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Previous issue date: 2012-05-23 / The phenomenon of adsorption is of fundamental importance for the treatment of textile effluents and removal of dyes. Chitosan is characterized as an excellent adsorbent material, not only for its adsorption capacity but also the low cost production. Equilibrium and kinetic studies were developed in this study to describe the mechanism of adsorption of
the anionic azo dye Orange G in chitosan, with the isotherms obtained from the variation of
the concentration of dye in the continuous phase. The kinetics of the process was analyzed
based on models involving the adsorption of molecules of the dye in nonpolar and polar sites.
Adsorption experiments were carried out in water and in saline media with different NaCl
concentrations, both for the determination of the equilibrium time as isotherms for making
kinetic curves in which the amount of dye adsorbed measured indirectly varied with time. The
experiments revealed the opening of the biopolymer structure with increasing concentration of
Orange G, accompanied by high pH values and change on the type of interaction between the
dye and the adsorbent surface, suggesting behavior advocated by the Langmuir equation in a
certain range of concentration of the adsorbate and following the Henry's Law at higher
concentrations, from the increased number of sites available for adsorption. The studies
conducted showed that the saline medium reduces the chitosan s adsorption capacity
according to a certain concentration, the occurrence of the cooperative adsorption process
steps kinetic mechanism suggested as a new alternative for the interpretation of the
phenomenon / O fen?meno da adsor??o ? de fundamental import?ncia no tratamento de efluentes
t?xteis e remo??o de corantes. A quitosana caracteriza-se como excelente material adsorvente,
n?o s? pela sua capacidade de adsor??o mas tamb?m pelo baixo custo de obten??o. Estudos
cin?ticos e de equil?brio foram desenvolvidos neste trabalho para descrever o mecanismo de
adsor??o do azo-corante ani?nico Alaranjado G em quitosana, com a obten??o de isotermas a
partir da varia??o da concentra??o de corante na fase cont?nua. A cin?tica do processo foi
analisada a partir de modelos envolvendo a adsor??o de mol?culas do corante em dois tipos de
s?tios: polares e apolares. Experimentos de adsor??o foram desenvolvidos em ?gua e em
meios salinos com diferentes concentra??es de NaCl, tanto para a determina??o do tempo de
equil?brio como para a confec??o de isotermas e curvas cin?ticas nas quais a quantidade de
corante adsorvido, medida de forma indireta, variou em fun??o do tempo. Os experimentos
revelaram abertura da estrutura do biopol?mero com a eleva??o da concentra??o do
Alaranjado G, acompanhada pela eleva??o do pH e modifica??o no tipo de intera??o entre o
corante e a superf?cie do adsorvente, sugerindo comportamento preconizado pela equa??o de
Langmuir em certa faixa de concentra??o do adsorvato e obedecendo ? lei de Henry em
concentra??es mais elevadas, a partir do aumento do n?mero de s?tios dispon?veis para a
adsor??o. Os estudos desenvolvidos mostraram que o meio salino reduz a capacidade de
adsor??o do Alaranjado G em quitosana e pode impedir, em certa concentra??o, a ocorr?ncia
de processo cooperativo de adsor??o conforme mecanismo cin?tico em etapas sugerido como
uma nova alternativa para a interpreta??o do fen?meno
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/17660 |
| Date | 23 May 2012 |
| Creators | Lima, Roberto Rodrigues Cunha |
| Contributors | CPF:90623207753, http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4788562T6, Wanderley Neto, Alcides de Oliveira, CPF:00738841463, http://lattes.cnpq.br/4789528535524269, Pontes, Ana Cristina Facundo de Brito, CPF:42396441353, http://lattes.cnpq.br/0435570420479356, Anna, Carlos Mauricio Rabello de Sant', CPF:82723222772, http://lattes.cnpq.br/2087099684752643, Fonseca, Jos? Luis Cardozo |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Qu?mica, UFRN, BR, F?sico-Qu?mica; Qu?mica |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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