Thermal decomposition of rice husk: a comprehensive artificial intelligence predictive model

Journal of Thermal Analysis and Calorimetry - This study explored the predictive modelling of the pyrolysis of rice husk to determine the thermal degradation mechanism of rice husk. The study can...     

Investigation of thermal decomposition of solids

Practical aspects of the studies of stages of thermal dissociation of solids, of the kinetics of the stages, and of utilization of general regularities of the process for verification of kinetic studies are discussed.

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Zusammenfassung Die praktischen Aspekte der Untersuchungen über die Stufen der thermischen Dissoziation von Festkörpern und ihrer Kinetik weiterhin über die Anwendungsmöglichkeiten der RegelmÄssigkeiten der Verifikation der kinetischen Untersuchungen werden erörtert.

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Effect of thermal treatment of rice husk ash on the surface properties of hydrated lime-rice husk ash binders

Rice husk ash fired at different temperatures, 450, 700 and 1000°C, was mixed with different concentrations of lime (molar lime/silica ash ratio of 0.2, 0.5 and 1.0). Each dry mixture was first ground and hydrated in the suspension form (water/solid ratio = 10) for various time intervals within the range of 1 to 365 days. The surface properties of the unhydrated and hydrated samples were studied by means of nitrogen adsorption measurements. The results indicated that the surface areas and total pore volumes of unhydrated solid mixtures and hydrated lime-rice husk ash samples, prepared with lime/silica ash ratio of 1.0, decrease with increasing firing temperature of rice husk ash. The effect of varying the lime/silica ash ratio of the solid mixture on the surface area and pore structure was fully discussed. The results of surface area and pore volume measurements could also be related to the crystal structure of silica produced from rice husk ash.     

Effect of thermal treatment of rice husk ash on surface properties of hydrated portland cement-rice husk ash pastes

Portland cement was mixed with rice husk ash (RHA) fired at 450, 700 and 1000C, in ratios of 5, 15 and 25% of RHA by mass. Cement-RHA pastes were made by using a water/solid mixture ratio of 0.30 by mass and then cured for various hydration periods within the range 3 to 90 days. The surface properties of the hydrated samples were studied by means of the nitrogen adsorption technique. The results indicated that the hydrated cement-RHA samples made from rice husks fired at 450 and 700C gave higher values of surface area than that for the hydrated cement-RHA sample made from rice husks fired at 1000C. The surface area and pore volume results could be related to the pore structure of the silica produced in the RHA, as controlled by its predicted degree of crystallinity.     

Investigation of thermal decomposition of phosphonic acids

The paper compares building and decomposition pathways of two phosphonic acids, amino trimethylene phosphonic acid (ATMP) and 1-hydroxy ethylidene-1,1-diphosphonic acid (HEDP).The theoretical formation reactions were composed using elementary reactions and compared to reaction routes published in literature. As result, summary reaction pathways for both phosphonic acids are proposed which only vary in the number of reaction steps required. These reaction steps include carbonyl reactions, S_N2-reactions, and ionic reactions. The synthesis of ATMP proceeds in three reaction steps, whereas HEDP is formed in one reaction. The thermal decomposition of both phosphonic acids in solid state was examined by combination of thermogravimetry coupled with infrared spectroscopy as well as pyrolysis gas chromatography coupled with mass spectrometry. Decomposition mechanisms were deduced and compared to the theoretical findings resulting in the conclusion that the decomposition processes of ATMP and HEDP follows the formation mechanism.Thus, the suitability of theoretical considerations for the understanding of thermal decomposition processes is shown.     

Investigation of thermal decomposition kinetics of taurine

The non-isothermal thermal decomposition of taurine was investigated by means of thermogravimetric analysis (TG) and differential thermal analysis (DTA). The experimental data were treated using Flynn–Wall–Ozawa, Doyle, Kissinger, and ?atava–?esták methods, respectively. The results show that the non-isothermal thermal decomposition mechanism of taurine is classified as phase boundary reaction, and the mechanism function is the Mampel Power law with n = 1. The forms of both integral and differential for the mechanism function are $ G(\alpha ) = \alpha $ and $ f(\alpha ) = 1 $ , respectively. The activation energy and the pre-exponential factor are 167.88 kJ mol^?1 and 1.82 × 10¹³min^?1, respectively.     

Hydrogenolysis of rice husk lignins

The hydrogenolysis of the protolignin, the hydrolysis lignin, and the dioxane lignin of rice husks in the presence of demethylated lignin as catalyst has been studied. The breakdown of the lignins into low-molecular-mass compounds took place with yields comparable with those obtained by hydrogenolysis using other catalysts.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 611–613, July–August, 1995. Original article submitted November 21, 1994.     

Investigation of thermal decomposition of hydrated aluminium oxide

The composition of a hydrated aluminium oxide was determined and the course of its thermal decomposition was investigated. The stages of the dissociation were established and all the solid and gaseous intermediates of the decomposition were identified. A correlation was observed between the peak temperatures for boehmite and the particle size and degree of crystallinity.

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Zusammenfassung Die Zusammensetzung eines hydratisierten Aluminiumoxids wurde bestimmt und der Verlauf der thermischen Zersetzung dieses Oxids untersucht. Die Dissoziationsstufen wurden ermittelt und alle gasförmigen und festen Zwischenprodukte der Zersetzung identifiziert. Es wurde eine Korrelation zwischen den Peak-Temperaturen für Böhmit und der Partikelgrö\e und dem Kristallisationsgrad beobachtet.

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A Study on the thermal destruction of rice husk in air and nitrogen atmosphere

The methods of X-ray analysis, infrared spectroscopy, differential thermal analysis and scanning electron microscopy were used in this study. The objects of the experiments were rice husk obtained during processing of rice, variety Krasnodarski 424. The rice husk was burnt in air and in non-oxygen medium at several burning temperatures. The color of the oxidized product was stipulated by the burning temperature. The X-ray analysis showed that the amorphous SiO₂ present in the rice husk begins to crystallize in the form of α-cristobalite at 850°C. Using differential thermal analysis, the thermal destruction of rice husk was studied in air and nitrogen media and the initial and final temperatures of the process were determined. The silica distribution was examined by scanning electron microscopy and infrared spectroscopic techniques.     

Characterization and kinetics analysis of the thermal decomposition of the humic substance from hazelnut husk

A humic substance was obtained from hazelnut husk using an alkali extraction. The chemical and morphological structure of the humic matter was characterized via elemental analysis, Fourier transform infrared spectrometry (FTIR), nuclear magnetic resonance, Brunauer-Emmet-Teller (BET) analysis, scanning electron microscopy (SEM), and thermogravimetric-FTIR (TG-FTIR). In addition, thermal analysis measurements TG analysis-differential thermogravimetry/differential scanning calorimetry (TGA-DTG/DSC) were performed under dynamic air conditions to better determine the origin, physical and chemical structure, and decomposition process of the humic matter. The Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods were used to calculate the kinetic parameters of the high-temperature decomposition process. It was observed that the activation energy values were almost constant at certain conversion and temperature intervals. In addition, the structure of the humic substance at different temperatures was also investigated via FTIR analysis. It was found that the obtained humic substance had a very stable structure and decomposed at a high temperature. The stability of the humic matter can be a useful tool in the environmental quality research of soil.     

Investigation of thermal decomposition of anthranilates of alkali metals

The thermal properties of the anthranilates of the alkali metals Li, Na, K, Rb and Cs were studied. Thermal, chemical and X-ray analyses and infrared spectroscopy were used to determine the reactions of decomposition of these compounds. The thermal properties of the anthranilates of the alkali metals were compared with those of other metals.This work was done within Project 01.17: New Methods in Analytical Chemistry and Their Application in the National Economy.     

Hydrogenolysis of rice husk protolignin. II

It has been established that the partial hydrogenolysis of rice husk protolignin (RHP) takes place at a temperature of 180°C and an initial hydrogen pressure of 10 atm in an alkaline medium. Conditions have been selected under which the greatest yield of low-molecular-weight products (91% on the Komarov lignin) is obtained: hydrogenolysis in an alkaline medium in the presence of an anthraquinone (AQ) catalyst. The addition of AQ increases the yield of low-molecular-weight products by a factor of 1.8. Semiempirical formulas have been derived for incompletely hydrolyzed lignin residues. A study of the molecular-weight distribution of these lignins has shown that they are polydisperse. It has been established that in the process of hydrogenolysis AQ promotes the demethoxylation of structural units with syringyl nuclei.Institute of the Chemistry of Plant Substances of the Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 734–738, September–October, 1987.     

Investigation of thermal decomposition of anthranilates of alkaline earth metals

The thermal properties of calcium, strontium and barium anthranilates (general formula MA₂·n H₂O, whsre M='metal, and) were studied. Thermal, chemical and X-ray analysis, as well as infrared spectra, were used to determine the mechanism of decomposition for these compounds. Calcium anthranilate is decomposed in four stages; the final reaction product is calcium oxide. The other anthranilates are decomposed in three stages; the final reaction products are strontium carbonate and barium carbonate.

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Zusammenfassung Die thermischen Eigenschaften von Kalzium-, Strontium- und Bariumanthranilat (mit der allgemeinen Zusammensetzung MA₂·n H₂O, M=Metall, wurden untersucht.Die Zersetzungsmechanismen dieser Verbindungen wurden durch thermische, chemische- und Röntgenanalyse und mit Infrarotspektroskopie ermittelt. Kalziumanthranilat zersetzt sich in vier Stufen. Das Endprodukt ist Kalziumoxyd. Die anderen Anthranilate zersetzen sich in drei Stufen und geben Strontiumkarbonat und Bariumkarbonat als Endprodukt.

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, MA₂·nH₂O, =, , , . . . .

     

Crystallite growth of rice husk ash silica

The effect of temperature of firing and time of annealing on crystallite size of silica obtained by burning boiled rice husk was studied by the X-ray broadening technique. The results showed that nuclei of disordered cristobalite were present in ash silica, and crystallite growth was governed by two processes, namely nucleation and growth taking place simultaneously with a rate varying with the temperature of treatment. The nucleation process manifested itself in the low temperature range of 800–900°C, while growth was more pronounced in the temperature range 1000–1100°C, occurring with different activation energies of 81.3 and 52.4 cal mole^?1, respectively. Both processes occurred with the same intensity at 964°C. A growth process and crystal perfection followed with an activation energy of 36.8 cal mole^?1.     

Hydrogenolysis of rice husk lignin. IV

The hydrogenolysis of rice husk protolignin and of rice husk hydrolysis lignin in the presence of catalyst D-101, which is used in the hydrocracking of petroleum, has been studied. A substantial amount of products with syringyl structures has been found in the lignin cleavage products. The hydrogen content of the hydrol lignins isolated was considerably higher than that of the analogous lignins obtained on hydrogenolysis with the use of other catalysts. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan. Scientific-Research Chemical and Technical Institute of the Medical and Microbiological Industry, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 602–605, July–August, 1993.     

Hydrogenolysis of rice husk lignin. IV

The hydrogenolysis of rice husk protolignin and of rice husk hydrolysis lignin in the presence of catalyst D-101, which is used in the hydrocracking of petroleum, has been studied. A substantial amount of products with syringyl structures has been found in the lignin cleavage products. The hydrogen content of the hydrol lignins isolated was considerably higher than that of the analogous lignins obtained on hydrogenolysis with the use of other catalysts.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan. Scientific-Research Chemical and Technical Institute of the Medical and Microbiological Industry, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 602–605, July–August, 1993.     

Hydrogenolysis of rice husk protolignin. II

It has been established that the partial hydrogenolysis of rice husk protolignin (RHP) takes place at a temperature of 180°C and an initial hydrogen pressure of 10 atm in an alkaline medium. Conditions have been selected under which the greatest yield of low-molecular-weight products (91% on the Komarov lignin) is obtained: hydrogenolysis in an alkaline medium in the presence of an anthraquinone (AQ) catalyst. The addition of AQ increases the yield of low-molecular-weight products by a factor of 1.8. Semiempirical formulas have been derived for incompletely hydrolyzed lignin residues. A study of the molecular-weight distribution of these lignins has shown that they are polydisperse. It has been established that in the process of hydrogenolysis AQ promotes the demethoxylation of structural units with syringyl nuclei.