Analytical Techniques as a Tool to Understand the Reaction Mechanism

Jakab, Emma

doi:10.1016/b978-0-444-63289-0.00003-x

Cited by 19 publications

(21 citation statements)

References 117 publications

(79 reference statements)

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“…The unfavorable properties of raw biomass can be improved by torrefaction, which is a thermal treatment between 200 and 300 °C in an inert atmosphere for the partial conversion of biomass. [1][2][3] The torrefaction process can be classified into light, mild and severe torrefaction, where the temperatures are approximately 200-235 °C, 235-270 °C and 270-300 °C, respectively. During torrefaction the moisture content of biomass is removed and the acidic functional groups of the hemicellulose component are cleaved.…”

Section: Introductionmentioning

confidence: 99%

Comprehensive Compositional Study of Torrefied Wood and Herbaceous Materials by Chemical Analysis and Thermoanalytical Methods

et al. 2016

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Section: Introductionmentioning

confidence: 99%

Comprehensive Compositional Study of Torrefied Wood and Herbaceous Materials by Chemical Analysis and Thermoanalytical Methods

et al. 2016

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“…Among the products of thermal decomposition of CMS-Na was revealed the presence of selected compounds from the group the BTEX (apart from ethylbenzene), and the efficiency of their formation may be associated with the presence of sodium originating from the sodium carboxymethyl group substituted into glucopyranose ring -the higher the degree of substitution, caused the lower the content of toluene and xylenes in products of decomposition of modified starch [12]. However, in comparison to the binder of Kaltharz U404 the amount of aromatic hydrocarbons emitted from the binder CMS-Na, in particular benzene and toluene, it is much lower [11].…”

Section: Discussionmentioning

confidence: 99%

“…The content of toluene and xylene emitted during decomposition of the CMS-NaH sample was, respectively, 1.5 and approx. 3 times lower compared to the test results from the decomposition of CMS-NaL This may be associated with higher amount of sodium ion from sodium carboxymethyl groups substituted in CMS-NaH structure, which reduces the yield of formation of volatile substances of higher molecular weight [12]. Comparing these results with the effect of the emission tests BTEX from 1 g of the cured urea-furan resin Kaltharz U404, it was found that the emission of benzene from CMS-Na, depending on the DS was between 2.7 and 2.9 times lower, and the content of toluene even 7.5 -12.4 times lower.…”

Section: Emission Of Btex Compoundsmentioning

confidence: 99%

“…a various share of sodium carboxymethyl group substituted [6]. Studies on the influence of alkaline metal ions on the process of thermal decomposition of natural polymers showed that the presence of the sodium ion in the structure may affect the efficiency of the overlap of dehydration, decarboxylation and charring of the material process [12].…”

Section: The Gases Emission From Moulding Sandsmentioning

confidence: 99%

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Studies on the Gases Emission under High Temperature Condition from Moulding Sands Bonded by Modified Starch CMS-Na

Kaczmarska

Bobrowski

Żymankowska-Kumon

et al. 2017

Archives of Foundry Engineering

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Emission of gases under high temperature after pouring molten metal into moulds, which contain the organic binder or other additives (solvents or curing agent), may be an important factor influencing both on the quality of the produced castings, and on the state of environment. Therefore, a comprehensive study of the emitted gases would allow to determine restrictions on the use of the moulding sands in foundry technologies, eg. the probability of occurrence of casting defects, and identify the gaseous pollutants emitted to the environment. The aim of the research presented in this paper was to determine the amount of gases that are released at high temperatures from moulding sands bonded by biopolymer binder and the quantitative assessment of the emitted pollutants with particular emphasis on chemical compounds: benzene, toluene, ethylbenzene and xylenes (BTEX). The water-soluble modified potato starch as a sodium carboxymethyl starch with low (CMS-NaL) or high (CMS-NaH) degree of substitution was a binder in the tested moulding sands. A tests of gases emission level were conducted per the procedure developed at the Faculty of Foundry Engineering (AGH University of Science and Technology) involving gas chromatography method (GC). The obtained results of the determination of amount of BTEX compounds generated during the decomposition process of starch binders showed lower emission of aromatic hydrocarbons in comparison with binder based on resin Kaltharz U404 with the acidic curing agent commonly used in the foundries.

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“…Incomplete decomposition of CMS-Na is probably related to the presence of sodium atoms in the sample. Sodium plays a key role in thermal decomposition of modified starch by influence on the efficiency of the dehydration, decarboxylation, carbonizing the material and the volatile substances of higher molecular mass and carbon oxides formation [15,20]. Table 1 summarizes the characteristic thermal data selected from the TG-DTG-DSC curves for a sample of CMS-Na (Polvitex Ò Z).…”

Section: Tg-dtg-dsc Thermal Analysismentioning

confidence: 99%

Thermal decomposition of binder based on etherified starch to use in foundry industry

Kaczmarska

Grabowska

Grabowski

et al. 2017

J Therm Anal Calorim

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In this work, the main purpose was the determination of the thermal stability of the modified starch: sodium carboxymethyl starch (CMS-Na) used in foundry technology as organic binder for molding sand. The analysis of the course of decomposition of the starch material under controlled heating in the range of 20-500°C was based on the results of thermal analysis methods (TG, DTG, DSC) in combination with the results of spectroscopic technology (DRIFT). The use of various methods of thermal analysis and spectroscopic methods was possible to determine more entirely the mechanism of the binder decomposition process comprising reactions at the molecular level with regard to the conditions prevailing in the mold. The onset temperature of degradation of the binder and at the same time the temperature at which it begins to lose binding properties were determined. It was found that the mechanism of the binder is multistage process. The decomposition of the starch binder CMS-Na involves the gradual evaporation of the water bound at a temperature of 20-120°C and water constitutional starch in the range of 120-200°C, degradation of the binder in the temperature range 200-342°C by breaking the glycosidic bonds in the polymer chains with the formation of volatile compounds and finally detaching the side groups and partial combustion of the starch material within a temperature range 342-500°C.

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Analytical Techniques as a Tool to Understand the Reaction Mechanism

Cited by 19 publications

References 117 publications

Comprehensive Compositional Study of Torrefied Wood and Herbaceous Materials by Chemical Analysis and Thermoanalytical Methods

Comprehensive Compositional Study of Torrefied Wood and Herbaceous Materials by Chemical Analysis and Thermoanalytical Methods

Studies on the Gases Emission under High Temperature Condition from Moulding Sands Bonded by Modified Starch CMS-Na

Thermal decomposition of binder based on etherified starch to use in foundry industry

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