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Toufiq M Reza - One of the best experts on this subject based on the ideXlab platform.
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cationic dye adsorption on Hydrochars of winery and citrus juice industries residues performance mechanism and thermodynamics
Energies, 2020Co-Authors: Nepu Saha, Maurizio Volpe, Luca Fiori, Roberto Volpe, Antonio Messineo, Toufiq M RezaAbstract: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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Hydrothermal Carbonization of Various Paper Mill Sludges: An Observation of Solid Fuel Properties
MDPI AG, 2019Co-Authors: Nepu Saha, Akbar Saba, Pretom Saha, Kyle Mcgaughy, Diana Franqui-villanueva, William J. Orts, William M. Hart-cooper, Toufiq M RezaAbstract: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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effect of hydrothermal carbonization temperature on ph dissociation constants and acidic functional groups on Hydrochar from cellulose and wood
Journal of Analytical and Applied Pyrolysis, 2019Co-Authors: Nepu Saha, Akbar Saba, Toufiq M RezaAbstract:Abstract The aims of this work were to quantify chemical states associated with the pH, dissociation constants, and pH at point of zero charge (pHPZC) of Hydrochar and to quantify the acidic functional groups on Hydrochar surface. Hydrochars from cellulose and wood treated at 180, 220, and 260 °C with 30 min residence time were produced. Boehm titration was applied to analyze acidic functional groups and dissociation constants on Hydrochar surfaces. FTIR spectroscopy was used to identify the functional groups qualitatively. The results of this study indicate that Hydrochar becomes more acidic due to a larger number of acidic functional groups on the Hydrochar surface with the increase of hydrothermal carbonization (HTC) temperature. The total number of acidic functional groups increased from 20.5 ± 0.3 μmol/g to 1267.9 ± 22.5 μmol/g and 576.6 ± 7.8 μmol/g to 680.8 ± 18.8 μmol/g for cellulose and wood, respectively.
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co hydrothermal carbonization of coal biomass blend influence of temperature on solid fuel properties
Fuel Processing Technology, 2017Co-Authors: Akbar Saba, Pretom Saha, Toufiq M RezaAbstract:Abstract Co-Hydrothermal Carbonization (Co-HTC) was performed on a blended feedstock of coal and miscanthus. The main goal of this work was to evaluate the synergistic effects of miscanthus on coal during Co-HTC. Fuel quality was assessed for all Hydrochars by evaluating mass yields, energy content, ultimate analysis, and proximate analysis. Calculation of combustion parameters showed experimental ignition and burnout indices of Co-HTC 260 °C Hydrochar were 29.0% and 26.5% lower than theoretical, non-interacting indices, respectively. Hydrochars shared the benefits of low sulfur and low ash content of miscanthus but maintaining higher energy content of coal. Hydrochars produced at 260 °C had energy contents as high as coal (27.3 ± 0.6 MJ kg − 1 ) and 73% less ash content and 74% less sulfur than raw coal as a result of the more acidic environment produced by miscanthus decomposition. Furthermore, Hydrochars were homogeneous as miscanthus-derived Hydrochar was formed on coal surface according to SEM imaging and verified by the reduced pore width from nitrogen adsorption. Co-HTC Hydrochars were pelletized in a single-press pellet press. Both mass and energy densities of Co-HTC pellets were increased with the increase of Co-HTC temperature. For instance, energy densities of pelletized Co-HTC Hydrochars were increased to 32.4 GJ m − 3 , whereas HTC coal contains energy density of 28 GJ m − 3 .
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characterization of products from hydrothermal carbonization of orange pomace including anaerobic digestibility of process liquor
Bioresource Technology, 2015Co-Authors: Ezgi Erdogan, Toufiq M Reza, Buse Atila, Jan Mumme, Asli Toptas, Murat Elibol, Jale YanikAbstract:Abstract In this study, the effect of the temperature and reaction time on hydrothermal carbonization (HTC) of orange pomace was investigated. In addition, a set of anaerobic batch tests were performed to determine the resulting biogas and methane potential of the spent liquor. Hydrochar yields followed a decreasing trend with the increasing temperature, whereas reaction time had no considerably effect on the yield. The evolution of the H/C and O/C atomic ratios from the raw material to the Hydrochars suggested that dehydration reactions prevail during HTC. The Hydrochars tended to become enriched in Ca, Mg and P minerals by increasing HTC temperature. The heavy metal contents in Hydrochars were found below limits and no PAH compound was detected. Anaerobic digestion tests showed that the aqueous phase from HTC can be used as feedstocks for biogas production.
Luca Fiori - One of the best experts on this subject based on the ideXlab platform.
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integrated thermochemical conversion process for valorizing mixed agricultural and dairy waste to nutrient enriched biochars and biofuels
Bioresource Technology, 2021Co-Authors: Juichun Lin, Maurizio Volpe, Luca Fiori, Dylan Mariuzza, Selim Ceylan, Jillian L GoldfarbAbstract:Hydrothermal carbonization (HTC) and pyrolysis are two promising thermochemical conversion strategies to valorize agricultural wastes, yet neither process can be implemented alone to sustainably upgrade both wet and dry feedstocks. HTC is ideal for wet feedstocks, such as manure, but its solid Hydrochars suffer from low surface area and stability. Pyrolysis is well suited to dry agricultural residues, but pyrolysis biochars have low nutrient contents and bio-oils are often highly oxygenated. We propose an integrated process that co-pyrolyzes a nutrient-rich cow manure Hydrochar with raw agricultural residues, which effectively reduces the environmental impact of these wastes while producing value-added bioproducts. Biochars produced from the proposed process are more suitable for soil amendments due to their enhancement in bioavailable nutrients and surface area than the manure Hydrochars and raw biomass. Co-pyrolysis of blends enriched with cow manure yield oils higher in alkanes and alkenes with fewer oxygenated compounds.
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cationic dye adsorption on Hydrochars of winery and citrus juice industries residues performance mechanism and thermodynamics
Energies, 2020Co-Authors: Nepu Saha, Maurizio Volpe, Luca Fiori, Roberto Volpe, Antonio Messineo, Toufiq M RezaAbstract: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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spent coffee enhanced biomethane potential via an integrated hydrothermal carbonization anaerobic digestion process
Bioresource Technology, 2018Co-Authors: Fabio Codignole Luz, Maurizio Volpe, Luca Fiori, Alessandro Manni, Stefano Cordine, Vincenzo Mulone, Vittorio RoccoAbstract:Abstract This study reports the implications of using spent coffee Hydrochar as substrate for anaerobic digestion (AD) processes. Three different spent coffee Hydrochars produced at 180, 220 and 250 °C, 1 h residence time, were investigated for their biomethane potential in AD process inoculated with cow manure. Spent coffee Hydrochars were characterized in terms of ultimate, proximate and higher heating value (HHV), and their theoretical bio-methane yield evaluated using Boyle-Buswell equation and compared to the experimental values. The results were then analyzed using the modified Gompertz equation to determine the main AD evolution parameters. Different Hydrochar properties were related to AD process performances. AD of spent coffee Hydrochars produced at 180 °C showed the highest biomethane production rate (46 mL CH4/gVS.d), a biomethane potential of 491 mL/gVS (AD lasting 25 days), and a biomethane gas daily composition of about 70%.
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from olive waste to solid biofuel through hydrothermal carbonisation the role of temperature and solid load on secondary char formation and Hydrochar energy properties
Journal of Analytical and Applied Pyrolysis, 2017Co-Authors: Maurizio Volpe, Luca FioriAbstract:Abstract Hydrothermal carbonisation was used to upgrade fuels from two types of agro-industrial wastes: olive tree trimmings and olive pulp. Hydrochar yield, elemental and proximate analyses, thermal stability, higher heating value (HHV), and energy yield at different reaction temperatures (120, 150, 180, 200, 220, 235 and 250 °C) and solid load (biomass to water ratios − B/W − equal to 7, 10, 15 and 25%) were assessed for a fixed reaction time of 30 min. HHV varied linearly with Hydrochar mass yield and reaction temperature in the temperature range 180–250 °C. Solid load proved to be a crucial parameter in determining the energy properties of Hydrochars. The higher B/W, the higher were the degree of carbonisation (in terms of fixed and total carbon), the Hydrochar HHV, and the Hydrochar yield. Elemental analysis showed that during HTC, olive pulp samples underwent a greater degree of carbonisation when compared to the corresponding olive tree trimmings residues. High solid load and high reaction temperature promoted secondary char formation. Secondary char showed a sphere-like structure formed by overlapping layers. EDS microanalysis showed that secondary char is characterised by a significantly higher carbon content than parent primary char, thus confirming its contribution towards enhancing the HHV of Hydrochars.
Maurizio Volpe - One of the best experts on this subject based on the ideXlab platform.
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integrated thermochemical conversion process for valorizing mixed agricultural and dairy waste to nutrient enriched biochars and biofuels
Bioresource Technology, 2021Co-Authors: Juichun Lin, Maurizio Volpe, Luca Fiori, Dylan Mariuzza, Selim Ceylan, Jillian L GoldfarbAbstract:Hydrothermal carbonization (HTC) and pyrolysis are two promising thermochemical conversion strategies to valorize agricultural wastes, yet neither process can be implemented alone to sustainably upgrade both wet and dry feedstocks. HTC is ideal for wet feedstocks, such as manure, but its solid Hydrochars suffer from low surface area and stability. Pyrolysis is well suited to dry agricultural residues, but pyrolysis biochars have low nutrient contents and bio-oils are often highly oxygenated. We propose an integrated process that co-pyrolyzes a nutrient-rich cow manure Hydrochar with raw agricultural residues, which effectively reduces the environmental impact of these wastes while producing value-added bioproducts. Biochars produced from the proposed process are more suitable for soil amendments due to their enhancement in bioavailable nutrients and surface area than the manure Hydrochars and raw biomass. Co-pyrolysis of blends enriched with cow manure yield oils higher in alkanes and alkenes with fewer oxygenated compounds.
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cationic dye adsorption on Hydrochars of winery and citrus juice industries residues performance mechanism and thermodynamics
Energies, 2020Co-Authors: Nepu Saha, Maurizio Volpe, Luca Fiori, Roberto Volpe, Antonio Messineo, Toufiq M RezaAbstract: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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spent coffee enhanced biomethane potential via an integrated hydrothermal carbonization anaerobic digestion process
Bioresource Technology, 2018Co-Authors: Fabio Codignole Luz, Maurizio Volpe, Luca Fiori, Alessandro Manni, Stefano Cordine, Vincenzo Mulone, Vittorio RoccoAbstract:Abstract This study reports the implications of using spent coffee Hydrochar as substrate for anaerobic digestion (AD) processes. Three different spent coffee Hydrochars produced at 180, 220 and 250 °C, 1 h residence time, were investigated for their biomethane potential in AD process inoculated with cow manure. Spent coffee Hydrochars were characterized in terms of ultimate, proximate and higher heating value (HHV), and their theoretical bio-methane yield evaluated using Boyle-Buswell equation and compared to the experimental values. The results were then analyzed using the modified Gompertz equation to determine the main AD evolution parameters. Different Hydrochar properties were related to AD process performances. AD of spent coffee Hydrochars produced at 180 °C showed the highest biomethane production rate (46 mL CH4/gVS.d), a biomethane potential of 491 mL/gVS (AD lasting 25 days), and a biomethane gas daily composition of about 70%.
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from olive waste to solid biofuel through hydrothermal carbonisation the role of temperature and solid load on secondary char formation and Hydrochar energy properties
Journal of Analytical and Applied Pyrolysis, 2017Co-Authors: Maurizio Volpe, Luca FioriAbstract:Abstract Hydrothermal carbonisation was used to upgrade fuels from two types of agro-industrial wastes: olive tree trimmings and olive pulp. Hydrochar yield, elemental and proximate analyses, thermal stability, higher heating value (HHV), and energy yield at different reaction temperatures (120, 150, 180, 200, 220, 235 and 250 °C) and solid load (biomass to water ratios − B/W − equal to 7, 10, 15 and 25%) were assessed for a fixed reaction time of 30 min. HHV varied linearly with Hydrochar mass yield and reaction temperature in the temperature range 180–250 °C. Solid load proved to be a crucial parameter in determining the energy properties of Hydrochars. The higher B/W, the higher were the degree of carbonisation (in terms of fixed and total carbon), the Hydrochar HHV, and the Hydrochar yield. Elemental analysis showed that during HTC, olive pulp samples underwent a greater degree of carbonisation when compared to the corresponding olive tree trimmings residues. High solid load and high reaction temperature promoted secondary char formation. Secondary char showed a sphere-like structure formed by overlapping layers. EDS microanalysis showed that secondary char is characterised by a significantly higher carbon content than parent primary char, thus confirming its contribution towards enhancing the HHV of Hydrochars.
Camelia Matei Ghimbeu - One of the best experts on this subject based on the ideXlab platform.
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olive mill wastewater from a pollutant to green fuels agricultural and water source and bio fertilizer hydrothermal carbonization
Science of The Total Environment, 2020Co-Authors: Ahmed Amine Azzaz, Mejdi Jeguirim, Vasiliki Kinigopoulou, Charalampos Doulgeris, Marylorene Goddard, Salah Jellali, Camelia Matei GhimbeuAbstract:Abstract Hydrothermal carbonization (HTC) is considered as a promising technique for wastes conversion into carbon rich materials for various energetic, environmental and agricultural applications. In this work, the HTC of olive mill wastewater (OMWW) was investigated at different temperatures (180–220 °C) and both, the solid (i.e., Hydrochars) and the final process liquid derived from the thermal conversion process were deeply analyzed. Results showed that the solid yield was affected by the temperature, i.e., decrease from 57% to 25% for temperatures of 180 °C and 220 °C, respectively. Furthermore, the Hydrochars presented an increasing fixed carbon percentage with the increase of the carbonization temperature, suggesting that decarboxylation is the main reaction driving the HTC process. The decrease in the O/C ratio promoted an increase of the high heating value (HHV) by 32% for Hydrochar prepared at 220 °C. The process liquids were sampled and their organic contents were analyzed using GC–MS technique. Acids, alcohols, phenols and sugar derivatives were detected and their concentrations varied with carbonization temperatures. The assessment of the physico-chemical properties of the generated HTC by-products suggested the possible application of the Hydrochars for energetic insights while the liquid fraction could be practical for in agricultural field.
Zhengang Liu - One of the best experts on this subject based on the ideXlab platform.
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combination of hydrothermal carbonization and oxy fuel combustion process for sewage sludge treatment combustion characteristics and kinetics analysis
Fuel, 2019Co-Authors: Tingting Liu, Qianqian Lang, Yu Xia, Zeliang Chen, Chao Gai, Zhengang LiuAbstract:Abstract Hydrothermal carbonization (HTC) and oxy-fuel combustion were combined for sewage sludge (SS) disposal for the first time. The combustion characteristics of HTC pretreated SS (Hydrochar) under air as well as oxy-fuel combustion atmosphere were investigated by thermal-gravimetric analyzer. On the basis of combustion experiments, the kinetics parameters including energy activation, pre-exponential factor and reaction order were evaluated by Flynn–Wall–Ozawa (FWO) model and Avrami’s theory. The results showed that the Hydrochars had higher ignition temperature, higher ignition index and narrower combustion stage than SS, which implied more stable combustion behaviors of the Hydrochars than SS. The lower activation energy of the Hydrochar obtained from HTC at the temperature of 200 °C demonstrated that the Hydrochars were more easily combusted in comparison to SS under identical oxy-fuel conditions. In addition, the ash problems of the slagging and fouling were mitigated by HTC treatment. In oxy-fuel atmosphere, the burnout temperature of the Hydrochars was lower than that in air. More importantly, the dewaterability of SS was substantially improved by HTC and more than 30% of drying energy consumption was saved prior to combustion. This study indicated that the combination of HTC treatment and oxy-fuel combustion offered a promising alternative for SS disposal with the benefits of energy consumption and energy recovery.
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gasification performance of the Hydrochar derived from co hydrothermal carbonization of sewage sludge and sawdust
Energy, 2019Co-Authors: Mengjun Chen, Zhengang Liu, Tianxue Yang, Wentao Jiao, Chao GaiAbstract:Abstract Co-hydrothermal carbonization (co-HTC) is recognized as a promising pretreatment for upgrading fuel quality of high moisture biomass prior to further thermal conversion. The properties of the Hydrochar derived from co-HTC of sewage sludge (SS) and sawdust (SD), and CO2 gasification characteristics of the Hydrochar were investigated. The results showed that the Hydrochar had enhanced aromatic degree and increased metals content compared to raw sludge. The Hydrochar also exhibited an enhanced gasification reactivity, resulting in high carbon monoxide content in the syngas than that from SS under identical conditions. The temperature and SD/SS mass ratio had a significant influence on the syngas composition mainly by the Boudouard reaction and water gas reaction. The gasification reactivity was strongly associated with the inorganic elements, and the KAlSi3O8 inhibited while the K2CO3 promoted the gasification reaction of Hydrochars. Under optimal conditions, a high gasification efficiency of 77.73% was obtained, and the lower heating value of the syngas reached 8.15 MJ/Nm3. This study indicated that co-HTC of SS and SD combined with subsequent gasification had promising potential towards syngas production with high quality.
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polycyclic aromatic hydrocarbons and toxic heavy metals in municipal solid waste and corresponding Hydrochars
Energy & Fuels, 2017Co-Authors: Nana Peng, Tingting Liu, Qianqian Lang, Chao Gai, Zhengang LiuAbstract:Hydrothermal carbonization (HTC) is an effective pretreatment technology for converting municipal solid waste (MSW) into homogenized, energy-dense, and carbon-rich Hydrochars with low energy consumption. In this study, heavy metals and free polycyclic aromatic hydrocarbons (PAHs) in MSW and corresponding Hydrochars were investigated. The results showed that the Hydrochar yield decreased with an increasing temperature from 160 to 260 °C. Heavy metal contents, including Cr, Cd, Hg, and Zn, in the Hydrochars were lower than those in MSW, while Pb, As, Ni, and Cu showed an accumulation in the Hydrochars at most temperatures. In addition, the Toxicity Characteristic Leaching Procedure test showed that the contents of heavy metals in leachates were all lower than the United States Environmental Protection Agency (U.S. EPA) limits. With regard to PAHs, total free PAH contents in the Hydrochars were higher than those of MSW, except for the Hydrochar obtained at 160 °C. The total PAHs in the Hydrochar increased wi...
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thermogravimetric investigation of Hydrochar lignite co combustion
Bioresource Technology, 2012Co-Authors: Zhengang Liu, Kent S Hoekman, Augustine Quek, M P Srinivasan, Rajasekhar BalasubramanianAbstract:Co-combustion of Hydrochar with lignite was investigated by means of thermogravimetric analysis. Hydrochars were produced from coconut fibers and eucalyptus leaves under hydrothermal conditions at 250°C. The Hydrochar was added in varying amounts to lignite for combustion. The results indicated that hydrothermal treatment decreased the volatile matter content and increased the fixed carbon content of the biomaterials. The elevated energy density and decreased ash content of the Hydrochar improved its combustion behavior when co-fired with lignite for energy production. The Hydrochars derived from coconut fiber and eucalyptus leaves had similar chemical compositions and showed similar influences on lignite combustion. Hydrochar addition increased the burnout and shortened the combustion range of the Hydrochar-lignite blends. High combustion efficiency was observed due to the synergistic interactions between Hydrochar and lignite during the co-combustion process. A kinetic study showed that the combustion process of Hydrochar-lignite blends followed first-order reaction rates.