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    Wyświetlanie 1-8 z 8
    Tytuł:
    Determination of degree of deacetylation of chitosan - comparision of methods
    Autorzy:
    Czechowska-Biskup, Renata
    Jarosińska, Diana
    Rokita, Bożena
    Ulański, Piotr
    Rosiak, Janusz M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1035372.pdf
    Data publikacji:
    2012
    Wydawca:
    Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
    Tematy:
    chitosan
    degree deacetylation
    methods
    Opis:
    Degree of deacetylation (DD) is one of the main parameters characterizing chitosan. The most precise measurements of DD require sophisticated equipment (NMR spectrometer), not available at many laboratories worldwide working on chitosan. There is a need for low-cost, simple, yet sturdy and reliable methods and procedures for DD determination. The aim of this work was to test and compare – on the same set of chitosan samples - a few of the existing analytical techniques and provide recommendation for selecting DD determination methods. Tests were performed on four chitosans of nominal DD in the range 70 - 95%. Three different methods of titration, two different methods of spectroscopy UV / Vis and infrared spectroscopy using various calculation approaches were used. The results are summarized and compared with values obtained by 1H NMR, considered as the reference method. Moreover, evaluation of the ease of performance and availability of reagents in the given methods was performed. On that basis, recommendations for selection of DD determination methods were formulated.
    Źródło:
    Progress on Chemistry and Application of Chitin and its Derivatives; 2012, 17; 5-20
    1896-5644
    Pojawia się w:
    Progress on Chemistry and Application of Chitin and its Derivatives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The influence of chitosan flake deacetylation degree on orthophosphate sorption efficiency from aqueous solutions
    Autorzy:
    Bugajska, Paula
    Filipkowska, Urszula
    Jóźwiak, Tomasz
    Kuczajowska-Zadrożna, Małgorzata
    Powiązania:
    https://bibliotekanauki.pl/articles/1034433.pdf
    Data publikacji:
    2018
    Wydawca:
    Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
    Tematy:
    chitosan
    deacetylation degree
    orthophosphate
    sorption
    Opis:
    The article presents the effectiveness of orthophosphate sorption from aqueous solutions depending on the deacetylation degree of chitosan flakes. The first stage of the research was to determine the pH value at which the sorption process was the most effective (from the pH range 2–11). In the second stage, research was carried out to determine the maximum sorption capacities of chitosan with deacetylation degrees of 75%, 85% and 90% in relation to PO43-. The highest effectiveness of orthophosphate removal on chitosan, regardless of its deacetylation degree, was obtained at pH 4. At pH 2 and 3, the chitosan flakes dissolved. This study showed that the sorption effectiveness of phosphorus compounds depends on the deacetylation degree of chitosan. Along with the increase in deacetylation degree, the sorption capacity of chitosan also increases in relation to orthophosphates. It is related to the higher number of amino groups in the structure of chitosan, which are responsible for the sorption of pollutants in the form of anions. The maximum sorption capacity of chitosan-DD = 75% in relation to biogen was 5.13 mg/g, chitosan-DD = 85% was 5.65 mg/g, and chitosan-DD = 90% was 5.91 mg/g. After 60 minutes, the desorption process had begun and was most likely caused by an increase in the pH of the solution. Due to chitosan's ability to neutralise the sample and the associated risk of desorption, the time of sorbent contact with sewage cannot be longer than 60 minutes.
    Źródło:
    Progress on Chemistry and Application of Chitin and its Derivatives; 2018, 23; 33-44
    1896-5644
    Pojawia się w:
    Progress on Chemistry and Application of Chitin and its Derivatives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The influence of the deacetylation degree of chitosan in the form of flakes on the effectiveness of nitrates v sorption from aqueous solutions
    Autorzy:
    Jóźwiak, Tomasz
    Filipkowska, Urszula
    Bugajska, Paula
    Kuczajowska-Zadrożna, Małgorzata
    Mielcarek, Artur
    Powiązania:
    https://bibliotekanauki.pl/articles/1034527.pdf
    Data publikacji:
    2018
    Wydawca:
    Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
    Tematy:
    chitosan
    deacetylation degree
    nitrate
    sorption
    Opis:
    The influence of the degree of deacetylation of chitosan from the range of DD = 75–90% on the effectiveness of sorption of nitrates from aqueous solutions was investigated. The scope of the research included: determining the effect of pH on the effectiveness of N-NO3 binding on chitosan sorbents and determining the sorption capacity of chitosan sorbents with different degrees of deacetylation after 5, 15, 30 and 60 minutes. The effectiveness of sorption of nitrates on chitosan sorbents increased in the series DD=75% < DD=85% < DD=90%. Regardless of the degree of deacetylation, the sorption effectiveness of nitrates on chitosan was the highest at pH 4. The amount of nitrate-related sorbents was the highest after 30 min of sorption. A process time which was too long resulted in desorption of nitrates. The maximum sorption capacity for chitosan with the degree of deacetylation DD = 75, 85 and 90% was 0.59 mg N-NO3/g, 0.60 mg N-NO3/g and 0.87 mg N-NO3/g, respectively.
    Źródło:
    Progress on Chemistry and Application of Chitin and its Derivatives; 2018, 23; 88-96
    1896-5644
    Pojawia się w:
    Progress on Chemistry and Application of Chitin and its Derivatives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Isolation and characterization of chitin from shells of the freshwater crab potamon algeriense
    Autorzy:
    Fadlaoui, Soufiane
    El Asri, Ouahid
    Mohammed, Lakrat
    Sihame, Addou
    Omari, Abdelouadoud
    Melhaoui, Mohammed
    Powiązania:
    https://bibliotekanauki.pl/articles/1034352.pdf
    Data publikacji:
    2019
    Wydawca:
    Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
    Tematy:
    Chitin
    Potamon algeriense
    chitosan
    deacetylation
    freshwater crab
    Opis:
    This work presents, for the first time, the extraction and characterization of chitin from the shell of the freshwater crab species Potamon algeriense with a standardized and revised chemical method. Chitin and chitosan were isolated following demineralization, deproteinization, decolouration (raw chitin), and deacetylation (chitosan). After boiling, drying, and grinding, 62.12% of the ground shell was obtained. A yield of 40.92% was obtained after demineralization of ground crab shell, while after the deproteinization process 8.74% was obtained. After decolourization, 8.27% of raw chitin was obtained, and the final amount of chitosan extracted from the crab shells was approximately 5.89%. We also characterized the isolated chitin by determining its physicochemical properties using X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA).
    Źródło:
    Progress on Chemistry and Application of Chitin and its Derivatives; 2019, 24; 23-35
    1896-5644
    Pojawia się w:
    Progress on Chemistry and Application of Chitin and its Derivatives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The influence of chitosan deacetylation degree on reactive black 5 sorption efficiency from aqueous solutions
    Autorzy:
    Jóźwiak, Tomasz
    Filipkowska, Urszula
    Szymczyk, Paula
    Kuczajowska-Zadrożna, Małgorzata
    Mielcarek, Artur
    Zyśk, Michał
    Powiązania:
    https://bibliotekanauki.pl/articles/1034679.pdf
    Data publikacji:
    2016
    Wydawca:
    Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
    Tematy:
    Reactive Black 5
    chitosan
    deacetylation degree
    sorption
    Opis:
    In the paper sorption capacity of chitosan having a deacetylation degree DD=75%, DD=85% and DD=90% relatively to the Reactive Black 5 were compared. Studies on the effectiveness of the dye sorption were carried out in a wide pH range – from 3 to 11. For each of the tested chitosan sorbents, sorption capacity has been determined. The results were described by isotherms Freundlich and Lagmuir isotherms, and a double Langmuir isotherm. Sorption of Reactive Black 5 most efficiently occurred at pH 4. At pH <4 chitosan sorbents underwent dissolution, regardless of the degree of deacetylation. The efficiency of dye sorption increased with the degree of deacetylation. The sorption capacity calculated after 12 h of the chitosan sorption with DD=75%, DD=85% and DD =90% was, relatively to the Reactive Black 5, respectively 433.03 mg/g and 464.52 mg/g and 532.14 mg/g. The impact of the deacetylation degree on pHZPC (zero point of charge) of the sorbent was also examined. Along with the increase in the deacetylation degree the value of chitosan pHZPC increased as well and at DD=75% DD=85% and DD=90%, pHZPC amounted respectively 7.6, 7.7 and 7.8.
    Źródło:
    Progress on Chemistry and Application of Chitin and its Derivatives; 2016, 21; 83-92
    1896-5644
    Pojawia się w:
    Progress on Chemistry and Application of Chitin and its Derivatives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The inhibition of human platelet aggregation by a low-molecular weight chitosan
    Autorzy:
    Drozd, Natalia N
    Logvinova, Yulia S.
    Shagdarova, Balzhima Ts.
    Il’ina, Alla V.
    Varlamov, Valery P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1034373.pdf
    Data publikacji:
    2018
    Wydawca:
    Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
    Tematy:
    chitosan
    deacetylation degree
    depolymerisation
    molecular weight
    platelet aggregation
    Opis:
    Chitosan derivatives were obtained by chemical (MW of 6 kDa, DD 99% - Ch6/99; MW13 kDa, DD 98% - Ch13/98) and enzymatic (MW of 5 kDa, DD 85% - Ch5/85; MW of 10 kDa, DD 85% - Ch10/85) depolymeri-sation of chitosan with a MW of 334 and 1000 kDa. Chitosan derivatives (almost identical MW pairs and different DD) possessed insignificant an-ticoagulant activity, did not promote human platelet aggregation and re-duced ADP or collagen-induced platelet aggregation. The studied sam-ples at a concentration of 2 mg/ml reduced the aggregation of platelets more than twice induced in 2x10-6M and 1x10-5M concentrations; at weak activation in 2x10-6M, the Ch10/85 sample was the most effective. The Ch6/99 and Ch13/98 samples were 20 times more effective at the inhibi-tion of collagen-induced platelet aggregation than the Ch10/85 sample. The latter can be explained by the greater value of positive charge (DD) and polydispersity (Mw/Mn) of chitosan samples obtained by chemical de-polymerisation
    Źródło:
    Progress on Chemistry and Application of Chitin and its Derivatives; 2018, 23; 55-65
    1896-5644
    Pojawia się w:
    Progress on Chemistry and Application of Chitin and its Derivatives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of chitosan molecular weight and degree of deacetylation on membrane physicochemical and separation properties in ethanol dehydration by the vapour permeation process
    Autorzy:
    Gnus, Małgorzata
    Powiązania:
    https://bibliotekanauki.pl/articles/1034007.pdf
    Data publikacji:
    2020
    Wydawca:
    Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
    Tematy:
    chitosan
    degree of deacetylation
    molecular weight
    separation properties
    vapour permeation
    Opis:
    Membranes were prepared using three chitosans with different molecular weights and degrees of deacetylation. The influence of chitosan features on membrane physicochemical properties, i.e. degree of swelling, contact angle and tensile strength, as well as membrane separation properties in ethanol dehydration by the vapour permeation process are discussed. The conducted experiments showed that an increase in the chitosan molecular weight led to an increase in the membrane surface contact angle concomitant with a decrease in the material selectivity coefficient. On the other hand, an increase in the chitosan degree of deacetylation caused a reduction in ethanol and improved the water permeate flux. There was greater selectivity in the test process for membranes prepared from chitosan with the lowest molecular weight.
    Źródło:
    Progress on Chemistry and Application of Chitin and its Derivatives; 2020, 25; 79-93
    1896-5644
    Pojawia się w:
    Progress on Chemistry and Application of Chitin and its Derivatives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Express analysis of chitosan and its derivatives by gel electrophoresis
    Autorzy:
    Konovalova, Mariya
    Shagdarova, Balzhima Ts.
    Zubov, Vitaliy
    Svirshchevskaya, Elena
    Powiązania:
    https://bibliotekanauki.pl/articles/1034210.pdf
    Data publikacji:
    2019
    Wydawca:
    Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
    Tematy:
    agarose gel electrophoresis
    chitosan
    chitosan derivatives
    degree of deacetylation
    molecular weight
    Opis:
    Chitosan is one of the most promising polymers for biomedical applications due to its unique properties, such as its biocompatibility, low toxicity, biodegradation, and the presence of reactive amino and hydroxyl groups. Analysis of physicochemical properties of chitosan and its derivatives is a time-consuming process and requires expensive equipment and large amounts of the sample. This paper proposes a method for express analysis of the molecular weight (MW), the degree of deacetylation (DD), the substitution degree (SD), and the charge of chitosan and its derivatives using agarose gel electrophoresis under acidic and neutral conditions with Coomassie staining. Positively charged chitosan samples required acidic Tris Acetate-EDTA (TAE) buffer to move in the gel. The electrophoretic mobility of chitosan depended on MW, DD, SD, and the chitosan charge. Based on the dependences obtained by the proposed method, the MW and DD of commercial chitosan samples were determined. Express analysis of chitosan and its derivatives in agarose gel can be used to monitor the reactions of chitosan modification and to analyse samples with unknown characteristics.
    Źródło:
    Progress on Chemistry and Application of Chitin and its Derivatives; 2019, 24; 84-95
    1896-5644
    Pojawia się w:
    Progress on Chemistry and Application of Chitin and its Derivatives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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