Articoli di riviste: "Char"

1

Jeyakumar, Jeya Vikranth, Ankur Sarker, Luis Antonio Garcia e Mani Srivastava. "X-CHAR". Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies 7, n. 1 (27 marzo 2022): 1–28. http://dx.doi.org/10.1145/3580804.

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End-to-end deep learning models are increasingly applied to safety-critical human activity recognition (HAR) applications, e.g., healthcare monitoring and smart home control, to reduce developer burden and increase the performance and robustness of prediction models. However, integrating HAR models in safety-critical applications requires trust, and recent approaches have aimed to balance the performance of deep learning models with explainable decision-making for complex activity recognition. Prior works have exploited the compositionality of complex HAR (i.e., higher-level activities composed of lower-level activities) to form models with symbolic interfaces, such as concept-bottleneck architectures, that facilitate inherently interpretable models. However, feature engineering for symbolic concepts-as well as the relationship between the concepts-requires precise annotation of lower-level activities by domain experts, usually with fixed time windows, all of which induce a heavy and error-prone workload on the domain expert. In this paper, we introduce X-CHAR, an eXplainable Complex Human Activity Recognition model that doesn't require precise annotation of low-level activities, offers explanations in the form of human-understandable, high-level concepts, while maintaining the robust performance of end-to-end deep learning models for time series data. X-CHAR learns to model complex activity recognition in the form of a sequence of concepts. For each classification, X-CHAR outputs a sequence of concepts and a counterfactual example as the explanation. We show that the sequence information of the concepts can be modeled using Connectionist Temporal Classification (CTC) loss without having accurate start and end times of low-level annotations in the training dataset-significantly reducing developer burden. We evaluate our model on several complex activity datasets and demonstrate that our model offers explanations without compromising the prediction accuracy in comparison to baseline models. Finally, we conducted a mechanical Turk study to show that the explanations provided by our model are more understandable than the explanations from existing methods for complex activity recognition.

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Zuo, Hai-bin, Wei-wei Geng, Jian-liang Zhang e Guang-wei Wang. "Comparison of kinetic models for isothermal CO2 gasification of coal char-biomass char blended char". International Journal of Minerals, Metallurgy, and Materials 22, n. 4 (aprile 2015): 363–70. http://dx.doi.org/10.1007/s12613-015-1081-3.

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Liu, Junfeng, Xiuqing Gao, Xiaosu Wu, Ziyang Zhang e Xiaoran Zhang. "Sorption of cadmium by rice husk char, bamboo char, and coconut shell char in aqueous solutions". IOP Conference Series: Earth and Environmental Science 208 (20 dicembre 2018): 012109. http://dx.doi.org/10.1088/1755-1315/208/1/012109.

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4

Al azizi, Aulia, Erdawati Erdawati e Suhartono Suhartono. "Pengaruh Massa Bio-char Kayu Akasia (Acacia mangium) Dan Waktu Perendaman Bio-char Terhadap Adsorpsi Sebum Buatan". JRSKT - Jurnal Riset Sains dan Kimia Terapan 8, n. 1 (9 ottobre 2019): 37–44. http://dx.doi.org/10.21009/jrskt.081.05.

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Abstrak Pada penelitian ini dibuat adsorben berupa Bio-char dari kayu akasia (Acacia mangium). Bio-char kayu akasia dibuat dengan cara dipirolisis. Sebum buatan dibuat dengan cara mencampurkan bahan-bahan penyusunnya sesuai komposisi berdasarkan literatur, yaitu squalene, asam lemak, trigliserida, ester wax dan kolesterol yang kemudian dilarutkan dengan toluena. Bio-char kemudian direndam ke dalam larutan sebum dengan variasi massa dan waktu. Kandungan gugus fungsi dari Bio-char kayu akasia ditunjukan melalui hasil analisis FTIR bahwa terdapat gugus amina, karboksil dan hidroksil. Hasil penelitian menunjukan bahwa semakin besar massa Bio-char maka akan semakin optimum daya adsorpsinya dengan waktu optimum 20 menit. Adsorpsi sebum buatan oleh Bio-char kayu akasia mengikuti isoterm adsorpsi yang menunjukan bahwa Bio-char kayu akasia bertipe mesopori. Kata kunci: adsorpsi, bio-char, mesopori, sebum Abstract In this research, an adsorbent was made in the form of Bio-char from acacia wood (Acacia mangium). Acacia wood Bio-char is made by pyrolysis. Artificial sebum is made by mixing the ingredients according to the composition based on literature, namely squalene, fatty acids, triglycerides, ester waxes, and cholesterol which are then dissolved with toluene. Bio-char immersed in a sebum solution with variations in mass and time. The functional group content of acacia wood Bio-char is shown through the results of the FTIR analysis that there are amine, carboxyl, and hydroxyl groups. The results showed that the greater mass of Bio-char, it’s more optimum the adsorption power, with the optimum time of 20 minutes. Adsorption of sebum made by acacia wood Bio-char follows the adsorption isotherm which shows that the Bio-char of acacia wood is mesoporous Keywords: adsorption, Bio-char, mesoporous, sebum

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5

Smorto, L. "Rene Char: Threshold". Literary Imagination 7, n. 3 (1 gennaio 2005): 390. http://dx.doi.org/10.1093/litimag/7.3.390.

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6

Vorobiev, Nikita, Manfred Geier, Martin Schiemann e Viktor Scherer. "Experimentation for char combustion kinetics measurements: Bias from char preparation". Fuel Processing Technology 151 (ottobre 2016): 155–65. http://dx.doi.org/10.1016/j.fuproc.2016.05.005.

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7

NAKAGAWA, Hiroyuki, Takahiro SUZUKI, Kouichi MIURA, Tomohisa OHTA, Daisuke AYUKWA e Hiroshi NISHINO. "Production of Activated Char from Pyrolysis Char for Dioxin Removal". Proceedings of the Symposium on Environmental Engineering 2002.12 (2002): 227–29. http://dx.doi.org/10.1299/jsmeenv.2002.12.227.

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8

Campbell, Paul A., Reginald E. Mitchell e Liqiang Ma. "Characterization of coal char and biomass char reactivities to oxygen". Proceedings of the Combustion Institute 29, n. 1 (gennaio 2002): 519–26. http://dx.doi.org/10.1016/s1540-7489(02)80067-0.

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9

Komarova, Evgeniia, Stefan Guhl e Bernd Meyer. "Brown coal char CO2-gasification kinetics with respect to the char structure. Part I: Char structure development". Fuel 152 (luglio 2015): 38–47. http://dx.doi.org/10.1016/j.fuel.2015.01.107.

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10

Van de steene, L., J. P. Tagutchou, F. J. Escudero Sanz e S. Salvador. "Gasification of woodchip particles: Experimental and numerical study of char–H2O, char–CO2, and char–O2 reactions". Chemical Engineering Science 66, n. 20 (ottobre 2011): 4499–509. http://dx.doi.org/10.1016/j.ces.2011.05.045.

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11

Dai, Bing, Jia-Yong Qiu, Shan Ren, Bu-Xin Su, Xiang Ding, Dian-Chun Ju, Ni Bai e Hong-Ming Long. "Kinetic analysis of CO2 gasification of biochar and anthracite based on integral isoconversional nonlinear method". High Temperature Materials and Processes 39, n. 1 (2 ottobre 2020): 527–38. http://dx.doi.org/10.1515/htmp-2020-0086.

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AbstractThe nonisothermal thermogravimetric analysis was implemented for gasification of sawdust char (SD-char), wheat straw char (WS-char), rice husk char (RH-char), bamboo char (BB-char) and anthracite coal (AC) in the presence of CO2. The dependence of activation energy upon conversion for different biochars and AC was obtained by the integral isoconversional nonlinear (NL-INT) method which is a model-free method. Based on the activation energy values from the NL-INT method, a model-fitting method called random pore model (RPM) was used to estimate the kinetic parameters including the preexponential factor and pore structure parameter from the experimental data. The results are shown that the gasification reactivity of different samples from high to low can be sorted as that of WS-char, SD-char, BB-char, RH-char and AC. In the early stage of gasification, the activation energy values of biochars increase generally with an increase in the conversion degree, whereas the value of AC decreases. Thereafter, the activation energy values remain almost unchanged when the conversion is up to some extent. When the conversion degree varies between about 0.3 and 0.9, these carbon materials can be sorted in the order of average activation energy from low to high as WS-char, SD-char, AC, RH-char and BB-char, respectively, 134.3, 143.8, 168.5, 184.8 and 193.0 kJ/mol. It is shown that a complex multistep mechanism occurs in the initial stage of gasification, while a single-step gasification mechanism exists in the rest of the gasification process. The RPM is suitable for describing the gasification of biomass chars and AC except the initial gasification. Additionally, it is found that the kinetic compensation effect (KCE) still exists in the gasification reactions of biochars and AC. However, the AC deviates markedly from the KCE curve. This may be caused by the similarity of carbonaceous structure of biochars and the difference in reactivity between biochars and AC.

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12

Yuan, Hui Feng, De Min He, Jun Guan e Qiu Min Zhang. "Simulation and Study on Texaco Gasification of Semi-Cokes Prepared by DG Coal Pyrolysis Process". Advanced Materials Research 557-559 (luglio 2012): 2189–96. http://dx.doi.org/10.4028/www.scientific.net/amr.557-559.2189.

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Simulation and study on Texaco gasification of semi-cokes prepared by DG coal pyrolysis process has been carried out by using Aspen Plus. The possibility that pyrolytic semi-cokes is used as the raw materials is discussed. Sensitivity study runs are performed to analyze the effects of oxygen-to-char mass ratio, mass percentage of char in char water slurry and gasification pressure on the gasification process. Simulations indicate that molar percent content of effective components (CO+H2) reaches as high as 67.94% under operational conditions which oxygen-to-char mass ratio is 0.75; char water slurry concentration is 62.5% and gasification pressure is 4.0MPa. So semi-cokes made by DG coal pyrolysis process is the excellent raw materials for gasification. Sensitivity analysis show that oxygen-to-char mass ratio and mass percentage of char in char water slurry are the main factors that affect the gasification process; gasification pressure has little effect on the results of char gasification.

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13

Chen, Yen-Hau, Max Schmid, Chia-Chi Chang, Ching-Yuan Chang e Günter Scheffknecht. "Lab-Scale Investigation of Palm Shell Char as Tar Reforming Catalyst". Catalysts 10, n. 5 (27 aprile 2020): 476. http://dx.doi.org/10.3390/catal10050476.

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This research investigated the application of palm shell char as a catalyst for the catalytic steam reforming of tar after the sorption enhanced gasification (SEG) process. The catalytic activities of palm shell char and metal-supported palm shell char were tested in a simulated SEG derived syngas with tar model compounds (i.e., toluene and naphthalene) at a concentration of 10 g m−3 NTP. The results indicated that palm shell char had an experimentally excellent catalytic activity for tar reforming with toluene and naphthalene conversions of 0.8 in a short residence time of 0.17 s at 900 °C. A theoretical residence time to reach the complete naphthalene conversion was 1.2 s at 900 °C for palm shell char, demonstrating a promising activity similar to wood char and straw char, but better than CaO. It was also found that potassium and iron-loaded palm shell chars exhibited much better catalytic activity than palm shell char, while the parallel reaction of gasification of K-loaded palm shell char influenced the conversion with its drastic mass loss. Moreover, contrary to CaO, palm shell char presented relatively low selectivity to benzene, and its spontaneous gasification generated extra syngas. In summary, the present study demonstrated that the low-cost material, palm shell char, can successfully be used as the tar-reforming catalyst after SEG process.

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Basu, Prabir. "A Review of Combustion of Single Coal Particles in Fluidized Beds". Transactions of the Canadian Society for Mechanical Engineering 9, n. 3 (settembre 1985): 142–50. http://dx.doi.org/10.1139/tcsme-1985-0021.

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The state of the art of the theory of the process of combustion of single coal particles in fluidized beds is reviewed. The process of combustion of coal is divided into two stages: devolatilisation, and burning of the char. The devolatilisation and the subsequent combustion of the volatile matter takes an order of magnitude less time than that for burning of the char. Therefore, the burning of char dominates the characteristics and performance of the combustor. Generally, the combustion of char is found to be controlled by the mass transfer to and reaction on the external surface if the area of pores in the char is less than 0.3 × 106m2/m3. Existing information suggests that in a fluidized bed oxygen diffuses to the carbon surface and it enters into heterogeneous reaction with carbon producing mainly CO. The carbon monoxide burns to CO2 in a diffusion flame surrounding the char particle. The surface temperature of the char, which is always higher than the bed temperature, is found to increase with decreasing size of the char, but it may start decreasing again if the site of CO oxidation moves away from the char surface for very small char particles. The mass transfer rate to the char particles may be calculated by considering the radial variation of local voidages, but this effect is significant only in limited cases.

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Li, Rui, Zhenqi Jing, Jingjing Ma, Long Qin, Kai Yan e Chang Wen. "The Influence of Pore Distribution of Coal Char in the Char Fragmentation and Included Minerals Partitioning: A Percolation Modeling". Atmosphere 13, n. 4 (15 aprile 2022): 628. http://dx.doi.org/10.3390/atmos13040628.

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The processes of char fragmentation, including mineral partitioning and particulate matter (PM) formation during dense and porous char combustion, were observed by a site percolation model. This model simulated the diffusion-controlled regime of char combustion, and the size distributions of included minerals in typical bituminous coal were determined by the computer-controlled scanning electron microscope (CCSEM), and the data were put into the char matrix randomly. The model presents the influence of initial pore distribution on char oxidation and fragmentation, the impact of the char conversion process on the extent of fragmentation, the change of ash distributions with the char conversion, and the particulate matters (PM) size distribution, which is derived from the consequence of the competition between char fragmentation and included minerals partitioning and coalescence. The results indicate that with increasing initial char porosity (φ), the number of large size pores increases but the number of pores decreases, which leads to open pores increasing, close pores decreasing, and the surface reaction area increasing. While φ ≥ 0.4, char fragmentation obviously occurs during the stage in which the rates of char conversion are 0.4–0.6, and it looks as though the maximum value of fragmentation will transfer to an earlier conversion stage if it has a larger φ. The enhanced φ shows a positive effect on the increase in the number and concentration of PM < 10 μm (nominally aerodynamic diameter), this is attributed to char fragments more drastically, and the probability of mineral coalescence reduces a lot.

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Wang, Alan L. T., e John F. Stubington. "Char Attrition from Australian Black Coals in Pressurized Fluidized Bed Combustion". Journal of Energy Resources Technology 125, n. 2 (1 giugno 2003): 113–18. http://dx.doi.org/10.1115/1.1524330.

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Char attrition is the main mechanism for the fine char generation in PFBC. The char attrition rates were significantly different for each of the two coal chars tested. Specific char attrition rate increased with the surface porosity of burning char particles. A coal with higher ratio of telocollinite/inertinite contents formed chars in PFBC with larger pores or higher porosity during devolatilization, which resulted in a higher specific attrition rate.

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Li, Nan, Yali Wang, Suping Cui e Xiaodong Jin. "Experimental and Kinetic Investigation on NO Reduction by Rice Husk Char and Catalytically with CO". Applied Sciences 10, n. 19 (25 settembre 2020): 6715. http://dx.doi.org/10.3390/app10196715.

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Biomass char is accepted as an environmentally friendly energy resource, and is promising for NO removal in industrial furnaces. NO reduction with biomass char (rice husk) was investigated in a fixed-bed quartz reactor. The influence of CO concentration, reaction temperature, initial NO concentration, and char loading on the NO reduction were evaluated. The results showed that the overall NO reduction reaction was dominated by the direct reaction of NO with char without CO. Increasing CO concentration resulted in an enhanced catalytic reaction between NO and CO over the char surface and a decreased carbon consumption of char. With decreasing temperature, the influence of CO concentration on NO reduction was strengthened. Over the test temperature range, char provided a surface to catalyze the NO–CO reaction at excess CO/NO ratio. Increasing the initial NO concentration led to an increasingly significant influence on NO reduction with the enhanced CO/NO ratio. With increased char loading, the enhancement of NO reduction became unobservable for excess CO/NO ratio. Reaction orders of NO and activation energy for NO reduction by char were 0.71 and 60.21 kJ·mol−1, respectively, against 0.82 and 34.60 kJ·mol−1, respectively, for NO reduction by CO, catalyzed by char.

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Abu El-Rub, Ziad, Eddy Bramer, Samer Al-Gharabli e Gerrit Brem. "Impact of Char Properties and Reaction Parameters on Naphthalene Conversion in a Macro-TGA Fixed Char Bed Reactor". Catalysts 9, n. 4 (28 marzo 2019): 307. http://dx.doi.org/10.3390/catal9040307.

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Catalytic tar removal is one of the main challenges restricting the successful commercialization of biomass gasification. Hot gas cleaning using a heterogeneous catalyst is one of the methods used to remove tar. In order to economically remove tar, an efficient low-cost catalyst should be applied. Biomass char has the potential to be such a catalyst. In this work, the reactor parameters that affect the conversion of a model tar component “naphthalene” were investigated employing an in situ thermogravimetric analysis of a fixed bed of biomass char. The following reactor and catalyst parameters were investigated: bed temperature (750 to 900 °C), gas residence time in the char bed (0.4 to 2.4 s), char particle size (500 to 1700 μm), feed naphthalene concentration, feed gas composition (CO, CO2, H2O, H2, CH4, naphthalene, and N2), char properties, and char precursor. It was found that the biomass char has a high activity for naphthalene conversion. However, the catalytic performance of the biomass char was affected by the gasification reactions that consumed its carbon, and the coke deposition that reduced its activity. Furthermore, high ash and iron contents enhanced char activity. The results of this work will be used in the design of a process that uses biomass char as an auto-generated catalyst in the gasification process.

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BERGROTH, NICI, MARKUS ENGBLOM, CHRISTIAN MUELLER e MIKKO HUPA. "CFD-Based Modeling of Kraft Char Beds • Part 1: Char Bed Burning Model". February 2010 9, n. 2 (1 marzo 2010): 6–13. http://dx.doi.org/10.32964/tj9.2.6.

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Understanding the physical and chemical phenomena governing char bed burning is important for stable and efficient operation of the recovery boiler. Stand-alone char bed models have been developed and evaluated to increase knowledge of the complex char bed conversion processes. Available computational fluid dynamics (CFD)-based recovery furnace models previously have been applied to evaluate lower and upper furnace processes rather than to investigate the behavior of the char bed. In this first of two papers, a stand-alone char bed model for predicting the chemical processes of char bed burning was modified and implemented into a CFD-based furnace model. The char bed model, which is fully coupled with the gas phase and a simplified black liquor droplet model, solves equations describing the mass and energy balance on the surface of the char bed and includes carbon conversion via direct oxidation, gasification reactions, and sulfate reduction. The model was tested by simulating a 3150 tons dry solids/day recovery boiler. Simulations for two different primary air distributions and using two sulfate reduction degrees in droplets arriving to the bed were performed to evaluate the char bed model. The effects on bed conversion processes were clearly revealed by the new char bed model. The model gives a reasonable description of the chemical processes occurring on the char bed in steady state. In the second part of this work, the model is applied to study the effects of droplet size and bed shape.

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Ponomarenko, E. V., e D. W. Anderson. "Importance of charred organic matter in Black Chernozem soils of Saskatchewan". Canadian Journal of Soil Science 81, n. 3 (1 agosto 2001): 285–97. http://dx.doi.org/10.4141/s00-075.

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A combination of both conventional and novel techniques, such as micromorphology, scanning electron microscopy, and high energy ultraviolet photo-oxidation, have been applied to estimate the proportion of charred organic C in Black Chernozem soils in Saskatchewan. Char was represented by products of incomplete combustion of both arboreal and herbaceous vegetation. Char was found in all particle size fractions of A horizons of Black soils. Char was represented by a variety of forms, from fresh and angular, to rounded and clay-coated particles in the silt fraction. It is likely that the surface area and ability to adsorb clay vary with the size and nature of char particles. Sand-sized char includes particles with various surface properties and adsorptive ability. Generally, younger and lighter char with hydrophobic properties appears to be in the clay-sized fractions, whereas the silt contains heavier char particles coated with clay or containing clay in pores. Ultrasound, used to disperse soils, may fracture larger particles to finer sizes. The proportion of organic C in soils and fractions that is resistant to UV-oxidation was as high as 60%, which, based on published guidelines, indicates a very substantial char component in Black soils. CPMAS 13C NMR spectra indicate a strong aromatic peak at 130 ppm, also consistent with the presence of char. Results indicate that char particles as fine as silt size are present in significant amounts in Black soils, suggesting that char is an important component, and indicating the need for a new concept of humus formation and storage in Black soils. Key words: Char, carbon flows, carbon pool, UV-oxidation, fire, soil organic matter

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Moon, Jaron V., Zahra Karimi, Alex Prlina, Chanel Van Ginkel, Eric Eddings e Roseanne Warren. "Flash Pyrolyzed Coal Char for Sodium Ion Battery Anodes". ECS Meeting Abstracts MA2023-01, n. 5 (28 agosto 2023): 943. http://dx.doi.org/10.1149/ma2023-015943mtgabs.

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Present day lithium ion batteries face challenges regarding the sustainability, cost, and natural resource availability of their components. Sodium has been shown to be a complementary energy storage material, providing usable volumetric energy density. In designing sodium ion batteries (SIBs), hard carbon is used at the anode in place of graphite, due to the necessary micro domain structure needed to store sodium ions. Coal char is a low cost material and viable source of hard carbon. The use of coal char in SIBs also provides a high value, secondary use pathway for the abundant char component of coal. In this work, flash pyrolyzation is explored as a novel approach for coal char synthesis for SIB anodes using a Utah local bituminous coal. During flash pyrolyzation, char is heated in a drop-tube furnace at 1000 oC/s vs. the traditional slow pyrolyzation approach where char is heated at 20 oC/min. Flash pyrolyzed (FP) char has a surface structure that is vastly different in comparison to the slow pyrolyzed (SP) char (Figure 1.), larger d-spacing (FP d-spacing = 0.379 nm, SP d-spacing = 0.364 nm) and a smaller closed micropore diameter (FP micropore = 1.52 nm, SP micropore = 1.91 nm), as concluded from X-ray diffraction (XRD) and small angle X-ray scattering (SAXS) analysis, respectively. The SIB performance of FP char vs. SP char is tested and compared in ether-based and ester-based electrolytes. FP char performs better as a SIB anode than SP char in both electrolytes. Additionally, both char anodes achieve higher reversible capacity and better initial coulombic efficiencies (ICE) in an ether-based vs. ester-based electrolyte. When FP char is combined with an ether-based electrolyte, a 10th cycle reversible capacity of 109.4 mAh/g is achieved, whereas a SP char with an ester-based electrolyte cell has a 10th cycle reversible capacity of 72.5 mAh/g, when both cells are cycled at 50 mA/g (sodium metal half-cells). FP ether cells also perform with an initial coulombic efficiency (ICE) of 64%, but SP ester cells only show an ICE value of 52%. The enhanced electrochemical performance of the FP cells is attributed to differences in surface/bulk structure due to the high heating rate. The improvement in char anode performance in ether-based cells is likely due to the formation of a thinner solid-electrolyte interphase and/or improved sodiation due to an ether-based electrolyte. Figure 1

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Mao, Haiyan, Dingguo Zhou, Zaher Hashisho, Sunguo Wang, Heng Chen, Haiyan (Helena) Wang e Masoud Jahandar Lashaki. "Microporous activated carbon from pinewood and wheat straw by microwave-assisted KOH treatment for the adsorption of toluene and acetone vapors". RSC Advances 5, n. 45 (2015): 36051–58. http://dx.doi.org/10.1039/c5ra01320h.

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Yu, Shilin, Zhaomin Lv, Yang Miao, Xiaohe Xiong e Houzhang Tan. "Experimental study on no heterogeneous reduction by char". Thermal Science 26, n. 5 Part B (2022): 4147–56. http://dx.doi.org/10.2298/tsci2205147y.

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The NO heterogeneous reduction by char is one of the most prominent options to control NOx emissions from coal-fired power plants. Experiments on the char-NO heterogeneous reaction were carried out in an electrically heated fixed-bed reac-tor to investigate the effect of temperature, type of char, pretreatment method, additives and reaction atmosphere on the NO reduction capacity of char. The re-sults showed that temperature plays a crucial role in the NO reduction by differ-ent char. The kinetic analysis showed that char-NO heterogeneous reaction is controlled by chemical kinetic below Tt and by diffusion kinetic above Tt. The value of transition temperature Tt depends on the types of char and ranges from 600?C to 800?C. The synergistic effect of specific surface area, mineral abun-dance and reactivity combine to result in the reduction efficiencies of different char. Oxygen has a promoting effect on the char-NO heterogeneous reaction, and the oxygen content of the promoting peak moves to low oxygen content with in-creasing temperature. At 1050 ?C, the denitrification efficiency at 0.25% O2 con-tent is 12.7% higher than that under oxygen-free conditions. At high tempera-tures, the promotion of the char-NO heterogeneous reaction by CO and the inhi-bition of the reaction by CH4 were more obvious.

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Harussani, M. M., Umer Rashid, S. M. Sapuan e Khalina Abdan. "Low-Temperature Thermal Degradation of Disinfected COVID-19 Non-Woven Polypropylene—Based Isolation Gown Wastes into Carbonaceous Char". Polymers 13, n. 22 (17 novembre 2021): 3980. http://dx.doi.org/10.3390/polym13223980.

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Yields of carbonaceous char with a high surface area were enhanced by decreasing the temperature to improve the conversion of hazardous plastic polypropylene (PP), the major component in abundantly used isolation gowns. This study applied pyrolysis with different low pyrolytic temperatures to convert disinfected PP-based isolation gown waste (PP-IG) into an optimised amount of char yields. A batch reactor with a horizontal furnace was used to mediate the thermal decomposition of PP-IG. Enhanced surface area and porosity value of PP-IG derived char were obtained via an optimised slow pyrolysis approach. The results showed that the amount of yielded char was inversely proportional to the temperature. This process relied heavily on the process parameters, especially pyrolytic temperature. Additionally, as the heating rate decreased, as well as longer isothermal residence time, the char yields were increased. Optimised temperature for maximum char yields was recorded. The enhanced SBET values for the char and its pore volume were collected, ~24 m2 g−1 and ~0.08 cm3 g−1, respectively. The char obtained at higher temperatures display higher volatilisation and carbonisation. These findings are beneficial for the utilisation of this pyrolysis model in plastic waste management and conversion of PP-IG waste into char for further activated carbon and fuel briquettes applications, with the enhanced char yields, amidst the COVID-19 pandemic.

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Bérubé, Michel, e Mark A. Curtis. "Transmission of Diphyllobothrium ditremum to Arctic Char (Salvelinus alpinus) in Two Subarctic Quebec lakes". Canadian Journal of Fisheries and Aquatic Sciences 43, n. 8 (1 agosto 1986): 1626–34. http://dx.doi.org/10.1139/f86-201.

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Diphyllobothrium ditremum (Cestoda: Pseudophyllidea) transmission to arctic char (Salvelinus alpinus) was investigated at two small (<10 ha) lakes in northern Quebec, where the char populations exhibit a marked difference in plerocercoid prevalence (78 vs. 18%) and abundance (27.7 vs. 1.2 plerocercoids/fish). The highly infected char population was characterized by slow growth and poor feeding conditions. Feeding behavior of char in the two lakes differed principally in the fall, when consumption of benthos significantly decreased in the highly infected population as char fed more on copepods or sticklebacks (Gasterosteus aculeatus). Presence of these two food items in char stomachs was associated with high abundance of D. ditremum. The availability of alternative foods, such as larval insects and amphipods, appears to prevent char from acquiring heavy infections of D. ditremum, even in circumstances where all potential hosts are present.

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Schürmann, Reiner, e Martin Rueff. "Situer René Char. Hölderlin, Heidegger, Char et le « Il y a »". Po&sie N° 119, n. 1 (2007): 40. http://dx.doi.org/10.3917/poesi.119.0040.

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27

Lunden, Melissa M., Nancy Y. C. Yang, Thomas J. Headley e Christopher R. Shaddix. "Mineral-char interactions during char combustion of a high-volatile coal". Symposium (International) on Combustion 27, n. 2 (gennaio 1998): 1695–702. http://dx.doi.org/10.1016/s0082-0784(98)80009-x.

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28

Li, Bin, Lijun Zhao, Xing Xie, Dan Lin, Huibin Xu, Shuang Wang, Zhixiang Xu et al. "Volatile-char interactions during biomass pyrolysis: Effect of char preparation temperature". Energy 215 (gennaio 2021): 119189. http://dx.doi.org/10.1016/j.energy.2020.119189.

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29

CHOU, M., e D. LOFFREDO. "Sulphur in char and char desulphurization by acid leaching and hydropyrolysis". Fuel 64, n. 6 (giugno 1985): 731–34. http://dx.doi.org/10.1016/0016-2361(85)90001-8.

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30

Huang, Yong, Yonggang Wang, Hao Zhou, Yaxuan Gao, Deliang Xu, Lei Bai e Shu Zhang. "Effects of Water Content and Particle Size on Yield and Reactivity of Lignite Chars Derived from Pyrolysis and Gasification". Molecules 23, n. 10 (22 ottobre 2018): 2717. http://dx.doi.org/10.3390/molecules23102717.

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Abstract (sommario):

Water inside coal particles could potentially enhance the interior char–steam reactions during pyrolysis and gasification. This study aims to examine the effects of water contents on the char conversion during the pyrolysis and gasification of Shengli lignite. The ex-situ reactivities of chars were further analyzed by a thermo gravimetric analyzer (TGA). Under the pyrolysis condition, the increase in water contents has monotonically decreased the char yields only when the coal particles were small (<75 µm). In contrast, the water in only large coal particles (0.9–2.0 mm) has clearly favored the increase in char conversion during the gasification condition where 50% steam in argon was used as external reaction atmosphere. The waved reactivity curves for the subsequent char–air reactions were resulted from the nature of heterogeneity of char structure. Compared to the large particles, the less interior char–steam reactions for the small particles have created more differential char structure which showed two different stages when reacting with air at the low temperature in TGA.

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31

ENGBLOM, MARKUS, NICI BERGROTH, CHRISTIAN MUELLER, ANDREW JONES, ANDERS BRINK e MIKKO HUPA. "CFD-Based Modeling of Kraft Char Beds • Part 2: A Study on the Effects of Droplet Size and Bed Shape on Bed Processes". February 2010 9, n. 2 (1 marzo 2010): 15–20. http://dx.doi.org/10.32964/tj9.2.15.

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Abstract (sommario):

This is the second of two papers. The first paper presented the char bed burning model used in this work. In this paper, the effects of liquor droplet size and bed shape on kraft char bed processes and lower furnace combustion are studied using a computational fluid dynamics (CFD)-based furnace model. The simulations show that droplet size affects not only the amount of in-flight conversion and the amount of combustible material reaching the bed, but also to what degree char carbon conversion in the char bed is due to direct oxidation or gasification. Droplet size also affects char bed burning indirectly through bed shape. Char bed shape affects the degree to which combustion air jets impinge on the bed surface, increasing carbon conversion by direct oxidation. In addition, changes in bed shape over time affect char bed processes. The results suggest that when a char bed starts to grow, the local carbon input to the bed could increase with bed height. In addition, carbon conversion decreases in locations of air jet impingement if the bed shape is not maintained.

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32

Gyselman, E. C. "Fidelity of Anadromous Arctic Char (Salvelinus alpinus) to Nauyuk Lake, N.W.T., Canada". Canadian Journal of Fisheries and Aquatic Sciences 51, n. 9 (1 settembre 1994): 1927–34. http://dx.doi.org/10.1139/f94-194.

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Abstract (sommario):

The estimated fidelity of anadromous Arctic char (Salvelinus alpinus) returning to Nauyuk Lake from 1974 to 1978 was low (53%). Seven percent of the fish were absent for 1 or 2 yr before returning. Fidelity was also size dependant. Intermediate-sized fish (35–65 cm) had the highest estimated fidelity, while smaller and larger fish had lower rates. The char leaving Nauyuk Lake each spring were categorized into three groups: postspawning char, char that had been observed returning to Nauyuk Lake at least once, and char that had not shown any fidelity to Nauyuk Lake in the past. The char that had shown fidelity to Nauyuk Lake previously had the highest fidelity rate (75%), while the postspawning char and those that had not shown any previous fidelity to Nauyuk Lake both had a fidelity rate of 45%. The low fidelity of the postspawning char was attributed to a higher mortality rate. Fidelity could not be correlated with the length of time a fish was at sea or when it left Nauyuk Lake in the spring.

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33

Ravikumar, K., G. V. Nagesh, R. Venkateswara Rao, Amruthaluru Saikiran, R. Swapna, Tulugu Gunavardhana Naidu e Sampatirao Hariprasad. "Synthesis and Characterization of Shape-Stable Bio-Char Composite PCM Material for Solar Desalination Application". Materials Science Forum 1099 (5 ottobre 2023): 27–36. http://dx.doi.org/10.4028/p-y7lhbl.

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Abstract (sommario):

In the present study, three different D-Mannitol based activated bio-char composite shape-stable phase change materials (PCM) were developed for medium temperature energy storage applications like solar desalination, solar thermal storage and waste heat recovery with varying bio-char compositions. The activated bio-char (A-BC) composite-based samples were prepared from sawdust by using the pyrolysis method. The phase composition, morphology, latent heat capacity and phase change temperature of the fabricated samples were assessed by XRD, SEM, differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). The fabricated bio-char composite materials exhibited good thermal properties and structural stability compared to pure PCM. The phase change material with a blend of minimum 15 wt.% activated bio-char and 85% D-Mannitol was observed to be leak resistant. FTIR and XRD results confirm that the chemical properties of the bio-char composite remain the same as the pure PCM, which confirms that there are no chemical interactions between the PCM and bio-char. PCM sample with 15% activated bio-char exhibited an enhanced thermal stability compared to the pure PCM.

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34

Zhang, Biao, Peng Wang, Zhen Guo Chen, Xun Gong e Ming Hou Xu. "XPS Analysis Pyrolytic Char of Cellulose with Different Crystallinity Based on Ionic Liquid Regeneration". Applied Mechanics and Materials 694 (novembre 2014): 129–35. http://dx.doi.org/10.4028/www.scientific.net/amm.694.129.

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Abstract (sommario):

Ionic liquid 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) was used to dissolve cellulose and cellulose was regenerated from the solution by two different methods. Original cellulose (OC) and regenerated cellulose have different crystallinity. The morphological characteristic of different crystallinity cellulose was analyzed by the scanning electron microscopy (SEM). The cellulose pyrolysis experiment was performed on a horizontal tube furnace reactor and a wire mesh reactor. The pyrolytic char was prepared at 300°C with 50% char yield. Surface structure of original char and water washed char prepared from above two reactors was analyzed by the XPS. The results reveal the impact of secondary reaction between the volatile and char and crystallinity on the char structure during cellulose pyrolysis.

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35

Li, Xiaoming, Jingxia He, Mengjie Liu, Jin Bai, Zongqing Bai e Wen Li. "Interaction between Coal and Biomass during Co-Gasification: A Perspective Based on the Separation of Blended Char". Processes 10, n. 2 (31 gennaio 2022): 286. http://dx.doi.org/10.3390/pr10020286.

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Abstract (sommario):

Co-gasification of coal and biomass is an important way to reduce the consumption of fossil fuels and achieve the efficient utilization of biomass resources. Two kinds of biomass containing corn straw (CS) and poplar sawdust (PS) were blended with different coal. Then, the coal char was separated from the blended char after co-pyrolysis based on the difference in particle size. The structural properties, including alkali and alkaline earth metals (AAEMs), microcrystalline structures, and molecular structures of the char samples were analyzed. Gasification reactivity of the char was determined by thermogravimetric analyzer (TGA). Results indicated that K and Mg contents in biomass evaporated easily and deposited on coal char, resulting in the increase in those in coal char during co-pyrolysis, and then the AAEMs contents in coal char were determined by the AAEM species and contents in biomass. Meanwhile, the inhibition effect on the graphitization degree of coal char increased with increasing blend ratio. Likewise, the inhibition effect of CS was higher than that of PS at the same blend ratio. The catalytic activity of inorganic mineral played a much more important role in predicting gasification reactivity than graphitization degree, and then the combination of alkali index and stacking layer number was proposed to better predict the reactivity of coal char.

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36

Cordioli, Patuzzi e Baratieri. "Thermal and Catalytic Cracking of Toluene Using Char from Commercial Gasification Systems". Energies 12, n. 19 (1 ottobre 2019): 3764. http://dx.doi.org/10.3390/en12193764.

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Abstract (sommario):

Tar formation hinders the development of biomass gasification technologies. The use of pyrolytic char as a catalyst for removing tar has been widely investigated; its large specific surface area and pores distribution make it a good candidate for the cracking of heavy hydrocarbons. The present work assesses the catalytic activity of char from a commercial gasifier. Thermal degradation tests in N2 and in CO2 proved that the char is suitable for high-temperature applications (catalytic cracking) and showed release of CO and H2, which might affect the catalytic performance of the char when used for tar removal applications. For inspecting the potential of the char for tar removal, toluene was chosen as model tar. Through GC-FID, toluene removal efficiency and the amount of benzene produced from its decomposition were evaluated. Tests up to 1273 K resulted in tar removal efficiencies as high as 99.0%, and empty reactor tests allowed for discerning the effects of thermal and catalytic cracking. The catalytic activity of the char was more pronounced at 1173 K, as char increased the toluene removal efficiency from 39.9% (empty reactor) to 60.3%. The results confirmed that gasification char, like pyrolytic char, has a high potential for catalytic tar removal applications.

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37

Zadelenov, V. A., E. V. Chetvertakova, E. A. Alekseeva, O. A. Timoshkina e O. A. Logacheva. "Dryagin’s Char Salvelinus drjagini Logaschev Sobachie Lake (Putorana Plateau)". Rybovodstvo i rybnoe hozjajstvo (Fish Breeding and Fisheries), n. 10 (11 ottobre 2022): 661–72. http://dx.doi.org/10.33920/sel-09-2210-02.

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Abstract (sommario):

The results of studies of some morphological, size-age and demographic characteristics of Dryagin char are presented. A distinctive feature of this char from the Boganid char common in Lake Sobachye is a wide body. Its height in mature fish reaches 27.9% of the body length. Dryagin’s char has 112–133 (121.6) perforated scales in the lateral line, 21–29 (26.11) rakers on the first gill arch. The Dryagin char differs from the Boganid char in the color of immature and adult fish. In the control catches, fish aged from 3 to 14 years were noted, fish aged 8–10 years dominated. The length of Dryagin’s char (SL) ranged from 318 to 810 mm, weight — 472–10 700 g. The sex ratio was approximately 60:40 in favor of males. At the age of 6 years, the fish reaches sexual maturity, the maturation period is extended to 8–9 years. The minimum values of individual absolute fecundity in char were noted at the age of 6 years — 3833, the maximum — 18 270, the average value of the trait — 8140 eggs. The value of fecundity functionally depends on the mass of the fish (correlation coefficient 0.83) and its size (correlation coefficient 0.77). It is concluded that the large size, with almost the same maturation time of Dryagin char and Boganid char, makes the former a more preferable object for introducing native species into aquaculture for the Krasnoyarsk Territory.

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38

Chen, Chunbao, Dianlong Wang, Ya Xin, Hao Shi e Qiaoxia Yuan. "Two-Step Gasification of Cattle Manure for Hydrogen-Rich Gas Production: Effect of Gasification Temperature, Steam Flow Rate, and Catalysts". Journal of the ASABE 66, n. 1 (2023): 107–14. http://dx.doi.org/10.13031/ja.15241.

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Abstract (sommario):

Highlights Steam gasification parameters of cattle manure char were optimized. Effects of slow heating and fast heating modes on char gasification were analyzed. 1.92 m3/kg syngas yield and 88.72% C-conversion efficiency were obtained at 850 °C, with fast heating, 1.66 g/min of steam flow rate, and K2CO3 catalyst. Abstract. This study investigated the hydrogen-rich gas production from cattle manure char by steam gasification. The characteristics of char were studied by proximate analysis, ultimate analysis, thermogravimetric analysis, and XRD analysis. The effects of temperature, heating mode, steam flow rate, and catalyst on syngas yield, hydrogen yield, gas composition, heating value, and carbon conversion efficiency were explored. The results showed that the fixed carbon content in cattle manure char was 34.46%, an increase of 2.24 times compared with that of cattle manure, and the cattle manure char had a high fixed carbon content and thermal stability. The steam gasification indicated that the high temperature and fast heating could obtain high syngas and hydrogen yields. The steam flow rate played an important role in the char and steam reforming reactions. The SiO2 and ash catalysts had an inhibitory effect on the steam gasification of char. However, the K2CO3 catalyst improved the syngas and hydrogen yields. The optimal parameters in this study were 850 °C, fast heating, 1.66 g/min of steam flow rate, and K2CO3 catalyst. By comparison, the syngas and hydrogen production of char were better than those of biomass. As a result, the steam gasification of char was a promising method for producing hydrogen-rich gas. Keywords: Catalysts, Cattle Manure Char, Hydrogen, Steam Flow Rate, Steam Gasification.

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39

Onokebhagbe, Victor Odiamehi, Kingsley Chinyere Uzoma, Adamu Karfi Uzaifa, Fatima Jibril e Temitope Joshua Dolapo. "PERFORMANCE OF JUTE MALLOW AS INFLUENCED BY ARBUSCULAR MYCORRHIZA FUNGI (Glomus deserticola) AND BONE CHAR ON AN ALFISOL OF SUDAN SAVANNAH AGROECOLOGY, NIGERIA". Plant Physiology and Soil Chemistry 3, n. 1 (3 gennaio 2023): 20–25. http://dx.doi.org/10.26480/ppsc.01.2023.20.25.

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Abstract (sommario):

The study investigated phosphorous release from bone char and the response of jute mallow to the combined application of arbuscular mycorrhiza fungi (AMF) and bone char as well. An Alfisol from the Sudan Savannah agro-ecology of Northern Nigeria was used for this study. The soil was sterilized and subjected to routine analysis. Fresh cow bones were collected from the abattoir of Dutse and pyrolysed at a temperature of 400oC. The bone char was inoculated and incubated with AMF (Glomus deserticola) to determine its effect on release of available P from the bonechar. The experiment adopted a completely randomized design and consisted of six treatment combinations (three rates of bone char: 10, 20 and 30 g; two levels of AMF: inoculated and uninoculated) replicated three times. Incubation studies revealed that Available Phosphorous (AP) obtained from bone char was enhanced under the influence of AMF with 364.60 mg kg-1 obtained from 30 g/pot bone char AMF combination. Agronomic parameters involving height, number of leaves and dry matter yield were recorded at 3, 6 and 9 weeks after planting. Sole bone char application at 10 g/pot recorded higher plant heights and number of leaves. Plants under sole bone char applications performed better than those with combined AMF inoculations and bone char. Dry matter yield obtained were poor and were not consistent with the treatment rates. Bone char proved to be a potential viable source of plant available phosphorous. There was a proportional and significant (p<0.05) increase in quantity of AP under the influence of AMF with increase in rates of bone char.

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40

Li, Yunchao, Xianhua Wang, Huawei Song, Jingai Shao, Hongtao Ma e Hanping Chen. "Phenols production from online catalytic conversion of corn stalk pyrolysis vapors using char in-situ". BioResources 13, n. 3 (10 maggio 2018): 4884–96. http://dx.doi.org/10.15376/biores.13.3.4884-4896.

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Abstract (sommario):

Char in-situ (char[is]) obtained from corn stalk pyrolysis was evaluated as a catalyst to upgrade corn stalk pyrolysis vapors. A catalyst evaluation device was introduced to conduct the experiments. The effects of reaction temperature and char[is] dose on catalytic performances in biomass pyrolysis were evaluated. The results showed that the char in-situ had a remarkable effect on the pyrolysis products. Under the action of char[is], the primary compounds of pyrolysis vapors were catalytically converted into phenolic products, such as phenol and 4-ethyl-phenol, while the acetic acid content was evidently reduced. The product selectivity was not dependent on the polar functional groups on the char[is]’s surface according to the Fourier transform infrared (FTIR) results, but might have been dependent on the mesoporous structure and the basicity sites of the charis as well as the metallic species in the char[is]. A possible reaction mechanism for phenols production and acetic acid inhibition was proposed.

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41

Song, Wei, Muting Wu, Yanrong He, Yuzhang Wu e Wei Qu. "The Evolution of Intumescent Char in Flame-Retardant Coatings Based on Amino Resin". Coatings 11, n. 6 (12 giugno 2021): 709. http://dx.doi.org/10.3390/coatings11060709.

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Abstract (sommario):

Intumescent flame-retardant (IFR) coatings have been gaining more attention. The behaviors of intumescent char in IFR coatings play the most important role in its flame-retardant properties. However, the evolution of intumescent char throughout the whole process of protection is still unclear. In this study, both the formation and shrinkage of char were studied. The formulation of IFR includes melamine modified urea-formaldehyde resin (MUF), ammonium polyphosphate (APP) and pentaerythritol (PER). The flame-retardant properties of the coating were measured by the cone calorimeter (CONE). The evolution of the volume and the pore size distribution of char were monitored. The morphological and chemical structures were characterized by the scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results show that the evolution of intumescent char could be divided into three stages. More than 50% shrinkage of char occurs in the second stage. There are obvious transformations of the morphological and chemical structures of char between the different stages.

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42

Haque, Mohammad, Md Ali, Md Sheikh, Ashrafun Nahar e Khadiza Kana. "Impact of Char Livelihood Program (CLP) of Char land Dwellers around the Char Areas in Sirajgonj District of Bangladesh". Fundamental and Applied Agriculture 2, n. 3 (2017): 1. http://dx.doi.org/10.5455/faa.278271.

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43

Ma, Zhibin, Jin Bai, Zongqing Bai, Lingxue Kong, Zhenxing Guo, Jingchong Yan e Wen Li. "Mineral Transformation in Char and Its Effect on Coal Char Gasification Reactivity at High Temperatures, Part 2: Char Gasification". Energy & Fuels 28, n. 3 (24 febbraio 2014): 1846–53. http://dx.doi.org/10.1021/ef402382m.

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44

Shen, Xin, Li Jia, Yanlin Wang, Baihe Guo, Haodong Fan, Xiaolei Qiao, Man Zhang e Yan Jin. "Study on Dynamic Characteristics of Residual Char of CFB Boiler Based on CPFD Method". Energies 13, n. 22 (11 novembre 2020): 5883. http://dx.doi.org/10.3390/en13225883.

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Abstract (sommario):

When the load of Circulating Fluidized Bed (CFB) boiler changes dynamically, the accumulation and consumption of residual char causes a large inertia and hysteresis in the boiler combustion system. Therefore, accurate estimation of the residual char in the boiler is of great significance to the control system and improve the combustion efficiency. Based on the Computational Particles Fluid Dynamics (CPFD) method, a numerical simulation of the variable load process of CFB boiler was carried out, and the dynamic changes of the residual char inventory were analyzed by combining the coal feed, ash discharge, and furnace calorific value. The results showed that after CFB boiler reached stable operation, the residual char fluctuated from 11,000 kg to 16,000 kg, accounting for about 3.7% of the total bed material, and the residual char was in a dynamic balance. During the load-up phase, the average residual char was 17,500 kg, and during the load-down phase, the average residual char was 15,000 kg. In the process of load dynamic change, reasonable residual char stock can ensure the boiler load from one steady state to another steady state rapid transition.

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45

Barau, Aliyu Akilu, Md Safiul Islam Afrad, Abdul Halim, GKM Mustafizur Rahman e Md Enamul Haque. "Crop Management Practices in Rural Riverine Islands of Bangladesh". Tropical Small Island Agriculture Management 1, n. 2 (31 dicembre 2021): 57–70. http://dx.doi.org/10.30598/tsiam.2021.1.2.57.

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Abstract (sommario):

This study focused on farmers’ crop management practices in selected rural riverine islands (Char lands) of Sariakandi Upazila, Bogura district, Bangladesh. Disproportionate stratified sampling was adopted to select the respondents. The data were elicited using an interview schedule and analyzed via Statistics 10 software. Results revealed that, on average, there was moderate knowledge on crop management practices, and the attitude towards the practices was favorable. But, in deviance from what is habitually obtained on mainland Bangladesh where rice cultivation dominates, jute (35.84%) and chili (28.4%) covered the majority in Char Ghagua and Char Shaluka, respectively. In Char Tengrakura, rice and chili covered a little above half (52.7%) of the crops cultivated by the respondents. In terms of the management practices, the lion’s share (81.7%, 74.7%, and 77.0%) of soil management practices was covered by chemical fertilizers in all the Char lands. Similarly, the use of chemicals dominated when handling pests and diseases. Triple cropping was foremost across the Char lands and had high mean coverage in Char Tengrakura (63.6%). The mean coverage of irrigation water management practices was virtually shallow tube well in the Char lands. Generally, there was moderate knowledge and a positive attitude towards crop management practices. That crop management practices (use synthetic materials and underground water) employed in the Char lands are unsustainable, tending to induce degradation of land and water resources.

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46

Hyder, A. H. M. G., Shamim A. Begum e Nosa O. Egiebor. "Sorption studies of Cr(VI) from aqueous solution using bio-char as an adsorbent". Water Science and Technology 69, n. 11 (22 marzo 2014): 2265–71. http://dx.doi.org/10.2166/wst.2014.143.

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Abstract (sommario):

The characteristics of sorption of hexavalent chromium (Cr(VI)) onto bio-char derived from wood chips (spruce, pine, and fir) were evaluated as a function of pH, initial Cr(VI) concentration and bio-char dosage using synthetic wastewater in batch tests. The initial Cr(VI) concentrations were varied between 10 and 500 mg/L to investigate equilibrium, kinetics, and isotherms of the sorption process. About 100% of Cr(VI) was removed at pH 2 with initial Cr(VI) concentration of 10 mg/L using 4 g of bio-char after 5 hours of sorption reaction. The maximum sorption capacity of the bio-char was 1.717 mg/g for an initial Cr(VI) concentration of 500 mg/L after 5 hours. The sorption kinetics of total Cr onto bio-char followed the second-order kinetic model. The Langmuir isotherm model provided the best fit for total Cr sorption onto bio-char. The bio-char used is a co-product of a down draft gasifier that uses the derived syngas to produce electricity. Bio-char as a low cost adsorbent demonstrated promising results for removal of Cr(VI) from aqueous solution. The findings of this study would be useful in designing a filtration unit with bio-char in a full-scale water and wastewater treatment plant for the Cr(VI) removal from contaminated waters.

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47

Dong, Lu, Liang Wang, Xuanzhou Huan, Bichen Liu, Baojun Yi, Hongyun Hu e Fang Huang. "Combustion and flue gas evolution characteristics of rice husk in various mixtures and layers with Al2O3 particles and char prepared with different pyrolysis parameters". BioResources 18, n. 4 (20 ottobre 2023): 8323–40. http://dx.doi.org/10.15376/biores.18.4.8323-8340.

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Abstract (sommario):

During pyrolysis and combustion experiments, rice husk and Al2O3 were combined in two ways, namely blending (rice husk was blended with Al2O3) and covering (rice husk was covered by Al2O3) modes, respectively. Rice husk biomass (RHB) char was prepared under different pyrolysis conditions. The resulting combustion characteristics and corresponding gaseous evolution of the biochar were compared. The maximum combustion rate decreased as particles accumulated, causing a shift in the thermo-gravimetric curve to higher temperature ranges. The combustion reaction was hindered in the covering mode. The combustion reactivity of the prepared char decreased as the char preparation time increased. During the char oxidation process, the release amounts of H2O and CO2 from char combustion increased first and then decreased, while the release amounts of CO, CH4, and organic components containing C=O gradually decreased with increasing char preparation time. Char prepared with the covering mode exhibited higher burn-out rates and combustion indices but lower activation energies required for combustion reaction. Additionally, the covering mode delayed the timely release of gases from the biomass heating in air, and the quantity of combustion gas released from the char produced at covering mode was greater than that released from the char produced at blending mode. The results obtained can improve the understanding of stacked biomass particles combustion process.

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48

Mwaniki, D. L. "Fluoride Sorption Characteristics of Different Grades of Bone Charcoal, Based on Batch Tests". Journal of Dental Research 71, n. 6 (giugno 1992): 1310–15. http://dx.doi.org/10.1177/00220345920710060801.

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Abstract (sommario):

Although bone charcoal (char) has been recommended for use in the de-fluoridation of drinking water in developing countries, parameters relating to fluoride (F) sorption characteristics by grade or type of bone char are unclear. Based on batch tests, the rate and capacity of F uptake were highest with black grade, followed by grey grade and lowest with white grade. Twenty-four- hour contact-time F sorption isotherms indicated saturation at capacities of 11.4 mg F per g of black grade, 2.4 mg F per g of grey grade, and less than 0.3 mg F per g of white grade bone char. Additional investigations showed that F-removal efficiency of black grade char decreased steadily with increasing F concentration. Its initial sorption kinetics were dependent on particle size, and the highest sorption rate was observed with particle sizes below 0.42 mm. For maximum sorption rate, the critical mixing time was between five and 15 min. The presence of chloride anions and elevated temperatures increased the rate of F uptake by black bone-char. The pH of distilled water following contact with bone char rose to 11.5 for white bone-char, 8.3 for grey bone-char, and 7.8 for black bone-char. The effects of processing temperature on the availability of intra- and extraapatitic F-binding sites, levels of oxides of calcium and magnesium, and the carbon content were viewed as possible causes of observed variations. These findings suggest that the black grade of bone char was the most efficacious for use in partial de-fluoridation of drinking water.

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49

Uddin, Mohammed Nasir, Fouzia Zannat, Mohammad Maruf Hasan, Mst Sharmin Akter e Md Zulfikar Rahman. "Livelihood Changes of Char (Dry Land) Women Due to Involvement in Activities of the Char Livelihood Program". Asian Journal of Agricultural Extension, Economics & Sociology 41, n. 11 (11 novembre 2023): 121–37. http://dx.doi.org/10.9734/ajaees/2023/v41i112268.

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Abstract (sommario):

Climatic hazards are common in Bangladesh on delta and riverine island communities, which are large sandbars formed in riverbeds due to silt and alluvium deposition. Specifically, these hazards are caused by the dynamic erosion and accretion of riverbanks. The natural disaster caused by the subsequent sediment buildup on the riverbed and river bank erosion poses a serious threat to the way of life for the residents of Char, particularly the women, by causing damage to or destruction of houses, crops, and family income. The Char Livelihood Program (CLP) attempted to strengthen women's resilience and sense of empowerment while simultaneously improving their livelihoods, nutrition, access to clean water, sanitation, and hygiene habits of char women. This study was mainly undertaken to investigate the extent of changes in the livelihood status of char women due to the involvement in Char Livelihood Program (CLP), explore the factors that may influence the livelihood changes of the char women due to involvement in the CLP. Besides, the problems faced by the char women while working in CLP were also investigated. Data were collected from four villages of Islampur Upazila (sub-district) under Jamalpur district purposively and analyzed using Multiple Linear Regression Models. The goal was to identify the variables that affect the char women's changes in their livelihood. Findings indicated that involvement in char livelihood program had significant influence on the livelihood of char women. The main factor included years of schooling, family size and knowledge of CLP. Collectively, the factors explained 32.3% variation in the livelihood changes of char women. The most influential challenges, from highest to lowest, included unavailability of transport and poor communication status, and lack of commitment of the service provider. Therefore, in order to overcome these obstacles, efforts must be made to ensure seasonal transportation system and enhance road communication infrastructure to enable char women to move around freely in order to carry agricultural products and to connect with relevant stakeholders for better farming and income operations.

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Zhang, Yu, Dongdong Feng, Yijun Zhao, Heming Dong, Guozhang Chang, Cui Quan, Shaozeng Sun e Yukun Qin. "Evolution of Char Structure During In-Situ Biomass Tar Reforming: Importance of the Coupling Effect Among the Physical-Chemical Structure of Char-Based Catalysts". Catalysts 9, n. 9 (24 agosto 2019): 711. http://dx.doi.org/10.3390/catal9090711.

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Abstract (sommario):

In order to illustrate the importance of a coupling effect in the physical-chemical structure of char-based catalysts on in-situ biomass tar reforming, three typical char-based catalysts (graphite, Zhundong coal char, and sawdust biochar) were studied in the fixed-bed/fluidized-bed reactor. The physical-chemical properties of carbon-based catalysts associated with their catalytic abilities were characterized by inductively coupled plasma-atomic emission spectroscopy (ICP-AES), Raman, X-ray photoelectron spectroscopy (XPS), scanning electron microscope–energy dispersive spectrometer (SEM-EDS) and N2 adsorption. The relationship between the specific reactivity and tar reforming ability of carbon-based catalysts was discussed through a micro fluidized bed reaction analyzer (MFBRA–MR). The results indicate that the char-based catalyst has a certain removal ability for in-situ biomass tar of corn straw in an inert atmosphere, which is as follows: sawdust biochar > Zhundong (ZD) coal char > graphite. During the in-situ tar reforming, the alkali and alkaline earth metal species (AAEMs) act as adsorption/reaction sites, affecting the evolution of the aromatic ring structure and oxygen-containing functional groups of the char-based catalyst, and also its pore structure. AAEM species on the surface of char-based catalysts are the active sites for tar reforming, which promotes the increase of active intermediates (C-O bond and C-O-AAEMs), and enhances the interactions between char-based catalysts and biomass tar. The abundant AAEMs may lead to the conversion of O=C–O and C=O to C–O. For tar reforming, the internal pore structure of char-based catalysts is little changed, mainly with the carbon deposit forming on the surface pore structure. The carbon deposit from the reformation of straw tar on the char surface has better reactivity than the inherent carbon structure of ZD coal char and sawdust biochar. There is a positive relationship between the MFBRA–MR specific reactivity and tar catalytic reforming ability of char-based catalysts (decided by the coupling effect in their physical-chemical structure), which can be used to determine the catalytic ability of char-based catalysts on tar reforming directly.

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