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Previous issue date: 2017-08-21 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Nanocristais de celulose s?o nanoestruturas derivados da celulose, que ? um recurso renov?vel
e abundante na natureza. Por apresentarem uma combina??o de propriedades como
alta resist?ncia mec?nica e m?dulo de elasticidade, superf?cie reativa e biodegradabilidade,
esses materiais t?m recebido grande interesse para aplica??es que incluem desde refor?o
em materiais polim?ricos, embalagens alimentares, a aplica??es na ?rea farmac?utica. A
produ??o de celulose nanom?trica a partir de fibras de algod?o tem sido relatada em v?rios
trabalhos publicados na literatura. O objetivo desta pesquisa foi estudar a obten??o de
nanocelulose a partir do res?duo de tecido de fibra de algod?o tingido com corante ?ndigo,
devido possuir alto conte?do de celulose, pelas vias de hidr?lise ?cida e enzim?tica. Nanocelulose
foi obtida com e sem a realiza??o de pr?-tratamento para remo??o do corante
e os efeitos do pr?-tratamento nas caracter?sticas da nanocelulose foram avaliados. Na
hidr?lise ?cida, foram avaliadas duas condi??es de tratamento para isolamento de nanocristais
de celulose: concentra??es de ?cido sulf?rico de 55% m/m a 60 C ou 65% m/m a
45 C, com tempos de 30 e 60 min. Na hidr?lise enzim?tica foram estudadas as influ?ncias
do tipo de complexo enzim?tico (Trichoderma reesei ATCC 26921 ou Aspergillus fumigatus),
o tempo (0 a 48h) e a carga enzim?tica (7,5 ou 12 FPU). As suspens?es obtidas
ap?s hidr?lise foram caracterizadas pelas t?cnicas de potencial zeta, microscopia de for?a
at?mica, microscopia eletr?nica de transmiss?o, espectrofotometria de infravermelho, difra??o
de raios X, an?lise termogravim?trica, a??cares redutores totais e cromatografia
l?quida de alto desempenho. Os resultados comprovaram a obten??o de nanocelulose a
partir do tecido de algod?o tingido com corante ?ndigo, tanto no processo via hidr?lise
?cida, como no de via enzim?tica. As imagens de microscopia indicaram nanocristais de
celulose com formato alongado (agulhas) a partir da hidr?lise ?cida. No caso da hidr?lise
enzim?tica, as imagens mostraram a presen?a de nanocelulose com formato esf?rico. A
hidr?lise ?cida realizada na condi??o de 65% a 45 C e tempo de 60 min resultou em nanocristais
com menor comprimento e di?metro, tanto para o tecido pr?-tratado como para o
sem pr?-tratamento. Com rela??o a hidr?lise enzim?tica, a realiza??o de pr?-tratamento
n?o alterou significativamente as caracter?sticas das estruturas micro e nanocristalina. O
tamanho m?dio das nanoceluloses obtidas foram na faixa de 80 a 230nm. Os resultados
do processo de hidr?lise enzim?tica indicam que as melhores convers?es de celulose em
glicose ocorreram utilizando o complexo enzim?tico produzido por Trichoderma reesei
ATCC 26921 com carga de enzima de 12 FPU e tempo de hidr?lise de 48h. Este trabalho
demonstrou que nanocristais de celulose podem ser obtidos a partir do tecido de algod?o
tingido com corante ?ndigo, sem a necessidade de pr?-tratamento para remo??o do corante, e as caracter?sticas dos nanomateriais obtidos dependem do processo de hidr?lise
utilizado. / Cellulose nanocrystals are nanomaterials derived from cellulose, which is a renewable and
abundant resource in nature. Due to combination of properties such as high mechanical
strength and modulus of elasticity, reactive surface and biodegradability, these materials
have received great attention for applications ranging from reinforcement in polymeric
materials, food packaging, to applications in the pharmaceutical area. The production of
nanometric cellulose from cotton fibers has been reported in several works published in
the literature. The objective of this research was to study the production of nanocellulose
from indigo-dyed cotton fibers from waste fabric, via acid and enzymatic hydrolysis
routes. Nanocellulose was obtained with and without pre-treatment for dye removal and
the effects of the pre-treatment on the characteristics of the nanocellulose were evaluated.
For the acid hydrolysis, two treatment conditions for the isolation of cellulose nanocrystals
were evaluated: sulfuric acid concentrations of 55% m / m at 60 C and 65% m/m
at 45 C, for 30 and 60 min. For the enzymatic hydrolysis, the influence of enzyme complex
type (Trichoderma reesei ATCC 26921 and Aspergillus fumigatus), time (0 to 48h)
and enzymatic load (7.5 and 12 FPU) were studied. The suspensions obtained after hydrolysis
were characterized by the techniques of zeta potential, atomic force microscopy,
transmission electron microscopy, infrared spectrophotometry, X-ray diffraction, thermogravimetric
analysis, total reducing sugars and high performance liquid chromatography.
The results demonstrated that nanocellulose was obtained from indigo dyed cotton fibers,
in both processing routes evaluated: via acid and enzymatic hydrolysis. Microscopy
images indicated needle shaped celulose from the acid hydrolysis. For the enzymatic hydrolysis,
the images showed the presence of nanocellulose with spherical shape. The acid
hydrolysis carried out at 65% at 45 C for 60 min resulted in nanocrystals of smaller length
and diameter, both for the pretreated fabric and the fabric without pretreatment. For the
enzymatic hydrolysis, the pretreatment did not affect significantly the characteristics of
the micro and nanocrystalline structures. The average size of the nanocellulose obtained
was in the range of 80 to 230 nm. The results of the enzymatic hydrolysis suggest that
the best cellulose to glucose conversions occurred using the enzymatic complex Trichoderma
reesei ATCC 26921 with enzymatic load of 12 FPU and hydrolysis time of 48h.
In summary, this study demonstrated that cellulose nanocrytals can be obtained from
indigo-dyed cotton fibers from waste fabric, without the need for pretreatment for dye
removal, and the characteristics of the nanomaterials obtained depend on the hydrolysis
process used.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/24141 |
| Date | 21 August 2017 |
| Creators | Cruz, Luciani Paola Rocha |
| Contributors | 46660640444, Barbosa, Ana Paula Cysne, 04561659676, Santos, Everaldo Silvino dos, 87510383404, Oliveira, Fernando Ribeiro, 03986506675, Azeredo, Henriette Cordeiro Monteiro de, 54600561600, Nascimento, Jos? Heriberto Oliveira do, 02452573493, Melo, Jos? Daniel Diniz |
| Publisher | PROGRAMA DE P?S-GRADUA??O EM ENGENHARIA MEC?NICA, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| 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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