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Hydrothermal carbonization (HTC) of carbohydrates and biomass is a straightforward method for preparing hydrochars at low temperatures of 180-250 °C. Hydrochars are more carbonized than their precursors. Increasing the carbonization degree of hydrochars at hydrothermal temperatures is a scientific quest that is addressed in this thesis. Hydrochars are known to have a spherical or irregular morphology. Here we address thin film hydrochars for the first time. Hydrochars themselves are carbon precursors for preparing activated carbons. Activated carbons are porous materials that can be used for gas adsorption applications. In this thesis, enhanced adsorption of VOCs at low pressures is addressed by using iron phosphate impregnated activated carbons. Finaly, any chemical process or product including those in this thesis such as HTC, activation, hydrochar and activated carbons may contribute to the issue of environmental degradation positively or negatively. Such environmental impacts are addressed by life cycle assessment of processes of HTC and activation and their related products in the last paper of this thesis. Briefly mentioned, in my first study (Paper I), I focused on the HTC of glucose in the presence of iron (II) sulfate. By changing the concentration of iron (II) sulfate, with a catalytic amount, blue hydrochars were formed at the bottom of the autoclave. The blueness was related to thin film interference. The thin film hydrochars were more carbonized than spherical hydrochars and the yield of HTC has increased in the presence of iron (II) sulfate. The second study (Paper II) is focused on the activation of hydrochars with H3PO4 and H3PO4+FeCl3. We showed that ultramicroporosity and impregnated iron phosphate species enhance the adsorption of VOCs at low pressure. The ACs were impregnated with Fe (PO3)2 and it was shown that Fe (PO3)2 acts as an activation agent which opens up for future studies. In the third study (Paper III), H3PO4-activated carbons were p

This is a brief but focused literature review of articles centered around pyrolysis and hydrothermal carbonization (HTC) using various feedstocks, including residues from industries, agriculture, and landfill waste. The deployment of bio-wastes will be the cornerstone of circular bio-economies in the future. The main emphasis is on gleaning how these two technologies can contribute to a sustainable circular (bio) economy, by understanding the process parameters influencing the quality, type and quantity of the final output. HTC and pyrolysis, it may be undeniably stated, can support the progress towards a clutch of sustainable development goals (SDGs), as they operate right at the confluence of solid waste management and renewable energy production. As mentioned in many of the articles reviewed in this paper, a high process temperature usually results in higher yields of bio-oil and biogas/pyrogas (and thereby less biochar), implying a higher energy recovery. HTC trumps pyrolysis on many counts – economy, energy-efficiency and product (hydrochar) quality. However, pyrolysis is a simpler method to regulate, and pyrochar, has a higher market value vis-à-vis hydrochar. While both these technologies generate valuable end-products regardless of the type of feedstock used; the articles reviewed clearly show that the feedstock does influence the quality of the output and thereby the application to which it can be directed. The review leads to recommendations for future research in collecting data and creating a model to in-vestigate various process parameters. Some of these recommendations are detailed comparative life cycle assessments (LCAs) to study the environmental impacts of technology-choices,, research into tailoring the optimal method and temperature to the feedstock deployed, and comprehensive forecast-based economic analysis of commercial-scale pyrolysis and HTC projects, are called for. As stated at the beginning, this is a brief review, which can also be expan

In a circular economy, the efficient utilization of all materials as valuable resources, with a focus on minimizing waste, is paramount. This study shows the possibilities of upgrading the lowest-valued residuals from the forest industry into a new product with both liming and fertilizing properties on forest soil. Hydrothermal carbonized sludge mixed with bark and ash in the proportions of 45:10:45 was densified into fertilizer pellets that meet the nutrient requirements of 120 kg N per hectare when 7 tons of pellets is spread in forests. The pellets met a high-quality result according to durability and density, which were above 95% and 900 kg/m3. However, pellets exposed to wet and cold conditions lost their hardness, making the pellets dissolve over time. Small amounts, <5‰, of nutrients, alkali ions, and heavy metals leached out from the pellets under all conditions, indicating good properties for forest soil amendment. The conclusion is that it is possible to close the circle of nutrients by using innovative thinking around forest industrial residual products.

Steel is an indispensable material of the modern society and yet the production of steel is one of the largest anthropogenic CO2 emission sources on the planet. The conventional blast-furnace-basic-oxygen-furnace (BOF) process is responsible for generating 85% of the steel industry’s total CO2 emissions, which is the result of a high coal consumption rate for the reduction of iron ores and for providing the heat necessary for the high-temperature process. In order to meet the climate goal set by the Paris Agreement, the iron and steel industry must drastically decrease its CO2 emissions and aim at achieving net-zero emissions by 2050. Bioenergy is a form of renewable energy, and if it is managed sustainably throughout its life cycle, it can be considered carbon-neutral. Replacing fossil fuels with biofuels consumed during the steelmaking processes is one way to decrease CO2 emissions. However, this approach has not been widely adopted by steelmakers over the world due to the high price and the limited availability of wood-based biofuels. Hydrochar is a coal-like solid material that is produced from the hydrothermal carbonization (HTC) of biomass. It has attracted great interest from steelmakers due to its coal-like properties and the fact that it can be produced from a wide range of organic waste streams that can be found in almost every country. Previous studies focused on the use of hydrochar for the blast furnace process. This thesis therefore examines the potential use of hydrochar in the direct-reduction-electric-arc-furnace (DR-EAF) process, and particularly in two applications where the use of fossil coal is difficult to abate—the coal-based direct reduction of iron ore and the carburization of liquid steel in the EAF. This thesis begins with a characterization study of a hydrochar produced from lemon peel waste (LPH) and its comparison with a fossil reference material (anthracite) and two bio-reference materials (charcoal). The results reveal that LPH is a h, Stål är ett oumbärligt material i det moderna samhället, men produktionen av stål representerar samtidigt en av de största antropogena CO2-utsläppskällorna på planeten. Den konventionella processen som kombinerar en masugn med en konverter genererar 85 % av stålindustrins totala CO2-utsläpp. Detta är orsakat av en hög kolförbrukningshastighet för att reducera järnmalm och för att tillhandahålla den värme som krävs för denna högtemperaturprocess. För att klara klimatmålen i Parisavtalet måste stålindustrin drastiskt minska sina CO2-utsläpp och sikta på att uppnå nettonollutsläpp till 2050. Bioenergi är en form av förnybar energi, som om den hanteras på ett hållbart sätt under hela sin livscykel, kan betraktas som koldioxidneutral. Därför är det positivt att ersätta fossila bränslen med biobränslen som förbrukas under ståltillverkningsprocesserna i syfte att minska CO2-utsläppen. Detta tillvägagångsätt har dock inte använts i stor utsträckning av ståltillverkare i världen, på grund av det höga priset och den begränsade tillgågen på träbaserade biobränslen. Hydrochar är ett kolliknande fast material som framställs från en hydrotermisk förkolning av biomassa. Materialet har uppmärksammats av ståltillverkare på grund av dess kolliknade egenskaper och det faktum att det kan produceras från ett brett utbud av organiska avfall som finns tillgängligt i nästan alla länder. Tidigare studier har fokuserat på användningen av hydrochar för masugnsprocessen, medan denna avhandling fokuserar på att studera den potentialla användningen av hydrochar i electriska ljusbågsugnar som chargeras med direktreduktionspellets (DR-EAF). Dessutom för speciellt två tillämpningar där användningen av fossilt kol är svår att minska, nämligen den kolbaserade direkta reduktionen av järnmalm och uppkolningen av flytande stål i ljusbågsugnen. Inledningsvis så presenteras resultaten av en karaktäriseringsstudie av hydrochar framställt från citronskalsavfall (LPH) och resultaten jämförs med ett fossilt r, OSMET 3.0

In a circular economy, the efficient utilization of all materials as valuable resources, with a focus on minimizing waste, is paramount. This study shows the possibilities of upgrading the lowest-valued residuals from the forest industry into a new product with both liming and fertilizing properties on forest soil. Hydrothermal carbonized sludge mixed with bark and ash in the proportions of 45:10:45 was densified into fertilizer pellets that meet the nutrient requirements of 120 kg N per hectare when 7 tons of pellets is spread in forests. The pellets met a high-quality result according to durability and density, which were above 95% and 900 kg/m3. However, pellets exposed to wet and cold conditions lost their hardness, making the pellets dissolve over time. Small amounts, <5‰, of nutrients, alkali ions, and heavy metals leached out from the pellets under all conditions, indicating good properties for forest soil amendment. The conclusion is that it is possible to close the circle of nutrients by using innovative thinking around forest industrial residual products.

This study evaluates the effectiveness of microalgal-based carbon-encapsulated iron nanoparticles (ME-nFe) in the removal of pharmaceutical compounds (PhACs) from water solutions and real municipal effluent at a laboratory scale. The investigated PhACs were chosen to represent different classes of synthetic drugs: antibiotics, anti-inflammatory drugs, antihypertensives, antiepileptics, neuroprotectors, and antidepressants. The adsorbent material was produced through hydrothermal carbonization (225 °C for 3 h), using microalgae grown on wastewater as the carbon source. ME-nFe showed heterogeneity in terms of porosity (with both abundance of macro and mesopores), a total pore volume of 0.65 mL g−1, a specific surface area of 117 m2 g−1 and a total iron content of 40%. Laboratory scale adsorption tests (1 g L−1 of nanoparticles with 2 min contact time) showed high removal for the most hydrophobic compounds. Removal efficiencies were high (over 98%) for Irbesartan, Ofloxacin and Diclofenac, promising (over 65–80%) for Clarithromycin, Fluoxetine, Lamotrigine and Metoprolol, but low for Gabapentin-Lactam and Propyphenazone (<20%). Electrostatic interactions between the drugs and the surface of the nanoparticles may account for the observed data, although additional removal mechanisms cannot be ruled out.

Background: The provision of safe sanitation services is essential for human well-being and environmental integrity, but it is often lacking in less developed communities with insufficient financial and technical resources. Hydrothermal carbonization (HTC) has been suggested as an alternative sanitation technology, producing value-added products from faecal waste. We evaluated the HTC technology for raw human waste treatment in terms of resource recovery. In addition, we constructed and tested a low-cost HTC reactor for its technical feasibility. Methods: Raw human faeces were hydrothermally treated in a mild severity range (≤ 200 °C and ≤ 1 hr). The total energy recovery was analysed from the energy input, higher heating value (HHV) of hydrochar and biomethane potential of process water. The nutrient contents were recovered through struvite precipitation employing process water and acid leachate from hydrochar ash. A bench-scale low-cost reactor (BLR) was developed using widely available materials and tested for human faeces treatment. Results: The hydrochar had HHVs (23.2 - 25.2 MJ/kg) comparable to bituminous coal. The calorific value of hydrochar accounted for more than 90% of the total energy recovery. Around 78% of phosphorus in feedstock was retained in hydrochar ash, while 15% was in process water. 72% of the initial phosphorus can be recovered as struvite when deficient Mg and NH 4 are supplemented. The experiments with BLR showed stable operation for faecal waste treatment with an energy efficiency comparable to a commercial reactor system. Conclusions: This research presents a proof of concept for the hydrothermal treatment of faecal waste as an alternative sanitation technology, by providing a quantitative evaluation of the resource recovery of energy and nutrients. The experiments with the BLR demonstrate the technical feasibility of the low-cost reactor and support its further development on a larger scale to reach practical implementation.

This study investigated the feasibility of a high-loading process with less water consumption for the valorization of wet biomass waste through hydrothermal carbonization (HTC) with and without N2 pressurization from the views of water saving, carbon utilization, and energy recovery. The results revealed that reducing the liquid-to-solid ratio from 10 to 2.5 significantly improved carbon storage in hydrochar due to preferential carbon sequestration as the solid phase (59.9%) instead of being lost in the liquid phase (∼10%). The pressurized HTC process resulted in a higher stability hydrochar through the devolatilization of secondary char that was less stable, yet resulted in ∼10% 15% more carbon transformation to the gas phase. A cost-benefit analysis further demonstrated the potential of the high-loading HTC process for enhancing energy recovery while minimizing energy consumption during hydrochar production from high-moisture yard waste. © 2023 Elsevier Ltd

In a circular economy, the efficient utilization of all materials as valuable resources, with a focus on minimizing waste, is paramount. This study shows the possibilities of upgrading the lowest-valued residuals from the forest industry into a new product with both liming and fertilizing properties on forest soil. Hydrothermal carbonized sludge mixed with bark and ash in the proportions of 45:10:45 was densified into fertilizer pellets that meet the nutrient requirements of 120 kg N per hectare when 7 tons of pellets is spread in forests. The pellets met a high-quality result according to durability and density, which were above 95% and 900 kg/m3. However, pellets exposed to wet and cold conditions lost their hardness, making the pellets dissolve over time. Small amounts, <5‰, of nutrients, alkali ions, and heavy metals leached out from the pellets under all conditions, indicating good properties for forest soil amendment. The conclusion is that it is possible to close the circle of nutrients by using innovative thinking around forest industrial residual products.

This is a brief but focused literature review of articles centered around pyrolysis and hydrothermal carbonization (HTC) using various feedstocks, including residues from industries, agriculture, and landfill waste. The deployment of bio-wastes will be the cornerstone of circular bio-economies in the future. The main emphasis is on gleaning how these two technologies can contribute to a sustainable circular (bio) economy, by understanding the process parameters influencing the quality, type and quantity of the final output. HTC and pyrolysis, it may be undeniably stated, can support the progress towards a clutch of sustainable development goals (SDGs), as they operate right at the confluence of solid waste management and renewable energy production. As mentioned in many of the articles reviewed in this paper, a high process temperature usually results in higher yields of bio-oil and biogas/pyrogas (and thereby less biochar), implying a higher energy recovery. HTC trumps pyrolysis on many counts – economy, energy-efficiency and product (hydrochar) quality. However, pyrolysis is a simpler method to regulate, and pyrochar, has a higher market value vis-à-vis hydrochar. While both these technologies generate valuable end-products regardless of the type of feedstock used; the articles reviewed clearly show that the feedstock does influence the quality of the output and thereby the application to which it can be directed. The review leads to recommendations for future research in collecting data and creating a model to in-vestigate various process parameters. Some of these recommendations are detailed comparative life cycle assessments (LCAs) to study the environmental impacts of technology-choices,, research into tailoring the optimal method and temperature to the feedstock deployed, and comprehensive forecast-based economic analysis of commercial-scale pyrolysis and HTC projects, are called for. As stated at the beginning, this is a brief review, which can also be expan

Untreated industrial effluent is causing alarming levels of water pollution in our modern world. Hydrochars, functional carbonaceous materials obtained during the hydrothermal carbonization of waste biomass, possess a great potential for use in industrial wastewater treatment. Their high reactivity and regenerative properties compensate its deficiency, which is reflected in a small specific surface area. In addition, these materials are amenable to additional functionalization and modification by various chemical treatments. Previous studies have demonstrated that incorporating metals onto the surface of hydrochar or treating it with hydrogen peroxide or alkalis can significantly enhance its adsorption capabilities. This paper provides a brief overview of using hydrochars from various sources as adsorbents for heavy metals. This review aims to assess the impact of material modification on its structural characteristics and sorption capacity.

In a circular economy, the efficient utilization of all materials as valuable resources, with a focus on minimizing waste, is paramount. This study shows the possibilities of upgrading the lowest-valued residuals from the forest industry into a new product with both liming and fertilizing properties on forest soil. Hydrothermal carbonized sludge mixed with bark and ash in the proportions of 45:10:45 was densified into fertilizer pellets that meet the nutrient requirements of 120 kg N per hectare when 7 tons of pellets is spread in forests. The pellets met a high-quality result according to durability and density, which were above 95% and 900 kg/m3. However, pellets exposed to wet and cold conditions lost their hardness, making the pellets dissolve over time. Small amounts, <5‰, of nutrients, alkali ions, and heavy metals leached out from the pellets under all conditions, indicating good properties for forest soil amendment. The conclusion is that it is possible to close the circle of nutrients by using innovative thinking around forest industrial residual products.

This is a brief but focused literature review of articles centered around pyrolysis and hydrothermal carbonization (HTC) using various feedstocks, including residues from industries, agriculture, and landfill waste. The deployment of bio-wastes will be the cornerstone of circular bio-economies in the future. The main emphasis is on gleaning how these two technologies can contribute to a sustainable circular (bio) economy, by understanding the process parameters influencing the quality, type and quantity of the final output. HTC and pyrolysis, it may be undeniably stated, can support the progress towards a clutch of sustainable development goals (SDGs), as they operate right at the confluence of solid waste management and renewable energy production. As mentioned in many of the articles reviewed in this paper, a high process temperature usually results in higher yields of bio-oil and biogas/pyrogas (and thereby less biochar), implying a higher energy recovery. HTC trumps pyrolysis on many counts – economy, energy-efficiency and product (hydrochar) quality. However, pyrolysis is a simpler method to regulate, and pyrochar, has a higher market value vis-à-vis hydrochar. While both these technologies generate valuable end-products regardless of the type of feedstock used; the articles reviewed clearly show that the feedstock does influence the quality of the output and thereby the application to which it can be directed. The review leads to recommendations for future research in collecting data and creating a model to in-vestigate various process parameters. Some of these recommendations are detailed comparative life cycle assessments (LCAs) to study the environmental impacts of technology-choices,, research into tailoring the optimal method and temperature to the feedstock deployed, and comprehensive forecast-based economic analysis of commercial-scale pyrolysis and HTC projects, are called for. As stated at the beginning, this is a brief review, which can also be expan

In a circular economy, the efficient utilization of all materials as valuable resources, with a focus on minimizing waste, is paramount. This study shows the possibilities of upgrading the lowest-valued residuals from the forest industry into a new product with both liming and fertilizing properties on forest soil. Hydrothermal carbonized sludge mixed with bark and ash in the proportions of 45:10:45 was densified into fertilizer pellets that meet the nutrient requirements of 120 kg N per hectare when 7 tons of pellets is spread in forests. The pellets met a high-quality result according to durability and density, which were above 95% and 900 kg/m3. However, pellets exposed to wet and cold conditions lost their hardness, making the pellets dissolve over time. Small amounts, <5‰, of nutrients, alkali ions, and heavy metals leached out from the pellets under all conditions, indicating good properties for forest soil amendment. The conclusion is that it is possible to close the circle of nutrients by using innovative thinking around forest industrial residual products.

This is a brief but focused literature review of articles centered around pyrolysis and hydrothermal carbonization (HTC) using various feedstocks, including residues from industries, agriculture, and landfill waste. The deployment of bio-wastes will be the cornerstone of circular bio-economies in the future. The main emphasis is on gleaning how these two technologies can contribute to a sustainable circular (bio) economy, by understanding the process parameters influencing the quality, type and quantity of the final output. HTC and pyrolysis, it may be undeniably stated, can support the progress towards a clutch of sustainable development goals (SDGs), as they operate right at the confluence of solid waste management and renewable energy production. As mentioned in many of the articles reviewed in this paper, a high process temperature usually results in higher yields of bio-oil and biogas/pyrogas (and thereby less biochar), implying a higher energy recovery. HTC trumps pyrolysis on many counts – economy, energy-efficiency and product (hydrochar) quality. However, pyrolysis is a simpler method to regulate, and pyrochar, has a higher market value vis-à-vis hydrochar. While both these technologies generate valuable end-products regardless of the type of feedstock used; the articles reviewed clearly show that the feedstock does influence the quality of the output and thereby the application to which it can be directed. The review leads to recommendations for future research in collecting data and creating a model to in-vestigate various process parameters. Some of these recommendations are detailed comparative life cycle assessments (LCAs) to study the environmental impacts of technology-choices,, research into tailoring the optimal method and temperature to the feedstock deployed, and comprehensive forecast-based economic analysis of commercial-scale pyrolysis and HTC projects, are called for. As stated at the beginning, this is a brief review, which can also be expan

Steel is an indispensable material of the modern society and yet the production of steel is one of the largest anthropogenic CO2 emission sources on the planet. The conventional blast-furnace-basic-oxygen-furnace (BOF) process is responsible for generating 85% of the steel industry’s total CO2 emissions, which is the result of a high coal consumption rate for the reduction of iron ores and for providing the heat necessary for the high-temperature process. In order to meet the climate goal set by the Paris Agreement, the iron and steel industry must drastically decrease its CO2 emissions and aim at achieving net-zero emissions by 2050. Bioenergy is a form of renewable energy, and if it is managed sustainably throughout its life cycle, it can be considered carbon-neutral. Replacing fossil fuels with biofuels consumed during the steelmaking processes is one way to decrease CO2 emissions. However, this approach has not been widely adopted by steelmakers over the world due to the high price and the limited availability of wood-based biofuels. Hydrochar is a coal-like solid material that is produced from the hydrothermal carbonization (HTC) of biomass. It has attracted great interest from steelmakers due to its coal-like properties and the fact that it can be produced from a wide range of organic waste streams that can be found in almost every country. Previous studies focused on the use of hydrochar for the blast furnace process. This thesis therefore examines the potential use of hydrochar in the direct-reduction-electric-arc-furnace (DR-EAF) process, and particularly in two applications where the use of fossil coal is difficult to abate—the coal-based direct reduction of iron ore and the carburization of liquid steel in the EAF. This thesis begins with a characterization study of a hydrochar produced from lemon peel waste (LPH) and its comparison with a fossil reference material (anthracite) and two bio-reference materials (charcoal). The results reveal that LPH is a h, Stål är ett oumbärligt material i det moderna samhället, men produktionen av stål representerar samtidigt en av de största antropogena CO2-utsläppskällorna på planeten. Den konventionella processen som kombinerar en masugn med en konverter genererar 85 % av stålindustrins totala CO2-utsläpp. Detta är orsakat av en hög kolförbrukningshastighet för att reducera järnmalm och för att tillhandahålla den värme som krävs för denna högtemperaturprocess. För att klara klimatmålen i Parisavtalet måste stålindustrin drastiskt minska sina CO2-utsläpp och sikta på att uppnå nettonollutsläpp till 2050. Bioenergi är en form av förnybar energi, som om den hanteras på ett hållbart sätt under hela sin livscykel, kan betraktas som koldioxidneutral. Därför är det positivt att ersätta fossila bränslen med biobränslen som förbrukas under ståltillverkningsprocesserna i syfte att minska CO2-utsläppen. Detta tillvägagångsätt har dock inte använts i stor utsträckning av ståltillverkare i världen, på grund av det höga priset och den begränsade tillgågen på träbaserade biobränslen. Hydrochar är ett kolliknande fast material som framställs från en hydrotermisk förkolning av biomassa. Materialet har uppmärksammats av ståltillverkare på grund av dess kolliknade egenskaper och det faktum att det kan produceras från ett brett utbud av organiska avfall som finns tillgängligt i nästan alla länder. Tidigare studier har fokuserat på användningen av hydrochar för masugnsprocessen, medan denna avhandling fokuserar på att studera den potentialla användningen av hydrochar i electriska ljusbågsugnar som chargeras med direktreduktionspellets (DR-EAF). Dessutom för speciellt två tillämpningar där användningen av fossilt kol är svår att minska, nämligen den kolbaserade direkta reduktionen av järnmalm och uppkolningen av flytande stål i ljusbågsugnen. Inledningsvis så presenteras resultaten av en karaktäriseringsstudie av hydrochar framställt från citronskalsavfall (LPH) och resultaten jämförs med ett fossilt r, OSMET 3.0

This is a brief but focused literature review of articles centered around pyrolysis and hydrothermal carbonization (HTC) using various feedstocks, including residues from industries, agriculture, and landfill waste. The deployment of bio-wastes will be the cornerstone of circular bio-economies in the future. The main emphasis is on gleaning how these two technologies can contribute to a sustainable circular (bio) economy, by understanding the process parameters influencing the quality, type and quantity of the final output. HTC and pyrolysis, it may be undeniably stated, can support the progress towards a clutch of sustainable development goals (SDGs), as they operate right at the confluence of solid waste management and renewable energy production. As mentioned in many of the articles reviewed in this paper, a high process temperature usually results in higher yields of bio-oil and biogas/pyrogas (and thereby less biochar), implying a higher energy recovery. HTC trumps pyrolysis on many counts – economy, energy-efficiency and product (hydrochar) quality. However, pyrolysis is a simpler method to regulate, and pyrochar, has a higher market value vis-à-vis hydrochar. While both these technologies generate valuable end-products regardless of the type of feedstock used; the articles reviewed clearly show that the feedstock does influence the quality of the output and thereby the application to which it can be directed. The review leads to recommendations for future research in collecting data and creating a model to in-vestigate various process parameters. Some of these recommendations are detailed comparative life cycle assessments (LCAs) to study the environmental impacts of technology-choices,, research into tailoring the optimal method and temperature to the feedstock deployed, and comprehensive forecast-based economic analysis of commercial-scale pyrolysis and HTC projects, are called for. As stated at the beginning, this is a brief review, which can also be expan

Traditional methods to develop biomass-based carbon adsorbents generally involve carbonization followed by chemical or physical activation. However, routes involving the hydrothermal treatment of biomass are receiving growing interest. In this work, two different strategies for the synthesis of sustainable CO2 adsorbents are compared, i.e., in situ ionic activation and hydrothermal treatment followed by activation with CO2. The latter is a green and simple procedure that does not require the addition of chemicals or acid-washing stages, and which leads to carbon adsorbents with relatively high CO2 adsorption capacity at low pressures, up to 0.64 mmol g−1 at 15 kPa and 50 °C, conditions relevant for postcombustion CO2 capture applications. On the other hand, in situ ionic activation can lead to carbon adsorbents with superior CO2 adsorption capacity in the aforementioned conditions, 0.78 mmol g−1, and with reduced cost and environmental impact compared to conventional chemical activation.

Hydrothermal carbonization (HTC) of carbohydrates and biomass is a straightforward method for preparing hydrochars at low temperatures of 180-250 °C. Hydrochars are more carbonized than their precursors. Increasing the carbonization degree of hydrochars at hydrothermal temperatures is a scientific quest that is addressed in this thesis. Hydrochars are known to have a spherical or irregular morphology. Here we address thin film hydrochars for the first time. Hydrochars themselves are carbon precursors for preparing activated carbons. Activated carbons are porous materials that can be used for gas adsorption applications. In this thesis, enhanced adsorption of VOCs at low pressures is addressed by using iron phosphate impregnated activated carbons. Finaly, any chemical process or product including those in this thesis such as HTC, activation, hydrochar and activated carbons may contribute to the issue of environmental degradation positively or negatively. Such environmental impacts are addressed by life cycle assessment of processes of HTC and activation and their related products in the last paper of this thesis. Briefly mentioned, in my first study (Paper I), I focused on the HTC of glucose in the presence of iron (II) sulfate. By changing the concentration of iron (II) sulfate, with a catalytic amount, blue hydrochars were formed at the bottom of the autoclave. The blueness was related to thin film interference. The thin film hydrochars were more carbonized than spherical hydrochars and the yield of HTC has increased in the presence of iron (II) sulfate. The second study (Paper II) is focused on the activation of hydrochars with H3PO4 and H3PO4+FeCl3. We showed that ultramicroporosity and impregnated iron phosphate species enhance the adsorption of VOCs at low pressure. The ACs were impregnated with Fe (PO3)2 and it was shown that Fe (PO3)2 acts as an activation agent which opens up for future studies. In the third study (Paper III), H3PO4-activated carbons were p

Steel is an indispensable material of the modern society and yet the production of steel is one of the largest anthropogenic CO2 emission sources on the planet. The conventional blast-furnace-basic-oxygen-furnace (BOF) process is responsible for generating 85% of the steel industry’s total CO2 emissions, which is the result of a high coal consumption rate for the reduction of iron ores and for providing the heat necessary for the high-temperature process. In order to meet the climate goal set by the Paris Agreement, the iron and steel industry must drastically decrease its CO2 emissions and aim at achieving net-zero emissions by 2050. Bioenergy is a form of renewable energy, and if it is managed sustainably throughout its life cycle, it can be considered carbon-neutral. Replacing fossil fuels with biofuels consumed during the steelmaking processes is one way to decrease CO2 emissions. However, this approach has not been widely adopted by steelmakers over the world due to the high price and the limited availability of wood-based biofuels. Hydrochar is a coal-like solid material that is produced from the hydrothermal carbonization (HTC) of biomass. It has attracted great interest from steelmakers due to its coal-like properties and the fact that it can be produced from a wide range of organic waste streams that can be found in almost every country. Previous studies focused on the use of hydrochar for the blast furnace process. This thesis therefore examines the potential use of hydrochar in the direct-reduction-electric-arc-furnace (DR-EAF) process, and particularly in two applications where the use of fossil coal is difficult to abate—the coal-based direct reduction of iron ore and the carburization of liquid steel in the EAF. This thesis begins with a characterization study of a hydrochar produced from lemon peel waste (LPH) and its comparison with a fossil reference material (anthracite) and two bio-reference materials (charcoal). The results reveal that LPH is a h, Stål är ett oumbärligt material i det moderna samhället, men produktionen av stål representerar samtidigt en av de största antropogena CO2-utsläppskällorna på planeten. Den konventionella processen som kombinerar en masugn med en konverter genererar 85 % av stålindustrins totala CO2-utsläpp. Detta är orsakat av en hög kolförbrukningshastighet för att reducera järnmalm och för att tillhandahålla den värme som krävs för denna högtemperaturprocess. För att klara klimatmålen i Parisavtalet måste stålindustrin drastiskt minska sina CO2-utsläpp och sikta på att uppnå nettonollutsläpp till 2050. Bioenergi är en form av förnybar energi, som om den hanteras på ett hållbart sätt under hela sin livscykel, kan betraktas som koldioxidneutral. Därför är det positivt att ersätta fossila bränslen med biobränslen som förbrukas under ståltillverkningsprocesserna i syfte att minska CO2-utsläppen. Detta tillvägagångsätt har dock inte använts i stor utsträckning av ståltillverkare i världen, på grund av det höga priset och den begränsade tillgågen på träbaserade biobränslen. Hydrochar är ett kolliknande fast material som framställs från en hydrotermisk förkolning av biomassa. Materialet har uppmärksammats av ståltillverkare på grund av dess kolliknade egenskaper och det faktum att det kan produceras från ett brett utbud av organiska avfall som finns tillgängligt i nästan alla länder. Tidigare studier har fokuserat på användningen av hydrochar för masugnsprocessen, medan denna avhandling fokuserar på att studera den potentialla användningen av hydrochar i electriska ljusbågsugnar som chargeras med direktreduktionspellets (DR-EAF). Dessutom för speciellt två tillämpningar där användningen av fossilt kol är svår att minska, nämligen den kolbaserade direkta reduktionen av järnmalm och uppkolningen av flytande stål i ljusbågsugnen. Inledningsvis så presenteras resultaten av en karaktäriseringsstudie av hydrochar framställt från citronskalsavfall (LPH) och resultaten jämförs med ett fossilt r, OSMET 3.0

Hydrothermal carbonization (HTC) of carbohydrates and biomass is a straightforward method for preparing hydrochars at low temperatures of 180-250 °C. Hydrochars are more carbonized than their precursors. Increasing the carbonization degree of hydrochars at hydrothermal temperatures is a scientific quest that is addressed in this thesis. Hydrochars are known to have a spherical or irregular morphology. Here we address thin film hydrochars for the first time. Hydrochars themselves are carbon precursors for preparing activated carbons. Activated carbons are porous materials that can be used for gas adsorption applications. In this thesis, enhanced adsorption of VOCs at low pressures is addressed by using iron phosphate impregnated activated carbons. Finaly, any chemical process or product including those in this thesis such as HTC, activation, hydrochar and activated carbons may contribute to the issue of environmental degradation positively or negatively. Such environmental impacts are addressed by life cycle assessment of processes of HTC and activation and their related products in the last paper of this thesis. Briefly mentioned, in my first study (Paper I), I focused on the HTC of glucose in the presence of iron (II) sulfate. By changing the concentration of iron (II) sulfate, with a catalytic amount, blue hydrochars were formed at the bottom of the autoclave. The blueness was related to thin film interference. The thin film hydrochars were more carbonized than spherical hydrochars and the yield of HTC has increased in the presence of iron (II) sulfate. The second study (Paper II) is focused on the activation of hydrochars with H3PO4 and H3PO4+FeCl3. We showed that ultramicroporosity and impregnated iron phosphate species enhance the adsorption of VOCs at low pressure. The ACs were impregnated with Fe (PO3)2 and it was shown that Fe (PO3)2 acts as an activation agent which opens up for future studies. In the third study (Paper III), H3PO4-activated carbons were p

Although industrial hydrothermal carbonization (HTC) uses wet feedstock, lab-scale studies tend to dry the feedstock under the assumption that the rehydration of the feedstock would restore its original properties. To the best of our knowledge, this assumption has not been thoroughly examined at the lab scale; therefore, its investigation is crucial to prevent any discrepancies that might affect the upscaling of HTC. This research aims to examine the effects of pre-drying biomass by comparing it to the use of wet biomass in HTC experiments, employing three different types of biomass (rejected tomatoes, rejected apples, and digestate). Additionally, the study investigates the influence of stirring on pre-dried and wet biomass under the selected HTC conditions. The results indicate a substantial disparity in studied hydrochar properties when using pre-dried biomass compared to wet biomass. For pre-dried biomass, there is a tendency for an increase in mass yield and solid carbon yield in most examined samples (5–10% dry basis) compared to the wet biomass. Regarding functional groups, wet tomatoes and apples exhibit more pronounced peaks than pre-dried samples. Conversely, digestate shows similar spectra across all examined scenarios. The effect of stirring appears insignificant for most of the studied scenarios; nevertheless, it reduced dehydration and decarboxylation reactions during HTC., Sanitary Engineering

Steel is an indispensable material of the modern society and yet the production of steel is one of the largest anthropogenic CO2 emission sources on the planet. The conventional blast-furnace-basic-oxygen-furnace (BOF) process is responsible for generating 85% of the steel industry’s total CO2 emissions, which is the result of a high coal consumption rate for the reduction of iron ores and for providing the heat necessary for the high-temperature process. In order to meet the climate goal set by the Paris Agreement, the iron and steel industry must drastically decrease its CO2 emissions and aim at achieving net-zero emissions by 2050. Bioenergy is a form of renewable energy, and if it is managed sustainably throughout its life cycle, it can be considered carbon-neutral. Replacing fossil fuels with biofuels consumed during the steelmaking processes is one way to decrease CO2 emissions. However, this approach has not been widely adopted by steelmakers over the world due to the high price and the limited availability of wood-based biofuels. Hydrochar is a coal-like solid material that is produced from the hydrothermal carbonization (HTC) of biomass. It has attracted great interest from steelmakers due to its coal-like properties and the fact that it can be produced from a wide range of organic waste streams that can be found in almost every country. Previous studies focused on the use of hydrochar for the blast furnace process. This thesis therefore examines the potential use of hydrochar in the direct-reduction-electric-arc-furnace (DR-EAF) process, and particularly in two applications where the use of fossil coal is difficult to abate—the coal-based direct reduction of iron ore and the carburization of liquid steel in the EAF. This thesis begins with a characterization study of a hydrochar produced from lemon peel waste (LPH) and its comparison with a fossil reference material (anthracite) and two bio-reference materials (charcoal). The results reveal that LPH is a h, Stål är ett oumbärligt material i det moderna samhället, men produktionen av stål representerar samtidigt en av de största antropogena CO2-utsläppskällorna på planeten. Den konventionella processen som kombinerar en masugn med en konverter genererar 85 % av stålindustrins totala CO2-utsläpp. Detta är orsakat av en hög kolförbrukningshastighet för att reducera järnmalm och för att tillhandahålla den värme som krävs för denna högtemperaturprocess. För att klara klimatmålen i Parisavtalet måste stålindustrin drastiskt minska sina CO2-utsläpp och sikta på att uppnå nettonollutsläpp till 2050. Bioenergi är en form av förnybar energi, som om den hanteras på ett hållbart sätt under hela sin livscykel, kan betraktas som koldioxidneutral. Därför är det positivt att ersätta fossila bränslen med biobränslen som förbrukas under ståltillverkningsprocesserna i syfte att minska CO2-utsläppen. Detta tillvägagångsätt har dock inte använts i stor utsträckning av ståltillverkare i världen, på grund av det höga priset och den begränsade tillgågen på träbaserade biobränslen. Hydrochar är ett kolliknande fast material som framställs från en hydrotermisk förkolning av biomassa. Materialet har uppmärksammats av ståltillverkare på grund av dess kolliknade egenskaper och det faktum att det kan produceras från ett brett utbud av organiska avfall som finns tillgängligt i nästan alla länder. Tidigare studier har fokuserat på användningen av hydrochar för masugnsprocessen, medan denna avhandling fokuserar på att studera den potentialla användningen av hydrochar i electriska ljusbågsugnar som chargeras med direktreduktionspellets (DR-EAF). Dessutom för speciellt två tillämpningar där användningen av fossilt kol är svår att minska, nämligen den kolbaserade direkta reduktionen av järnmalm och uppkolningen av flytande stål i ljusbågsugnen. Inledningsvis så presenteras resultaten av en karaktäriseringsstudie av hydrochar framställt från citronskalsavfall (LPH) och resultaten jämförs med ett fossilt r, OSMET 3.0

The low energy density of biomass is a crucial limitation for their application in the steel industry. This study used catalyst-catalysed hydrothermal carbonization (HTC) to prepare higher-quality hydrochar from biomass. The effects of acid-base homogeneous catalysts (Fe(NO3)3·9H2O and CaO), liquid phase product (circulating water) and carbonization temperatures on the physicochemical properties and microscopic morphology of hydrochars were investigated. The results showed that higher carbonization temperature, circulating water and Fe(NO3)3·9H2O all raised the higher heating value (HHV) of hydrochar. When 4% of Fe(NO3)3·9H2O was added, the HHV of hydrochar reached 30.05 MJ/kg, which was 1.15 times higher than without catalysts. The above three conditions can also make the ordering degree in the carbonaceous structure lower ordered and enhance the reaction performance of the hydrochar. Meanwhile, the addition of Fe(NO3)3·9H2O at 240 °C can reduce the hydrochar ignition and burnout temperatures and enhance the combustion performance. Moreover, it was demonstrated that circulating water promoted the HTC more than deionized water. In conclusion, adding Fe(NO3)3·9H2O or circulating water to the HTC process can produce higher-quality hydrochar., QC 20231115

The distribution of inorganic elements between solid and liquid phases during biomass hydrothermal carbonization (HTC) is a poorly investigated topic despite its importance for process optimization. To fill in this gap, the distribution of inorganic elements and their forms were determined for three agro-food waste feedstocks converted at HTC temperatures of 180, 220, and 260 °C in 12 h. Satisfactory balances were achieved, with values between 80 and 92% for C and N, and 80 and 110% for most inorganic elements. At 180 °C, over 90% of P, Mg, Ca, K, Na, and Mn were removed from hydrochars whatever feedstock. At higher temperatures, P, Mg, Ca, and Mn were partly reincorporated into hydrochars (between 7 and 53%), possibly due to the formation of insoluble precipitates, while K and Na remained in the liquid. On the opposite, some minor elements, Cu and Al, remained in the hydrochars, whatever temperature. Si showed different removal behaviors according to feedstock and temperature. These results show the possibility of optimizing the removal of inorganic elements from hydrochars using different temperatures.

The distribution of inorganic elements between solid and liquid phases during biomass hydrothermal carbonization (HTC) is a poorly investigated topic despite its importance for process optimization. To fill in this gap, the distribution of inorganic elements and their forms were determined for three agro-food waste feedstocks converted at HTC temperatures of 180, 220, and 260 °C in 12 h. Satisfactory balances were achieved, with values between 80 and 92% for C and N, and 80 and 110% for most inorganic elements. At 180 °C, over 90% of P, Mg, Ca, K, Na, and Mn were removed from hydrochars whatever feedstock. At higher temperatures, P, Mg, Ca, and Mn were partly reincorporated into hydrochars (between 7 and 53%), possibly due to the formation of insoluble precipitates, while K and Na remained in the liquid. On the opposite, some minor elements, Cu and Al, remained in the hydrochars, whatever temperature. Si showed different removal behaviors according to feedstock and temperature. These results show the possibility of optimizing the removal of inorganic elements from hydrochars using different temperatures.

In agroindustry, a significant amount of waste is generated, which can be treated using various thermochemical technologies such as hydrothermal carbonization. Biomass yield and carbon content are two of the most common characteristics studied within the processes generated by these thermochemical technologies, and chemical analyses and statistical techniques are usually employed. These techniques include t-student tests, analysis of variance, or response surface models to optimize or estimate the effects of certain factors. Unlike research conducted in this field of chemistry, this study aimed to introduce alternative statistical techniques for modeling such data, proposing diverse analysis strategies to enhance understanding of the studied phenomena. To achieve this, the statistical modeling of two datasets derived from apple pomace and blueberries was presented, encompassing four factors (time, humidity, power, temperature) and two separate responses (carbon content and process yield). This study reveals that time, temperature, and humidity collectively affect process yield and carbon content in apple biomass. It is concluded that techniques like generalized linear models with beta response and generalized additive models for location, scale, and shape provide a deeper understanding of the phenomenon of interest and the ability to estimate the effects of studied factors on responses that do not naturally follow a normal distribution., En la agroindustria se genera una considerable cantidad de residuos, los cuales pueden ser tratados usando diversas tecnologías termoquímicas como la carbonización hidrotermal. El rendimiento y contenido de carbono de biomasas son dos de las características más comunes que se estudian dentro del proceso generado en estas tecnologías tecnoquímicas, y usualmente se aplican análisis químicos y técnicas estadísticas, tales como pruebas t-student, análisis de varianza o modelos de superficies de respuestas para optimizar estas respuestas o estimar el efecto que ciertos factores puedan tener sobre estas. A diferencia de las investigaciones abordadas en esta área de la química, este estudio tuvo como propósito introducir diferentes técnicas alternativas de la estadística para la modelación de este tipo de datos con el fin de proponer diferentes estrategias de análisis que permitan ampliar el conocimiento de los fenómenos estudiados en esta área. Para ello, se presentó la modelación estadística de dos bases de datos provenientes de bagazo de manzana y de arándanos que contienen un total de cuatro factores (tiempo, humedad, potencia, temperatura) y dos respuestas a analizar por separado (contenido de carbono y rendimiento del proceso). En este estudio se observa que el tiempo, la temperatura y la humedad tienen un efecto conjunto sobre el rendimiento del proceso y el contenido de carbono de la biomasa proveniente de la manzana. Se concluye que, técnicas como modelos lineales generalizados con respuesta beta y los modelos aditivos generalizados de posición, escala y forma, proporcionan un mayor conocimiento del fenómeno de interés y la capacidad de estimar el efecto de los factores estudiados sobre respuestas que naturalmente no poseen un comportamiento distribucional como el modelo normal.

Hydrothermal carbonization of carbohydrate and biomass is a straightforward method for preparing hydrochars at low temperature. Hydrochars are more carbonized than their precursors. Hydrochars themselves are carbon precursors for preparing activated carbons. Activated carbons are porous materials that can be used for water and air purification. In my first study (Paper I), I have focused on hydrothermal carbonization of glucose in presence of iron (II)sulfate. By changing the concentration of iron (II) sulfate, with a catalytic amount, blue hydrochars were formed at the bottom of the autoclave. The blueness was related to thin film interference. The thin film hydrochars were more carbonized than spherical hydrochars and the yield of HTC has increased in presence of iron (II)sulfate. The second study (Paper II) is focused on the activation of hydrochars with H3PO4 and H3PO4+FeCl3. We showed that ultramicroporsity and impregnated iron phosphate species enhance the adsorption of VOCs at low pressure. The ACs were impregnated with Fe(PO3)2 and it is shown that Fe(PO3)2 acts as an activation agent which opens up for future studies. In the third study (Paper III), H3PO4 activated carbons were prepared and impregnated with FeS and FeSe. ACs were used for the removal of Cd2+ and Pb2+ in the third study. The uptake of heavy metals by FeS/AC and FeSe/ACs was significantly increased compared to other studies in the literature. In the last study (Paper IV), prickly pear seed biomass from agro sector in Tunisia was hydrothermal carbonized. The hydrochars were then activated into ACs by CO2 activation. The life cycle assessment of the HTC and activation process was investigated.

Hydrothermal carbonization of carbohydrate and biomass is a straightforward method for preparing hydrochars at low temperature. Hydrochars are more carbonized than their precursors. Hydrochars themselves are carbon precursors for preparing activated carbons. Activated carbons are porous materials that can be used for water and air purification. In my first study (Paper I), I have focused on hydrothermal carbonization of glucose in presence of iron (II)sulfate. By changing the concentration of iron (II) sulfate, with a catalytic amount, blue hydrochars were formed at the bottom of the autoclave. The blueness was related to thin film interference. The thin film hydrochars were more carbonized than spherical hydrochars and the yield of HTC has increased in presence of iron (II)sulfate. The second study (Paper II) is focused on the activation of hydrochars with H3PO4 and H3PO4+FeCl3. We showed that ultramicroporsity and impregnated iron phosphate species enhance the adsorption of VOCs at low pressure. The ACs were impregnated with Fe(PO3)2 and it is shown that Fe(PO3)2 acts as an activation agent which opens up for future studies. In the third study (Paper III), H3PO4 activated carbons were prepared and impregnated with FeS and FeSe. ACs were used for the removal of Cd2+ and Pb2+ in the third study. The uptake of heavy metals by FeS/AC and FeSe/ACs was significantly increased compared to other studies in the literature. In the last study (Paper IV), prickly pear seed biomass from agro sector in Tunisia was hydrothermal carbonized. The hydrochars were then activated into ACs by CO2 activation. The life cycle assessment of the HTC and activation process was investigated.

Hydrothermal carbonization (HTC) technology upgrades combustible waste (CW) to high-quality fuel known as hydrochar. However, there is a research gap regarding the application limit of hydrochar instead of fossil fuels in blast furnaces. In this study, the physical, chemical, and metallurgical properties of hydrochar were thoroughly analyzed. The results showed that gross calorific value, grindability, ignition temperature, explosivity, combustion and gasification all improved by HTC process compared with the waste feedstocks. Moreover, the HTC process can effectively remove harmful elements (K, Na, Cl, and S) from feedstocks into liquid and gas phase without adding other reagents, reducing harmful effects in the blast furnace. Removal rates by HTC were >80% for alkali metals and >73.9% for Cl (reaching 98.18% for polyvinyl chloride hydrochar). The environmental benefit calculation shows that the CO2 emission reduction of replacing bituminous coal with 40% HTC-treated maize straw can reach 94.7 kg/tHM. The annual CO2 reduction can reach 1.7 x 107 kg and the annual coal reduction is 1.5 x 107 kg of a blast furnace. The results showed that hydrochar is a clean energy source compared with fossil fuel alternatives and meets the blast furnace injection requirements., QC 20230117

Hydrothermal carbonization of carbohydrate and biomass is a straightforward method for preparing hydrochars at low temperature. Hydrochars are more carbonized than their precursors. Hydrochars themselves are carbon precursors for preparing activated carbons. Activated carbons are porous materials that can be used for water and air purification. In my first study (Paper I), I have focused on hydrothermal carbonization of glucose in presence of iron (II)sulfate. By changing the concentration of iron (II) sulfate, with a catalytic amount, blue hydrochars were formed at the bottom of the autoclave. The blueness was related to thin film interference. The thin film hydrochars were more carbonized than spherical hydrochars and the yield of HTC has increased in presence of iron (II)sulfate. The second study (Paper II) is focused on the activation of hydrochars with H3PO4 and H3PO4+FeCl3. We showed that ultramicroporsity and impregnated iron phosphate species enhance the adsorption of VOCs at low pressure. The ACs were impregnated with Fe(PO3)2 and it is shown that Fe(PO3)2 acts as an activation agent which opens up for future studies. In the third study (Paper III), H3PO4 activated carbons were prepared and impregnated with FeS and FeSe. ACs were used for the removal of Cd2+ and Pb2+ in the third study. The uptake of heavy metals by FeS/AC and FeSe/ACs was significantly increased compared to other studies in the literature. In the last study (Paper IV), prickly pear seed biomass from agro sector in Tunisia was hydrothermal carbonized. The hydrochars were then activated into ACs by CO2 activation. The life cycle assessment of the HTC and activation process was investigated.

Hydrothermal carbonization of carbohydrate and biomass is a straightforward method for preparing hydrochars at low temperature. Hydrochars are more carbonized than their precursors. Hydrochars themselves are carbon precursors for preparing activated carbons. Activated carbons are porous materials that can be used for water and air purification. In my first study (Paper I), I have focused on hydrothermal carbonization of glucose in presence of iron (II)sulfate. By changing the concentration of iron (II) sulfate, with a catalytic amount, blue hydrochars were formed at the bottom of the autoclave. The blueness was related to thin film interference. The thin film hydrochars were more carbonized than spherical hydrochars and the yield of HTC has increased in presence of iron (II)sulfate. The second study (Paper II) is focused on the activation of hydrochars with H3PO4 and H3PO4+FeCl3. We showed that ultramicroporsity and impregnated iron phosphate species enhance the adsorption of VOCs at low pressure. The ACs were impregnated with Fe(PO3)2 and it is shown that Fe(PO3)2 acts as an activation agent which opens up for future studies. In the third study (Paper III), H3PO4 activated carbons were prepared and impregnated with FeS and FeSe. ACs were used for the removal of Cd2+ and Pb2+ in the third study. The uptake of heavy metals by FeS/AC and FeSe/ACs was significantly increased compared to other studies in the literature. In the last study (Paper IV), prickly pear seed biomass from agro sector in Tunisia was hydrothermal carbonized. The hydrochars were then activated into ACs by CO2 activation. The life cycle assessment of the HTC and activation process was investigated.

Hydrothermal carbonization of carbohydrate and biomass is a straightforward method for preparing hydrochars at low temperature. Hydrochars are more carbonized than their precursors. Hydrochars themselves are carbon precursors for preparing activated carbons. Activated carbons are porous materials that can be used for water and air purification. In my first study (Paper I), I have focused on hydrothermal carbonization of glucose in presence of iron (II)sulfate. By changing the concentration of iron (II) sulfate, with a catalytic amount, blue hydrochars were formed at the bottom of the autoclave. The blueness was related to thin film interference. The thin film hydrochars were more carbonized than spherical hydrochars and the yield of HTC has increased in presence of iron (II)sulfate. The second study (Paper II) is focused on the activation of hydrochars with H3PO4 and H3PO4+FeCl3. We showed that ultramicroporsity and impregnated iron phosphate species enhance the adsorption of VOCs at low pressure. The ACs were impregnated with Fe(PO3)2 and it is shown that Fe(PO3)2 acts as an activation agent which opens up for future studies. In the third study (Paper III), H3PO4 activated carbons were prepared and impregnated with FeS and FeSe. ACs were used for the removal of Cd2+ and Pb2+ in the third study. The uptake of heavy metals by FeS/AC and FeSe/ACs was significantly increased compared to other studies in the literature. In the last study (Paper IV), prickly pear seed biomass from agro sector in Tunisia was hydrothermal carbonized. The hydrochars were then activated into ACs by CO2 activation. The life cycle assessment of the HTC and activation process was investigated.

Hydrothermal carbonization (HTC) can mitigate the disposal costs of sewage sludge in a wastewater treatment plant. This study analyzes the impact of integrating HTC with anaerobic digestion (AD) and combustion from a combined energy and economic performance perspective. Net energy balance and investment opportunity are investigated for a number of technical scenarios considering i) different combinations of the technologies: AD + HTC, AD + thermal dryer + combustion, and AD + HTC + combustion, ii) different options for HTC process water treatment: wet oxidation (WO) + AD, and direct return to AD, and iii) different products: heat-only, heat and electricity, hydrochar, and phosphorus. The results show trade-offs between investment cost, self-supplement of heat, and output electricity when WO is used. In AD + HTC, net heat output decreases compared to the reference plant, but avoided disposal costs and hydrochar revenue result in profitable investment when the process water is directly returned to the AD. Although HTC has a lower heat demand than the thermal dryer, replacing the thermal dryer with HTC is only possible when AD, HTC, and combustion are connected, or when WO covers HTC’s heat demand. HTC may impair the electricity production because of the necessity for a high-temperature heat source, whereas the thermal dryer can utilize a low-temperature heat source. In conclusion, energy advantages of HTC in AD + HTC + combustion are insufficient to provide a promising investment opportunity due to high investment costs of HTC. The investment opportunity improves by co-combustion of hydrochar and external sludge., Validerad;2023;Nivå 2;2023-08-15 (joosat);Licens fulltext: CC BY License;This article has previously appeared as a manuscript in a thesis.

Different hydrothermal carbonization (HTC) conditions will affect the yield, physicochemical properties and application of agricultural waste hydrochar. The hydrochar prepared under different HTC conditions was systematically studied through various experimental methods, and the experimental results were further verified and explained by ReaxFF molecular dynamics method. The results show that the higher HTC temperature, higher liquid-solid ratio and longer reaction time can reduce the yield of solid product. The volatile content of rice straw (RS) hydrochar decreased with the progresses of HTC, but the fixed carbon content increased. The HTC process is accompanied by the breakage of C-H bonds, C-O bonds, C-C bonds and O-H bonds, with C-O bond breaks comprising the most. The HTC process is also accompanied by the C-C bonds regeneration, indicating that decomposition and polymerization reactions coexist in the HTC process. At higher HTC temperature and longer reaction time, RS hydrochar showed lower specific surface area and porosity. The effect of the HTC temperature is the largest, while the effect of holding time is the smallest. Therefore, to expand the potential use of RS hydrochar, it is important to thoroughly investigate the influence of HTC conditions on the physicochemical properties of RS., QC 20230904

Hydrothermal carbonization (HTC) technology was used to carbonize and improve biomass raw material to obtain hydrochar. The effects of HTC temperature and holding time on the yield, composition, structure, combustion behavior, and safety of hydrochar were studied systematically. In addition, the results show that with the increase in HTC temperature and the prolongation of holding time, the yield of hydrochar gradually reduces, the fixed carbon content of hydrochar increases, the volatile content decreases, and a large number of ash and alkali metals enter the liquid phase and are removed. Further, the analysis of the combustion properties and the structure of hydrochar can be observed in that, as the HTC process promotes the occurrence of polymerization reactions, the specific surface area gradually reduces, the degree of carbon ordering increases, and the combustion curve moves toward the high-temperature zone and gradually approaches bituminous coal. Since biomass hydrochar has the characteristic of being carbon neutral, blast furnace injection hydrochar can reduce CO2 emissions, and every 1 kg/tHM of biomass hydrochar can reduce CO2 emissions by 1.95 kg/tHM., QC 20230321

Hydrothermal carbonization (HTC) can mitigate the disposal costs of sewage sludge in a wastewater treatment plant. This study analyzes the impact of integrating HTC with anaerobic digestion (AD) and combustion from a combined energy and economic performance perspective. Net energy balance and investment opportunity are investigated for a number of technical scenarios considering i) different combinations of the technologies: AD + HTC, AD + thermal dryer + combustion, and AD + HTC + combustion, ii) different options for HTC process water treatment: wet oxidation (WO) + AD, and direct return to AD, and iii) different products: heat-only, heat and electricity, hydrochar, and phosphorus. The results show trade-offs between investment cost, self-supplement of heat, and output electricity when WO is used. In AD + HTC, net heat output decreases compared to the reference plant, but avoided disposal costs and hydrochar revenue result in profitable investment when the process water is directly returned to the AD. Although HTC has a lower heat demand than the thermal dryer, replacing the thermal dryer with HTC is only possible when AD, HTC, and combustion are connected, or when WO covers HTC’s heat demand. HTC may impair the electricity production because of the necessity for a high-temperature heat source, whereas the thermal dryer can utilize a low-temperature heat source. In conclusion, energy advantages of HTC in AD + HTC + combustion are insufficient to provide a promising investment opportunity due to high investment costs of HTC. The investment opportunity improves by co-combustion of hydrochar and external sludge., Validerad;2023;Nivå 2;2023-08-15 (joosat);Licens fulltext: CC BY License;This article has previously appeared as a manuscript in a thesis.

The increasing need for water remediation due to water scarcity and the accumulation of persistent pollutants in water cycles requires innovative materials and their more sustainable synthesis processes. The aim of this work was therefore to develop an approach for the bottom-up synthesis of colloidal Fe/C composites. It was tested whether the composites fulfill the main criteria for use as injectable adsorbents and reducing agents for the removal of chlorinated pollutants in in-situ groundwater remediation. After screening different Fe and C precursors, the bottom-up synthesis of a particulate and reactive Fe/C composite was developed via hydrothermal carbonization (HTC) of mixtures of ferrous and sodium gluconate in a one-pot HTC and subsequent carbothermal reduction at 800 °C. The produced particles show good dispersibility with particle diameters in the range of d10 ≥ 2 µm, d50 ≈ 11 µm and d90 ≤ 40 µm in aqueous suspensions. By varying the molar ratio of Fe to gluconate in the HTC process, the final content of zero-valent iron equivalents (ZVI) in the composite could be adjusted between (24 ± 12) and (49 ± 15) wt.-%. The chemical reactivity of the composite was tested by reductive dechlorination of chloroform (CF) as a test reaction. The characterization of the composites before and after reductive dechlorination with X-ray diffraction (XRD) shows that not only pristine Fe0 but also Fe3C is active in the reductive dechlorination reaction. Palladization of the composite material shifts the product selectivity from dichloromethane as the main product to the non-chlorinated products methane (up to 77 mol-%) and ethane (up to 9 mol-%) without any external H2 feed. The dispersiblity and intrinsic reactivity of the synthesized composites meet the requirements for application in water remediation where contaminants need to be retained and degrad

Water pollution caused by industrial effluents without prior purification treatment represents one of the serious environmental concerns in contemporary times. Lately, due to its surface characteristics, pronounced chemical reactivity, and efficient regeneration ability, hydrochar obtained by hydrothermal carbonization of waste biomass has been explored as sustainable adsorbents for the removal of different pollutants. Besides, potential disadvantages of this material, such as low specific surface area and porosity, are easily overcome by surface modifications and composites synthesis. Previous reported studies have shown that chemical methods that include hydrogen peroxide or alkalis treatment, and incorporation of metals onto hydrochar surface can significantly improve its adsorption performances. Within this study, the potential application of hydrochars from different precursors and its composites as efficient sorbents of organic dyes and heavy metals from aqueous solutions will be discussed. Special attention will be directed towards structural changes caused by modification, achieved adsorption capacities and potential adsorption mechanisms. In general, the valorisation of hydrochar as a polluter sorbent solves the problems of sustainable and efficient material for purification and disposal of waste with permanent consequences to the environment.

In recent years, promising developments in the hydrothermal carbonization (HTC) of sewage sludge, as well as the potential to reclaim phosphorus and nitrogen, have emerged. In this study, the HTC of digested sewage sludge (DSS) was investigated for the downstream production of heavy metal (HM)-free fertilizer and the use of freeze concentration (FC) as a novel technology for process water treatment. To obtain clean fertilizer, phosphatic acid extracts were first treated with ion-exchange resins to remove dissolved HM, as well as phosphorus precipitating agents (i.e., aluminum and iron). Over 98% of the aluminum (Al) and 97% of the iron (Fe) could be removed in a single treatment step. The purified extract was then used for the precipitation of HM-free struvite crystals, with P-recovery rates exceeding 89%. Process water (PW) makes up the largest share of the two main HTC-products (i.e., hydrochar and PW) and is very rich in organic compounds. Compared to evaporation or membrane separation, FC is a promising technology for concentrating solutes from PW. Separation experiments resulted in the recovery of over 90% of the dissolved compounds in the concentrate. In our study, the concentrate was later utilized as an ammonium source for struvite precipitation, and the subsequent aerobic digestion of the remaining ice water resulted in an 85% reduction in chemical oxygen demand (COD) in 15 days.

The distribution of inorganic elements between solid and liquid phases during biomass hydrothermal carbonization (HTC) is a poorly investigated topic despite its importance for process optimization. To fill in this gap, the distribution of inorganic elements and their forms were determined for three agro-food waste feedstocks converted at HTC temperatures of 180, 220, and 260 °C in 12 h. Satisfactory balances were achieved, with values between 80 and 92% for C and N, and 80 and 110% for most inorganic elements. At 180 °C, over 90% of P, Mg, Ca, K, Na, and Mn were removed from hydrochars whatever feedstock. At higher temperatures, P, Mg, Ca, and Mn were partly reincorporated into hydrochars (between 7 and 53%), possibly due to the formation of insoluble precipitates, while K and Na remained in the liquid. On the opposite, some minor elements, Cu and Al, remained in the hydrochars, whatever temperature. Si showed different removal behaviors according to feedstock and temperature. These results show the possibility of optimizing the removal of inorganic elements from hydrochars using different temperatures.

The distribution of inorganic elements between solid and liquid phases during biomass hydrothermal carbonization (HTC) is a poorly investigated topic despite its importance for process optimization. To fill in this gap, the distribution of inorganic elements and their forms were determined for three agro-food waste feedstocks converted at HTC temperatures of 180, 220, and 260 °C in 12 h. Satisfactory balances were achieved, with values between 80 and 92% for C and N, and 80 and 110% for most inorganic elements. At 180 °C, over 90% of P, Mg, Ca, K, Na, and Mn were removed from hydrochars whatever feedstock. At higher temperatures, P, Mg, Ca, and Mn were partly reincorporated into hydrochars (between 7 and 53%), possibly due to the formation of insoluble precipitates, while K and Na remained in the liquid. On the opposite, some minor elements, Cu and Al, remained in the hydrochars, whatever temperature. Si showed different removal behaviors according to feedstock and temperature. These results show the possibility of optimizing the removal of inorganic elements from hydrochars using different temperatures.

The corn cob was investigated as available agrowaste material for the production of potential efficient material for heavy metals removal. The hydrothermal carbonization (HTC) technology is one of the appropriate methods for biomass transformation into high-value carbonaceous products than can be utilized as adsorbents. In this study, modified pyrohydrochar derived from corn cob (MCC) was effectively prepared by modification with Mg-Fe solution and pyrolysis. This material was used for Pb ions removal from aqueous solutions. The effect of solution pH, contact time and initial Pb concentration were examined in batch system. The achieved results revealed that the most effective Pb adsorption take place at pH 5. The experimental results were fitted to Langmuir, Freundlich, Sips and Redlich-Peterson isotherm models. The best data fit was achieved with the Sips isotherm model with maximum adsorption capacity for Pb removal of 214.9 mg/g. Additionally, the experimentally results from kinetic study were fitted by pseudo-first and pseudo-second order models. According to kinetic parameters, the Pb removal using MCC follows pseudo-second order model, which assumes that chemical interaction between Pb ions and functional groups on the MCC surface was involved in metal adsorption. According to data from this investigation and in comparisons to other adsorbents can be concluded that investigated material can be used as potential suitable adsorbent of Pb from aqueous solutions.

In the context of advocating carbon neutrality, there are new requirements for sustainable management of municipal sludge (MS). Hydrothermal carbonization (HTC) is a promising technology to deal with high-moisture MS considering its low energy consumption (without drying pretreatment) and value-added products (i.e., hydrochar). This study applied machine learning (ML) methods to conduct a holistic assessment with higher heating value (HHV) of hydrochar, carbon recovery (CR), and energy recovery (ER) as model targets, yielding accurate prediction models with R2 of 0.983, 0.844 and 0.858, respectively. Furthermore, MS properties showed positive (e.g., carbon content, HHV) and negative (e.g., ash content, O/C, and N/C) influences on the hydrochar HHV. By comparison, HTC parameters play a critical role for CR (51.7%) and ER (52.5%) prediction. The primary sludge was an optimal HTC feedstock while anaerobic digestion sludge had the lowest potential. This study provided a comprehensive reference for sustainable MS treatment and industrial application.

According to existing literature, there are no conclusive results on the impact of stirring on hydrothermal carbonization (HTC); some studies report a significant impact on the product's properties, while others indicate no influence. This study investigates the influence of stirring rate on several responses and properties of HTC products, including solid mass yield, solid carbon fraction, surface area, surface functional groups, morphology, and the fate of inorganic elements during HTC. Waste biomass was introduced as a feedstock to a 2 L HTC reactor, where the effects of temperature (180–250 °C), residence time (4–12 h), biomass to water (B/W) ratio (1–10%), and stirring rate (0–130 rpm) were investigated. The findings of this study conclusively indicated that the stirring rate does not influence any of the studied responses or properties of hydrochar under the selected experimental conditions used in this study. Nevertheless, the results indicated that a low-stirring rate (5 RPM) is enough to slightly enhanced the heating-up phase of the HTC reactor. For future research, it is recommended to examine the impact of stirring rate on the HTC of other types of biomass using the methodology developed in this study., Sanitary Engineering

In this study, Mg-based pyro-hydrochars derived from waste grape pomace (Mg-GP), corn cob (Mg-CC), and Miscanthus x giganteus (Mg-MIS) were successfully prepared applying one-step hydrothermal carbonization followed by pyrolysis. The structural characteristics and surface analysis of the prepared materials were characterized by various techniques, while its adsorption ability was examined through remediation of methylene blue (MB) under batch adsorption experiments. The obtained results revealed that pyro-hydrochars are highly effective adsorbents of MB with achieved capacities of 289.65 mg g(-1), 262.30 mg g(-1), and 232.48 mg g(-1) for Mg-GP, Mg-CC and Mg-MIS, respectively. The binding of MB to the surface on either of the tested material was achieved by a complex mechanism that unifies electro-static interaction, hydrogen bonding, pi-pi interaction, surface complexation, and ion-exchange mechanism. The kinetic study display that the adsorption process onto used Mg-doped pyro-hydrochars is favorable and follows pseudo-second order kinetics, while the isotherm equilibriums were determined by Sips isotherm model. Tested materials can be effectively reused for at least 3 cycles, with minimal loss of efficiency. Overall, findings from this work promote Mg-doped pyro-hydrochars form different precursors as promising, sustainable, and efficient adsorbents of MB from polluted wastewaters.

Recent innovative adsorption technologies for water purification rely on micrometer-sized activated carbon (AC) for ultrafast adsorption or in situ remediation. In this study, the bottom-up synthesis of tailored activated carbon spheres (aCS) from sucrose as renewable feedstock is demonstrated. The synthesis is based on a hydrothermal carbonization step followed by a targeted thermal activation of the raw material. This preserves its excellent colloid properties, i.e., narrow particle size distribution around 1 µm, ideal spherical shape and excellent aqueous dispersibility. We investigated the ageing of the freshly synthesized, highly de-functionalized AC surface in air and aqueous media under conditions relevant to the practice. A slow but significant ageing due to hydrolysis and oxidation reactions was observed for all carbon samples, leading to an increase of the oxygen contents with storage time. In this study, a tailored aCS product was generated within a single pyrolysis step with 3 vol.-% H2O in N2 in order to obtain the desired pore diameters and surface properties. Adsorption characteristics, including sorption isotherms and kinetics, were investigated with monochlorobenzene (MCB) and perfluorooctanoic acid (PFOA) as adsorbates. The product showed high sorption affinities up to log (KD/[L/kg]) of 7.3 ± 0.1 for MCB and 6.2 ± 0.1 for PFOA, respectively.

Waste-derived hydrochars are presented for the first time as promising materials to reduce the consumption of natural resources and the carbon footprint of the cement industry, while eliminating waste and sequestering a high amount of carbon in civil infrastructures. Rice husk (RH) and stabilized organic waste from a mixed municipal waste mechanical-biological treatment plant (SOW) were subjected to hydrothermal carbonization at 200 °C for 2 h and the resulting hydrochars were thoroughly evaluated as cement substitutes in fresh and hardened mortars. Compared to the control, mortars with 1.25–5 wt% of cement replaced by hydrochar from stabilized organic fraction caused a decrease in compressive strength of about 50–60% at 28 days of curing, while flexural strength was diminished by about 38–47%. The use of rice husk-derived hydrochar led to a reduction of 32–47% in compressive strength and of 22–34% in flexural strength. With compressive and flexural strengths of 27–41 and 3.31–4.92 MPa, respectively, blended mortars (28 days) display good prospects for use in plastering, rendering, masonry, partition panels and low-load paving. On the other hand, substituting 5 wt% of cement by hydrochar decreases the thermal conductivity and increases electrical resistivity of the mortar by 25–30%, which enhances thermal insulation properties and potential durability. This approach opens a new avenue for large-scale application of biowaste hydrochars as secondary raw materials for sustainable construction.

The integration of microalgae-bacteria consortia within existing wastewater treatment plants as alternative biological treatment could be an interesting option to improve the sustainability of these facilities. However, the fate of the produced biomass is decisive to make that option economically attractive. The present study aimed to valorize the microalgae grown at a pilot scale and used for the treatment of the centrate from municipal sewage sludge, producing microalgal-based iron nanoparticles (ME-nFe), by hydrothermal carbonization. The final product had high carbon content, strong sorbent power, and reducing properties, due to the presence of zerovalent iron. Different synthesis conditions were tested, comparing iron (III) nitrate nonahydrate (Fe (NO3)(3)center dot 9H(2)O) and ammonium iron (III) sulfate dodecahydrate (NH4 Fe (SO4)(2)center dot 12 H2O) as iron sources, four different Fe/C molar ratios (0.02, 0.05, 0.1, 0.2), and three process temperatures (180, 200, 225 degrees C). Based on the characterization of all the prototypes, the best one (having a specific area of 110 m(2)g(-1)) was chosen and tested for the removal of selected heavy metals by Jar tests. The removal of copper, zinc, cadmium, and nickel from the treated effluent from the wastewater treatment plant was 99.6%, 97.8%, 96.4%, and 80.3%, respectively, also for very low starting concentrations (1 mg L-1). The removal of total chromium, on the contrary, was only 12.4%. Thanks to the magnetic properties, the same batch of ME-nFe was recovered and used effectively for three consecutive Jar tests.