Article
Geochemistry & Geophysics
Tiit Kaljuvee, Mai Uibu, Can Rustu Yoruk, Marve Einard, Andres Trikkel, Rein Kuusik, Olev Trass, Igor Stubna, Tomas Hulan, Valli Loide, Jekaterina Jefimova
Summary: The research focused on the thermooxidative decomposition of Estonian oil shale samples from different deposits and the utilization of oil shale ashes formed during combustion. The study found that the differences in thermal behavior of oil shale samples are due to variations in organic matter, chemical and mineralogical composition, and sample morphology. Additionally, grinding and water treatment of oil shale ashes improved SO2 binding efficiency, while post-granulation treatment conditions affected the strength and leachability of granulated oil shale ashes, enhancing their soil neutralizing ability.
Article
Chemistry, Analytical
Peng Ling, Jun Xu, Tao Liu, Xiaoxue An, Xin Wang, Mohamed E. Mostafa, Hengda Han, Kai Xu, Long Jiang, Yi Wang, Sheng Su, Song Hu, Jun Xiang
Summary: This study investigated the pyrolysis kinetics and pyrolytic products distribution of coal slime and compared it with raw coal. The results showed that the pyrolysis of coal slime consists of three reaction stages, with the decomposition of volatiles as the main stage. The presence of inorganic minerals significantly influenced the pyrolysis reaction, and the alkene content of pyrolysis products decreased while the contents of CO2 and aromatics increased in coal slime compared to raw coal. These findings provide theoretical and practical guidance for the efficient thermochemical conversion and utilization of coal slime.
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
(2022)
Article
Chemistry, Physical
Simeng Cheng, Shaowu Jiu, Hui Li
Summary: The analysis of gaseous products reveals the characteristics, mechanisms, and kinetic equations describing the dehydroxylation and decarburization in coal series kaolinite. The results show that the dehydroxylation of coal series kaolinite arises from the calcination of kaolinite and boehmite within the temperature range of 350-850 degrees C. Decarburization is a two-step reaction, occurring as a result of the combustion of carbon and the decomposition of a small amount of calcite.
Article
Engineering, Chemical
Tiit Kaljuvee, Igor Stubna, Tomas Hulan, Mai Uibu, Marve Einard, Rainer Traksmaa, Mart Viljus, Jekaterina Jefimova, Andres Trikkel
Summary: The thermal behavior of clay samples from Hungary and Estonia was studied using thermal and thermo-dilatometric analysis methods. The results showed that water and other compounds were released at different temperatures, and oxidation, dehydroxylation, and decomposition were the main mechanisms involved. The addition of new types of oil shale ashes and cement bypass dust affected the thermal behavior of the clays.
Article
Thermodynamics
Yuan Jiang, Peijie Zong, Bin Tian, Xue Ming, Fanfan Xu, Yuanyu Tian, Yingyun Qiao, Dawei Li, Qingshuo Song, Qiankun Yu
Summary: Studying the pyrolysis behavior of the saturate component in coal, which mainly consists of volatile substances, through the combined utilization of TG-FTIR and Py-GC/MS revealed a free radical reaction mechanism. The research provides a methodological model for exploring other group components and reveals specific details about the pyrolysis of coal.
Article
Environmental Sciences
Zhibin Chen, Zhiliang Chen, Jingyong Liu, Ping Zhuang, Fatih Evrendilek, Shengzheng Huang, Tao Chen, Wuming Xie, Yao He, Shuiyu Sun
Summary: This study investigated the co-combustion of aboveground and belowground biomass of Pfaffia glomerata with pulverized coal. The results showed that the mixtures of 30% aboveground biomass and 70% coal and 10% belowground biomass and 90% coal exhibited the strongest co-combustion synergy, reducing dependence on fossil fuels and stabilizing heavy metals in ash.
SCIENCE OF THE TOTAL ENVIRONMENT
(2023)
Article
Chemistry, Analytical
Yitao Liu, Zhiyuan Zhao, Ruiyu Chen, Xiaokang Xu
Summary: This study investigates the thermal decomposition behaviors of polymers infiltrated with combustible liquids, providing a theoretical basis and guidance for predicting fire development, selecting or designing fire detection systems, and designing ventilation and fire extinguishing systems.
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
(2023)
Article
Thermodynamics
Wenwen Kong, Boxiong Shen, Jiao Ma, Jia Kong, Shuo Feng, Zhuozhi Wang, Lifu Xiong
Summary: The pyrolysis characteristics of Spirulina platensis, Tetradesmus obliquus, and Chlorella vulgaris were investigated by various techniques. The elemental and biochemical composition of different microalgae influenced their pyrolysis behavior. The pyrolysis process of the three microalgae could be divided into several stages, and the major reaction occurred at a certain temperature range. Different products and activation energies were observed for each microalgae. The pyrolysis of Spirulina platensis produced more CO2 and compounds containing C=O bonds, while Tetradesmus obliquus and Chlorella vulgaris produced slightly higher levels of hydrocarbons.
Article
Chemistry, Physical
Zhonghua Du, Wu Li
Summary: In this study, the pyrolysis characteristics of tar-rich coal were investigated using TG-MS-FTIR. It was found that there were two stages of mass loss in the pyrolysis process and the gas release signal detected by mass spectrometry was consistent with the functional group information detected by FTIR. The main gaseous products included H-2, H2O, CO, CO2, and CH4.
Article
Engineering, Environmental
Jingjing Li, Binlin Dou, Hua Zhang, Hao Zhang, Haisheng Chen, Yujie Xu
Summary: The pyrolysis and combustion processes of camphor biomass waste were studied using DSC/TGA-DTG/GC-MS/FTIR, with non-isothermal kinetics investigated under different heating rates. The results indicated different phases of mass loss, accompanied by exothermic and/or endothermic reactions.Activation energies for main mass losses in the second phase were determined to be 39.98-56.25 and 109.26-135.84 kJ/mol, respectively.
JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING
(2021)
Article
Engineering, Environmental
Quan Chen, Fanfan Xu, Peijie Zong, Fanhao Song, Bo Wang, Yuanyu Tian, Fengchang Wu, Xiaoli Zhao, Yingyun Qiao
Summary: This study investigated the thermal decomposition process and product formation mechanisms of waste tires in the presence of calcium oxide. The results showed that calcium oxide could enhance the production of isoprene and D-limonene and had an impact on desulfurization process.
JOURNAL OF HAZARDOUS MATERIALS
(2022)
Article
Thermodynamics
Lichao Ge, Can Zhao, Simo Chen, Qian Li, Tianhong Zhou, Han Jiang, Xi Li, Yang Wang, Chang Xu
Summary: In the preparation process of coal-based activated carbon, the carbonization process plays a significant role in the release of volatiles and the formation of pore structure. This study analyzed the properties of two raw materials and investigated their pyrolysis carbonization characteristics using thermogravimetric and Fourier transform infrared spectroscopy. The results showed that the heating rate had a significant impact on the release of volatiles during the carbonization process.
Article
Environmental Sciences
Zeshui Cao, Qiang Xu, Haopeng Kang, Jian Shi, Xuyang Lu, Bin Chen, Liejin Guo
Summary: Biochar is a renewable, carbon-neutral energy source that can replace traditional fossil fuels for iron and steel production, reducing carbon emissions and pollution. This study used a thermogravimetric analyzer to investigate the reaction characteristics and kinetics of biomass pyrolysis gas, biochar, and iron ore powder. It was found that the biochar with a C/O ratio of 1 could completely reduce hematite. The reduction process involved four stages, including the transformation of hematite to metallic iron. The results also showed that biochar played a leading role in the reduction process at temperatures below 700 degrees C, while CO produced by biochar gasification played a leading role at higher temperatures.
SCIENCE OF THE TOTAL ENVIRONMENT
(2023)
Article
Engineering, Chemical
Tiit Kaljuvee, Kaia Tonsuaadu, Marve Einard, Valdek Mikli, Eliise-Koidula Kivimae, Toivo Kallaste, Andres Trikkel
Summary: In this study, the thermal behavior of Estonian graptolite-argillite samples was investigated, revealing the complex mechanism of their thermal decomposition. The samples were found to have high proportions of orthoclase and quartz, and lower proportions of muscovite, jarosite, and pyrite. The thermal decomposition of the samples occurred in multiple steps.
Article
Engineering, Environmental
Fahim Ullah, Guozhao Ji, Lei Zhang, Muhammad Irfan, Zegang Fu, Zakia Manzoor, Aimin Li
Summary: The COVID-19 pandemic has led to an increase in medical waste, and proper disposal is crucial to prevent disease transmission. Advanced analytical techniques were used to study the pyrolysis reactions and gas release behavior of medical waste. The results showed that different waste types have different temperature ranges and activation energies during pyrolysis. Pyrolysis of mixed waste releases various volatile components.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Thermodynamics
B. Kostova, V Petkova, Vl Kostov-Kytin, Y. Tzvetanova, G. Avdeev
Summary: This paper investigated the thermal properties and decomposition mechanism of natural thaumasite, revealing the formation of different solid phases during thermal decomposition. A chemical reaction scheme of thaumasite decomposition was proposed based on the experimental results, which is of fundamental importance for identifying thaumasite and practical applications in chemical archaeology, cement, and cement-based materials chemistry.
THERMOCHIMICA ACTA
(2021)
Article
Geochemistry & Geophysics
Tiit Kaljuvee, Mai Uibu, Can Rustu Yoruk, Marve Einard, Andres Trikkel, Rein Kuusik, Olev Trass, Igor Stubna, Tomas Hulan, Valli Loide, Jekaterina Jefimova
Summary: The research focused on the thermooxidative decomposition of Estonian oil shale samples from different deposits and the utilization of oil shale ashes formed during combustion. The study found that the differences in thermal behavior of oil shale samples are due to variations in organic matter, chemical and mineralogical composition, and sample morphology. Additionally, grinding and water treatment of oil shale ashes improved SO2 binding efficiency, while post-granulation treatment conditions affected the strength and leachability of granulated oil shale ashes, enhancing their soil neutralizing ability.
Article
Materials Science, Multidisciplinary
Bilyana Kostova, Vilma Petkova, Ventseslav Stoyanov, Zh Uzunov
Summary: This study focused on the changes in a natural mineral aggregate before and after high energy milling and thermal treatment, aiming to analyze the properties of the natural CaO-SiO2-P2O5 ceramic system. The activation effects were monitored through various analytical techniques, revealing alterations in chemical bond strength, formation of new phases, and increased reactivity leading to solid-phase crystallization. These results have potential applications in ceramic and cement materials research, among other areas.
MATERIALS TODAY COMMUNICATIONS
(2021)
Article
Thermodynamics
Sanoop Kumar Puthiya Veetil, Kaarel Rebane, Can Rustu Yoruk, Margus Lopp, Andres Trikkel, Michael Hitch
Summary: The study evaluated the development of a Ca-based CO2 capture sorbent from a limestone-rich mine waste via aqueous mineral carbonation. It was found that optimal dissolution and carbonation of calcium occurred at 2.5% pulp density, resulting in the production of pure calcite during the process. The promising CO2 uptake capacity of the developed sorbent suggests its potential for direct CO2 capture.
Article
Chemistry, Physical
Vilma Petkova, Ventseslav Stoyanov, Bilyana Kostova, Vladislav Kostov-Kytin, Alexander Kalinkin, Irina Zvereva, Yana Tzvetanova
Summary: This study focuses on the properties of cement composites, investigating hydration and decomposition mechanisms of different samples. The results have practical applications in architecture and construction, as well as potential uses in the study of archaeological artifacts like ancient mortar.
Article
Engineering, Chemical
Tiit Kaljuvee, Igor Stubna, Tomas Hulan, Mai Uibu, Marve Einard, Rainer Traksmaa, Mart Viljus, Jekaterina Jefimova, Andres Trikkel
Summary: The thermal behavior of clay samples from Hungary and Estonia was studied using thermal and thermo-dilatometric analysis methods. The results showed that water and other compounds were released at different temperatures, and oxidation, dehydroxylation, and decomposition were the main mechanisms involved. The addition of new types of oil shale ashes and cement bypass dust affected the thermal behavior of the clays.
Article
Chemistry, Multidisciplinary
Siim Link, Patrik Yrjas, Daniel Lindberg, Andres Trikkel
Summary: This study investigated the ash melting behavior of a blend of reed and wheat straw using various laboratory methods. The results showed that the melting started at 660-680 degrees C and the liquid mass fraction was 13.8% at this temperature, indicating the blend could become sticky. Intensive melting occurred in the temperature range of 800-980 degrees C, with rapid melting between 950 and 980 degrees C caused by the melting of SiO2 and K2MgSi5O12.
Article
Geosciences, Multidisciplinary
Ekaterina Serafimova, Vilma Petkova
Summary: The negative impact of natural inorganic building materials on people due to radionuclides can be significant. Effective prevention of public health issues and reduction of exposure can be achieved through the development of national-level strategies and various actions. The content of natural radionuclides in rock materials for construction purposes in Southern Bulgaria has been determined, with values close to the maximum permissible concentrations in some samples.
SPISANIE NA B LGARSKOTO GEOLOGICHESKO DRUZHESTOV-REVIEW OF THE BULGARIAN GEOLOGICAL SOCIETY
(2021)
Article
Energy & Fuels
Siim Link, Patrik Yrjas, Daniel Lindberg, Andres Trikkel, Valdek Mikli
Summary: This study investigated the melting behavior of fuel ash blends of reed, pine wood pellets and Douglas fir wood chips. Various methods were used to examine the morphology and composition of the ash samples at different temperatures. The results revealed different reactions and gas releases during the melting process.
Article
Geochemistry & Geophysics
Mustafa Cem Usta, Can Rustu Yoruk, Mai Uibu, Tiina Hain, Andre Gregor, Andres Trikkel
Summary: In this study, fly ash compacts were prepared by accelerated carbonation using locally available ashes in Estonia. Various variables such as compaction pressure, curing temperature, CO2 concentration, and pressure were investigated to understand their influence on CO2 uptake and strength development. The porous surface structure of the compacts changed after carbonation, with an increase in CO2 uptake levels observed under higher temperature, gas pressure, and CO2 concentration.
Article
Engineering, Chemical
Tiit Kaljuvee, Kaia Tonsuaadu, Marve Einard, Valdek Mikli, Eliise-Koidula Kivimae, Toivo Kallaste, Andres Trikkel
Summary: In this study, the thermal behavior of Estonian graptolite-argillite samples was investigated, revealing the complex mechanism of their thermal decomposition. The samples were found to have high proportions of orthoclase and quartz, and lower proportions of muscovite, jarosite, and pyrite. The thermal decomposition of the samples occurred in multiple steps.
Article
Environmental Sciences
Ekaterina Serafimova, Vilma Petkova, Ventseslav Stoyanov
Summary: Fuel supply and quality are key topics for future innovations and sustainable industrial development. This study focuses on analyzing the composition and heat capacity of treated fuel mixtures to promote their efficient use. Thermo-gravimetric differential analysis and scan calorimetry were conducted to assess the carbon, hydrogen, and sulfur content in coal, oil, and water fuel mixtures under various gas conditions. The results provide insights into the thermal stability and enthalpy of the samples, recommending the pretreatment applied in sample NV-RQ-1.
FRESENIUS ENVIRONMENTAL BULLETIN
(2022)
Article
Environmental Sciences
Ekaterina Serafimova, Vilma Petkova
Summary: Exposure to indoor air pollutants is a significant health issue, especially in developed economies where people spend a majority of their time indoors. The sources and levels of indoor air pollutants can vary greatly, making it challenging to model and estimate exposure. This study evaluates the negative impact of chemical contaminants on human health in schools and kindergartens in Southeast Bulgaria, with a focus on the age group of 5 to 15 years old. The findings highlight organic carbonyl compounds in building materials as the main source of pollutants.
FRESENIUS ENVIRONMENTAL BULLETIN
(2022)
Article
Chemistry, Inorganic & Nuclear
Kaia Tonsuaadu, Juha Kallas, Rein Kuusik, Gizem Hacialioglu-Erlenheim, Andres Trikkel
Summary: The study investigated the kinetics of apatite dissolution in diluted acids using thermodynamic calculations and experiments, and found that the dissolution rate can be tracked by changes in pH values.
Article
Energy & Fuels
Mai Uibu, Kadriann Tamm, Regiina Viires, Janek Reinik, Peeter Somelar, Lembi Raado, Tiina Hain, Rein Kuusik, Andres Trikkel
Summary: The modernisation of the oil shale industry in Estonia has led to significant changes in the composition and binding properties of the ash generated, impacting its environmental impact. Sample collection from various points along different combustion plants can aid in optimizing deposition conditions and guiding utilization-recycling processes for the changing oil shale characteristics. Mapping out the properties of oil shale ash is crucial in developing circular economy aspects of oil shale utilisation.
