Caracterização de quitosanas comerciais de diferentes origens

Abstract

Chitosan is a linear polysaccharide obtained from the deacetylation of chitin. The physico-chemical properties of chitosan dependent on the average degree of acetylation ( DA ) and of the average molar mass ( M ). Several applications of chitosan have been proposed in the literature, mainly in water treatment, cosmetic and drug manufacturing, food additives, semipermeable membranes and development of biomaterials. In this work, three commercial chitosan samples were characterized by proton nuclear magnetic resonance ( 1 H NMR), infrared spectroscopy (IR), conductimetric titration and thermal analysis (TG and DSC) in order to compare commercial chitosans from different supplies. The average viscosimetric molecular weight M v was estimated from the intrinsic viscosity. The results confirmed remarkable differences in relation to the mean degree of acetylation ( DA ) (or desacetylation, DD ). The thermal analysis data permitted to follow the dehydration, decomposition, and glass transition temperature (Tg).

Effect of shrimp shells milling on the molar mass of chitosan

“…Chitin extraction was confirmed by determining the rates of demineralization and deproteination, and the average degree of acetylation of chitosan was obtained by 1 H NMR, using a Bruker Avance III spectrometer and 9.4 Tesla, in the following experimental conditions: 400 MHz for hydrogen frequency (SWH), experimental temperature of 323 K, 16 scans (ns), wait time of 10 s (d1), acquisition time of 6.83 s (aq), and 65,536 data points (td). The %DA and %DD were calculated as described by Santos et al [20] . Figure 2 shows the particle size distribution for shrimp shells after milling under different times.…”

Use of natural coagulants in the treatment of food industry effluent replacing ferric chloride: a review

“…The production of chitosan can be obtained by partial or complete hydrolysis of the acetyl grouping with concentrated sodium hydroxide solutions or enzymatic hydrolysis, as different methods result in chitosans with different degrees of deacetylation and molecular mass by determining their applicability (Freepons, 1986;Tolaimatea et al, 2003;Weska et al, 2007;Wibowo et al, 2007;Capelete, 2011). Santos et al (2003) mentions various applications of chitosan as water treatment, production of cosmetics, medications, food additives, semipermeable membranes and biomaterials development.…”

Caracterização química e efeito cicatrizante de quitosana, com baixos valores de massa molar e grau de acetilação, em lesões cutâneas

“…O GA da quitosana, obtido por titulação potenciométrica, foi de 5,9%, inferior aos reportados por Santos et al [19] , que obtiveram, em diferentes quitosanas comerciais, graus de acetilação variando entre 9,8 e 23,0%. Este grau também está relacionado com a solubilidade da quitosana, em meios de acidez moderada, pois seu valor expressa a quantidade de grupos amino disponíveis para protonação e que geram cargas (-NH 3 + ) na cadeia polimérica.…”

“…A composição percentual de nitrogênio, carbono e hidrogênio da quitosana (Tabela 1) diferiu ligeiramente da encontrada por Santos et al [19] , que obtiveram, em diferentes quitosanas comerciais, porcentagens variando entre 7,0 e 8,5%; 41,2 e 44,5% e 6,0 e 6,7%, para nitrogênio, carbono e hidrogênio, respectivamente.…”