| Summary: | Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-03-02T22:55:04Z
No. of bitstreams: 1
GiselleKallineGomesCarvalho_DISSERT.pdf: 2257540 bytes, checksum: e731412b34e93ab422b0df96d21ad8b7 (MD5) === Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-03-04T00:24:44Z (GMT) No. of bitstreams: 1
GiselleKallineGomesCarvalho_DISSERT.pdf: 2257540 bytes, checksum: e731412b34e93ab422b0df96d21ad8b7 (MD5) === Made available in DSpace on 2016-03-04T00:24:44Z (GMT). No. of bitstreams: 1
GiselleKallineGomesCarvalho_DISSERT.pdf: 2257540 bytes, checksum: e731412b34e93ab422b0df96d21ad8b7 (MD5)
Previous issue date: 2014-11-28 === Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq === Atividades industriais de minera??o, galvanoplastia e o processo de extra??o do
petr?leo, vem aumentando os n?veis de metais pesados, tais como Cu, Fe, Mg e Cd, nos
ecossistemas aqu?ticos. Este aumento est? relacionado ao descarte de efluentes contendo
teores desses elementos acima do valor m?ximo permitido por lei. M?todos como troca
i?nica, filtra??o por membranas e precipita??o qu?mica vem sendo estudados como meios de
tratamentos de efluentes contaminados por esses metais. A precipita??o de metais utilizando
tensoativos ani?nicos obtidos a partir de ?cidos carbox?licos surgiu como uma alternativa para
a remo??o de metais de efluentes industriais. A rea??o entre ?ons bivalentes dos metais e esses
tipos de tensoativos em solu??o aquosa leva a forma??o de carboxilatos de metais, que podem
precipitar na forma de flocos e serem removidos, posteriormente, por um processo de
decanta??o dos flocos formados ou por uma filtra??o simples. Neste trabalho, a extra??o de
metais ? realizada por meio da utiliza??o do tensoativo hexadecanoato de s?dio como agente
extrator. O objetivo principal ? estudar o efeito da varia??o da temperatura do meio, pH da
solu??o de metal e concentra??o do tensoativo no processo de remo??o do metal. A
modelagem estat?stica do estudo mostrou que o processo ? diretamente dependente das
varia??es de pH e concentra??o do tensoativo, por?m inversamente proporcional e pouco
dependente da varia??o de temperatura, sendo esse ?ltimo efeito considerado desprez?vel na
maioria dos casos. O estudo individual do efeito da temperatura apresenta uma forte
depend?ncia do processo ? temperatura de Kraft, tanto do tensoativo utilizado como agente
extrator como do tensoativo obtido ap?s a rea??o desse tensoativo com o metal. A partir dos
dados de temperaturas e concentra??es do tensoativo foi poss?vel o c?lculo da constante de
equil?brio para a rea??o entre o hexadecanoato de s?dio e ?ons cobre. Posteriormente, foram
determinados par?metros termodin?micos, comprovando que o processo ? exot?rmico e
espont?neo. === Industrial activities like mining, electroplating and the oil extraction process, are
increasing the levels of heavy metals such as Cu, Fe, Mg and Cd in aquatic ecosystems. This
increase is related to the discharge of effluents containing trace of this elements above the
maximum allowed by law. Methods such as ion exchange, membrane filtration and chemical
precipitation have been studied as a means of treatment of these metals contamination. The
precipitation of metals using anionic surfactants derived from carboxylic acids emerged as an
alternative for the removal of metals from industrial effluents. The reaction between bivalent
ions and these types of surfactants in aqueous solution leads to the formation of metal
carboxylates, which can precipitate in the form of flakes and are subsequently removed by a
process of decantation or simple filtration. In this work the metals extraction is performed by
using the surfactant sodium hexadecanoate as extracting agent. The main purpose was to
study the effect of temperature, solution pH, and concentration of surfactant in the metal
removal process. The statistical design of the process showed that the process is directly
dependent to changes in pH and concentration of surfactant, but inversely proportional and
somewhat dependent to temperature variation, with the latter effect being considered
negligible in most cases. The individual study of the effect of temperature showed a strong
dependence of the process with the Kraft point, both for the surfactant used as extracting
agent, as for the surfactant obtained after the reaction of this surfactant with the metal. From
data of temperatures and concentrations of the surfactant was possible to calculate the
equilibrium constant for the reaction between sodium hexadecanoate and copper ions. Later,
thermodynamic parameters were determined, showing that the process is exothermic and
spontaneous.
|
|---|
