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Previous issue date: 2015-02-27 === Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES === A necessidade de preservar o meio ambiente tem levado a busca de novos materiais para
a elimina??o eficiente de compostos qu?micos que alteram a estabilidade dos nossos
recursos naturais. Entre estes recursos, se destaca em primeiro lugar a ?gua, como um
bem precioso e escasso, o que conduz ao uso adequado e seu reuso. Em virtude disso, a
Organiza??o Mundial da Sa?de estabeleceu valores m?ximos admiss?veis em ?guas
pot?veis, tais como: 50 mg/L, 0,1mg/L e 0,5mg/L para NO-
3, NO-
2, NH+
4,
respectivamente. Por estas raz?es, avalia-se a implementa??o de novos materiais e
processos no tratamento de ?guas objetivando a remo??o desses compostos, a exemplo
de aluminas, tanto em p? como suporte para um sistema catal?tico utilizando
membranas inorg?nicas capazes de suportar condi??es mais severas de temperatura e
press?o abrindo novas possibilidades de aplica??es dos reatores de membrana; como
tamb?m, tratamentos eletroqu?micos com eletrodos de diamante dopado com
bobo(DDB), como ?nodo e cobre como c?todo. Para tal intento, foi realizado o estudo
da adsor??o de nitratos em diferentes tempos para avaliar o tempo necess?rio para
alcan?ar o equil?brio empregando tr?s aluminas comerciais denominadas: aluminas
?cida, b?sica e neutra, com posterior tratamento na alumina ?cida impregnando-se
metais (Pd-Cu/Al2O3) para a rea??o catal?tica. Os materiais foram previamente
caracterizados pelas t?cnicas de DRX, MEV e ABET. As aluminas apresentaram uma
capacidade adsortiva consider?vel de nitrato nos primeiros trinta minutos, equivalente a
50% de remo??o alcan?ando equil?brio nesse tempo. Ap?s tratamento, utilizando a
alumina como catalisador para a rea??o no reator em batelada (Pd-Cu/Al2O3), os
resultados foram mais favor?veis, totalizando 64% de redu??o do ?on NO3
-
no final de
tr?s horas. Em contrapartida, os resultados para a rea??o catal?tica utilizando o suporte
catal?tico Pd-Cu/TiO2 no reator de membrana mostrou-se baixa, sendo dessa forma,
necess?rio aprimorar as condi??es do sistema catal?tico. J?, para os testes
eletroqu?micos usando eletrodos de DDB1, como ?nodo, e Cu, como c?todo, houve uma
redu??o de nitrato bastante significativa, cerca de 80% de remo??o do ?on durante tr?s
horas de tratamento com custos de aplica??es vi?veis. === The need to preserve the environment has led to the search for new materials for
efficient disposal of chemical compounds that alter the stability of our natural resources.
Among these resources, stands in first place the water, as a precious commodity and
scarce, leading to the proper use and reuse. As a result, the World Health Organization
has established maximum permissible values in drinking water, such as: 50 mg/L, 0, 1
mg/L and 0, 5 mg/L to at-3, at-2, NH 4, respectively. For these reasons, assesses the
implementation of new materials and water treatment processes aiming at the removal
of these compounds, such as alumina, in the form of powder or as a support for a
catalytic system using inorganic membranes capable of supporting more severe
conditions of temperature and pressure by opening new possibilities for applications of
membrane reactors; and also for electrochemical treatments with doped diamond bobo
electrodes (BDD) as anode and copper as cathode. For such purpose, was conducted the
study of adsorption of nitrate in different times to assess the time required to achieve
equilibrium by employing three commercial alumina called: acidic, basic and neutral
alumina, with subsequent treatment only in the acidic alumina impregnating metals (PdCu/Al2O3)
for the catalytic reaction. The materials were previously characterized by
XRD, SEM techniques and ABET. Aluminas presented a considerable adsortive
capacity of nitrate in the first thirty minutes, equivalent to 50% of removal reaching
equilibrium in that time. After treatment, using alumina as catalyst for the reaction in
batch reactor (Pd-Cu/Al2O3), the results were more favourable, totalling 64% reduction
of ion NO3-at the end of three hours. On the other hand, the results for the catalytic
reaction using the catalytic support Pd-Cu/TiO2 in membrane reactor proved to be low.
-if, in this way, improve the conditions of catalytic system to optimize the process.
Already, for the electrochemical tests using DDB1 electrodes as anode, and Cu, as
cathode, there was a fairly significant nitrate reduction, approximately 80% of ion
removal during three hours and cost viable applications.
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