Thermal treatment of chitosan in various conditions

Zawadzki, Jerzy; Kaczmarek, Halina

doi:10.1016/j.carbpol.2009.11.037

Cited by 295 publications

(195 citation statements)

References 12 publications

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“…The mechanism of thermal degradation of pure chitosan has been discussed previously in detail [19,[29][30][31]. As generally accepted, the thermal degradation of chitosan is a free radical mechanism.…”

Section: Effect Of Water Contentmentioning

confidence: 99%

“…At higher temperatures, the degraded chitosan residue undergoes carbonization and final mixture of products depends on the atmosphere in which the thermal decomposition was carried out [29]. In the air atmosphere, at the process beginning, the oxidation competes with the fragmentation.…”

Section: Effect Of Water Contentmentioning

confidence: 99%

“…It should be noted that in other samples, characterized by a lower water content, such stable structure does not arise. The evidence of the creation of unsaturated and aromatic structures in pyrolyzed CS has been provided by FTIR spectroscopy studies [29].…”

Section: Effect Of Water Contentmentioning

confidence: 99%

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Effect of side substituents on thermal stability of the modified chitosan and its nanocomposites with magnetite

Ziegler-Borowska

Chełminiak

Kaczmarek

et al. 2016

J Therm Anal Calorim

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Three different novel chitosan derivatives for medical or biotechnological applications have been successfully obtained by chemical modification of reactive amino and hydroxyl groups in chitosan chain. The modification has led to incorporation of different amount (one to three) of long-distanced amino and imine groups into each repeating unit. These highly functionalized chitosan derivatives were used as a matrix for magnetite nanoparticles. The thermal stability of all obtained chitosan materials has been determined using thermogravimetric analysis in oxidative and inert atmosphere. Chitosan containing two side substituents behaves differently from the other two, which is caused by the significant water uptake. Magnetite causes decrease in thermal stability of studied chitosan derivatives. The highest stability is observed for the nanocomposite obtained from chitosan with three side groups. The changes in the structure of the magnetite core have been observed above 600°C in nitrogen. Due to the different competitive reactions occurring in the modified chitosan, the proposed mechanism of thermal degradation is very complex.Keywords Modified chitosan Á Side group effect Á Thermogravimetric analysis Á Effect of water residue Á Thermal degradation mechanism

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Section: Effect Of Water Contentmentioning

confidence: 99%

Section: Effect Of Water Contentmentioning

confidence: 99%

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Effect of side substituents on thermal stability of the modified chitosan and its nanocomposites with magnetite

Ziegler-Borowska

Chełminiak

Kaczmarek

et al. 2016

J Therm Anal Calorim

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“…Literature data shows that the thermal degradation of CS structure does not follow a single mechanism but is a complex reaction that gives different decomposition products [43][44][45][46] . The decomposition starts from a random scission pathway of C-O-C bond of the pyranose ring and is followed by a further formation of small molecules and volatile compounds including acetic acid, acetic anhydride, acetamide and aromatic heterocycles such as pyrazines, pyridines, pyrroles and furans.…”

Section: Resultsmentioning

confidence: 99%

Preparation and Characterization of Cross-Linked Chitosan Microcapsules for Controlled Delivery of Oxytetracycline

Larbi-Bouamrane¹,

Bal²,

Aliouche³

et al. 2016

pharmaceutical-sciences

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Larbi-Bouamrane, et al.: Preparation of Chitosan Microcapsules for Delivery of OxytetracyclineFormulations of encapsulated oxytetracycline in chitosan spherical beads have been developed in this work through the ionotropic gelation method in sodium tripolyphosphate or hexametaphosphate and characterized as drug delivery system to the gastrointestinal tract by Fourier transform infrared spectroscopy, thermal analysis and in vitro drug release in simulated gastric fluids. The Fourier transform infrared spectroscopy and differential scanning calorimetry measurements showed that tripolyphosphate and hexametaphosphate are cross-linked ionically to chitosan and there was no significant drug interaction between the entrapped drug and the carrying polymer. With respect to chitosan cross-linking features, sodium hexametaphosphate seems to give better swelling, higher diffusion and faster release kinetics, while addition of glutaraldehyde as a second cross-linking agent lowers the drug discharge. Release extent and kinetics were found to be pH dependent and approximated very well by the multistep models equations of Makoid-Banakar, PeppasSahlin and Korsmeyer-Peppas. Key words: Oxyteracycline, chitosan, encapsulation, crosslinking, release kineticsTetracyclines are broad spectrum antibiotics that exhibit activity against a wide range of Gram-positive and Gram-negative bacteria. Their favourable antimicrobial properties and the absence of major adverse effects have led to their extensive use in the therapy of human and animal infections [1][2][3][4] . Unfortunately, like the other antibiotic and as a result of the extensive prescription in conventional formulations, the emergence of microbial resistance has limited their effectiveness. So, other strategies are needed to keep tetracycline's and other antibiotics as resources for the next generation and to restore their initial antimicrobial activity. These strategies are based on the development of new classes of drugs with unique antibacterial mechanisms or new formulations enabling the reduction of amounts of antimicrobials used worldwide. In particular, investigation of new formulations has been carried out in order to overcome the disadvantages resulting from the administration of antibiotics in conventional forms [5][6][7] .The specific addressing of active molecules to the organ, tissue or cell is considered now as a major challenge and promising route for the treatment of various human diseases, including bacterial infections, cancer or genetic diseases [8] . New carrying and targeting approaches for drug delivery have been extensively studied in recent years. Most of them are centered on the development of nano-or micro-scale carrying systems [9][10][11] or specific molecules to improve and maximize drug bioavailability and hence therapeutic effects over a period of time. This highly selective approach would ensure an optimum response from the dosage form which significantly lowers the side effects and reduce treatment's expense.As non-conventional pharmaceutical dos...

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“…The peaks at 1605, 1416, 1250, and 1022 cm −1 represent COOasymmetric stretching [28], COO-symmetric stretching [29,30], CH 3 symmetric bending [31], and C-O-C anti-symmetric stretching [32,33], respectively. For C. crispus biomass, the main bands relate to -OH overlapping (3283 cm −1 ) [26], C-H stretching (2924 cm −1 ) [27], C=C stretching (1644 cm −1 ) [34], N-H bending and C-N stretching (1531 cm −1 ) [35], COO− symmetric stretching (1416 cm −1 ) [29,30], S-O stretching (1152 and 1221 cm −1 ) [36,37], C−O−C antisym. stretching (1152 and 1034 cm −1 ) [32,33], and CH bending (696 cm −1 ) [38].…”

Section: Characterizationmentioning

confidence: 99%

A Comparison of Palladium Sorption Using Polyethylenimine Impregnated Alginate-Based and Carrageenan-Based Algal Beads

2018

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Two kinds of algal beads were prepared using a carrageenan-based alga (Chrondrus crispus) and an alginate-based alga (Laminara digitata) ionotropically gelled with K(I) and Ca(II), respectively: the process consists of biopolymer partial extraction followed by hydrogel formation. The beads were modified with branched polyethylenimine (bPEI) and glutaraldehyde (GA) using the impregnation method to improve their sorption capacity for Pd(II) in acid solution. SEM-EDX and FTIR techniques were used for characterizing the beads. The impacts of pH and presence of anions, cations, and Pt(IV) were studied in batch experiments. The beads were also applied for Pd(II) recovery from synthesized leaching liquors of a spent catalyst and a car catalytic converter via the sorption-desorption process. Results show that Pd is concentrated in the outer layer of L. digitata-bPEI-GA composite (LD/PEI) beads, while in the case of the C. crispus-bPEI-GA composite (CC/PEI), it is homogenously distributed in the whole mass of the sorbents. The difference is attributed to the repulsive force of the outer Ca(II)-alginate barrier of LD/PEI beads that makes it difficult for the branched polymer PEI to penetrate through the layer and be immobilized in the inner compartment. As a result, LD/PEI beads possess a lower maximum sorption capacity, but a slightly faster uptake at pH 1 than CC/PEI beads. In addition, CC/PEI beads present a better recovery performance compared to LD/PEI beads when applied for the treatment of synthesized leaching liquors.

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Thermal treatment of chitosan in various conditions

Cited by 295 publications

References 12 publications

Effect of side substituents on thermal stability of the modified chitosan and its nanocomposites with magnetite

Effect of side substituents on thermal stability of the modified chitosan and its nanocomposites with magnetite

Preparation and Characterization of Cross-Linked Chitosan Microcapsules for Controlled Delivery of Oxytetracycline

A Comparison of Palladium Sorption Using Polyethylenimine Impregnated Alginate-Based and Carrageenan-Based Algal Beads

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