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1
Sivaranjanee, R., and P. Senthil Kumar. "Enhanced Adsorption of Rose Bengal Dye from Aqueous Solution Using NaOH Activated Hydrochar Derived from Corncob Waste." Adsorption Science & Technology 2023 (November 8, 2023): 1–19. http://dx.doi.org/10.1155/2023/6695350.
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A potential approach to the preparation of affordable activated hydrochar is the hydrothermal carbonization of biomass wastes. In this study, hydrochar was made by hydrothermally carbonizing corncob wastes and then activating them with sodium hydroxide (NaOH). According to the findings, the adsorption capabilities of hydrochar generated at prolonged retention durations, lesser liquid-to-solid ratios, and elevated temperatures were considerably greater. The hydrochars were then analyzed utilizing a variety of characterization methods, and batch tests involving the sorption of rose bengal dye were carried out under a variety of conditions. According to the findings, activated hydrochar has a specific surface area of 12.794 m2/g. In order to better understand and characterize the process of rose bengal dye adsorption, sorption kinetics, and sorption equilibrium onto the produced hydrochars, sorption kinetics and isotherms were further examined through experimental data fitting. The NaOH-activated hydrochar’s adsorption capacity was 799.9 mg/g, respectively. The objective of this research was to assess the viability of using NaOH-activated hydrochar derived from corncobs as an economical and efficient sorbent for eliminating anionic dyes like rose bengal from aqueous solutions. Additionally, the study sought to investigate how various factors influence its sorption capabilities and to provide insights into the adsorption process through kinetic and isotherm analyses.
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Islam, Md Tahmid, Al Ibtida Sultana, Cadianne Chambers, Swarna Saha, Nepu Saha, Kawnish Kirtania, and M. Toufiq Reza. "Recent Progress on Emerging Applications of Hydrochar." Energies 15, no. 24 (December 9, 2022): 9340. http://dx.doi.org/10.3390/en15249340.
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Hydrothermal carbonization (HTC) is a prominent thermochemical technology that can convert high-moisture waste into a valuable product (called hydrochar) at a relatively mild treatment condition (180–260 °C and 2–10 MPa). With rapidly growing research on HTC and hydrochar in recent years, review articles addressing the current and future direction of this research are scarce. Hence, this article aims to review various emerging applications of hydrochars, e.g., from solid fuel to soil amendment, from electron storage to hydrogen storage, from dye adsorption, toxin adsorption, heavy metal adsorption to nutrient recovery, and from carbon capture to carbon sequestration, etc. This article further provides an insight in the hydrochar’s working mechanism for various applications and how the applications can be improved through chemical modification of the hydrochar. Finally, new perspectives with appropriate recommendations have been made to further unveil potential applications and its improvement through hydrochar and its modified version.
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Saha, Nepu, Maurizio Volpe, Luca Fiori, Roberto Volpe, Antonio Messineo, and M. Toufiq Reza. "Cationic Dye Adsorption on Hydrochars of Winery and Citrus Juice Industries Residues: Performance, Mechanism, and Thermodynamics." Energies 13, no. 18 (September 9, 2020): 4686. http://dx.doi.org/10.3390/en13184686.
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With the increasing needs of clean water supplies, the use of biomass wastes and residues for environmental remediation is essential for environmental sustainability. In this study, the residues from winery and citrus juice industries, namely grape skin and orange peel, respectively, were first converted to hydrochars by hydrothermal carbonization (HTC) and then a cationic dye (methylene blue) adsorption was studied on hydrochars. Hydrochars from both feedstocks were produced at three different temperatures (180, 220, and 250 °C) and a fixed residence time (1 h) to evaluate the hydrochar’s performance on the dye adsorption. The hydrochars were characterized in terms of their pH, pH at point of zero charge (pHPZC), surface functionalities, and surface area. A batch adsorption study of the dye was carried out with variable adsorbate concentration, pH, and temperature. Two adsorption isotherms namely Langmuir and Freundlich models were fitted at 4, 20, and 36 °C. The thermodynamic properties of adsorption (Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS)) were evaluated from the isotherms fittings. Results showed that the dye adsorption on both hydrochars was significant and followed Langmuir isotherm. The maximum adsorption capacity on citrus waste hydrochar was higher than the winery waste hydrochar at any corresponding HTC temperature. Although hydrochars showed the lowest surface area (46.16 ± 0.11 and 34.08 ± 1.23 m2/g for citrus and winery wastes, respectively) at 180 °C, their adsorption was the highest, owing to their maximum density of total oxygen functional groups (23.24 ± 0.22 and 32.69 ± 1.39 µmol/m2 for citrus and winery wastes, respectively), which decreased with the increase in HTC temperature. This research shows a sustainable route for the production of highly effective adsorbent materials at lower HTC temperatures from citrus and winery wastes.
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Tran, Lien Thi, Minh Quang Nguyen, Ha Trong Hoang, Hoang Tien Nguyen, and Thu Ha Thi Vu. "Catalytic Hydrothermal Carbonization of Avocado Peel." Journal of Chemistry 2022 (October 7, 2022): 1–10. http://dx.doi.org/10.1155/2022/5766269.
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The hydrothermal carbonization (HTC) of avocado peel was investigated by varying the reaction temperature, reaction time, and catalyst/feedstock ratio. After the HTC process, there was a drastic change in both the structure and chemical composition of the hydrochar compared to the feedstock. This modification aids hydrochar’s improved fuel characteristics, as seen by a drop in the H/C and O/C ratios, as well as an increase in fixed carbon content. The higher heating value (HHV) increased in the feedstock to a maximum value of 27.15 MJ·kg−1, corresponding to hydrochar, which is obtained at an optimized condition. Notably, the HHV and carbon content of the noncatalytic sample are only higher than those of the feedstock but lower than those of the samples surveyed. The combustion behavior and thermal characteristics of hydrochars show that the HTC of the avocado peel in the presence of FeCl3 catalyst introduces a possible direction of application in converting agro-industrial by-products into fuel.
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Thawornchaisit, Usarat, Tanrawee Onlamai, Nontakorn Phurkphong, and Rawiwan Sukharom. "Sugarcane Bagasse-derived Hydrochar: Modification with Cations to Enhance Phosphate Removal." Environment and Natural Resources Journal 19, no. 5 (July 15, 2021): 1–10. http://dx.doi.org/10.32526/ennrj/19/202100036.
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Cation modified hydrochars were synthesized by hydrothermal carbonization (HTC) of sugarcane bagasse, followed by impregnation of three different cations (Ca, Mg, and Fe) or co-precipitation of Fe3+ and Fe2+. HTC enhanced the hydrochar surface area and increased the enrichment of oxygen functional groups on the hydrochar surface confirmed by FTIR. The oxygen functional groups further improve the adsorption capacity for cations during hydrochar chemical modification. Physical appearance, FTIR and XRF confirmed that Ca2+, Mg2+ and Fe2+ or Fe3+ were well retained in the bagasse-derived hydrochar. The pHpzc values of all chemically modified hydrochars were greater than the unmodified hydrochar or bagasse alone. Modification with different cations improved phosphate uptake capacity. The Fe-modified hydrochar with about 45-50% Fe content showed greater phosphate removal efficiency than Ca- and Mg-modified hydrochars. In addition, hydrochars decorated by impregnation of Fe3+ demonstrated better phosphate removal than ones produced by co-precipitation of Fe3+ and Fe2+. Thus, chemically modified hydrochars could be used as an environmentally alternative adsorbent for phosphate removal from aqueous solutions.
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Wutthipattarathorn, Kamyaporn, Usarat Thawornchaisit, and Suwannee Janyapoon. "Enhanced Removal of Phosphorus from Aqueous Solutions by Cation-Modified Hydrochar." Trends in Sciences 20, no. 10 (July 31, 2023): 5808. http://dx.doi.org/10.48048/tis.2023.5808.
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In this study, cassava stem-derived hydrochar was modified with sodium hydroxide (NaOH) treatment, followed by loading of minerals, was used to prepare cation-modified hydrochars with enhanced phosphate removal ability. Cassava stems were converted to hydrochar by hydrothermal carbonization at 240 °C for 60 min, then it was soaked in 2 M NaOH for 3 h. The NaOH-treated hydrochars were then loaded with iron (Fe), magnesium (Mg) and calcium (Ca). The cassava stems and the derived hydrochars were analyzed for carbon, hydrogen, nitrogen and oxygen content, surface morphology and elemental compositions. Methylene Blue Numbers (MBN) measured surface area and porosity, and pH at the point of zero charge (pHpzc) was determined. Modification with Fe, Mg and Ca improved phosphate removal efficiency of the resulting hydrochars. Treatment of synthetic wastewater containing 50 mg P/L at pH 7 with the dosage of 2 g/L of the cation-modified hydrochars for 360 min showed that phosphate removal efficiency of these modified hydrochars were - Fe-modified 81 %, Mg-modified 66 % and Ca-modified 56 %. When the adsorbent dosage increased to 20 g/L, more than 98 % of phosphate was removed by the hydrochars modified with Fe, Ca and Mg. In the same conditions, phosphate removal efficiency was for the NaOH-treated hydrochars - 89 %, hydrochar derived from cassava steam - 69 % and the starting material - 59 %. The phosphate removal ability of these cation-modified hydrochars increased even when initial phosphorus concentration was increased to 100 mg P/L. This work demonstrated that an abundant agricultural residue, cassava stems, can be converted into effective phosphate adsorbents. HIGHLIGHTS Cassava stem were converted to hydrochar by aqueous carbonization at elevated temperature and pressure - hydrothermal carbonization (HTC) Sequential steps of alkali treatment and chemical modification, following HTC, were used to improve the phosphate removal ability of the cassava stem-derived hydrochar Loading of minerals (Fe, Mg and Ca) was a vital way to increase the adsorption of phosphates on hydrochar Phosphorus removal efficiency of Fe-loaded hydrochar was better than Mg- and Ca-loaded hydrochars Cation-modified hydrochars showed good phosphate removal ability over a wider concentration range GRAPHICAL ABSTRACT
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Ferrentino, Roberta, Riccardo Ceccato, Valentina Marchetti, Gianni Andreottola, and Luca Fiori. "Sewage Sludge Hydrochar: An Option for Removal of Methylene Blue from Wastewater." Applied Sciences 10, no. 10 (May 16, 2020): 3445. http://dx.doi.org/10.3390/app10103445.
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Municipal sewage sludge was subjected to a hydrothermal carbonization (HTC) process for developing a hydrochar with high adsorption capacity for water remediation in terms of dye removal. Three hydrochars were produced from municipal sewage sludge by performing HTC at 190, 220 and 250 °C, with a 3 h reaction time. Moreover, a portion of each hydrochar was subjected to a post-treatment with KOH in order to increase the adsorption capacity. Physicochemical properties of sludge samples, raw hydrochars and KOH-modified hydrochars were measured and batch adsorption studies were performed using methylene blue (MB) as a reference dye. Data revealed that both raw and modified hydrochars reached good MB removal efficiency for solutions with low MB concentrations; on the contrary, MB in high concentration solutions was efficiently removed only by modified hydrochars. Interestingly, the KOH treatment greatly improved the MB adsorption rate; the modified hydrochars were capable of capturing above 95% of the initial MB amount in less than 15 min. The physicochemical characterization indicates that alkali modification caused a change in the hydrochar surface making it more chemically homogeneous, which is particularly evident for the 250 °C hydrochar. Thus, the adsorption process can be regarded as a complex result of various phenomena, including physi- and chemi-sorption, acid–base and redox equilibria.
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Fregolente, Laís G., João Vitor dos Santos, Giovanni Vinci, Alessandro Piccolo, Altair B. Moreira, Odair P. Ferreira, Márcia C. Bisinoti, and Riccardo Spaccini. "Insights on Molecular Characteristics of Hydrochars by 13C-NMR and Off-Line TMAH-GC/MS and Assessment of Their Potential Use as Plant Growth Promoters." Molecules 26, no. 4 (February 15, 2021): 1026. http://dx.doi.org/10.3390/molecules26041026.
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Hydrochar is a carbon-based material that can be used as soil amendment. Since the physical-chemical properties of hydrochar are mainly assigned to process parameters, we aimed at evaluating the organic fraction of different hydrochars through 13C-NMR and off-line TMAH-GC/MS. Four hydrochars produced with sugarcane bagasse, vinasse and sulfuric or phosphoric acids were analyzed to elucidate the main molecular features. Germination and initial growth of maize seedlings were assessed using hydrochar water-soluble fraction to evaluate their potential use as growth promoters. The hydrochars prepared with phosphoric acid showed larger amounts of bioavailable lignin-derived structures. Although no differences were shown about the percentage of maize seeds germination, the hydrochar produced with phosphoric acid promoted a better seedling growth. For this sample, the greatest relative percentage of benzene derivatives and phenolic compounds were associated to hormone-like effects, responsible for stimulating shoot and root elongation. The reactions parameters proved to be determinant for the organic composition of hydrochar, exerting a strict influence on molecular features and plant growth response.
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Delahaye, Louise, John Thomas Hobson, Matthew Peter Rando, Brenna Sweeney, Avery Bernard Brown, Geoffrey Allen Tompsett, Ayten Ates, N. Aaron Deskins, and Michael Thomas Timko. "Experimental and Computational Evaluation of Heavy Metal Cation Adsorption for Molecular Design of Hydrothermal Char." Energies 13, no. 16 (August 14, 2020): 4203. http://dx.doi.org/10.3390/en13164203.
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A model hydrochar was synthesized from glucose at 180 °C and its Cu(II) sorption capacity was studied experimentally and computationally as an example of molecular-level adsorbent design. The sorption capacity of the glucose hydrochar was less than detection limits (3 mg g−1) and increased significantly with simple alkali treatments with hydroxide and carbonate salts of K and Na. Sorption capacity depended on the salt used for alkali treatment, with hydroxides leading to greater improvement than carbonates and K+ more than Na+. Subsequent zeta potential and infrared spectroscopy analysis implicated the importance of electrostatic interactions in Cu(II) sorption to the hydrochar surface. Computational modeling using Density Functional Theory (DFT) rationalized the binding as electrostatic interactions with carboxylate groups; similarly, DFT calculations were consistent with the finding that K+ was more effective than Na+ at activating the hydrochar. Based on this finding, custom-synthesized hydrochars were synthesized from glucose-acrylic acid and glucose-vinyl sulfonic acid precursors, with subsequent improvements in Cu(II) adsorption capacity. The performance of these hydrochars was compared with ion exchange resins, with the finding that Cu(II)-binding site stoichiometry is superior in the hydrochars compared with the resins, offering potential for future improvements in hydrochar design.
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Faradilla, RH Fitri, Lucian Lucia, and Marko Hakovirta. "Remarkable Physical and Thermal Properties of Hydrothermal Carbonized Nanoscale Cellulose Observed from Citric Acid Catalysis and Acetone Rinsing." Nanomaterials 10, no. 6 (May 29, 2020): 1049. http://dx.doi.org/10.3390/nano10061049.
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Citric acid (CA) was used for the hydrothermal carbonization (HTC) of cellulose nanofiber and found to exert remarkable effects on the chemistry and physical aspects of the product distribution. More specifically, the morphology, yield, elemental and proximate composition, chemical functional groups, thermal properties and surface properties of the resultant hydrochars were studied extensively. The morphological properties of the final char were the singularly most surprising and unique finding of this study. The cellulose nanofiber hydrochars were contrasted to hydrochars from bleached softwood pulp, having a similar composition with the former, to pinpoint the role of nano-dimensions. Without the presence of CA, the pulp hydrochar lacked several of the spherical dimensions shown in the nanocellulose; however, and unexpectedly, the presence of CA caused a homogenization of the final product distribution for both samples. Finally, thermally stable and high surface area hydrochars were obtained when the hydrochar was rinsed with acetone.
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Peng, Na Na, and Zhen Gang Liu. "Preparation of Solid Fuel Hydrochars from Waste Biomass by Hydrothermal Carbonization." Applied Mechanics and Materials 768 (June 2015): 73–81. http://dx.doi.org/10.4028/www.scientific.net/amm.768.73.
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Coconut fiber (CF) and eucalyptus leaves (EL) were upgraded by hydrothermal carbonization (HTC) and fuel qualities of corresponding hydrochars were determined in the present study. Compared to raw biomass, the hydrochars have increased energy density, and the decreased nitrogen and sulfur contents showed that reduced pollutant emissions are produced during hydrochar combustion. The ignition temperatures of hydrochars were higher and the combustion also shifted to higher temperature ranges. In addition, HTC significantly reduced the slagging and fouling tendencies of raw biomass and the fouling index of CF and EL changed from 2.59 to 0.09 and 1.11 to 0.24, respectively. This study demonstrated that solid fuel with high quality can be produced by HTC and improved thermal efficiency and environmental benefits can be achieved by hydrochar combustion.
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Diaz, Elena, Ines Sanchis, Charles J. Coronella, and Angel F. Mohedano. "Activated Carbons from Hydrothermal Carbonization and Chemical Activation of Olive Stones: Application in Sulfamethoxazole Adsorption." Resources 11, no. 5 (April 28, 2022): 43. http://dx.doi.org/10.3390/resources11050043.
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This work focuses on the production of activated carbons by hydrothermal carbonization of olive stones at 220 °C, followed by chemical activation with KOH, FeCl3 and H3PO4 of the hydrochar obtained. In addition, N-doped hydrochars were also obtained by performing the hydrothermal carbonization process with the addition of (NH4)2SO4. All hydrochars, N-doped and non-doped, showed low BET surface areas (4–18 m2 g−1). Activated hydrochars prepared using H3PO4 or KOH as activating agents presented BET surface areas of 1115 and 2122 m2 g−1, respectively, and those prepared from N-doped hydrochar showed BET surface area values between 1116 and 2048 m2 g−1 with an important contribution of mesoporosity (0.55–1.24 cm3 g−1). The preparation procedure also derived inactivated hydrochars with predominantly acidic or basic groups on their surface. The resulting materials were tested in the adsorption of sulfamethoxazole in water. The adsorption capacity depended on both the porous texture and the electrostatic interactions between the adsorbent and the adsorbate. The adsorption equilibrium data (20 °C) fitted fairly well to the Langmuir equation, and even better to the Freundlich equation, resulting in the non-doped hydrochar activated with the KOH as the best adsorbent.
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Lee, Jongkeun, Sungwan Cho, Daegi Kim, JunHee Ryu, Kwanyong Lee, Haegeun Chung, and Ki Young Park. "Conversion of Slaughterhouse Wastes to Solid Fuel Using Hydrothermal Carbonization." Energies 14, no. 6 (March 22, 2021): 1768. http://dx.doi.org/10.3390/en14061768.
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In this study, cattle and pig slaughterhouse wastes (SHWs) were hydrothermally carbonized at 150–300 °C, and the properties of SHW-derived hydrochar were evaluated for its use as a solid fuel. The results demonstrated that increasing the hydrothermal carbonization (HTC) treatment temperature improved the energy-related properties (i.e., fuel ratio, higher heating value, and coalification degree) of both the cattle and pig SHW-derived hydrochars. However, the improvements of cattle SHW-derived hydrochars were not as dramatic as that of pig SHW-derived hydrochars, due to the lipid-rich components that do not participate in the HTC reaction. In this regard, there was no merit of using HTC treatment on cattle SHW for the production of hydrochar or using the hydrochar as a solid fuel in terms of energy retention efficiency. On the other hand, a mild HTC treatment at approximately 200 °C was deemed suitable for converting pig SHW to value-added solid fuel. The findings of this study suggest that the conversion of SHWs to hydrochar using HTC can provide an environmentally benign method for waste treatment and energy recovery from abandoned biomass. However, the efficiency of energy recovery varies depending on the chemical composition of the raw feedstock.
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Khalaf, Nidal, Wenxuan Shi, Owen Fenton, Witold Kwapinski, and J. J. Leahy. "Hydrothermal carbonization (HTC) of dairy waste: effect of temperature and initial acidity on the composition and quality of solid and liquid products." Open Research Europe 2 (September 6, 2023): 83. http://dx.doi.org/10.12688/openreseurope.14863.3.
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Background: Hydrothermal carbonization (HTC) of dairy processing waste was performed to investigate the effect of temperature and initial pH on the yield and composition of the solid (hydrochar) and liquor produced. All hydrochars met the EU requirements of organo-mineral solid fertilizers defined in the Fertilizing Products Regulation in terms of phosphorus (P) and mineral content. Methods: Laboratory scale HTC was performed using pressurized reactors, and the products (solid and liquid) were collected, stored and analyzed for elemental composition and nutrient content using Inductively coupled plasma optical emission spectroscopy (ICP-OES), ultraviolet-visible spectrophotometry (UV-Vis) and other analytic techniques. Results: Maximum hydrochar yield (60.67%) was observed at T=180℃ and pH=2.25, whereas the maximum P-recovery was 80.38% at T=220℃ and pH=4.6. The heavy metal content of the hydrochars was mostly compliant with EU limitations, except for Ni at T=220℃ and pH=8.32. Meanwhile, further study of Chromium (Cr) species is essential to assess the fertilizer quality of the hydrochars. For the liquid product, the increase in temperature beyond 200℃, coupled with an increase in initial acidity (pH=2.25) drove P into the liquor. Simultaneously, increasing HTC temperature and acidity increased the concentration of NO 3 - and NH 4 + in the liquid products to a maximum of 278 and 148 mg/L, respectively, at T=180℃ and pH=4.6. Furthermore, no direct relation between final pH of liquor and NH 4 + concentration was observed. Conclusions: HTC allows for the production of hydrochar as a potential fertilizer material that requires further processing. Adjusting HTC conditions enhanced P-recovery in the hydrochar, while retrieving higher nitrate concentrations in the liquid product. Optimizing HTC for the production of qualified hydrochars requires further treatment of Cr content, studying the availability of P in the products and enhancing the hydrochar yield for economic feasibility.
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Lau Abdullah, Myra Shahira, and NoorAshrina A. Hamid. "Turning Coconut Residue into Hydrochar using Hydrothermal Carbonization." IOP Conference Series: Materials Science and Engineering 1192, no. 1 (November 1, 2021): 012033. http://dx.doi.org/10.1088/1757-899x/1192/1/012033.
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Abstract The use of renewable and sustainable energy resources is critical, especially considering the scarcity of fossil fuels and the need to combat air pollution. Various types of biomass feedstock, including coconut husk, have been studied in the past to convert into useful forms of hydrochar. However, no one had attempted to use coconut residue to produce hydrochar through hydrothermal carbonization. The goal of this study is to investigate the properties of synthesised hydrochar from coconut residue under various operating conditions in order to determine the highest yield of hydrochar produced prior to methylene blue degradation. Hydrochar was created from coconut residue using hydrothermal carbonization (HTC). The hydrochar was synthesised over a range of residence times of 6 hours, 12 hours, 18 hours, 24 hours, and 48 hours at a constant temperature of 200°C. Prior to the degradation of methylene blue, the properties of hydrochar were investigated using elemental analysis. The oxygen-to-carbon (O/C) and hydrogen-to-carbon (H/C) ratios for all hydrochars were 0.36-0.16 and 1.78-1.17, respectively. For all concentrations, the highest rate of methylene blue removal was approximately 70-80 percent. Overall, residence time had a minor impact on the chemical properties of hydrochars.
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Lentz, Zac, Praveen Kolar, and John J. Classen. "Valorization of Swine Manure into Hydrochars." Processes 7, no. 9 (August 23, 2019): 560. http://dx.doi.org/10.3390/pr7090560.
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There is a significant interest in valorizing swine manure that is produced in enormous quantities. Therefore, considering the high moisture content in swine manure, the objective of this research was to convert manure slurry into hydrochars via hydrothermal carbonization and analyze the yields, pH, energy contents, and thermal and oxidation kinetic parameters. Experiments were performed in triplicate in 250 mL kettle reactors lined with polypropylene at 180 °C, 200 °C, 240 °C, 220 °C, and 260 °C for 24 h. Analyses of the results indicated that the process temperature affected the hydrochar yields, with yield generally decreasing with increasing temperature, but it had little effect on the composition of the hydrochar. The hydrochars were found to have higher volatile contents and H/C and O/C ratios and about 85% of the energy compared to coal. However, the presence of high fraction (35–38%) of ash in hydrochars is a serious concern and needs to be addressed before the complete utilization of hydrochars as fuels. The surface characterization of hydrochars coupled with wet chemistry experiments indicated that hydrochars were equipped with nitrogen functional groups with points of zero charges between 6.76 and 7.85, making them suitable as adsorbents and soil remediation agents and energy storage devices.
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Valdés-Rodríguez, Evelyn Mirelle, Leonardo Frias-Gasparri, Didilia Ileana Mendoza-Castillo, Verónica Janeth Landin-Sandoval, and Adrián Bonilla-Petriciolet. "Preparation of Tetra Pak-Based Hydrochars for Cleaning Water Polluted by Heavy Metal Ions: Physicochemical Properties and Removal Mechanism." International Journal of Chemical Engineering 2023 (August 2, 2023): 1–13. http://dx.doi.org/10.1155/2023/3169510.
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This paper addresses the analysis of hydrothermal carbonization of Tetra Pak residues using diluted sulfuric acid to obtain hydrochars for cleaning water polluted by heavy metal ions. The hydrochar samples were prepared under different carbonization conditions, and a detailed study of their composition, textural parameters, and surface functionalities was performed. It was found that the hydrothermal carbonization and dwell time of the Tetra Pak wastes significantly affected the composition of the hydrochars. These hydrochar samples contained oxygenated functional groups and aluminum-silicon moieties that were responsible for the Pb2+, Zn2+, and Hg2+ adsorption. The removal of these heavy metal ions using Tetra Pak hydrochars was an endothermic and multi-ionic process. Hydrothermal carbonization is a promising approach to improve Tetra Pak waste management, generating materials with interesting properties for addressing the problem of wastewater and industrial effluent depollution.
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Saha, Nepu, Akbar Saba, Pretom Saha, Kyle McGaughy, Diana Franqui-Villanueva, William Orts, William Hart-Cooper, and M. Reza. "Hydrothermal Carbonization of Various Paper Mill Sludges: An Observation of Solid Fuel Properties." Energies 12, no. 5 (March 5, 2019): 858. http://dx.doi.org/10.3390/en12050858.
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Each year the pulp and paper industries generate enormous amounts of effluent treatment sludge. The sludge is made up of various fractions including primary, secondary, deinked, fiber rejects sludge, etc. The goal of this study was to evaluate the fuel properties of the hydrochars produced from various types of paper mill sludges (PMS) at 180 °C, 220 °C, and 260 °C. The hydrochars, as well as the raw feedstocks, were characterized by means of ultimate analysis, proximate analysis, moisture, ash, lignin, sugar, and higher heating value (HHVdaf) measurements. Finally, combustion indices of selected hydrochars were evaluated and compared with bituminous coal. The results showed that HHVdaf of hydrochar produced at 260 °C varied between 11.4 MJ/kg and 31.5 MJ/kg depending on the feedstock. This implies that the fuel application of hydrochar produced from PMS depends on the quality of feedstocks rather than the hydrothermal carbonization (HTC) temperature. The combustion indices also showed that when hydrochars are co-combusted with coal, they have similar combustion indices to that of coal alone. However, based on the energy and ash contents in the produced hydrochars, Primary and Secondary Sludge (PPS2) could be a viable option for co-combustion with coal in an existing coal-fired power plant.
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Arauzo, Pablo J., María Atienza-Martínez, Javier Ábrego, Maciej P. Olszewski, Zebin Cao, and Andrea Kruse. "Combustion Characteristics of Hydrochar and Pyrochar Derived from Digested Sewage Sludge." Energies 13, no. 16 (August 12, 2020): 4164. http://dx.doi.org/10.3390/en13164164.
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In this paper, hydrochars and pyrochars were produced at 260 °C under different residence times (2 and 4 h) using anaerobic digested sewage sludge (SSL) as initial feedstock. The effect of reaction time on the fuel properties of hydrochars and pyrochars was evaluated. Moreover, the combustion kinetics of raw SSL and the derived pyrochars and hydrochars without coal blending were determined at two different air flows (20 and 90 mL/min) and compared. In the same conditions, the yield of hydrochar was significantly lower than that of pyrochar, confirming the different reaction pathways followed in each process. The results showed hydrochars have lower carbon recovery and energy yield than pyrochars, making the latter more suitable for energy purposes. The thermogravimetric combustion study showed that both thermochemical treatments increased the ignition temperature but decreased the burnout temperature, which results in higher stability during handling and storage. However, raw SSL is better for combustion than hydrochar according to the combustibility index. In addition, the kinetic study showed that the activation energy of the combustion of biochars, especially pyrochar, is lower than that of raw SSL, which is advantageous for their combustion.
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Ahmad Ikhwan Muaz Abd Rahman, Nur Alwani Ali Bashah, Wan Zuraida Wan Kamis, Norain Isa, Mohamed Syazwan Osman, Vicinisvarri Inderan, Moses Aderemi Olutoye, and Azam Taufik Mohd Din. "Synthesis of Hydrochars via Hydrothermal Carbonization of Zinc Chloride Activated Cotton Textile Waste." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 114, no. 2 (March 3, 2024): 196–204. http://dx.doi.org/10.37934/arfmts.114.2.196204.
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Anthropogenic pollution from fossil fuel combustion due to increasing global populations and emerging industries poses a serious threat to the environment. Therefore, it is vital to explore alternative green energy sources. Hence, this study synthesized renewable solid fuel hydrochars by utilizing biomass of cotton textile waste (CTW) as feedstock. ZnCl2 was selected as a catalyst due to its Lewis acid properties promoting hydrolysis and dehydration of raw materials towards hydrochar formation. The ZnCl2-activated cotton textile waste (ZnCl2-CTW) was prepared via the wet impregnation method at different ZnCl2 loading. The hydrochars were synthesized via hydrothermal carbonization of ZnCl2-CTW in a Parr batch reactor at the reaction temperature of 200 °C for 3 h. The hydrochars and CTW were characterized using a thermogravimetric analyser (TGA) to evaluate the proximate analysis, whereas an elemental analysis and determination of higher heating value (HHV) were conducted employing a CHNS analyser. The proximate analysis indicates the hydrochars volatile matter increases at higher catalyst loading, possibly due to the high content of bio-oil adsorbed on the hydrochars surface. The elemental analysis shows higher carbon and lower oxygen content for hydrochars compared to CTW, mainly due to the dehydration, decarboxylation, and aromatization reactions during HTC. Meanwhile, the HHV of hydrochars increases as catalyst loading increases to 1.5 g, which obtained the highest value of 18.41 MJ/kg, indicating good quality of solid fuel. This demonstrated that the ZnCl2 catalyst was useful in improving the energy density of hydrochars. Overall, ZnCl2 catalyst loading of 1.5 g has exhibited good performance in producing hydrochars via HTC of CTW. Thus, ZnCl2-CTW has the potential to produce hydrochar suitable as solid fuel, contributing to the conversion of waste into energy and the preservation of the environmental.
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Marrocchi, Assunta, Elisa Cerza, Suhas Chandrasekaran, Emanuela Sgreccia, Saulius Kaciulis, Luigi Vaccaro, Suanto Syahputra, Florence Vacandio, Philippe Knauth, and Maria Luisa Di Vona. "Hydrochar from Pine Needles as a Green Alternative for Catalytic Electrodes in Energy Applications." Molecules 29, no. 14 (July 11, 2024): 3286. http://dx.doi.org/10.3390/molecules29143286.
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Hydrothermal carbonization (HTC) serves as a sustainable method to transform pine needle waste into nitrogen-doped (N-doped) hydrochars. The primary focus is on evaluating these hydrochars as catalytic electrodes for the oxygen reduction reaction (ORR) and carbon dioxide reduction reaction (CO2RR), which are pivotal processes with significant environmental implications. Hydrochars were synthesized by varying the parameters such as nitrogen loading, temperature, and residence time. These materials were then thoroughly characterized using diverse analytical techniques, including elemental analysis, density measurements, BET surface area analysis, and spectroscopies like Raman, FTIR, and XPS, along with optical and scanning electron microscopies. The subsequent electrochemical assessment involved preparing electrocatalytic inks by combining hydrochars with an anion exchange ionomer (AEI) to leverage their synergistic effects. To the best of our knowledge, there are no previous reports on catalytic electrodes that simultaneously incorporate both a hydrochar and AEI. Evaluation metrics such as current densities, onset and half-wave potentials, and Koutecky–Levich and Tafel plots provided insights into their electrocatalytic performances. Notably, hydrochars synthesized at 230 °C exhibited an onset potential of 0.92 V vs. RHE, marking the highest reported value for a hydrochar. They also facilitated the exchange of four electrons at 0.26 V vs. RHE in the ORR. Additionally, the CO2RR yielded valuable C2 products like acetaldehyde and acetate. These findings highlight the remarkable electrocatalytic activity of the optimized hydrochars, which could be attributed, at least in part, to their optimal porosity.
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Calucci, Lucia, and Claudia Forte. "Influence of Process Parameters on the Hydrothermal Carbonization of Olive Tree Trimmings: A 13C Solid-State NMR Study." Applied Sciences 13, no. 3 (January 24, 2023): 1515. http://dx.doi.org/10.3390/app13031515.
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Chars obtained from the hydrothermal carbonization (HTC) of agricultural wastes are increasingly being employed as solid biofuels. Their properties are strongly dependent on HTC process parameters. In this study, 13C solid-state NMR spectroscopy was applied to semiquantitatively investigate carbon functionalities present in olive tree trimming feedstock and in the corresponding hydrochar samples,. Hydrochars were obtained by HTC under different conditions, that is, at two different temperatures (180 and 250 °C), with two different biomass/water ratios (B/W of 7 and 25% w/w) and with reaction times at peak temperatures of 30, 60, and 180 min. The NMR analysis was complemented by infrared spectroscopy experiments. A detailed analysis of carbon functionalities and their evolution during HTC allowed the transformation of feedstock into hydrochar to be followed and the structure of hydrochars to be correlated to the different reactions occurring during HTC in dependence on reaction time, temperature, and B/W ratio, as well as to the hydrochar properties fundamental for their application as solid biofuel reported in previous studies. 13C solid-state NMR spectroscopy revealed a powerful tool for explaining hydrochar properties as a function of HTC parameters.
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Castro-Cárdenas, Marisol, Nahum Andrés Medellín-Castillo, Lázaro Adrián González-Fernández, Roberto Leyva-Ramos, Cesar Fernando Azael Gómez-Duran, Yvan Gariepy, K. R. Jolvis Pou, and Vijaya Raghavan. "Innovative Solution for Invasive Species and Water Pollution: Hydrochar Synthesis from Pleco Fish Biomass." Processes 12, no. 6 (June 4, 2024): 1158. http://dx.doi.org/10.3390/pr12061158.
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In recent years, the invasive pleco fish has emerged as a global concern due to its adverse effects on ecosystems and economic activities, particularly in various water bodies in Mexico. This study introduces an innovative solution, employing microwave-assisted hydrothermal carbonization (MHTC) to synthesize hydrochar from pleco fish biomass. The research aimed to optimize synthesis conditions to enhance hydrochar yield, calorific value, and adsorption capacities for fluoride and cadmium in water. MHTC, characterized by low energy consumption, high reaction rates, and a simple design, was employed as a thermochemical process for hydrochar production. Key findings revealed that through response surface analysis, the study identified the optimal synthesis conditions for hydrochar production, maximizing yield and adsorption capacities while minimizing energy consumption. Physicochemical characterization demonstrated that hydrochars derived from pleco fish biomass exhibited mesoporous structures with fragmented surfaces, resembling hydroxyapatite, a major component of bone. Hydrochars derived from pleco fish biomass exhibited promising adsorption capacities for fluoride and cadmium in water, with hydrochar from Exp. 1 (90 min, 160 °C) showing the highest adsorption capacity for fluoride (4.16 mg/g), while Exp. 5 (90 min, 180 °C) demonstrated superior adsorption capacity for cadmium (98.5 mg/g). Furthermore, the utilization of pleco fish biomass for hydrochar production not only offers an eco-friendly disposal method for invasive species but also addresses fluoride and cadmium contamination issues, contributing to sustainable waste management and water treatment solutions. The resulting hydrochar, rich in solid fuel content with low pollutant emissions, presents a promising approach for waste management and carbon sequestration. Moreover, the optimized synthesis conditions pave the way for sustainable applications in energy production, addressing critical environmental and public health concerns. This research provides valuable insights into the potential of microwave-assisted hydrothermal carbonization for transforming invasive species into valuable resources, thereby mitigating environmental challenges and promoting sustainable development.
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Song, Eunhye, Seyong Park, Seongkuk Han, Eusil Lee, and Ho Kim. "Characteristics of Hydrothermal Carbonization Hydrochar Derived from Cattle Manure." Energies 15, no. 23 (December 4, 2022): 9195. http://dx.doi.org/10.3390/en15239195.
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The characteristics of hydrothermal carbonization hydrochar derived from cattle manure including excrements and lignocellulosic biomass were analyzed. The effects of hydrothermal carbonization were evaluated by varying the reaction temperatures in the range of 180~240 °C. The hydrochars were evaluated with respect to their usefulness as renewable fuels via physicochemical analysis and pyrolysis processes. As reaction temperatures increased, the fractions of fixed carbon in proximate analyses, carbon elements in ultimate analyses, and higher heating values of hydrothermally carbonized biochars increased in correlation with the primary reactions of coalification. Various correlations were derived with the characteristics of hydrochars in order to be utilized for operating and designing HTC reactors for cattle manure. The correlation between the O/C and H/C ratios was deduced on the basis of a van Krevelen diagram. The interaction equation was represented with the increased fraction of HHV compared to the reaction temperature of hydrothermal carbonization. The ultimate correlation for the estimation of higher heating values was suggested for HTC hydrochars. Moreover, the pyrolysis characteristics and kinetic parameters of the cattle manure and hydrochar were deduced by utilizing a multi-step kinetic model scheme. As the HTC reaction temperature increased, the global activation energy and the pre-exponential factors of hydrochars decreased in the low-temperature section and increased in the high-temperature section.
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Karim, Adnan Asad, Mᵃ Lourdes Martínez-Cartas, and Manuel Cuevas-Aranda. "Industrial Two-Phase Olive Pomace Slurry-Derived Hydrochar Fuel for Energy Applications." Polymers 16, no. 11 (May 29, 2024): 1529. http://dx.doi.org/10.3390/polym16111529.
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The present study aims to resolve the existing research gaps on olive pomace (OP) hydrochars application as a fuel by evaluating its molecular structures (FTIR and solid NMR analysis), identifying influential characteristics (Pearson correlation analysis), process optimization (response surface methodology), slagging–fouling risks (empirical indices), and combustion performance (TG-DSC analysis). The response surfaces plot for hydrothermal carbonization (HTC) of OP slurry performed in a pressure reactor under varied temperatures (180–250 °C) and residence times (2–30 min) revealed 250 °C for 30 min to be optimal conditions for producing hydrochar fuel with a higher heating value (32.20 MJ·Kg−1) and energy densification ratio (1.40). However, in terms of process efficiency and cost-effectiveness, the optimal HTC conditions for producing the hydrochar with the highest energy yield of 87.9% were 202.7 °C and 2.0 min. The molecular structure of hydrochar was mainly comprised of aromatic rings with methyl groups, alpha-C atoms of esters, and ether bond linkages of lignin fractions. The slagging and fouling risks of hydrochars were comparatively lower than those of raw OP, as indicated by low slagging and fouling indices. The Pearson correlation analysis emphasized that the enrichment of acid-insoluble lignin and extractive contents, carbon densification, and reduced ash content were the main pivotal factors for hydrochar to exhibit better biofuel characteristics for energy applications.
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Xiong, Jiangbo, Shuaiwei Chen, Jiaxin Wang, Yujie Wang, Xiaolin Fang, and Huajun Huang. "Speciation of Main Nutrients (N/P/K) in Hydrochars Produced from the Hydrothermal Carbonization of Swine Manure under Different Reaction Temperatures." Materials 14, no. 15 (July 23, 2021): 4114. http://dx.doi.org/10.3390/ma14154114.
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Hydrothermal carbonization (HTC) has been proved to be a promising technology for swine manure (SM) treatment. Currently, there is a lack of systematic understanding of the transformation characteristics of nutrient speciation in the HTC of SM. In this study, the speciation of the main nutrients (N/P/K) in SM-derived hydrochar produced at different reaction temperatures (200–280 °C) was investigated. The recovery of P (61.0–67.1%) in hydrochars was significantly higher than that of N (23.0–39.8%) and K (25.5–30.0%), and the increase in reaction temperature promoted the recovery of P and reduced the recovery of N. After the HTC treatment, the percentage of soluble/available P was reduced from 61.6% in raw SM to 4.0–23.9% in hydrochars, while that of moderately labile/slow-release P was improved from 29.2% in raw SM feedstock to 65.5–82.7%. An obvious reduction was also found in the amounts of available N (from 51.3% in raw SM feedstock to 33.0–40.5% in hydrochars). The percentages of slow-release N and residual N in hydrochars produced at 240 °C reached the maximum and minimum values (46.4% and 18.9%), respectively. A total of 49.5–58.3% of K retained in hydrochars was residual (invalid) potassium. From the perspective of the mobility and availability of N, P and K only, it was suggested that the HTC of SM should be carried out at 220–240 °C. Compared with the original SM, it is safer and more effective to use the SM-derived hydrochar as an organic fertilizer.
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Vardiambasis, Ioannis O., Theodoros N. Kapetanakis, Christos D. Nikolopoulos, Trinh Kieu Trang, Toshiki Tsubota, Ramazan Keyikoglu, Alireza Khataee, and Dimitrios Kalderis. "Hydrochars as Emerging Biofuels: Recent Advances and Application of Artificial Neural Networks for the Prediction of Heating Values." Energies 13, no. 17 (September 3, 2020): 4572. http://dx.doi.org/10.3390/en13174572.
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In this study, the growing scientific field of alternative biofuels was examined, with respect to hydrochars produced from renewable biomasses. Hydrochars are the solid products of hydrothermal carbonization (HTC) and their properties depend on the initial biomass and the temperature and duration of treatment. The basic (Scopus) and advanced (Citespace) analysis of literature showed that this is a dynamic research area, with several sub-fields of intense activity. The focus of researchers on sewage sludge and food waste as hydrochar precursors was highlighted and reviewed. It was established that hydrochars have improved behavior as fuels compared to these feedstocks. Food waste can be particularly useful in co-hydrothermal carbonization with ash-rich materials. In the case of sewage sludge, simultaneous P recovery from the HTC wastewater may add more value to the process. For both feedstocks, results from large-scale HTC are practically non-existent. Following the review, related data from the years 2014–2020 were retrieved and fitted into four different artificial neural networks (ANNs). Based on the elemental content, HTC temperature and time (as inputs), the higher heating values (HHVs) and yields (as outputs) could be successfully predicted, regardless of original biomass used for hydrochar production. ANN3 (based on C, O, H content, and HTC temperature) showed the optimum HHV predicting performance (R2 0.917, root mean square error 1.124), however, hydrochars’ HHVs could also be satisfactorily predicted by the C content alone (ANN1, R2 0.897, root mean square error 1.289).
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Soroush, Sepideh, Frederik Ronsse, Jihae Park, and Philippe M. Heynderickx. "Comparison Study on the Water-to-Biomass Ratio in Hydrothermal Carbonization of Fresh Seaweed." Processes 11, no. 4 (April 5, 2023): 1123. http://dx.doi.org/10.3390/pr11041123.
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Upgrading wet biomass to char via hydrothermal carbonization is a promising method to produce valuable resources for adsorption of organic impurities. In this work, a fresh green seaweed, Ulva pertusa, was investigated to demonstrate the effects of pre-drying and pre-washing on the process and the hydrochar production. Surface moisture and bound moisture were found to affect this process. Hydrochar produced from fresh seaweed with additional water showed similar adsorption capacity to fresh seaweed without additional water and 38% higher than hydrochar from soaked dry seaweed. This was supported by FTIR spectra analysis, which showed that these hydrochars produced from fresh seaweed without additional water have the highest proportion of carboxyl functional groups.
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Brown, Aaron E., Jessica M. M. Adams, Oliver R. Grasham, Miller Alonso Camargo-Valero, and Andrew B. Ross. "An Assessment of Different Integration Strategies of Hydrothermal Carbonisation and Anaerobic Digestion of Water Hyacinth." Energies 13, no. 22 (November 16, 2020): 5983. http://dx.doi.org/10.3390/en13225983.
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Water hyacinth (WH) is an invasive aquatic macrophyte that dominates freshwater bodies across the world. However, due to its rapid growth rate and wide-spread global presence, WH could offer great potential as a biomass feedstock, including for bioenergy generation. This study compares different integration strategies of hydrothermal carbonisation (HTC) and anaerobic digestion (AD) using WH, across a range of temperatures. These include (i) hydrochar combustion and process water digestion, (ii) hydrochar digestion, (iii) slurry digestion. HTC reactions were conducted at 150 °C, 200 °C, and 250 °C. Separation of hydrochars for combustion and process waters for digestion offers the most energetically-feasible valorisation route. However, hydrochars produced from WH display slagging and fouling tendencies; limiting their use in large-scale combustion. AD of WH slurry produced at 150 °C appears to be energetically-feasible and has the potential to also be a viable integration strategy between HTC and AD, using WH.
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Kohzadi, Shadi, Nader Marzban, Kazem Godini, Nader Amini, and Afshin Maleki. "Effect of Hydrochar Modification on the Adsorption of Methylene Blue from Aqueous Solution: An Experimental Study Followed by Intelligent Modeling." Water 15, no. 18 (September 10, 2023): 3220. http://dx.doi.org/10.3390/w15183220.
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Wheat straw, which is a carbon-rich precursor and a common agriculture waste in Sanandaj, was modified to produce hydrochar with high adsorption capacity by the hydrothermal carbonization (HTC) method. The hydrochars were tested as adsorbents to remove methylene blue (MB) from aqueous solution, and the effects of various interfering parameters, including pH, MB concentration, and adsorbent dosage, were investigated using artificial neural networks (ANNs) on adsorption modeling. Adsorption isotherms and kinetics were studied to explain the MB adsorption process. The prepared hydrochars were characterized using Brunauer–Emmett–Teller (BET), scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDAX), and high-performance liquid chromatography (HPLC) instruments. The maximum MB removal efficiency achieved by hydrochar modified by KOH (0.1 M) and adsorption data fitted well with the Langmuir isotherm and pseudo-second-order kinetics. In terms of elemental composition, the hydrochar sample contained 52.19% carbon (C), 3.37% hydrogen (H), 0.1% nitrogen (N), 0.15% sulfur (S), and 35.66% oxygen (O). The ash content in the sample was 8.50%. The recorded hydrogen-to-carbon ratio (H/C) and oxygen-to-carbon ratio (O/C) indicated a shift towards humification, implying the influence of KOH addition during the hydrochar production process. Additionally, the specific surface area of the hydrochar, as measured by the BET method, was found to be 11.54 m²/g. Among the aromatics, a significant presence of hydroxymethylfurfural (HMF) was detected, with a concentration of 4.70 g/kg DM. The modeling results demonstrated that the concentration of MB had the most substantial impact on the predicted removal, followed by pH, adsorbent dosage, and contact time.
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Saha, Swarna, Md Tahmid Islam, Joshua Calhoun, and Toufiq Reza. "Effect of Hydrothermal Carbonization on Fuel and Combustion Properties of Shrimp Shell Waste." Energies 16, no. 14 (July 21, 2023): 5534. http://dx.doi.org/10.3390/en16145534.
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Shrimp shell is a popularly consumed seafood around the globe which generates a substantial quantity of solid wet waste. Hydrothermal carbonization (HTC) could be a viable pathway to convert wet shrimp shell waste into energy-dense hydrochar. The present study aims to assess the fuel properties, physicochemical attributes, and combustion properties of shrimp shell hydrochar generated with a wide range of HTC temperatures (110–290 °C). Results showed that a rise in carbonization rate results in a decline in mass yield to as low as 25.7% with the increase in HTC temperature. Thermogravimetric analysis indicates shrimp shell hydrochars to be more thermally stable than raw dried feedstock. Results from the bomb calorimeter report a maximum HHV of 27.9 MJ/kg for SS-290, showing a 13% increase in energy densification compared to raw shrimp shell. The slagging and fouling indices determined for the hydrochars further assisted in addressing the concern regarding increasing ash content changing from 17.0% to 36.6%. Lower ratings of the slagging index, fouling index, alkali index, and chlorine content for hydrochars at higher temperature indicate the reduced probability of reactor fouling during combustion. The findings of the analysis demonstrate that HTC is a promising approach for transforming shrimp shell waste into a potential fuel replacement.
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Naranjo, Jhosué, Evelyn Juiña, Carlos Loyo, Michelle Romero, Karla Vizuete, Alexis Debut, Sebastian Ponce, and Herman A. Murillo. "Preparation of Adsorbent Materials from Rice Husk via Hydrothermal Carbonization: Optimization of Operating Conditions and Alkali Activation." Resources 12, no. 12 (December 12, 2023): 145. http://dx.doi.org/10.3390/resources12120145.
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Hydrothermal carbonization (HTC) of rice husk was optimized in terms of the adsorption capacity at equilibrium (qe) and hydrochar mass yield (MY). The studied variables were reaction temperature, residence time, and biomass-to-water ratio by means of response surface methodology. In both cases, reaction temperature resulted the most significant parameter promoting high qe values at higher temperatures when treating methylene blue (MB) as the target pollutant. Nevertheless, MY was low (~40%) when focusing on a possible industrial application. Hence, maximizing qe and MY simultaneously by optimization of multiple responses emerges as a promising solution to improve MY values (>60%) with no significant differences regarding the qe response. Furthermore, additional activation was conducted on optimal hydrochars to further investigate the enhancement of qe. As a result, no statistical differences between non-modified and activated hydrochars were observed for qe; however, the pseudo-second-order constant (k2) seemed to be increased after alkali activation, mainly due to a larger surface area. Non-modified and activated hydrochars were characterized via SEM, FTIR, XRD, and BET, resulting in two significant effects contributing to MB adsorption: increased surface area and functionalized hydrochar surface. Consequently, this work provides valuable insights on subsequent application of this HTC optimization scheme at an industrial scale.
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Kalderis, D., M. S. Kotti, A. Méndez, and G. Gascó. "Characterization of hydrochars produced by hydrothermal carbonization of rice husk." Solid Earth 5, no. 1 (June 11, 2014): 477–83. http://dx.doi.org/10.5194/se-5-477-2014.
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Abstract. Biochar is the carbon-rich product obtained when biomass, such as wood, manure or leaves, is heated in a closed container with little or no available air. In more technical terms, biochar is produced by so-called thermal decomposition of organic material under limited supply of oxygen (O2), and at relatively low temperatures (< 700 °C). Hydrochar differentiates from biochar because it is produced in an aqueous environment, at lower temperatures and longer retention times. This work describes the production of hydrochar from rice husks using a simple, safe and environmentally friendly experimental set-up, previously used for degradation of various wastewaters. Hydrochars were obtained at 200 °C and 300 °C and at residence times ranging from 2 to 16 h. All samples were then characterized in terms of yield, surface area, pH, conductivity and elemental analysis, and two of them were selected for further testing with respect to heating values and heavy metal content. The surface area was low for all hydrochars, indicating that porous structure was not developed during treatment. The hydrochar obtained at 300 °C and 6 h residence times showed a predicted higher heating value of 17.8 MJ kg−1, a fixed carbon content of 46.5% and a fixed carbon recovery of 113%, indicating a promising behaviour as a fuel.
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Sui, Zifeng, Jie Wu, Jiawei Wang, Yutong Cao, Qihao Wang, and Weipeng Chen. "Effect of hydrothermal carbonization temperature on fuel properties and combustion behavior of high-ash corn and rice straw hydrochar." Thermal Science, no. 00 (2022): 186. http://dx.doi.org/10.2298/tsci220813186s.
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Hydrothermal carbonization (HTC) has been proven to improve the fuel properties of low-ash straw biomass. To explore the effect of HTC on high-ash straw biomass, the fuel properties and combustion behavior of hydrochar prepared by high-ash rice straw and corn straw at different temperature were studied. The results showed that increased reaction temperature could improve the C content, fixed carbon, heating value and fuel ratios (FC/VM) in high-ash straw hydrochars, which is similar to the change trend of low-ash biomass. The hydrochar prepared at 260?C has similar H/C and O/C atomic ratios and FC/VM to lignite. In addition, the highest energetic recovery efficiency is obtained at 200?C. While at 180?C, the comprehensive combustion characteristic index of the hydrochar is the best, which is 5.04?10-11 (min-2?K-3) and 6.42?10-11 (min-2?K-3). In addition, the C content in the hydrochars at 180?C was lower than the raw material, and the ash content increases with the reaction temperature, which is quite different from the low-ash biomass. In conclusion, the HTC could improve the fuel quality of high-ash straw, while its ash content remains at a high level.
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Kahilu, Gentil Mwengula, Samson Bada, and Jean Mulopo. "Coal Discards and Sewage Sludge Derived-Hydrochar for HIV Antiretroviral Pollutant Removal from Wastewater and Spent Adsorption Residue Evaluation for Sustainable Carbon Management." Sustainability 14, no. 22 (November 15, 2022): 15113. http://dx.doi.org/10.3390/su142215113.
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The effects of various parameter interactions on the textural structure of hydrochars produced via hydrothermal (HTC) and co-hydrothermal (Co-HTC) treatments of coal discards and sewage sludge (wastes), as well as the subsequent use of the hydrochars (HCs) synthesized for HIV drug (nevirapine and lamivudine) removal from wastewater, were investigated in this study. The HTC and Co-HTC process improved the carbon content of the raw material by 13.47%, 7.08%, and 30.65% for hydrochar coal tailing (HCT), hydrochar coal slurry (HCS), and hydrochar from coal–sewage blend (HCB), respectively. The Co-HTC-derived HCB had a high SBET of 20.35 m2/g and pore volume of 0.38 cm3/g, leading to significant adsorptive reductions of nevirapine (NEV) and lamivudine (LAM) (97.19% and 93.32%, respectively). HCT and HCS displayed high NEV and LAM adsorption capacities (50 mg g−1, 42 mg g−1 and 52 mg g−1, 41 mg g−1), respectively, despite being less effective than HCB (53.8 mg g−1, 42.8 mg g−1). In addition, the use of spent adsorption residues for energy storage applications was investigated further. The findings showed that spent adsorption residues are an effective carbonaceous material precursor to produce electrical double-layer capacitors (EDLCs).
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Multhaupt, Hendrik, Patrick Bottke, and Michael Wark. "Enhanced Breaking of Lignin and Mesopore Formation in Zinc Chloride Assisted Hydrothermal Carbonization of Waste Biomasses." C 7, no. 4 (November 11, 2021): 77. http://dx.doi.org/10.3390/c7040077.
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Hydrochars from hydrothermal carbonization of different biowaste materials (dried dandelion, sawdust, coconut shell powder) formed in the presence of aqueous salt solutions were compared to those obtained by the common method in pure water. Hydrochars with increased carbon contents, pore volume and surface areas were specifically obtained from coconut shell powder in the presence of zinc chloride. Compositional and structural changes within the hydrochar products caused by the process conditions and/or the additive were characterized by solid state 13C NMR spectroscopy, proving that cellulose and, in particular, lignin units in the biomass are more easily attacked in the presence of the salt. Under saline conditions, a distinct particle break-up led to the creation of mesoporosity, as observable from hysteresis loops in nitrogen adsorption isotherms, which were indicative of the presence of pores with diameters of about 3 to 10 nm. The obtained hydrochars were still rich in functional groups which, together with the mesoporosity, indicates the compounds have a high potential for pollutant removal. This was documented by adsorption capacities for the methylene blue and methyl orange dyes, which exceeded the values obtained for other hydrochar-based adsorbers. A subsequent physical activation of the mesoporous hydrochars in steam at different temperatures and times resulted in a further drastic increase in the surface areas, of up to about 750 m2/g; however, this increase is mainly due to micropore formation coupled with a loss of surface functionality. Consequently, the adsorption capacity for the quite large dyes does not provide any further benefit, but the uptake of smaller gas molecules is favored.
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Fan, Fangyu, Zongling Yang, Han Li, Zhengjun Shi, and Huan Kan. "Preparation and properties of hydrochars from macadamia nut shell via hydrothermal carbonization." Royal Society Open Science 5, no. 10 (October 2018): 181126. http://dx.doi.org/10.1098/rsos.181126.
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Macadamia nut shell (MNS) is a type of waste lignocellulose obtained from macadamia nut production processing. Large MNS wastes caused serious resource waste and environmental pollution. So, preparation of hydrochars from MNS via hydrothermal carbonization (HTC) is of great significance. HTC of MNS was conducted to study the effect of process parameters, including HTC temperature (180–260°C) and residence time (60–180 min) on the properties of hydrochars. Results showed that the increase in HTC temperature and residence time decreased the mass yield of hydrochars and increased the high heating value of hydrochars. Furthermore, the C content of hydrochars increased, whereas the H and O contents decreased. Mass yield of hydrochar is 46.59%, energy yield is 64.55% and the higher heating value is 26.02 MJ kg −1 at a temperature of 260°C and time of 120 min. The surface structure of hydrochars was rougher compared with that of MNS as observed via scanning electron microscopy. The chemical and combustion behaviour of MNS and hydrochars was analysed by Fourier transform infrared spectroscopy, and thermogravimetric analysis indicated that decarboxylation and dehydration reactions were the predominant pathways during the HTC process. Results showed that HTC can facilitate the transformation of MNS into solid fuel.
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Paneque, Marina, Heike Knicker, Jürgen Kern, and José María De la Rosa. "Hydrothermal Carbonization and Pyrolysis of Sewage Sludge: Effects on Lolium perenne Germination and Growth." Agronomy 9, no. 7 (July 9, 2019): 363. http://dx.doi.org/10.3390/agronomy9070363.
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The pyrolysis and hydrothermal carbonization (HTC) of sewage sludge (SS) resulted in products free of pathogens, with the potential for being used as soil amendment. With this work, we evaluated the impact of dry pyrolysis-treated (600 °C, 1 h) and HTC-treated (200 °C, 260 °C; 0.5 h, 3 h) SS on the germination, survival, and growth of Lolium perenne during an 80 day greenhouse experiment. Therefore, the hydrochars and pyrochars were amended to a Calcic Cambisol at doses of 5 and 25 t ha−1. The addition of sludge pyrochars to the Cambisol did not affect Lolium germination, survival rates or plant yields. However, the use 25 t ha−1 of wood biochar reduced germination and survival rates, which may be related to the low N availability of this sample. In comparison to the control, higher or equal plant biomass was produced in the hydrochar-amended pots, even though some hydrochars decreased plant germination and survival rates. Among all the evaluated char properties, only the organic and inorganic N contents of the chars, along with their organic C values, positively correlated with total and shoot biomass production. Our work demonstrates the N fertilization potential of the hydrochar produced at low temperature, whereas the hydrochar produced at 260 °C and the pyrochars were less efficient with respect to plant yields.
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Thakur, Himanshi. "Hydrochar Production Methods: Comparative Insights into Hydrothermal and Microwave Processes." African Journal of Biological Sciences 6, no. 7 (June 17, 2024): 3033–44. http://dx.doi.org/10.48047/afjbs.6.7.2024.3033-3044.
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This study compares hydrochar production from agricultural waste using conventional hydrothermal carbonization (HTC) and microwave-assisted carbonization methods. Wheat straw (HWS), rice straw (HRS), and bagasse (HBG) were used as feedstocks. Microwave-assisted carbonization resulted in higher yields and distinct chemical structures compared to conventional HTC. Microwave hydrochars (m-HWS, m-HRS, mHBG) showed lower surface areas but increased pore volumes and thermal stability. They also exhibited enhanced heavy metal adsorption capacities, particularly at higher pH levels. These findings highlight the advantages of microwave-assisted carbonization for producing hydrochar with superior properties, offering insights for optimizing production processes and expanding applications.
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Petrovic, Jelena, Marija Simic, Marija Mihajlovic, Marija Koprivica, Marija Kojic, and Ivona Nuic. "Upgrading fuel potentials of waste biomass via hydrothermal carbonization." Chemical Industry 75, no. 5 (2021): 297–305. http://dx.doi.org/10.2298/hemind210507025p.
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In recent decades, massive exploitation of fossil fuels caused a growing demand for the production of energies from renewable sources. Hydrochar obtained from waste biomass via hydrothermal carbonization (HTC) possesses good potentials as a biofuel. Therefore, we performed HTC of corn cob, paulownia leaves, and olive pomace at different temperatures (180, 220, and 260oC). The main goal of this study was to comparatively evaluate the influence of HTC conditions on the structure and fuel characteristics of the obtained solids. The results showed that the yields of hydrochar decrease significantly with increasing temperature in all samples. The carbon content and higher heating value increased and reached the highest values in hydrochars obtained at 260?C, while the content of volatile matter decreased. Furthermore, the Van Krevelen diagram reveals that the transformation of feedstock to lignite-like products upon HTC was achieved. In this study, the results showed that processes of dehydration and decarboxylation during HTC provoke intensive biomass transformation and that hydrochars obtained at higher temperatures have significantly enhanced fuel properties and fewer volatiles compared to the feedstock.
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Gonnella, Gabriella, Giulia Ischia, Luca Fambri, and Luca Fiori. "Thermal Analysis and Kinetic Modeling of Pyrolysis and Oxidation of Hydrochars." Energies 15, no. 3 (January 27, 2022): 950. http://dx.doi.org/10.3390/en15030950.
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This study examines the kinetics of pyrolysis and oxidation of hydrochars through thermal analysis. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques were used to investigate the decomposition profiles and develop two distributed activation energy models (DAEM) of hydrochars derived from the hydrothermal carbonization of grape seeds produced at different temperatures (180, 220, and 250 °C). Data were collected at 1, 3, and 10 °C/min between 30 and 700 °C. TGA data highlighted a decomposition profile similar to that of the raw biomass for hydrochars obtained at 180 and 220 °C (with a clear distinction between oil, cellulosic, hemicellulosic, and lignin-like compounds), while presenting a more stable profile for the 250 °C hydrochar. DSC showed a certain exothermic behavior during pyrolysis of hydrochars, an aspect also investigated through thermodynamic simulations in Aspen Plus. Regarding the DAEM, according to a Gaussian model, the severity of the treatment slightly affects kinetic parameters, with average activation energies between 193 and 220 kJ/mol. Meanwhile, the Miura–Maki model highlights the distributions of the activation energy and the pre-exponential factor during the decomposition.
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Gronwald, M., A. Don, B. Tiemeyer, and M. Helfrich. "Effects of fresh and aged chars from pyrolysis and hydrothermal carbonization on nutrient sorption in agricultural soils." SOIL 1, no. 1 (June 18, 2015): 475–89. http://dx.doi.org/10.5194/soil-1-475-2015.
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Abstract. Leaching of nutrients from agricultural soils causes major environmental problems that may be reduced with amendments of chars derived from pyrolysis (pyrochars) or hydrothermal carbonization (hydrochars). Chars are characterized by a high adsorption capacity – i.e. they may retain nutrients such as nitrate and ammonium. However, the physicochemical properties of the chars and hence their sorption capacity likely depend on feedstock and the production process. We investigated the nutrient retention capacity of pyrochars and hydrochars from three different feedstocks (digestates, Miscanthus, woodchips) mixed into different soil substrates (sandy loam and silty loam). Moreover, we investigated the influence of char degradation on its nutrient retention capacity using a 7-month in situ field incubation of pyrochar and hydrochar mixed into soils at three different field sites. Pyrochars showed the highest ability to retain nitrate, ammonium and phosphate, with pyrochar from woodchips being particularly efficient in nitrate adsorption. Ammonium adsorption of pyrochars was controlled by the soil type of the soil–char mixture. We found some ammonium retention on sandy soils, but no pyrochar effect or even ammonium leaching from the loamy soil. The phosphate retention capacity of pyrochars strongly depended on the pyrochar feedstock with large phosphate leaching from digestate-derived pyrochar and some adsorption capacity from woodchip-derived pyrochar. Application of hydrochars to agricultural soils caused small, and often not significant, effects on nutrient retention. In contrast, some hydrochars did increase the leaching of nutrients compared to the non-amended control soil. We found a surprisingly rapid loss of the chars' adsorption capacity after field application of the chars. For all sites and for hydrochar and pyrochar, the adsorption capacity was reduced by 60–80 % to less or no nitrate and ammonium adsorption. Thus, our results cast doubt on the efficiency of char applications to temperate zone soils to minimize nutrient losses via leaching.
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Luthfi, Numan, Takashi Fukushima, Xiulun Wang, and Kenji Takisawa. "Hydrochar as an Alternative to Coal: A Comparative Study of Lignocellulosic and Nonlignocellulosic Biomass." Resources 13, no. 4 (March 31, 2024): 49. http://dx.doi.org/10.3390/resources13040049.
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Hydrothermal carbonization (HTC) is a widely used process for converting biomass with a wide range of moisture. Biomass selection poses challenges in producing hydrochar with desired properties because of their different constituents. In this study, we investigated the fuel properties of hydrochar of sorghum bagasse (SB) and microalgae (MA) at different severity factors (SFs = 4.08, 4.43, 5.56, 5.90, and 6.63) and their potential as alternatives to coal. The results show that during HTC, both biomasses underwent dehydration, in addition to the noticeable decarboxylation of MA. Fixed carbon increasingly developed in the SB hydrochar, in contrast to the MA hydrochar, which formed volatile hydrocarbon; thus, the MA hydrochar released heat values of 26.7–36.2 MJ·kg−1, which was higher than that of SB at 19.7–28.0 MJ·kg−1. However, owing to the stable hydrocarbons, SB hydrochar is assumed to combust more stably and ignite more decently, as indicated by its fuel ratio (0.83), approaching 0.9–1.5. Moreover, the greater number of solids recovered in SB after carbonization makes its conversion more techno-commercially viable, retaining 1.8 times more of the original energy. Conflating these fuel properties reveals that SB hydrochar (SF = 6.63) is a promising alternative to steam coal, and MA hydrochar is an attractive alternative to both steam (SF = 4.08–5.90) and coking coals (SF = 6.63). Concisely, both biomasses are practically promising as value-added hydrochars, but only SB can be developed beyond the current HTC severity owing to the thermal stability of its hydrocarbons.
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Guo, Shuai, Weinan Xiao, Zhaoyuan Liu, Deng Zhao, Kaixin Chen, Chenchen Zhao, Xingcan Li, and Guangyu Li. "Fuel Characteristics and Removal of AAEMs in Hydrochars Derived from Sewage Sludge and Corn Straw." Molecules 28, no. 2 (January 12, 2023): 781. http://dx.doi.org/10.3390/molecules28020781.
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Co-hydrothermal carbonization (Co-HTC) of sewage sludge (SS) and corn straw (CS) for fuel preparation is a waste treatment method that reduces the pre-treatment cost of solid waste and biomass fuel. Based on the response surface methodology (RSM), a test was designed to prepare SS and CS hydrochars using a hydrothermal high-pressure reactor. The test examined the higher heating value (HHV) and the concentrations of alkali metals and alkaline earth metals (AAEMs) and Cl. The HHV of SS-hydrochar decreased with an increase in reaction temperature, but that of CS-hydrochar increased. The yield of CS-hydrochar was at 26.74–61.26%, substantially lower than that of SS-hydrochar. Co-hydrochar has the advantages of HHV and an acceptable yield. The HHV of co-hydrochar was 9215.51–12,083.2 kJ/kg, representing an increase of 12.6–47.6% over single component hydrochar, while the yield of co-hydrochar was 41.46–72.81%. In addition, the stabilities of AAEM and Cl in the co-hydrochar were Mg > Ca > K > Na > Cl. SS and CS had a synergistic effect on dechlorination efficiency (DE), which had a negative effect on the removal efficiency (RE) of Ca and Na. The optimal hydrocharization conditions were a temperature of approximately 246.14 °C, a residence time of approximately 90 min, and a mixing ratio of SS–CS of approximately 57.18%. The results offer a way to utilize SS and CS by Co-HTC and convert them into low-chlorine and low-alkali fuel, thus pushing the improvement of this promising waste-to-energy technology.
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Farru, Gianluigi, Chau Huyen Dang, Maja Schultze, Jürgen Kern, Giovanna Cappai, and Judy A. Libra. "Benefits and Limitations of Using Hydrochars from Organic Residues as Replacement for Peat on Growing Media." Horticulturae 8, no. 4 (April 13, 2022): 325. http://dx.doi.org/10.3390/horticulturae8040325.
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New technologies for the production of peat-substitutes are required to meet the rising demand for growing media in horticulture and the need to preserve natural peatlands. Hydrothermal conversion of organic residues into char materials, hydrochars, with peat-like properties may produce such substitutes, reducing environmental impacts and CO2 emissions from improper management. To assess their potential as a component in growing media, cress seed germination tests are used to assess hydrochars from digestate (D), spent coffee grounds (SCG), and grape marc (GM). Pre- and post-treatments (extraction, washing, and drying) are applied to remove phytotoxic compounds associated with process waters retained on the hydrochars, and a nitrification bioassay with process water is used to predict their toxicity. All hydrochars achieve similar or better germination results compared to their feedstock, showing a potential to replace at least 5% of peat in growing media. SCG and GM hydrochars show inhibition above 5%, while all post-treated D-hydrochar mixtures produce >3 times longer roots than the control. The nitrification test shows a high sensitivity and good agreement with the high inhibition trends found in the germination tests with process water. Such tests can be a good way to optimize process combinations for the hydrothermal production of peat replacements.
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Ciuoderis-Aponte, Karl A., and Julieta E. Ochoa-Amaya. "Lesiones tuberculoides y neumonía piogranulomatosa en un Chigüiro (Hydrocharis hydrochaeris)." Orinoquia 14, no. 2 sup (December 1, 2010): 126–35. http://dx.doi.org/10.22579/20112629.101.
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Titulo en ingles: Tuberculoid lesions and pyogranulomatous pneumonia in a Capybara (Hydrochaeris hidrochaeris)RESUMEN: Corynebacterium kutscheri, un bacilo ligeramente curvado, gram positivo, acido alcohol resistente, provoca una infección en roedores denominada corinebacteriosis murina la cual fue llamada en un principio como pseudotuberculosis murina por que se semejaba con la tuberculosis del ratón, una enfermedad clínica con presencia de abscesos pulmonares y necrosis caseosa. La mayor parte de las infecciones por C. kutscheri en roedores son subclínicas y sólo efectos inmunosupresores revelan los casos clínicos que se presentan con secreción nasal y ocular, disnea, artritis y abscesos cutáneos que forman nódulos grises de unos 15 mm de diámetro. Las corinebacterias se consideran zoonóticas y el hombre adquiere la infección por el contacto con animales enfermos, sus órganos o sus productos; asimismo entre animales la infección se transmite de un animal con un absceso abierto a otro con abrasiones como las producidas durante las disputas territoriales. El presente reporte de caso describe la presentación de una reacción piogranulomatosa pulmonar.ABSTRACT: Corynebacterium kutscheri, a gram positive, and acid- alcohol resistant slightly curved bacillus, causes an infection in rodents called murine corynebacteriosis which was named at first as murine pseudotuberculosis due resembled the mouse tuberculosis, a clinical disease with abscesses pulmonary and caseous necrosis. The majority of infections in rodents are subclinical and only immunosuppressive effects reveals the clinical cases that are presented with nasal and ocular discharge, dyspnea, arthritis and skin abscesses forming 15 mm gray nodules. Corynebacterias are considered zoonotic, and the man becomes infected through direct contact with sick animals, their organs or their products; among animals, the infection also is transmitted from one animal with an opened abscess to the other with abrasions as those produced during territorial disputes.This case report describes the presentation of pulmonary pyogranulomatous reaction.
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Khalaf, Nidal, Wenxuan Shi, Witold Kwapinski, and J. J. Leahy. "Hydrothermal carbonization (HTC) of dairy waste: effect of temperature and initial acidity on the composition and quality of solid and liquid products." Open Research Europe 2 (June 23, 2022): 83. http://dx.doi.org/10.12688/openreseurope.14863.1.
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Background: Hydrothermal carbonization (HTC) of dairy processing waste was performed to investigate the effect of temperature and initial pH on the yield and composition of the solid (hydrochar) and liquor produced. All hydrochars met the EU requirements of organo-mineral solid fertilizers defined in the Fertilizing Products Regulation in terms of phosphorus (P) and mineral content. Methods: Laboratory scale HTC was performed using pressurized reactors, and the products (solid and liquid) were collected, stored and analyzed for elemental composition and nutrient content using Inductively coupled plasma optical emission spectroscopy (ICP-OES), ultraviolet-visible spectrophotometry (UV-Vis) and other analytic techniques. Results: Maximum hydrochar yield (60.67%) was observed at T=180℃ and pH=2.25, whereas the maximum P-recovery was 80.38% at T=220℃ and pH=4.6. The heavy metal content of the hydrochars was mostly compliant with EU limitations, except for Ni at T=220℃ and pH=8.32. Meanwhile, further study of Chromium (Cr) species is essential to assess the fertilizer quality of the hydrochars. For the liquid product, the increase in temperature beyond 200℃, coupled with an increase in initial acidity (pH=2.25) drove P into the liquor. Simultaneously, increasing HTC temperature and acidity increased the concentration of NO3- and NH4+ in the liquid products to a maximum of 278 and 148 mg/L, respectively, at T=180℃ and pH=4.6. Furthermore, no direct relation between final pH of liquor and NH4+ concentration was observed. Conclusions: HTC improved the nutrient content of dairy waste, allowing for the production of potential solid organo-mineral fertilizers requiring additional treatment to ensure safe fertilizer application.
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Khalaf, Nidal, Wenxuan Shi, Owen Fenton, Witold Kwapinski, and J. J. Leahy. "Hydrothermal carbonization (HTC) of dairy waste: effect of temperature and initial acidity on the composition and quality of solid and liquid products." Open Research Europe 2 (July 12, 2022): 83. http://dx.doi.org/10.12688/openreseurope.14863.2.
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Background: Hydrothermal carbonization (HTC) of dairy processing waste was performed to investigate the effect of temperature and initial pH on the yield and composition of the solid (hydrochar) and liquor produced. All hydrochars met the EU requirements of organo-mineral solid fertilizers defined in the Fertilizing Products Regulation in terms of phosphorus (P) and mineral content. Methods: Laboratory scale HTC was performed using pressurized reactors, and the products (solid and liquid) were collected, stored and analyzed for elemental composition and nutrient content using Inductively coupled plasma optical emission spectroscopy (ICP-OES), ultraviolet-visible spectrophotometry (UV-Vis) and other analytic techniques. Results: Maximum hydrochar yield (60.67%) was observed at T=180℃ and pH=2.25, whereas the maximum P-recovery was 80.38% at T=220℃ and pH=4.6. The heavy metal content of the hydrochars was mostly compliant with EU limitations, except for Ni at T=220℃ and pH=8.32. Meanwhile, further study of Chromium (Cr) species is essential to assess the fertilizer quality of the hydrochars. For the liquid product, the increase in temperature beyond 200℃, coupled with an increase in initial acidity (pH=2.25) drove P into the liquor. Simultaneously, increasing HTC temperature and acidity increased the concentration of NO3- and NH4+ in the liquid products to a maximum of 278 and 148 mg/L, respectively, at T=180℃ and pH=4.6. Furthermore, no direct relation between final pH of liquor and NH4+ concentration was observed. Conclusions: HTC improved the nutrient content of dairy waste, allowing for the production of potential solid organo-mineral fertilizers requiring additional treatment to ensure safe fertilizer application.
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Wu, Xiaoming, and Chichun Hu. "Greener Solution to Waste Corn Stalks and Shortage of Asphalt Resource: Hydrochar Produced by Hydrothermal Carbonization as a Novel Performance Enhancer for Asphalt Binder." Materials 14, no. 6 (March 15, 2021): 1427. http://dx.doi.org/10.3390/ma14061427.
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Utilization of waste corn stalks (CS) has seized extensive attention due to high annual output and hazardous impact of piling aside or direct combustion on environment. However, previously there has been a lot of emphasis on improvement of its energy efficiency as solid fuel while limited investigations are available which explore the possibility of applying corn stalks as performance enhancer in asphalt binder. The purpose of this study is to examine the potential of employing hydrochar as modifiers in asphalt binder by a series of experimental tests. In this study, two hydrochar were produced from corn stalks by a novel process called hydrothermal carbonization at a different reaction temperature. The two hydrochar and their responding hydrochar-modified asphalt (HCMA) were tested by chemical and rheological tests. Chemical analysis detected the interaction between hydrochar and binder factions, resulting in poor compatibility but satisfying anti-aging property. Even though hydrochar increased the viscosity of bitumen, implying worse workability, and caused poor storage stability, ameliorated performance of asphalt binder at high temperature by incorporating hydrochar was verified by various criteria such as higher performance grade (PG) failure temperature and lower non-recoverable creep compliance (Jnr). Moreover, higher reaction temperature makes hydrochar’s particles smaller and more homogeneous, which results in slightly lower enhanced high temperature performance, more satisfying workability, better storage stability, and greater anti-aging effect of hydrochar-modified asphalt. Eventually, this study provided a promising win-win solution to environment problems concerning corn stalk treatment and shortage of asphalt binder. Further exploration of methods to improve HCMA’s storage stability, real-scale corroboration on trial section and life cycle assessment of asphalt pavement containing hydrochar modifiers will be followed in the future.
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Țurcanu, Anca Andreea, Ecaterina Matei, Maria Râpă, Andra Mihaela Predescu, Andrei-Constantin Berbecaru, George Coman, and Cristian Predescu. "Walnut Shell Biowaste Valorization via HTC Process for the Removal of Some Emerging Pharmaceutical Pollutants from Aqueous Solutions." International Journal of Molecular Sciences 23, no. 19 (September 21, 2022): 11095. http://dx.doi.org/10.3390/ijms231911095.
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This research emphasizes the performance of some eco-friendly carbon materials as hydrochars (HC) obtained by the hydrothermal carbonization (HTC) process applied to walnut shell (WS) biowaste. These materials display promising properties that can be used for environmental applications such as emerging pharmaceutical pollutant retention from water sources. Thus, three hydrochars coded HCWS1, HCWS2, and HCWS3 were obtained using a dynamic autoclave in specific conditions—temperature of 220 °C, autogenous pressure, 1:10 biomass–water weight ratio—and for three different reaction times, 1 h, 6 h, and 12 h. The HCWSs were characterized by means of ATR-FTIR and SEM-EDS analyses and tested as possible adsorbents to assess the removal efficiencies of some emerging pharmaceutical pollutants (paracetamol and methylene blue) by UV–VIS spectrophotometry. Kinetic and adsorption studies were carried out. The best results were obtained for the HCWS3 hydrochar. Further perspectives include an activation step of the hydrochars and their testing on other emerging pharmaceutical pollutants.