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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.
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Estudo da efici?ncia eletroqu?mica para tratamento de chorume gerado em aterro sanit?rio brasileiroXavier, Daniela Karla de Souza 29 January 2015 (has links)
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Previous issue date: 2015-01-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Este trabalho foi desenvolvido realizando estudos de degrada??o de efluentes mediante o tratamento eletroqu?mico usando o eletrodo de PbO2. A oxida??o eletroqu?mica (OE) de hidroquinona (H2Q) foi realizada, em meio ?cido, utilizando eletrodo de PbO2 por eletr?lise galvanost?tica, aplicando densidade de corrente de 10 e 30 mA/cm2. A concentra??o de H2Q foi monitorada por voltametria de pulso diferencial (DPV). Os resultados experimentais de eletr?lise galvanost?tica mostraram que os desempenhos do processo dependem significativamente da densidade de corrente aplicada, obtendo efici?ncias de remo??o de 100% e 80% aplicando 30 e 10 mA/cm2, respectivamente. Al?m disso, a t?cnica eletroanal?tica foi eficiente ao ser utilizada como um m?todo de detec??o de H2Q. Com o intuito de testar a efici?ncia do eletrodo de PbO2, foi realizado o tratamento eletroqu?mico de um efluente real, chorume de um aterro. O res?duo l?quido percolado (600 mL do efluente) foi tratado numa c?lula eletroqu?mica em batelada, com ou sem adi??o de NaCl, aplicando 7 mA/cm2. A efici?ncia da OE foi avaliada em fun??o da remo??o de coliformes termo-tolerantes, carbono org?nico total (COT), f?sforo total e metais (cobre, cobalto, cromo, ferro e n?quel). Estes resultados mostraram que, uma eficiente remo??o de coliformes foi obtida (100 %), e ainda ocorreu a diminui??o da concentra??o de metais pesados mediante os processos ao catodo. Entretanto, os resultados de COT n?o foram satisfat?rios, atingindo baixas remo??es da carga org?nica total dissolvida. Por se tratar de um efluente considerado complexo foram desenvolvidos outros testes com este efluente para acompanhar um n?mero maior de par?metros de descontamina??o (Turbidez, S?lidos Totais, Cor, Condutividade, Carbono Org?nico Total (COT) e metais (B?rio, Cromo, L?tio, Mangan?s e Zinco)), comparando a efici?ncia do tipo de tratamento eletroqu?mico (EO ou eletrocoagula??o) usando uma c?lula em fluxo. Neste ensaio foi comparado a eletrooxida??o em fluxo cont?nuo. No caso da OE, Ti/IrO2-TaO5 foi usado como anodo, no entanto, no processo de eletrocoagula??o, eletrodos de alum?nio foram usados; aplicando densidades de correntes de 10, 20 e 30 mA/cm2, na presen?a e aus?ncia de NaCl como eletr?lito. Os resultados mostraram que a EO usando Ti/IrO2-TaO5 como anodo foi eficiente quando o Cl- estava presente no efluente. Contrariamente, a eletrocoagula??o em fluxo reduz a mat?ria org?nica dissolvida no efluente, sob certas condi??es experimentais. / This work was performing effluent degradation studies by electrochemical treatment.
The electrochemical oxidation (EO) hydroquinone (H2Q) was carried out in acid medium,
using PbO2 electrode by galvanostatic electrolysis, applying current densities of 10 and 30
mA/cm2
. The concentration of H2Q was monitored by differential pulse voltammetry (DPV).
The experimental results showed that the galvanostatic electrolysis process performance
significantly depends on the applied current density, achieving removal efficiencies of 100%
and 80 % and 10 applying 30 mA/cm2
, respectively. Furthermore, the electroanalytical
technique was effective in H2Q be used as a detection method. In order to test the efficiency
of PbO2 electrode, the electrochemical treatment was conducted in an actual effluent, leachate
from a landfill. The liquid waste leachate (600ml effluent) was treated in a batch
electrochemical cell, with or without addition of NaCl by applying 7 mA/cm2
. The efficiency
of EO was assessed against the removal of thermo-tolerant coliforms, total organic carbon
(TOC), total phosphorus and metals (copper, cobalt, chromium, iron and nickel). These
results showed that efficient removal of coliforms was obtained (100%), and was further
decrease the concentration of heavy metals by the cathode processes. However, results were
not satisfactory TOC, achieving low total removal of dissolved organic load. Because it is
considered an effluent complex were developed other tests with this effluent to monitor a
larger number of decontamination parameters (Turbidity, Total Solids, Color, Conductivity,
Total Organic Carbon (TOC) and metals (barium, chromium, lithium, manganese and Zinc),
comparing the efficiency of this type of electrochemical treatment (EO or electrocoagulation)
using a flow cell. In this assay was compared to electro streaming. In the case of the OE,
Ti/IrO2-TaO5 was used as the anode, however, the electrocoagulation process, aluminum
electrodes were used; applying current densities of 10, 20 and 30 mA/cm2
in the presence and
absence of NaCl as an electrolyte. The results showed that EO using Ti/IrO2?TaO5 was anode
as efficient when Cl- was present in the effluent. In contrast, the electrocoagulation flow
reduces the dissolved organic matter in the effluent, under certain experimental conditions.
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Estudos eletroqu?micos e te?ricos sobre a oxida??o de compostos org?nicos modelo no eletrodo de diamante dopado com boro: comportamento eletroqu?mico, mecanismos de oxida??o e DFTSilva, ?mison Rick Lopes da 20 July 2016 (has links)
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Previous issue date: 2016-07-20 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A oxida??o eletroqu?mica ? um tipo de processo que pode ocorrer diretamente no ?nodo, a partir de uma transfer?ncia direta com a superf?cie, ou tamb?m atrav?s de uma oxida??o indireta mediante a gera??o de esp?cies ativas de oxig?nio as quais podem ser fisicamente adsorvidas (na forma de radicais hidroxila (?OH), ou quimicamente adsorvidas (oxig?nio se apresenta em estrutura de ?xido), na superf?cie do eletrodo. Esse processo est? relacionado ao tipo do material an?dico utilizado e a sua atividade eletrocatal?tica. Por?m, essa atividade pode ser tamb?m, prejudicada devido ? forma??o de filmes polim?ricos, rea??es paralelas de produ??o de oxidantes bem como, a rea??o de evolu??o de oxig?nio. Dentre os materiais eletrocatal?ticos mais estudados encontra-se os filmes de diamante dopado com boro (DDB). O eletrodo de DDB possui excelentes propriedades tais como estabilidade eletroqu?mica a elevadas densidades de correntes, estabilidade a corros?o, superf?cie inerte com baixas propriedades de adsor??o e dureza. A alta efici?ncia do DDB para remo??o dos compostos org?nicos ? atribu?da ? capacidade de produzir uma grande quantidade de radicais hidroxilas mediante a eletr?lise da ?gua. Estes radicais apresentam alta reatividade com os compostos org?nicos, devido ? sua fraca intera??o (fracamente adsorvido) com o filme de DDB s?o tamb?m, n?o seletivos e mineralizam completamente poluentes org?nicos com uma alta efici?ncia de corrente. Entretanto, alguns compostos org?nicos s?o de f?cil degrada??o em rela??o a outros, bem como, alguns compostos org?nicos tamb?m interagem com a superf?cie do DDB. Assim, devido ? necessidade de entender o processo qu?mico em escala molecular, a inclus?o de estudos te?ricos computacionais esta sendo de maior interesse, na qual s?o desenvolvidos c?lculos f?sico-qu?micos advindos da qu?mica qu?ntica, utilizando a Teoria do Funcional da Densidade (DFT). A DFT trata sistemas com muitos el?trons usando fun??es que representam a densidade eletr?nica das mol?culas a fim de se obter: propriedades eletr?nicas, cargas at?micas e energias dos intermedi?rios que comp?e a superf?cie de energia potencial de uma rea??o qu?mica, avaliar a estabilidade de modo comparativo entre compostos e entender os mecanismos de rea??o seguidos e propostos. Assim, o objetivo deste trabalho foi o uso de DDB para o estudo do comportamento eletroqu?mico de compostos org?nicos (hidroquinona, catecol, resorcinol, ?cido ac?tico, ?cido f?rmico e ?cido ox?lico) bem como o entendimento do processo de degrada??o, dos mesmos quando eletrolisados. Al?m disso, estudos computacionais referentes ao comportamento das esp?cies qu?micas frente ao eletrodo de DDB com a inten??o de obter as configura??es de intera??o do composto org?nico na superf?cie do eletrodo ou no entendimento de desvendar as intera??es entre as esp?cies oxidantes fortes em solu??o com os compostos org?nicos durante sua degrada??o. / The Electrochemical Oxidation is a kind of process that can occur directly at the anode from a direct transfer to the surface, or also by means of indirect oxidation by the generation of active oxygen species which can be physically adsorbed (in form of hydroxyl radical (? OH)), or chemically adsorbed (oxygen is present in oxide structure) on the electrode surface. this process is related to the type of anode material used and its electrocatalytic activity. However, this activity can also be impaired due to the formation of polymeric films, production of parallel oxidant reactions as well reaction of oxygen evolution. Among the most studied electrocatalytic material is diamond films doped with boron (BDD). the BDD electrode has excellent electrochemical properties such as stability at high current densities, corrosion stability, inert surface with low adsorption properties, and hardness. The high efficiency of the BDD for removal of organic compounds is attributed to their ability to produce a large amount of hydroxyl radicals by the electrolysis of water. These radicals have high reactivity with organic compounds, due to their weak interaction (weakly adsorbed) with the film BDD, they are also not selective and completely mineralize organic pollutants with a high current efficiency. However, some organic compounds are easy to degradation than others, as well as certain organic compounds also interact with the surface of BDD. Thus, because of the need to understand the chemical process at the molecular level, including computational theoretical studies that are of most interest, which are developed physico-chemical calculations arising from quantum chemistry, using Density Functional Theory (DFT). The DFT is systems with many electrons using functions representing the electron density of molecules in order to obtain electronic, atomic charges and derivatives of energy the potential energy surface of a chemical reaction, to evaluate the stability of the compounds and understand the reaction mechanisms followed and proposed. The objective of this work was the use of BDD to study the electrochemical behavior of organic compounds (hydroquinone, catechol, resorcinol, acetic acid, formic acid and oxalic acid) as well as the understanding of the degradation process of the same when in electrolysis. Moreover, computational studies on the behavior of chemical species across the BDD electrode with the intention of obtaining the organic compound interaction settings on the surface of the electrode or the understanding to unravel the interactions between strong oxidizing species in solution with organic compounds during its degradation.
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Avalia??o dos coeficientes de transfer?ncia de massa e hidrodin?mica de diferentes geometrias de c?lulas eletroqu?micas para o tratamento de BTX / Evaluation of mass transfer coeficients and hydrodinamics from diferents geometrys of electrochemical cells for BTXN?brega, Diogo Rosembergh da Silva 05 March 2015 (has links)
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Previous issue date: 2015-03-05 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Na ind?stria do petr?leo, a ?gua produzida ? o maior volume l?quido produzido com
grande capacidade poluidora. Dentre os contaminantes org?nicos, os arom?ticos apresentam o
principal risco ao meio ambiente e ? sa?de da popula??o principalmente BTEX. Ao longo dos
?ltimos anos, a eletroqu?mica tem se mostrado eficiente na degrada??o desses compostos,
envolvendo apenas a utiliza??o de el?trons como reagentes. Entretanto, o desenho do reator
eletroqu?mico, hidrodin?mica e, consequentemente, o coeficiente de transfer?ncia de massa
s?o par?metros determinantes na efici?ncia do processo eletroqu?mico. Dentro desse contexto,
o objetivo deste trabalho foi investigar geometrias de c?lulas eletroqu?micas, visando
determinar os coeficientes de transfer?ncia de massa e entender a sua hidrodin?mica. Foram
estudadas c?lulas em batelada e em fluxo, variando a pot?ncia da agita??o, posi??o da
agita??o e espa?amento entre os eletrodos, empregando a t?cnica de corrente limite, com um
gradiente de concentra??o de 4 a 24 mmol/dm? de K4[Fe(CN)]6 em propor??o molar de 2:1
para K3[Fe(CN)]6 em meio de NaOH 0,5 mol/dm?, a fim de determinar a corrente limite, e
consequentemente o coeficiente de transfer?ncia de massa (km). Os resultados obtidos
mostraram claramente que na c?lula em batelada, o aumento da agita??o e a posi??o da
agita??o influenciaram o km; na c?lula em fluxo, o afastamento dos eletrodos n?o mostra
influencia significativa quando a agita??o (fluxo) ? direcionada ? superf?cie do eletrodo; e
ainda, as c?lulas em fluxo se mostraram mais eficientes no que diz respeito ? elimina??o de
resist?ncias f?sicas inerentes ao tratamento eletro-oxidativo. Por fim, os resultados alcan?ados
mostraram que ? poss?vel a aplica??o do reator eletroqu?mico no tratamento de BTX, uma vez
que foi identificada uma geometria com o melhor coeficiente de massa, favorecendo a
oxida??o das esp?cies na superf?cie do eletrodo, de forma mais r?pida e eficiente. / The oil and gas production processes generate large volumes of waste with high
toxicity. In this industry, produced water is the most produced liquid volume with great
polluting capacity. Among the organic contaminants, the aromatics, mainly BTEX, present a
major risk to the environment and people's health. Over the past years, many studies have
been conducted under the electrooxidation of aromatic compounds, showing that the
electrochemical degradation is efficient for these substances, even more importantly, the
process involves only the use of electrons as reactants. However, the design of the
electrochemical reactor, hydrodynamics and mass transfer coefficients are critical parameters
on the efficiency of the electrochemical process. In this context, the objective of this study
was to investigate geometries of electrochemical cells, to determine the mass transfer
coefficients and understand their hydrodynamics. Cells were studied in batch and flow design,
varying stirring rate, the stirring position and spacing between electrodes. In order to
determine the current limit, and thus the mass transfer coefficient (Km), it was used a
concentration gradient of K4[FeCN]6 / K3[FeCN]6 (2:1) from 4 to 24 mM, in medium of 0.5
M NaOH. The results clearly showed that regarding the batch cell, increasing stirring rate and
changing its position promote a considerable effect on Km; in the flow cell, no influences were
achieved when the spacing of the electrodes was modified when the stirring (flow) is directed
to the electrode surface; and, the flow cells are more efficient with regard to the elimination of
inherent physical resistance to the electrochemical treatment. Finally, the results showed that
the application of reactor is possible to treat electrochemically BTX because the better
geometry has been identified, favoring the oxidation of the species on the electrode surface
more rapidly and efficiently.
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