Aug 22, 2019   6:41 a.m. Tichomír
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doc. Ing. Michal Jablonský, PhD.
Identification number: 4025
University e-mail: michal.jablonsky [at] stuba.sk
 
Docent CSc.,PhD. - Department of Wood, Pulp and Paper (IPM FCFT)

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Basic information

Basic information about a final thesis

Type of thesis: Diploma thesis
Thesis title:Characterization of the properties of precipitated lignins
Written by (author): Ing. Jakub Kočiš
Department: Department of Wood, Pulp and Paper (IPM FCFT)
Thesis supervisor: doc. Ing. Michal Jablonský, PhD.
Opponent:doc. Ing. Milan Vrška, PhD.
Final thesis progress:Final thesis was successfully defended.


Additional information

Additional information about the final thesis follows. Click on the language link to display the information in the desired language.

Language of final thesis:Slovak

Slovak        English

Title of the thesis:Characterization of the properties of precipitated lignins
Summary:Lignin from grasses of annual plants was isolated by various acids, i.e. sulfuric acid, hydrochloric acid, nitric acid, and acetic acid (5%). Precipitated with toa normal and fractional way. Sulfuric acid at evaluating the effect of the different concentrations (5%, 25%, 50%, 72%) precipitated lignin. Analysis of lignin was carried out by the methods of UV/Vis spectroscopy, elemental analysis, gel permeation chromatography, heat of combustion, nitrobenzene oxidation, thermogravimetric analysis and pyrolysis. The results refer that of all the acids is nitric acid (normal precipitated method) with the highest yield of precitiption39.32%(30,42% pure lignin) at pH 2. This acid also contained phenolic structures than 2.882 mmol/g (pH 5, normal precipitation). Fractional precipitation showed that most inorganic acids precipitated fraction at pH - 5, and the organic acetic acid has precipitated at pH - 6.3. Elemantárna analysis points to increase the nitrogen content (2.14%) and sulfur (1.87%) with nitric acid and sulfuric acid. Gel permeation chromatography confirmed that the fractional precipitation is first precipitated fraction of higher molecular weight, for normal precipitation were no substantial changes in size distribution of molecules. Most stable lignin oxidizing atmosphere thermogravimetric analysis (210-650 ° C) is precipitated lignin by acetic acid in the normal way at pH - 6.3 with a 34.37% loss. Under an inert atmosphere is stable lignin (210-500 ° C) precipitated with sulfuric acid at pH - 6 in the normal way with a minimum loss of 37.29%. For precipitation of lignin various concentrated sulfuric acid we can according to analyzes say that yield is dependent on the acid concentration.
Key words:lignin, precipitation , acid

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