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Journal articles on the topic 'Lignite Oxidation'

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Author: Grafiati

Published: 10 December 2022

Last updated: 28 January 2023

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1

Gong, Gui Zhen, Ji Ming Chu, Xian Yong Wei, and Zhi Min Zong. "Oxidation of Huolinguole Lignite with NaOCl." Advanced Materials Research 734-737 (August 2013): 584–87. http://dx.doi.org/10.4028/www.scientific.net/amr.734-737.584.

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Huolinguole lignite (HL) was oxidized with aqueous NaOCl solution under mild conditions. The oxidation products were analyzed by GC/MS. In total 111 products from the HL oxidation were detected, most of which were benzene polycarboxylic acids and short-chain alkanoic acids, while a predominant chlorinated compounds such as trichloromethane, dichloroacetic acid, trichloroacetic acid were also identified. These results indicate that oxidation of coals with aqueous NaOCl solution may be a promising method for high value-added utilization of coals.

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2

Zhao, Huan, Jun Shuai Liu, Jiang Long Yu, Bin Bin Xin, and Xiu Zhen Geng. "A Review on Low-Temperature Oxidation of Lignite: Oxygen Transport, Effects of Drying and Measures for Restraining Coal Oxidation." Advanced Materials Research 1070-1072 (December 2014): 571–76. http://dx.doi.org/10.4028/www.scientific.net/amr.1070-1072.571.

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Drying of lignite alters the physical and chemical structure of coal, and influences the oxygen transport on the low temperature oxidation process. This paper provides a comprehensive overview on low-temperature oxidation of lignite and its dried products, including oxygen transport during the oxidation process, changes of physical structure and chemical compositions occurring at the drying process and its effects on the oxygen transport, and restraint of dried lignite oxidation.

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3

Ge, Wu Jie, Qun Shao, Hui Xu, and Ya Li Wan. "Low Temperature Oxidation Effects on Lignite Molecular Structure." Advanced Materials Research 550-553 (July 2012): 2797–800. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.2797.

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The paper studied the change of the coal characteristics based on the influence of lignite naturally oxidated in air. The original lignite and lignite naturally oxidated under different time were analyzed by the FTIR technology. The reason that metamorphism of lignite was vulnerable by oxygen was analyzed from the side of coal molecular structure. It indicates that lignite of a low rank coal easily oxidated is mainly because lignite has more active groups in coal molecular such as methyl, methylene, hydroxyl, aromatic ether, oxygen button and ether key. In lignite molecular, side chains of aromatic ring structure unit is firstly oxidized. The bridge button or side chains of coal molecular structure unit are easily oxidized at the same time with the structure of the bridge between units fracturing oxidation. Number of aromatic hydrocarbons remains stable after oxidation. General trend of cycloparafin hydrocarbon as well as aliphatic hydrocarbon are gradually reduced over the oxidized time.

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4

Yang, Fan, Yucui Hou, Shuhang Ren, and Weize Wu. "Selective oxidation of lignite to carboxyl chemicals." SCIENTIA SINICA Chimica 48, no. 6 (May 23, 2018): 574–89. http://dx.doi.org/10.1360/n032017-00219.

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5

Lalvani, Shashi, Milan Pata, and Robert W. Coughlin. "Electrochemical oxidation of lignite in basic media." Fuel 65, no. 1 (January 1986): 122–28. http://dx.doi.org/10.1016/0016-2361(86)90152-3.

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6

Li, Ya, Zhi-Min Zong, Yang-Yang Zhang, Xian-Yong Wei, and Yu Zhu. "Thermal treatment of Shengli lignite and subsequent oxidation." Journal of Analytical and Applied Pyrolysis 152 (November 2020): 104810. http://dx.doi.org/10.1016/j.jaap.2020.104810.

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7

Doskočil, Leoš, Laurent Grasset, Dana Válková, and Miloslav Pekař. "Hydrogen peroxide oxidation of humic acids and lignite." Fuel 134 (October 2014): 406–13. http://dx.doi.org/10.1016/j.fuel.2014.06.011.

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8

Uğuz, Özlem, Hanzade Haykiri-Açma, and Serdar Yaman. "Combustion kinetics of lignite preheated under oxygen-enriched conditions." Energy & Environment 31, no. 5 (October 21, 2019): 813–24. http://dx.doi.org/10.1177/0958305x19882393.

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This study bases on the testing of the solid-state kinetic models to determine the combustion kinetics of thermally pretreated Turkish lignite (Adiyaman–Golbasi) in O2-enriched environment. The lignite sample was first preheated in a horizontal tube furnace at temperatures of 200°C, 400°C and 600°C that correspond to torrefaction, partly devolatilization and partly ashing temperatures. Oxidative environments that have the O2 concentrations of 21, 30, 40 and 50 vol.%. were created during this treatment by changing the ratio of O2/N2 in the binary gas mixtures. The solid residues remaining after oxidation were then subjected to non-isothermal combustion conditions in a thermal analyzer up to 900°C under dry air atmosphere. The conversion degrees calculated from the thermogravimetric analysis were used to establish the kinetic parameters based on the Coats–Redfern method. It was concluded that the first-order reaction model fits well for both the combustion of volatiles and the burning of the char. It was also seen that the concentration of O2 in the pre-oxidation stage plays an important role as treatment temperature also increases. Moreover, it was also concluded that the activation energies for the char burning regions of the samples treated at 200°C and 400°C differ seriously.

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9

Huang, Zhi an, Ling hua Zhang, Jing jing Wang, Rui Yang, Ying hua Zhang, Hui Wang, Yu yan Chen, and Yu kun Gao. "Influence of initial oxidation and secondary oxidation on spontaneous combustion of lignite." International Journal of Microstructure and Materials Properties 14, no. 1 (2019): 60. http://dx.doi.org/10.1504/ijmmp.2019.098115.

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10

Gao, Yu kun, Yu yan Chen, Hui Wang, Ying hua Zhang, Jing jing Wang, Ling hua Zhang, Rui Yang, and Zhi an Huang. "Influence of initial oxidation and secondary oxidation on spontaneous combustion of lignite." International Journal of Microstructure and Materials Properties 14, no. 1 (2019): 60. http://dx.doi.org/10.1504/ijmmp.2019.10019613.

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11

Erol, Murat Ī., and Aral Olcay. "OXIDATION OF TUNC cedil;BĪLEK LIGNITE WITH CUPRIC HYDROXIDE." Fuel Science and Technology International 12, no. 3 (January 1994): 433–42. http://dx.doi.org/10.1080/08843759408916187.

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12

Xie, Heng Shen, Zhi Min Zong, Qing Wei, Pei Zhi Zhao, Jian Jun Zhao, Tong Liu, Xiang En Han, and Xian Yong Wei. "Photocatalytic Oxidation of Shenfu Bituminous Coal and Xilinhaote Lignite with H₂O₂ over TiO₂." Advanced Materials Research 233-235 (May 2011): 1684–89. http://dx.doi.org/10.4028/www.scientific.net/amr.233-235.1684.

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Shenfu bituminous coal (SFBC) and Xilinhaote lignite (XL) were subject to photo-catalytic oxidation with hydrogen peroxide over titanium dioxide. The reaction mixtures were extracted with acetone exhaustively. The extracts were analyzed with FTIR and GC/MS. The results show that coals be oxidized selectively and degraded partially. Compared with the bituminite coal, the oxidation effect of the lignite coal with active hydrogens is more obvious. The alkyl side chains of the macromolecules, particularly, chains of methyl, methylene and aromatic, are the most vulnerable in relation to other compounds in coals. Moreover, the increasing of straight-chain alkanes and the decreasing of condensed nucleus in SFBC and XL through oxidation suggest that the oxidation is an effective method of coal utilization with no difficultly, also be friendly towards the environment after treated as well as in the process of the treatment.

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13

Milicevic, Zoran, and Petar Petrovic. "Determination of the optimal conditions for obtaining potassium nitro-humate from lignite." Chemical Industry 58, no. 1 (2004): 19–25. http://dx.doi.org/10.2298/hemind0401019m.

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Raw lignite is enriched by humic acids by oxidation with nitric acid. The optimal conditions for producing potassium nitro-humate were defined by investigating the level of neutralization of the oxidized lignite, by means of potassium hydroxide. The increased content of humic acids and potassium in potassium nitro-humate makes it applicable as an organic-mineral fertilizer.

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14

Yang, Fan, Yucui Hou, Weize Wu, and Zhenyu Liu. "The generation of benzene carboxylic acids from lignite and the change in structural characteristics of the lignite during oxidation." Fuel 203 (September 2017): 214–21. http://dx.doi.org/10.1016/j.fuel.2017.04.096.

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15

Wang, Yu-Gao, Chun-Hui Bo, Jun Shen, Zhi-Lei Wang, Yan-Xia Niu, and Xian-Yong Wei. "Effect of pyrolysis on Zhaotong lignite oxidation with aqueous sodium hypochlorite." Carbon Resources Conversion 4 (2021): 1–9. http://dx.doi.org/10.1016/j.crcon.2021.01.002.

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16

Xin, Lin, Min Xu, Mingze Feng, Kaixuan Li, Zhigang Wang, Jun Xie, Limin Han, and Weitao Liu. "Compositional evolution of lignite during spontaneous combustion under low-temperature oxidation." Combustion Theory and Modelling 25, no. 4 (June 5, 2021): 695–717. http://dx.doi.org/10.1080/13647830.2021.1934549.

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17

Larionov, Kirill, Ilya Mishakov, Alexander Gromov, Andrey Zenkov, and Vladimir Glaktionov. "Research of lignite oxidation kinetic parameters modified by CuSO4and NaNO3initiation additives." MATEC Web of Conferences 110 (2017): 01048. http://dx.doi.org/10.1051/matecconf/201711001048.

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18

Jiang, Wei-Jia, Yu-Gao Wang, Ze-Shi Niu, and Jun Shen. "Production of benzenepolycarboxylic acids by oxidation of pre-pyrolyzed Shengli lignite." Energy Sources, Part A: Recovery, Utilization, and Environmental Effects 40, no. 11 (May 24, 2018): 1359–65. http://dx.doi.org/10.1080/15567036.2018.1476621.

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19

Wang, Wenhua, Yucui Hou, Weize Wu, Muge Niu, and Weina Liu. "Production of Benzene Polycarboxylic Acids from Lignite by Alkali-Oxygen Oxidation." Industrial & Engineering Chemistry Research 51, no. 46 (November 7, 2012): 14994–5003. http://dx.doi.org/10.1021/ie3021297.

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20

Meng, Fanrui, Arash Tahmasebi, Jianglong Yu, Huan Zhao, Yanna Han, John Lucas, and Terry Wall. "Low-Temperature Oxidation Characteristics of Lignite Chars from Low-Temperature Pyrolysis." Energy & Fuels 28, no. 9 (August 18, 2014): 5612–22. http://dx.doi.org/10.1021/ef501004t.

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21

Liu, Jing, Xian-Yong Wei, Yu-Gao Wang, Dong-Dong Zhang, Tie-Min Wang, Jing-Hui Lv, Juan Gui, Meng Qu, and Zhi-Min Zong. "Mild oxidation of Xiaolongtan lignite in aqueous hydrogen peroxide–acetic anhydride." Fuel 142 (February 2015): 268–73. http://dx.doi.org/10.1016/j.fuel.2014.11.027.

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22

Howaniec, Natalia. "Combined Effect of Pressure and Carbon Dioxide Activation on Porous Structure of Lignite Chars." Materials 12, no. 8 (April 23, 2019): 1326. http://dx.doi.org/10.3390/ma12081326.

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Lignite is an important natural resource with the application potential covering present and future energy systems, including conventional power plants and gasification systems. Lignite is also a valuable precursor for the production of porous materials of tailored properties for various environmental applications, including the removal of contaminants from gaseous or liquid media. Although the lignite-based activated carbons are commercially available, various approaches to produce carbon materials of desired properties are still being reported, covering temperature, partial oxidation and chemical activation effects on surface and structural properties of these materials. Limited data is, however, available on the effects of pressure as the activation parameter in shaping the porous structure of carbonaceous materials, in particularly lignite-derived. In the study presented the combined effect of carbon dioxide activation and pressure in the range of 1–3 MPa at the temperature of 800 °C on the development of porous structure of lignite chars was reported. The study was also focused on poor-quality resources valorization by using a relatively low calorific value, low volatiles and high ash content lignite as a carbon material precursor. The results showed that the application of pressure in carbon dioxide-activation process at 800 °C results in generation of chars of comparable or higher specific surface area than the carbon materials previously received with demineralization and carbon dioxide activation of lignite. They also proved that the combined pressure and carbon dioxide activation may be effectively applied in conversion of low quality lignite into valuable porous materials.

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23

Moskalenko, Tatiana, Valery Mikheev, and Elena Vorsina. "Intensification of humic acid extraction from lignites." E3S Web of Conferences 192 (2020): 02024. http://dx.doi.org/10.1051/e3sconf/202019202024.

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One of the methods of initial properties of solid fuels changing by their organic mass oxidation is considered in the paper. Creation of innovative ways of intensification of existing solid fuels processing and their adoption by industry has always been and remains an actual task. Thus the chemical process is the most important stage of raw materials processing into target products. Chemical exposure allows to optimize the technological mode, expanding the scope of control of technological process parameters and, to a certain extent, modify the properties of the resulting products. The article presents the results of experimental research of influence of preliminary oxidation on the lignite organic mass from Kharanorsk and Kangalas deposits by different chemical reagents to determine a degree of this process impact on the efficiency of their processing into humic substances. Inorganic and organic oxidizers of different concentrations were used as reagents. The greatest effect for increasing the humic acids yield was observed when using 6-10 % hydrogen peroxide for oxidation, and 10 % hydrochloric acid. The results of experiments on the coal preoxidation effect can be used as a basis for the development of a new method of lignites processing into humic substances.

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24

Marczak-Grzesik, Marta, Stanisław Budzyń, Barbara Tora, Szymon Szufa, Krzysztof Kogut, and Piotr Burmistrz. "Low-Cost Organic Adsorbents for Elemental Mercury Removal from Lignite Flue Gas." Energies 14, no. 8 (April 13, 2021): 2174. http://dx.doi.org/10.3390/en14082174.

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The research presented by the authors in this paper focused on understanding the behavior of mercury during coal combustion and flue gas purification operations. The goal was to determine the flue gas temperature on the mercury emissions limits for the combustion of lignites in the energy sector. The authors examined the process of sorption of mercury from flue gases using fine-grained organic materials. The main objectives of this study were to recommend a low-cost organic adsorbent such as coke dust (CD), corn straw char (CS-400), brominated corn straw char (CS-400-Br), rubber char (RC-600) or granulated rubber char (GRC-600) to efficiently substitute expensive dust-sized activated carbon. The study covered combustion of lignite from a Polish field. The experiment was conducted at temperatures reflecting conditions inside a flue gas purification installation. One of the tested sorbents—tire-derived rubber char that was obtained by pyrolysis—exhibited good potential for Hg0 into Hg2+ oxidation, resulting in enhanced mercury removal from the flue. The char characterization increased elevated bromine content (mercury oxidizing agent) in comparison to the other selected adsorbents. This paper presents the results of laboratory tests of mercury sorption from the flue gases at temperatures of 95, 125, 155 and 185 °C. The average mercury content in Polish lignite was 465 μg·kg−1. The concentration of mercury in flue gases emitted into the atmosphere was 17.8 µg·m−3. The study analyzed five low-cost sorbents with the average achieved efficiency of mercury removal from 18.3% to 96.1% for lignite combustion depending on the flue gas temperature.

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25

Wang, Yongyu, Fuding Mei, and Sheng Xue. "Comparative analysis of microstructure evolution and oxidation performance of acid-treated lignite." Fuel Processing Technology 215 (May 2021): 106750. http://dx.doi.org/10.1016/j.fuproc.2021.106750.

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26

Ban, Yan Peng, Yang Li, Yan Hua Tang, Jie Wang, Quan Sheng Liu, Ke Duan Zhi, Ya Jie Wu, and Yuan Fan. "Low-Temperature Oxidation Gas Products and Spontaneous Combustion Tendency of Shengli Lignite." Advanced Materials Research 953-954 (June 2014): 1210–14. http://dx.doi.org/10.4028/www.scientific.net/amr.953-954.1210.

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Oxygen adsorption and CO2produced of samples at different adsorption temperatures was investigated, Combined with thermal analysis method, the combustion properties of coal samples was determined. The results show that the oxygen adsorption capacity and CO2produced of the samples increase and later decrease with the enhanced of pyrolysis degree. In the process of low-temperature oxidation, coal molecular side chains break, then H2O, CO, CO2and so on are detected in turn; with the enhanced of pyrolysis degree, it reveals that combustion reaction activity decreased and spontaneous combustion tendency weakened.

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27

Liu, Fangchun, Shangjun Xing, and Zhenyu Du. "Nitric Acid Oxidation for Improvement of a Chinese Lignite as Soil Conditioner." Communications in Soil Science and Plant Analysis 42, no. 15 (August 15, 2011): 1782–90. http://dx.doi.org/10.1080/00103624.2011.587566.

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28

Wang, Wenhua, Yucui Hou, Weize Wu, Muge Niu, and Tong Wu. "High-Temperature Alkali-Oxygen Oxidation of Lignite to Produce Benzene Polycarboxylic Acids." Industrial & Engineering Chemistry Research 52, no. 2 (December 18, 2012): 680–85. http://dx.doi.org/10.1021/ie3029398.

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29

YILDIRIM, MEHMET. "Aerial Oxidation of Kangal/Sivas Lignite at 70°C and 90°C." Energy Sources 25, no. 10 (October 2003): 1023–32. http://dx.doi.org/10.1080/00908310390232479.

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30

Wang, Yongyu, Sheng Xue, Yibo Tang, Fuding Mei, Wei He, and Haifeng Pan. "Effect of NaOH Treatment on the Low-Temperature Oxidation Behavior of Lignite." Energy & Fuels 33, no. 9 (August 13, 2019): 9161–70. http://dx.doi.org/10.1021/acs.energyfuels.9b01516.

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31

Zhang, Huawei, Jitao Chen, Peng Liang, and Li Wang. "Mercury oxidation and adsorption characteristics of potassium permanganate modified lignite semi-coke." Journal of Environmental Sciences 24, no. 12 (December 2012): 2083–90. http://dx.doi.org/10.1016/s1001-0742(11)61047-4.

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32

Li, Ying-Ying, Guang-Yue Li, Hang Zhang, Jie-Ping Wang, An-Qi Li, and Ying-Hua Liang. "ReaxFF study on nitrogen-transfer mechanism in the oxidation process of lignite." Fuel 193 (April 2017): 331–42. http://dx.doi.org/10.1016/j.fuel.2016.12.081.

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33

Liu, Fang-Jing, Xian-Yong Wei, Ying Zhu, Juan Gui, Yu-Gao Wang, Xing Fan, Yun-Peng Zhao, Zhi-Min Zong, and Wei Zhao. "Investigation on structural features of Shengli lignite through oxidation under mild conditions." Fuel 109 (July 2013): 316–24. http://dx.doi.org/10.1016/j.fuel.2013.01.020.

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34

Azik, Murat, Yuda Yurum, and Alec F. Gaines. "Air oxidation of Turkish Beypazari lignite. 1. Change of structural characteristics in oxidation reactions of 150 .degree.C." Energy & Fuels 7, no. 3 (May 1993): 367–72. http://dx.doi.org/10.1021/ef00039a006.

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35

Jiang, Peng Wei, Zhi Jun Ma, and Yue Xin Han. "Experimental Study on Extracting Humic Acid from Lignite." Advanced Materials Research 158 (November 2010): 56–63. http://dx.doi.org/10.4028/www.scientific.net/amr.158.56.

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Humic acid has been extensively used in the fields like industry, agriculture, medicine, environment protection, etc. As a kind of potential organic resources that being developed and utilized, humic acid is drawing more and more attention from the world. China is abundant in coal resource; the lignite of China contains a lot of humic acid. Extraction humic acid from lignite creates favorable conditions for the development of coal industry and agriculture industry, has broad utilization prospect. By combining the method of nitric acid preoxidation and the method of alkali solution and acid eduction, the humic acid was extracted from the lignite. The orthogonal experimental method and FTIR were integrated in this study. The influences of nitrate concentrations, acid-coal proportion, oxidized temperature, oxidation time, extraction liquid concentration, liquid-solid ratio, extraction temperature and extraction time etc. on the process of extracting humic acid were examined. The results indicate the optimal processing condition can achieved when using sodium pyrophosphate and sodium hydroxide solution as the extraction agents, the rate of humic acid production can reach to 39.25%. And the total content of humic acid production can reach to 46.14%.

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36

Wang, Yugao, Xiaochen Liu, Zhilei Wang, Chuan Dong, Jun Shen, and Xing Fan. "Insight into Relationship between Thermal Dissolution of Low-Rank Coals and Their Subsequent Oxidative Depolymerization." Energies 15, no. 1 (December 21, 2021): 32. http://dx.doi.org/10.3390/en15010032.

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Oxidative depolymerization of low-rank coals is promising for obtaining benzene carboxylic acids (BCAs). However, it is hindered by the low yield of BCAs along with a large number of alphatic acids. Thermal dissolution could modify the physico-chemical structural features of low-rank coals, which is expected to improve the oxidation of LRCs. In this paper, lignite and subbituminous coal were firstly subjected to thermal dissolution with cyclohexane at 250 °C for 2 h. Then, the raw coal and the corresponding thermal insoluble portion (TIP) were oxidized by NaOCl under the same conditions. The residual yields of TIPs oxidation were both lower than those of raw coals oxidation, indicating that TIPs were more easily oxidized than the raw coals. The yield of BCAs obtained by TIPs oxidation was above 19% higher than that from the oxidation of raw coals. Meanwhile, the selectivity of BCAs was improved in the resulting oxidation products from TIPs compared with that from the raw coals. The relationship between BCAs generation and thermal dissolution of low rank coals was investigated by ultimate analysis, Fourier transform infrared spectroscopy, and nitrogen adsorption-desorption analysis. The results suggested that thermal dissolution could enrich aromatic portion in the remaining TIPs, resulting in an increasing of the yield and selectivity of BCAs. Simultaneously, thermal dissolution raised the specific surface area and expanded the looser space structure of TIPS, which were beneficial for the sufficient collision between aromatic structures and oxidant, facilitating the oxidative depolymerization of TIPs. This investigation would provide a novel route for promoting BCAs production by mild oxidative depolymerization of low-rank coals.

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37

Kantiranis, N., Α. Georgakopoulos, A. Fiiippidis, and A. Drakoulis. "MINERALOGY AND ORGANIC MATTER CONTENT OF BOTTOM ASH SAMPLES FROM AGIOS DIMITRIOS POWER PLANT, GREECE." Bulletin of the Geological Society of Greece 36, no. 1 (January 1, 2004): 320. http://dx.doi.org/10.12681/bgsg.16673.

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Four bottom ash samples from the Power Units of the Agios Dimitrios Power Plant were studied by the method of PXRD to determine their semi-quantitative mineralogical composition. Their organic matter content was calculated by a wet chemical process. Also, the loss on ignition was measured. The samples are constituted mainly of calcite, quartz and feldspars, while micas, clays, gehlenite and portlandite were determined in a few samples in smaller quantities. The amorphous material varied between 10-43 wt. %, while organic matter varied between 5-42 wt. %. Measurements of the loss on ignition overestimate the unburned lignite contents in the bottom ash samples. The management of bottom ashes with high contents of unburned lignite should differ to that of the fly ashes. The oxidation of the inorganic compounds of the unburned lignite may lead to environmental degradation of the landfill areas. Samples showing lower values of organic matter are suitable for a series of uses, such as: snow and ice control, as an aggregate in lightweight concrete masonry units,as a raw feed material for portland cement, as an aggregate in cold mix emulsified asphalt mixes, base or sub-base courses, or in shoulder construction. Systematic study of the unburned lignite of bottom ashes is needed for possible re-combustion.

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38

Zubrik, Anton, Marek Matik, Michal Lovás, Zuzana Danková, Mária Kaňuchová, Slavomír Hredzák, Jaroslav Briančin, and Vladimír Šepelák. "Mechanochemically Synthesised Coal-Based Magnetic Carbon Composites for Removing As(V) and Cd(II) from Aqueous Solutions." Nanomaterials 9, no. 1 (January 16, 2019): 100. http://dx.doi.org/10.3390/nano9010100.

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The continued decrease in water quality requires new advances in the treatment of wastewater, including the preparation of novel, effective, environmentally friendly, and affordable sorbents of toxic pollutants. We introduce a simple non-conventional mechanochemical synthesis of magnetically responsive materials. Magnetic lignite and magnetic char were prepared by high-energy ball co-milling from either raw Slovak lignite or coal-based char together with a ferrofluid. The products were characterised by X-ray diffraction, electron microscopy, 57Fe Mössbauer spectroscopy, X-ray photoelectron spectroscopy (XPS), volumetric magnetic susceptibility, and low-temperature nitrogen adsorption, and both magnetic carbons were comparatively tested as potential sorbents of As(V) oxyanions and Cd(II) cations in aqueous solutions. The magnetic char was an excellent sorbent of As(V) oxyanions (Qm = 19.9 mg/g at pH 3.9), whereas the magnetic lignite was less effective. The different sorption properties towards arsenic anions may have been due to different oxidation states of iron on the surfaces of the two magnetic composites (determined by XPS), although the overall state of iron monitored by Mössbauer spectroscopy was similar for both samples. Both magnetic composites were effective sorbents for removing Cd(II) cations (Qm (magnetic lignite) = 70.4 mg/g at pH 6.5; Qm (magnetic char) = 58.8 mg/g at pH 6.8).

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39

Shao, Qun, Lingpo Kong, Hui Xu, and Sen Li. "Effect of Oxidation at Low Temperature on Thermal Dynamics Activation Energy of Lignite." Asian Journal of Chemistry 25, no. 10 (2013): 5710–12. http://dx.doi.org/10.14233/ajchem.2013.oh69.

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40

Zhang, Hong-Xi, Zhen-Yu Liu, and Qing-Ya Liu. "Case Study of Quantification of Aromatic Ring Structures in Lignite Using Sequential Oxidation." Energy & Fuels 30, no. 3 (February 12, 2016): 2005–11. http://dx.doi.org/10.1021/acs.energyfuels.5b02617.

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41

Yürüm, Yuda, and Nurşen Altuntaş. "Air oxidation of Beypazari lignite at 50°C, 100°C and 150°C." Fuel 77, no. 15 (December 1998): 1809–14. http://dx.doi.org/10.1016/s0016-2361(98)00067-2.

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42

Grützmacher, Gesche, Roland Hindel, Wilfried Kantor, and Roland Wimmer. "Chemical investigations of aquifers affected by pyrite oxidation in the Bitterfeld lignite district." Waste Management 21, no. 2 (April 2001): 127–37. http://dx.doi.org/10.1016/s0956-053x(00)00062-3.

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43

Kučerík, Jiří, Jan Kovář, Miloslav Pekař, and Peter Šimon. "Evaluation of oxidation stability of lignite humic substances by DSC induction period measurement." Naturwissenschaften 92, no. 7 (May 19, 2005): 336–40. http://dx.doi.org/10.1007/s00114-005-0638-9.

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Bai, Zujin, Jun Deng, Caiping Wang, Yanni Zhang, Chi-Min Shu, and Seeram Ramakrishna. "Effect of anions in ionic liquids on microstructure and oxidation characteristics of lignite." Fuel 339 (May 2023): 127446. http://dx.doi.org/10.1016/j.fuel.2023.127446.

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Bobei, Vasile, and Daniela Ciolea. "Studies on Lignite Quality Depending on Storage Conditions." Mining Revue 28, no. 4 (December 1, 2022): 14–23. http://dx.doi.org/10.2478/minrv-2022-0026.

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Abstract A small increase in the relative humidity in the air in a coal deposit can cause a 1% increase in the moisture content of the deposit resulting in the probability of spontaneous ignition. By depositing the freshly extracted coal over the coal already in the deposit, there is a direct contact between the two surfaces that have different characteristics in terms of physical and chemical properties, so that the latter acts as a primer. The coal with a higher temperature gives up the excess temperature to the coal with a lower temperature, thus initiating the formation of self-heating nuclei followed by self-ignition ones. The phenomenon is easy to observe in the colder periods of the season and especially usually after rain, when the vapors resulting from the exchange of temperature between the two types of coal are released into the atmosphere. The common cause is the movement of water vapor through the deposit correlated with the adsorption on the coal granules. The heat of condensation of vapor at storage temperature is about 580 cal./gram of water. Condensing the amount of water required to increase the content from 3% of the weight of the coal to 4% leads to an increase in the temperature of the coal by more than 170C. This increase in temperature is sufficient to increase the oxidation rate by 5 times.

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Cholewiński, Maciej, and Wiesław Rybak. "Lab-scale evaluation of possible mercury speciation in flue gas and mercury emission from combustion of pulverised solid fuels." EPJ Web of Conferences 201 (2019): 06001. http://dx.doi.org/10.1051/epjconf/201920106001.

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In this work a new lab-scale method dedicated to the evaluation of both concentration and oxidation level of mercury in flue gases from pulverised fuel fired boiler was proposed. To detect the abovementioned parameters, 2 main steps need to be evaluated. Firstly, a calorimeter bomb is utilised - by a proper implementation of mass balance of mercury within substrates and products, the quantity of oxidised mercury in gaseous products can be evaluated. Then, to simulate solid fuel fired power unit and to calculate mercury concentrations in flue gases, one of the stoichiometric mathematical models of combustion process must be applied. Early validation of the method showed considerable differences between solid fuels in mercury oxidation efficiencies and concentrations in flue gasses. Four examined fuels (lignite, hard coal and 2 types of solid biomass) was investigated. Calculated mercury concentrations in raw flue gas (>700°C) varied between 4 and 75 µg/m3ref. The lowest quantity of oxidised forms ofHg in flue gases were identified in the case of investigated lignite (27% of total Hg), while significantly higher – for selected hard coal (72%) and one type of biomass (with high chlorine concentration; up to 98%).

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Fatima, Noureen, Asif Jamal, Zaixing Huang, Rabia Liaquat, Bashir Ahmad, Rizwan Haider, Muhammad Ishtiaq Ali, et al. "Extraction and Chemical Characterization of Humic Acid from Nitric Acid Treated Lignite and Bituminous Coal Samples." Sustainability 13, no. 16 (August 11, 2021): 8969. http://dx.doi.org/10.3390/su13168969.

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Currently, conversion of coal into alternative fuel and non-fuel valuable products is in demand and growing interest. In the present study, humic acid was extracted from two different ranks of coal, i.e., low rank and high rank (lignite and bituminous), through chemical pretreatment by nitric acid. Samples of lignite and bituminous coal were subjected to nitric acid oxidation followed by extraction using KOH and NaOH gravimetric techniques. The chemical pretreatment of both types of coal led to enhanced yields of humic acid from 21.15% to 57.8% for lignite low-rank coal and 11.6% to 49.6% bituminous high rank coal. The derived humic acid from native coal and nitric acid treated coal was analyzed using elemental analysis, E4/E6 ratio of absorbance at 465 nm and 665 nm using UV-Visible spectrophotometry and Fourier transformed infrared spectroscopy FTIR. The chemical characteristics of coal treated with nitric acid have shown increased molecular weight and improved aromaticity with more oxygen and nitrogen and lower C, H, and sulphur content. The E4/E6 ratio of nitric acid-treated low and high ranks of coal was high. The FTIR spectroscopic data of nitric acid-treated lignite coal indicates an intensive peak of carboxyl group at 2981.84 cm−1, while bituminous coal was shown in cooperation with the N-H group at 2923.04 cm−1. SEM was performed to detect the morphological changes that happen after producing humic acid from HNO3 treatment and native coal. The humic acid produced from HNO3 treated coal had shown clear morphological changes and some deformations on the surface. SEM-EDS detected the major elements, such as nitrogen, in treated humic acid that were absent in raw coal humic acid. Hence, the produced humic acid through HNO3 oxidation showed a more significant number of humic materials with improved efficiency as compared to native coal. This obtained humic acid can be made bioactive for agriculture purposes, i.e., for soil enrichment and improvement in growth conditions of plants and development of green energy solutions.

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Azik, Murat, Yuda Yurum, and Alec F. Gaines. "Air oxidation of Turkish Beypazari lignite. 2. Effect of demineralization on structural characteristics in oxidation reactions at 150 .degree.C." Energy & Fuels 8, no. 1 (January 1994): 188–93. http://dx.doi.org/10.1021/ef00043a030.

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Bożęcki, Piotr, Grzegorz Rzepa, and Tadeusz Ratajczak. "Results of Microbiological Research in the Polish Part of the Muskau Arch - The Largest Amd Environment in Poland - Final Report." Civil And Environmental Engineering Reports 12, no. 1 (June 26, 2014): 17–26. http://dx.doi.org/10.2478/ceer-2014-0002.

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Abstract This work presents the results of microbiological investigations carried out in the Polish part of the Muskau Arch. In this abandoned lignite mining area highly acidified Fe-rich waters have been formed as a result of sulphide oxidation. Microbiological tests have shown that all studied groups of microorganisms exhibit both time and spatial variability. The most common group of microorganisms are bacteria Galionella sp.

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Fan, Xing, and Fei Wang. "Molecular Distributions of Soluble Oxidation Products from Coals Characterized by Mass Spectrometers." International Journal of Analytical Chemistry 2018 (2018): 1–7. http://dx.doi.org/10.1155/2018/5174172.

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Oxidation of three coals with rank from lignite to anthracite in NaOCl aqueous solution was investigated in this study. The oxidation products were characterized by using gas chromatography/mass spectrometry and direct analysis in real-time mass spectrometry. The results showed that most of organic compounds in coals were converted into water-soluble species under mild conditions, even the anthracite. Benzene polycarboxylic acids (BPCAs) and chloro-substituted alkanoic acids (CSAAs) were major products from the reactions. The products from lower rank coals consist of considerable CSAAs and most products from high rank coals are BPCAs. As coal rank increases, the yield of BPCAs with more carboxylic groups increases.

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