavilium), que ? o principal pigmento encontrado nesta planta. O presente trabalho
teve como objetivo geral o estudo sobre a extra??o supercr?tica e a extra??o convencional
(s?lido-l?quido) de folhas da Arrabidaea chica, avaliando-se o rendimento dos processos
extrativos, a atividade antioxidante e a quantifica??o de Carajurina contida nos extratos. As
extra??es supercr?ticas utilizaram CO2 como solvente, adicionado de co-solvente (mistura
etanol/?gua), e foram conduzidas pelo m?todo din?mico em um extrator de leito fixo. Os
ensaios obedeceram a um planejamento fatorial fracion?rio 24-1, tendo como vari?veis
resposta o rendimento do processo, o poder antioxidante e a concentra??o de Carajurina, e
como vari?veis independentes a press?o, a temperatura, a concentra??o de co-solvente (v/v) e
a concentra??o de ?gua no co-solvente (v/v). Os rendimentos (massa de extrato seco/massa de
mat?ria-prima utilizada) obtidos da extra??o supercr?tica variaram de 15,1% a 32%, sendo que
o melhor resultado foi obtido a 250 bar e 40?C, com uso do co-solvente a 30% (v/v) e
concentra??o de ?gua no co-solvente igual a 50% (v/v). Atrav?s de an?lise estat?stica,
verificou-se que a concentra??o de co-solvente apresentou efeito significativo sobre o
rendimento. Os resultados de rendimento em massa para as extra??es convencionais foram de
8,1% (?gua) e 5,5% (etanol). Atrav?s de an?lises cromatogr?ficas em CLAE (Cromatografia L?quida de Alta Efici?ncia), a Carajurina foi quantificada em todos os extratos obtidos e os
valores de concentra??o (massa de Carajurina/massa de extrato seco) variaram entre 1% e
2,21% para os extratos supercr?ticos. Quanto ?s extra??es convencionais, n?o foi detectada
Carajurina no extrato aquoso, enquanto o extrato etan?lico apresentou teor de Carajurina igual
a 7,04%, sendo, portanto, mais seletivo em Carajurina do que as extra??es supercr?ticas. A
avalia??o do poder antioxidante (m?todo do sequestro do radical 2,2-difenil-1-picril-hidrazilDPPH)
dos extratos supercr?ticos resultou em valores de EC50 (concentra??o efetiva que
neutraliza 50% dos radicais livres) compreendidos entre 38,34 e 86,13 ?g/mL, enquanto que
as extra??es convencionais resultaram em valores de EC50 de 167,34 (?gua) e 42,58 (etanol)
?g/mL. J? a quantifica??o dos compostos fen?licos (m?todo espectrofotom?trico de FolinCiocalteau)
dos extratos supercr?ticos resultou em valores compreendidos entre 48,93 e 88,62
mg EAG/g extrato (EAG = Equivalentes de ?cido G?lico), enquanto que as extra??es s?lidol?quido
resultaram em valores de 37,63 (?gua) e 80,54 (etanol) mg EAG/g extrato. A boa
atividade antioxidante pode ser atribu?da n?o somente ? presen?a de Carajurina, mas tamb?m
? exist?ncia de outros compostos fen?licos e antioxidantes na Arrabidaea chica. Atrav?s da
otimiza??o do planejamento experimental, foi poss?vel identificar o experimento que
apresentou o melhor resultado considerando as quatro vari?veis resposta em conjunto. Este
experimento foi realizado nas seguintes condi??es: press?o de 200 bar, temperatura de 40?C,
concentra??o de co-solvente igual a 30% (v/v) e concentra??o de ?gua no co-solvente igual a
30% (v/v). Conclui-se que, dentro da faixa estudada, ? poss?vel obter o resultado ?timo
utilizando condi??es operacionais mais amenas, o que implica em menores custos e maior
facilidade de opera??o. / The use of plants for medicinal purposes is ancient, with widespread application in medicinal
drugs. Although plants are promising sources for the discovery of new molecules of
pharmacological interest, estimates show that only 17% of them have been studied for their
possible use in medicine. Thus, biodiversity of Brazilian flora represents an immense
potential for economic use by the pharmaceutical industry. The plant Arrabidaea chica,
popularly known as ?pariri?, is common in the Amazon region, and it is assigned several
medicinal properties. The leaves of this plant are rich in anthocyanins, which are phenolic
compounds with high antioxidant power. Antioxidant compounds play a vital role in the
prevention of neurological and cardiovascular diseases, cancer and diabetes, among others.
Within the anthocyanins found in Arrabidaea chica, stands out Carajurin (6,7-dihydroxy-5,4?-
dimethoxy-flavilium), which is the major pigment encountered in this plant. The present work
aimed to study on supercritical extraction and conventional extraction (solid-liquid extraction)
in leaves of Arrabidaea chica, evaluating the efficiency of the extractive processes,
antioxidant activity and quantification of Carajurin contained in the extracts. Supercritical
extraction used CO2 as solvent with addition of co-solvent (ethanol/water mixture) and were
conducted by the dynamic method in a fixed bed extractor. The trials followed a 24-1
fractional factorial design, the dependent variables were: process yield, concentration of
Carajurin and antioxidant activity; and independent variables were: pressure, temperature,
concentration of co-solvent (v/v) and concentration of water in the co-solvent mixture (v/v).
Yields (mass of dry extract/mass of raw material used) obtained from supercritical extraction
ranged from 15.1% to 32%, and the best result was obtained at 250 bar and 40 ?C, co-solvent
concentration equal to 30% and concentration of water in the co-solvent mixture equal to
50%. Through statistical analysis, it was found that the concentration of co-solvent revealed
significant effect on the yield. Yields obtained from conventional extractions were of 8.1%
(water) and 5.5% (ethanol). Through HPLC (High-performance liquid chromatography)
analysis, Carajurin was quantified in all the extracts and concentration values (Carajurin
mass/mass of dry extract) ranged between 1% and 2.21% for supercritical extraction. For
conventional extraction, Carajurin was not detected in the aqueous extract, while the ethanol
extract showed Carajurin content of 7.04%, and therefore, more selective in Carajurin than the
supercritical extraction. Evaluation of antioxidant power (radical 2,2-diphenyl-1-picrylhydrazyl
? DPPH ? sequestration method) of the supercritical extracts resulted in EC50 values
(effective concentration which neutralizes 50% of free radicals) ranged from 38.34 to 86.13 ?g/mL, while conventional extraction resulted in EC50 values of 167.34 (water) and 42.58
(ethanol) ?g/mL. As for the quantification of total phenolic content (Folin-Ciocalteau
analysis) of the supercritical extracts resulted in values ranged from 48.93 and 88.62 mg
GAE/g extract (GAE = Gallic Acid Equivalents), while solid-liquid extraction resulted in
values of 37.63 (water) and 80.54 (ethanol) mg GAE/g extract. The good antioxidant activity
cannot be attributed solely to the presence of Carajurin, but also the existence of other
compounds and antioxidants in Arrabidaea chica. By optimizing the experimental design, it
was possible to identify the experiment that presented the best result considering the four
dependent variables together. This experiment was performed under the following conditions:
pressure of 200 bar, temperature of 40 ?C, co-solvent concentration equal to 30% and
concentration of water in the co-solvent mixture equal to 30%. It is concluded that, within the
studied range, it is possible to purchase the optimum result using milder operating conditions,
which implies lower costs and greater ease of operation.
|
157 |
Estudo do tratamento sequencial (adsor??o e eletro-oxida??o) para remedia??o de efluente sint?tico contaminado com BTX / Study of sequential treatment (adsorption and electrooxidation) for synthetic effluent remediation contaminated with BTXAlmeida, Camila Carvalho de 26 January 2015 (has links)
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Previous issue date: 2015-01-26 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / O presente trabalho prop?s o estudo do tratamento de um efluente sint?tico
contaminado com BTX por eletro-oxida??o em batelada com o ?nodo de Ti/PbO2, e a
adsor??o de BTX utilizando perlita expandida como material adsorvente, tendo como objetivo
avaliar as melhores condi??es operacionais em ambas as metodologias a fim de realizar um
tratamento sequencial (adsor??o e eletro-oxida??o) e obter uma maior efici?ncia na remo??o
dos compostos. As condi??es operacionais avaliadas foram: temperatura, densidade de
corrente aplicada e quantidade de material adsorvente, atrav?s de an?lises de UV-vis e
Demanda Qu?mica de Oxig?nio (DQO). De acordo com os resultados experimentais obtidos,
o tratamento eletro-oxidativo se mostrou eficiente na degrada??o dos compostos BTX
(Benzeno, Tolueno e Xilenos) no efluente sint?tico em raz?o das propriedades
eletrocatal?ticas do ?nodo de Ti/PbO2. A densidade de corrente aplicada e a temperatura
promoveram o aumento da efici?ncia da remo??o de DQO, chegando a obter percentuais
superiores a 70%. No processo de adsor??o, o aumento da temperatura n?o se mostrou um
fator determinante para a remo??o da mat?ria org?nica, enquanto que o aumento na
quantidade de material adsorvente levou a um acr?scimo no percentual de remo??o, obtendo
66,30% utilizando 2g de adsorvente. As condi??es operacionais selecionadas de ambos os
tratamentos realizados separadamente levaram em considera??o a efici?ncia de remo??o da
mat?ria org?nica, e o baixo consumo energ?tico e custos operacionais, logo, o tratamento
sequencial se mostrou satisfat?rio atingindo 87,26% de remo??o de DQO utilizando a
adsor??o como um pr?-tratamento. A quantifica??o do BTX atrav?s das an?lises de
cromatografia gasosa ao t?rmino dos tratamentos tamb?m confirmou a efici?ncia da remo??o
dos compostos org?nicos, outorgando proeminentes vantagens ao tratamento sequencial. / This paper proposed the study of the treatment of a synthetic wastewater contaminated
with BTX by electro-oxidation batch with the anode of Ti/PbO2, and the adsorption of BTX
using expanded perlite as adsorbent material, and to evaluate the best operating conditions
both methods in order to perform a sequential treatment (adsorption and electro-oxidation)
and achieve greater efficiency in the removal of the compounds. The operating conditions
were measured: temperature, current density and applied amount of the adsorbent material, by
UV-VIS analysis and Demand Chemical oxygen demand (COD). According to the
experimental results, the electro-oxidative treatment was efficient in the degradation of the
compounds BTX (benzene, toluene and xylenes) in synthetic sewage due to the
electrochemical properties of the anode of Ti/PbO2. The applied current density and
temperature promoted increased efficiency of COD removal, reaching obtain percentages
greater than 70%. In the adsorption process, the temperature increase was not a factor in the
removal of organic matter, while the increase in the amount of adsorbent material led to an
increase in the percentage removal, obtaining 66.30% using 2 g of adsorbent. The selected
operating conditions of both treatments performed separately take into account the removal
efficiency of organic matter, and the low energy consumption and operating costs, so the
sequential treatment were satisfactory reaching 87.26% of COD removal using adsorption as a
pretreatment. Quantification of BTX through the analysis of gas chromatography at the end of
the treatments also confirmed the removal efficiency of organic compounds, giving
outstanding advantages to sequential treatment.
|
158 |
Petrologia das fraturas associadas a fei??es t?picas de dissolu??o hipog?nica na Forma??o Salitre, Bacia de Irec?, Bahia, BrasilSantos, Cristiane Paulino de Menezes 05 May 2015 (has links)
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Previous issue date: 2015-05-05 / O reconhecimento dos reservat?rios c?rsticos em rochas carbon?ticas
tornou-se cada vez mais comum. No entanto, a maioria das fei??es c?rsticas
s?o pequenas para serem reconhecidos em se??es s?smicas ou maiores do
que o esperado para serem investigadas com os dados de po?os. Um
caminho a seguir tem sido o estudo de afloramentos an?logos e cavernas. O
presente estudo investiga litof?cies e processos c?rsticos, que levaram ?
gera??o do maior sistema de cavernas da Am?rica do Sul. A ?rea de estudo
situa-se no norte do Munic?pio de Campo Formoso-BA, no contexto geol?gico
da Forma??o Salitre, Grupo Una, que corresponde ?s coberturas
neoproterozoicas da Bacia de Irec?. Esta unidade disp?e de um sistema de
cavernas, em rochas carbon?ticas, que incluem as cavernas da Toca da Boa
Vista e Toca da Barriguda, consideradas as maiores cavernas da Am?rica do
Sul. Estas cavernas foram formadas principalmente em dolomitos da
Forma??o Salitre, que foram depositados em um mar epicontinental raso. A
Forma??o Salitre na ?rea da caverna compreende camadas de
mudstones/wackestones, grainstones intracl?sticos, grainstones oncol?ticos,
grainstones ool?ticos, laminitos microbiais, estromat?litos colunares,
trombolitos e rochas silicicl?sticas finas (margas, folhelhos e siltitos). Uma
camada fina e n?dulos de s?lex tamb?m ocorrem na parte superior da unidade
de carbonato. Os dados preliminares indicam que as dobras e as juntas
associadas controlam o principal evento de carstifica??o, teriam ocorrido no
final da Orogenia Brasiliana (740-540 Ma). Foram reconhecidas cinco
litof?cies principais no sistema de cavernas: (1) camadas inferiores de
grainstone com estratifica??o cruzada, as quais constituem a principal unidade
afetada pela espeleog?nese, (2) grainstone fino com intercala??es de siltito,
(3) laminito microbial, (4) estromat?litos colunares, e (5) camada superior
composta por siltito. Os n?veis de (1) a (3) s?o os mais afetados pelo intenso
fraturamento, enquanto os n?veis (4) e (5) apresentam comportamento
selante, constituindo o teto da caverna e sofrendo menos fraturamento. Veios
preenchidos por chert e calcita atravessam as unidades carbon?ticas e
desempenham um papel importante na diag?nese. Nosso estudo preliminar
indica que a espelogenese hipog?nica ? o principal processo de
desenvolvimento c?rstico. O estudo das fraturas, sua distribui??o em cada
litof?cies, o material que preenche essas fraturas e sua intera??o com a rocha
encaixante, ? muito importante para se entender que tipo de fluido atuou na
espeleog?nese e como esse processo contribuiu significativamente para a
gera??o de porosidade e permeabilidade secund?rias nas unidades de
carbonatos. / The recognition of karst reservoirs in carbonate rocks has become
increasingly common. However, most karst features are small to be
recognized in seismic sections or larger than expected to be investigated with
borehole data. One way forward has been the study of analogue outcrops and
caves. The present study investigates lithofacies and karst processes, which
lead to the generation of the largest system of caves in South America. The
study area is located in the Neoproterozoic Una Group in central-eastern
Brazil. This province comprises several systems of carbonate caves (Karmann
and Sanch?z, 1979), which include the Toca da Boa Vista and Barriguda
caves, considered the largest caves in South America (Auler and Smart,
2003). These caves were formed mainly in dolomites of the Salitre Formation,
which was deposited in a shallow marine environment in an epicontinental sea
(Medeiros and Pereira, 1994). The Salitre Formation in the cave area
comprises laminated mud/wakestones, intraclastic grainstones, oncolitic
grainstones, oolitic grainstones, microbial laminites, colunar stromatolites,
trombolites and fine siliciclastic rocks (marls, shales, and siltites). A thin layer
and chert nodules also occur at the top of the carbonate unit. Phosphate
deposits are also found. Our preliminary data indicate that folds and
associated joints control the main karstification event at the end of the
Brasiliano orogeny (740-540 Ma). We recognized five lithofacies in the cave
system: (1) Bottom layers of grainstone with cross bedding comprise the main
unit affected by speleogenesis, (2) thin grainstone layers with thin siltite layers,
(3) microbial laminites layers, (4) layers of columnar stromatolites, and a (5)
top layer of siltite. Levels (1) to (3) are affected by intense fracturing, whereas
levels (4) and (5) seal the caves and have little fracturing. Chert, calcite and
gipsite veins cut across the carbonate units and play a major role in
diagenesis. Our preliminary study indicate that hypogenic spelogenesis is the
main process of karst development and contributed significantly to the
generation of secondary porosity and permeability in the carbonate units.
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Estudo de m?todos de tratamento de efluentes (troca i?nica e eletroqu?mico) separados e sequenciais para elimina??o de derivados de petr?leo / Study of effluent treatment methods (ion exchange and electrochemical) separated and sequential for disposal of petroleum productsMelo, Maria Jucilene de Macedo 12 December 2014 (has links)
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Previous issue date: 2014-12-12 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq / A gera??o de res?duo e a quantidade de ?gua produzida proveniente das atividades de
produ??o e extra??o de petr?leo tem sido um enorme desafio para as empresas petrol?feras
com rela??o ? adequa??o ambiental em fun??o da sua toxicidade. O descarte ou reuso desse
efluente contendo compostos org?nicos como o BTEX (benzeno, tolueno, etilbenzeno e
xileno) pode causar s?rios problemas ambientais e a sa?de humana. Assim, o objetivo desse
trabalho foi estudar o desempenho de dois processos (separadamente e sequenciais) em um
efluente sint?tico para a remo??o de benzeno, tolueno e xileno (hidrocarbonetos vol?teis
presentes na ?gua produzida) atrav?s de tratamento eletroqu?mico usando o eletrodo de Ti/Pt e
resina de troca i?nica utilizada no processo de adsor??o. A solu??o sint?tica de BTX foi
preparada com concentra??o de 22,8 mg L-1, 9,7 mg L-1 e 9,0 mg L-1, respectivamente em
Na2SO4 0,1 mol L-1. Os experimentos foram realizados em batelada com 0,3 L de solu??o a
25?C. O processo de oxida??o eletroqu?mica foi realizado com o eletrodo de Ti/Pt aplicando
diferentes densidades de corrente (J = 10, 20 e 30 mA cm-2). No processo de adsor??o, foi
empregada uma resina troca i?nica (Purolite MB 478), usando diferentes quantidades de
massa (2,5; 5 e 10 g). Para verificar a efici?ncia dos processos no tratamento sequencial, foi
fixada uma densidade de corrente de 10 mA cm-2 e massa da resina de 2,5 g. As an?lises de
espectrofotometria UV-vis, demanda qu?mica de oxig?nio (DQO) e cromatografia gasosa com
detector seletivo de fotoioniza??o (PID) e ioniza??o em chama (FID), confirmaram a alta
efici?ncia de remo??o dos compostos org?nicos ap?s o tratamento. Constatou-se que o
processo eletroqu?mico (separado e sequencial) ? mais eficiente do que a adsor??o,
alcan?ando valores da remo??o da DQO superiores a 70%, confirmado pelo estudo da
voltametria c?clica e curvas de polariza??o. Enquanto que na adsor??o (separado), a remo??o
da DQO n?o ultrapassou 25,8%, devido ?s intera??es da resina. Contudo, o processo
sequencial (oxida??o eletroqu?mica e adsor??o) se mostrou uma alternativa adequada,
eficiente e com boa rela??o custo-benef?cio para o tratamento de efluentes petroqu?micos. / The produce of waste and the amount of the water produced coming from activities of
petroleum production and extraction has been a biggest challenge for oil companies with
respect to environmental compliance due to toxicity. The discard or the reuse this effluent
containing organic compounds as BTEX (benzene, toluene, ethylbenzene and xylene) can
cause serious environmental and human health problems. Thus, the objective this paper was
study the performance of two process (separately and sequential) in one synthetic effluent for
the benzene, toluene and xylene removal (volatile hydrocarbons presents in the produced
water) through of electrochemical treatment using Ti/Pt electrode and exchange resin ionic
used in the adsorption process. The synthetic solution of BTX was prepared with
concentration of 22,8 mg L-1, 9,7 mg L-1 e 9,0 mg L-1, respectively, in Na2SO4 0,1 mol L-1.
The experiments was developed in batch with 0.3 L of solution at 25?C. The electrochemical
oxidation process was accomplished with a Ti/Pt electrode with different current density (J =
10, 20 e 30 mA.cm-2). In the adsorption process, we used an ionic exchange resin (Purolite
MB 478), using different amounts of mass (2,5, 5 and 10 g). To verify the process of technics
in the sequential treatment, was fixed the current density at 10 mA cm-2 and the resin weight
was 2.5 g. Analysis of UV-VIS spectrophotometry, chemical oxygen demand (COD) and gas
chromatography with selective photoionization detector (PID) and flame ionization (FID),
confirmed the high efficiency in the removal of organic compounds after treatment. It was
found that the electrochemical process (separate and sequential) is more efficient than
absorption, reaching values of COD removal exceeding 70%, confirmed by the study of the
cyclic voltammetry and polarization curves. While the adsorption (separately), the COD
removal did not exceed 25,8%, due to interactions resin. However, the sequential process
(electrochemical oxidation and adsorption) proved to be a suitable alternative, efficient and
cost-effectiveness for the treatment of effluents petrochemical.
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Desenvolvimento de material BaCexPr1-xO3 (0 ? X ? 1) com estrutura perovskita para oxida??o catal?tica do CO a CO2 em reator de leito fixoLobato, Maxwell Ferreira 19 June 2015 (has links)
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Previous issue date: 2015-06-19 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / O Cerato de b?rio (BaCeO3) tem estrutura perovskita do tipo ABO3, na qual A e B
s?o c?tions met?licos. Estes materiais, dopados ou n?o, t?m sido estudados por apresentarem
caracter?sticas que os tornam promissores na aplica??o em c?lulas a combust?vel de ?xido
s?lido, permea??o de hidrog?nio e oxig?nio, como catalisadores, entre outros. Por?m, como os
materiais cer?micos de condutividade mista t?m sido produzidos por m?todos distintos de
s?ntese, algumas condi??es influenciam diretamente as propriedades finais, sendo uma das mais
importantes a dopagem do s?tio B, que pode ter influ?ncia direta no tamanho de cristalito, que
por sua vez pode influenciar a sua atividade catal?tica. No presente trabalho, perovskitas do tipo
(BaCexO3) tiveram o c?rio gradativamente substitu?do pelo praseod?mio para obten??o de
materiais tern?rios do tipo BaCexPr1-xO3 e bin?rios BaPrO3. Esses materiais foram sintetizados
pelo m?todo de complexa??o combinando EDTA-Citrato, sendo o material caracterizado via
DRX, MEV e BET para identifica??o da sua estrutura, morfologia e ?rea superficial. Al?m
disso foram realizados, em todos os materiais, testes catal?ticos em reator de leito fixo visando
a identifica??o daquele respons?vel pela convers?o total de CO em CO2 na menor temperatura
de opera??o, etapa que poder? ser utilizada como posterior ? produ??o de g?s de s?ntese
(CO+H2) a partir da oxida??o do metano. No presente trabalho a fase cristalina foi obtida
apresentando estrutura ortorr?mbica para todas as composi??es, com morfologia formada por
aglomerados de part?culas. O tamanho m?dio dos cristais variou entre 100 nm e 142,2 nm. As
?reas superficiais foram de 2,62 m?g-
1
para a composi??o BaCeO3, de 3,03 m?g-
1
para a
composi??o BaCe0,5Pr0,5O3 e de 2,37 m?g-
1
para a composi??o BaPrO3. Em rela??o aos testes
catal?ticos, pode-se concluir que a vaz?o ?tima de opera??o do reator foi de 50 ml/min e que a
composi??o que obteve a taxa m?xima de convers?o com a menor temperatura foi o BaCeO3,
para 400? C. Enquanto isso, observou-se que ao substituir parcialmente o c?rio pelo praseod?mio
houve uma diminui??o na atividade catal?tica do material. / Barium Cerate (BaCeO3) is perovskite type structure of ABO3, wherein A and B are metal
cations. These materials, or doped, have been studied by having characteristics that make them
promising for the application in fuel cells solid oxide, hydrogen and oxygen permeation, as
catalysts, etc .. However, as the ceramic materials mixed conductivity have been produced by
different synthesis methods, some conditions directly influence the final properties, one of the
most important doping Site B, which may have direct influence on the crystallite size, which in
turn directly influences their catalytic activity. In this study, perovskite-type (BaCexO3) had
cerium gradually replaced by praseodymium to obtain ternary type materials BaCexPr1-xO3 and
BaPrO3 binaries. These materials were synthesized by EDTA/Citrate complexing method and
the material characterized via XRD, SEM and BET for the identification of their structure,
morphology and surface area. Moreover were performed on all materials, catalytic test in a
fixed bed reactor for the identification of that person responsible for complete conversion of
CO to CO2 at low operating temperature, which step can be used as the subsequent production
of synthesis gas (CO + H2) from methane oxidation. In the present work the crystalline phase
having the orthorhombic structure was obtained for all compositions, with a morphology
consisting of agglomerated particles being more pronounced with increasing praseodymium in
the crystal structure. The average crystal size was between 100 nm and 142,2 nm. The surface
areas were 2,62 m?g-1
for the BaCeO3 composition, 3,03 m?g-1
to BaCe0,5Pr0,5O3 composition
and 2,37 m?g-1
to BaPrO3 composition. Regarding the catalytic tests, we can conclude that the
optimal flow reactor operation was 50 ml / min and the composition regarding the maximum
rate of conversion to the lowest temperature was BaCeO3 to 400? C. Meanwhile, there was
found that the partially replaced by praseodymium, cerium, there was a decrease in the catalytic
activity of the material.
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