Preparation and Application of Biochar

A special issue of Environments (ISSN 2076-3298).

Deadline for manuscript submissions: closed (31 March 2024) | Viewed by 18460

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VALORIZA—Research Center for Endogenous Resource Valorization, Campus Politécnico, 10, 7300-555 Portalegre, Portugal
Interests: bioenergy; biofuels; biochar; pyrolysis; gasification; refuse derived fuels; biomass wastes
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BIOREF–Laboratório Colaborativo para as Biorrefinarias, Rua Amieira, Apartado 1089, 4466-901 S.Mamede de Infesta, Portugal
Interests: anaerobic digestion; electrochemistry; low-cost catalysts; biochar; effluent treatment

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BIOREF–Laboratório Colaborativo para as Biorrefinarias, Rua Amieira, Apartado 1089, 4466-901 S.Mamede de Infesta, Portugal
Interests: solid recoverd fuels; rdf; waste-derived chars; gasification; carbonization; hydrothermal carbonization; biochars

Special Issue Information

Dear Colleagues,

As of late, there has been an increased interest in the production of sustainable biochar, mostly because biochar presents very versatile physicochemical properties, is easily produced with potential to use several feedstocks and has large applicability in various fields.

Biochar is a carbon-rich and porous solid material that can be produced through the thermochemical conversion of biomass (pyrolysis, hydrothermal carbonization, gasification, torrefaction) with presence of little or no oxygen. This material has very unique qualities, including a large surface area, calorific value, hydrophobicity, high porosity, valuable functional groups, high cation exchange capacity and stability. These properties have great importance to a wide variety of applications that can address several pressing ecosystem challenges, namely, soil amendment, remediation of environmental pollutants and wastewaters, carbon capture and storage (climate change mitigation), bioenergy, renewable gases production, metal production, catalysts (e.g., biodiesel production, tar reduction and enhanced syngas production, deNOx reactions, microbial fuel cell electrodes) or overall gas cleaning. Indeed, specific end-user applications have different requirements for biochar properties, and these properties are noticeably affected by production technology, process conditions, feedstock type and post modifications (e.g., activation processes).

Considering the current interest and the several positive features of biochar, this Special Issue is dedicated to collecting high-quality research on biochar preparation technologies and applications, including technical, scientific, economic and environmental topics

Dr. Catarina Nobre
Prof. Dr. Paulo Brito
Dr. Gonçalo Lourinho
Dr. Octávio Alves
Guest Editors

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Keywords

  • biochar
  • waste-derived char
  • bioenergy
  • pyrolysis
  • oxidative torrefaction
  • carbonization
  • gasification
  • soil amendment
  • fuel cells
  • adsorption
  • forestry wastes
  • agricultural wastes
  • carbon sequestration
  • policy

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Related Special Issue

Published Papers (6 papers)

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Research

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18 pages, 2050 KiB  
Article
Potential Use of Biochar as a Mitigation Strategy for Salinity-Related Issues in Tomato Plants (Solanum lycopersicum L.)
by Eleonora Coppa, Giulia Quagliata, Rachele Venanzi, Alessandro Bruschini, Leonardo Bianchini, Rodolfo Picchio and Stefania Astolfi
Environments 2024, 11(1), 17; https://doi.org/10.3390/environments11010017 - 17 Jan 2024
Cited by 1 | Viewed by 2323
Abstract
The continuous growth of the population, along with climate change and the resulting surge in food demand, requires the development of alternative crop cultivation strategies that reduce the excessive use of freshwater for agricultural purposes. Biochar, which is a carbon-rich material made from [...] Read more.
The continuous growth of the population, along with climate change and the resulting surge in food demand, requires the development of alternative crop cultivation strategies that reduce the excessive use of freshwater for agricultural purposes. Biochar, which is a carbon-rich material made from organic waste through pyrolysis, has been recommended as a potential soil amendment to mitigate the negative effects of salinity. Biochar has unique properties such as high porosity, an ion exchange capacity, and the ability to retain water and nutrients. The purpose of this study was to evaluate the feasibility and effectiveness of using saline water for the cultivation of tomato plants (Solanum lycopersicum L.) and to investigate the potential use of biochar as a mitigation strategy for salinity-related issues in tomato cultivation. The concentration of NaCl during the experiment was 100 mM. We examined the impact of salt stress on plant growth, protein and chlorophyll content, the activation of the antioxidant response, and nutritional status. Our results indicated that salt treatments led to a significant accumulation of Na and Cl in shoots (regardless of the biochar addition) but did not result in a corresponding reduction in plant growth. However, the degree of oxidative damage caused by NaCl treatment, measured as malondialdehyde (MDA) accumulation, was reduced by biochar addition to the growth medium, most likely because of an increased guaiacol peroxidase (GPX) activity, which led to lower MDA accumulation. The strong positive effect of biochar on GPX activity could be reasonably attributed to increased Mo accumulation. In conclusion, the findings of this study represent a valuable starting point for developing crop management strategies based on biochar application to enhance plant performance under unfavorable conditions and reduce freshwater dependence in agriculture. Full article
(This article belongs to the Special Issue Preparation and Application of Biochar)
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18 pages, 5042 KiB  
Article
Torrefaction of Forest Residues Using a Lab-Scale Reactor
by Marta Martins, Maria Amélia Lemos, Francisco Lemos and Helena Pereira
Environments 2023, 10(12), 202; https://doi.org/10.3390/environments10120202 - 23 Nov 2023
Viewed by 1625
Abstract
Forest residues have been gaining interest as a source of renewable fuels due to their availability and the risks they represent for increasing forest fires. A major drawback for their removal and processing is the cost of transportation, which can be overcome through [...] Read more.
Forest residues have been gaining interest as a source of renewable fuels due to their availability and the risks they represent for increasing forest fires. A major drawback for their removal and processing is the cost of transportation, which can be overcome through densification procedures, e.g., torrefaction. To optimize the torrefaction parameters, Cistus ladanifer residues from the Portuguese forest were torrefied for 30 min in a lab-scale reactor at 250 and 350 °C. The quality of the torrefied material was assessed, and its energy and mass yields were determined through thermal analysis. The changes in morphological structure occurring during torrefaction were analysed through scanning electron microscopy. When compared to the original biomass, the charcoal obtained at 350 °C had a substantial increase in energy density accompanied by a significant mass reduction. Increasing the mass in the reactor had a positive effect on the energy yield. For the highest mass tested, a mass reduction of around 30% was obtained and a char with no loss in energy content (with a cumulative heat flow (CHF) of 9.0 MJ/kg compared to 5.8 MJ/kg of the original biomass). Modelling of the reactor allowed the analysis of the heat profile required for torrefaction. Full article
(This article belongs to the Special Issue Preparation and Application of Biochar)
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17 pages, 3792 KiB  
Article
Use of By-Products from Gasification and Carbonization from Polymeric Residues and Biomass for Application in Liquid Phase Adsorption
by Ana Carolina Assis, Roberta Panizio, Luis Calado, Paulo Brito and Paulo Mourão
Environments 2023, 10(5), 74; https://doi.org/10.3390/environments10050074 - 27 Apr 2023
Cited by 1 | Viewed by 2332
Abstract
The search for strategies that contribute to circular economy, based on the valorization of by-products of the most diverse industries and processes, is one of the main environmental objectives at present. This study aims to evaluate the possibility of valorizing by-products from the [...] Read more.
The search for strategies that contribute to circular economy, based on the valorization of by-products of the most diverse industries and processes, is one of the main environmental objectives at present. This study aims to evaluate the possibility of valorizing by-products from the gasification and carbonization of polymeric residues and biomass of natural origin through their application in adsorption processes. The selected residues and carbon by-products resulting from thermochemical conversion by the gasification and carbonization processes, after their physical and chemical characterization, presented improved structural and chemical properties which allow their application in adsorption processes. The characterization of the materials and samples prepared in this work involved a variety of analytical techniques, such as thermogravimetric analysis, polarized attenuated Fourier transform infrared spectroscopy, X-ray fluorescence, ultimate analysis, and nitrogen adsorption at 77 K. It was possible to observe that the material has between 40% and 50% volatile matter, and when carbonized, these values decrease to the range of 5% and 10%. The BET surface area analysis of these chars shows values between 100 and 400 m2g−1. For the chemically activated samples and for the phenol molecule, the samples with the best results are those that were prepared using olive prunings as a precursor. For the physically activated samples and also for phenol adsorption, the samples that showed the most potential were the ones prepared via air activation. Regarding the gasified samples, the best results were achieved with the samples without the incorporation of waste-derived fuel. Full article
(This article belongs to the Special Issue Preparation and Application of Biochar)
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17 pages, 6340 KiB  
Article
The Potential of Waste Phloem Fraction of Quercus cerris Bark in Biochar Production
by Umut Sen, Andrei Longo, Margarida Gonçalves, Isabel Miranda and Helena Pereira
Environments 2023, 10(5), 71; https://doi.org/10.3390/environments10050071 - 26 Apr 2023
Cited by 5 | Viewed by 2248
Abstract
Quercus cerris phloem is a lignocellulosic waste fraction obtained from bark fractionation. Biochars are technologically interesting functional materials that may be produced from lignocellulosic solid materials. This study explores the solid material properties of Quercus cerris phloem, evaluates biochar production from it, and [...] Read more.
Quercus cerris phloem is a lignocellulosic waste fraction obtained from bark fractionation. Biochars are technologically interesting functional materials that may be produced from lignocellulosic solid materials. This study explores the solid material properties of Quercus cerris phloem, evaluates biochar production from it, and explores its application as an adsorbent. In the first part of the study, thermogravimetric analysis, SEM microscopy observations, FT-IR spectroscopy, and ICP-AES analyses were performed on raw Quercus cerris phloem. In the second part of the study, biochars and activated carbons were produced and their structure, surface functional groups, methylene blue adsorption properties, and specific surface areas were determined. The results showed that Quercus cerris phloem is a lignocellulosic solid material that decomposes in a wide temperature range between 265 and 765 °C. The activation energy of phloem pyrolysis ranged between 82 and 172 kJ mol−1 in pyrolysis. The mineral composition is mainly calcium (88%) and potassium (4%). The biochar yield of Quercus cerris phloem ranged between 28% and 42% at different moderate temperature–time combinations. Raw phloem, phloem biochars, and phloem-activated carbons show high methylene blue removal efficiencies. Methylene blue adsorption follows pseudo-second-order kinetics. The BET surface areas of Quercus cerris phloem-activated carbons varied between 262.1 m2 g−1 and 317.5 m2 g−1. Full article
(This article belongs to the Special Issue Preparation and Application of Biochar)
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14 pages, 4159 KiB  
Article
Slow Pyrolysis of Quercus cerris Cork: Characterization of Biochars and Pyrolysis Volatiles
by Umut Sen, Marta Martins, Everton Santos, Maria Amelia Lemos, Francisco Lemos and Helena Pereira
Environments 2023, 10(1), 4; https://doi.org/10.3390/environments10010004 - 22 Dec 2022
Cited by 4 | Viewed by 3364
Abstract
Waste cork granules of Quercus cerris bark were subjected to isothermal and non-isothermal slow pyrolysis. The heat of the reaction, as well as the yields and properties of biochar, bio-oil, and pyrolysis gas were investigated by thermogravimetric analysis, FT-IR, CHN elemental analysis, higher [...] Read more.
Waste cork granules of Quercus cerris bark were subjected to isothermal and non-isothermal slow pyrolysis. The heat of the reaction, as well as the yields and properties of biochar, bio-oil, and pyrolysis gas were investigated by thermogravimetric analysis, FT-IR, CHN elemental analysis, higher heating value (HHV) determinations, scanning electron microscopy (SEM), and gas chromatography (GC). The slow pyrolysis was carried out in a semi-batch reactor using an isothermal or a non-isothermal dynamic approach. The results demonstrated that isothermal or non-isothermal slow pyrolysis of cork is a slightly exothermic reaction that produces biochars. The elemental analysis results indicated that non-isothermally produced chars have similar fuel properties compared to isothermally produced chars. The FT-IR results showed that cork suberin undergoes a higher degree of degradation in isothermal chars and aromatization begins in the char structure. Bio-oils are also produced and they consist of C5–C12 hydrocarbons with C8 carbon compounds making up the main fraction. Lighter components, mainly C1–C2 hydrocarbons are collected in the gas phase. The overall results indicate a possible reduced-cost route for the production of cork-based biochars by using non-isothermal slow pyrolysis. Full article
(This article belongs to the Special Issue Preparation and Application of Biochar)
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Review

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21 pages, 1985 KiB  
Review
Effects of Biochar on the C Use Efficiency of Soil Microbial Communities: Components and Mechanisms
by Laura Giagnoni and Giancarlo Renella
Environments 2022, 9(11), 138; https://doi.org/10.3390/environments9110138 - 4 Nov 2022
Cited by 11 | Viewed by 4462
Abstract
Biochar production and incorporation into soil is gaining momentum as a sustainable strategy for climate change mitigation, supported by ever increasing reports of significant carbon (C) sequestration in soil and reduction in greenhouse gas (GHG) emissions from the amended soils. With the progression [...] Read more.
Biochar production and incorporation into soil is gaining momentum as a sustainable strategy for climate change mitigation, supported by ever increasing reports of significant carbon (C) sequestration in soil and reduction in greenhouse gas (GHG) emissions from the amended soils. With the progression in biochar testing and use, there is also emerging evidence that biochar induces C sequestration in soil, and that it may not be solely caused by its inherent chemical stability, but also by the complex microbially driven processes and an increase in C use efficiency (CUE) through soil microbial metabolism. This evidence contradicts the current paradigm that sees the microbial CUE decrease during the degradation of recalcitrant material due to thermodynamic constraints, as observed only in several short-term and pilot-scale trials. As the CUE in soil results from interactions between several abiotic and biotic factors, in this paper we examine the link between the biochar properties, soil physico-chemical properties and microbial physiology to explain the CUE increase reported for biochar-amended soils. Based on the large body of physico-chemical literature, and on the high functional diversity and metabolic flexibility of soil microbial communities, we hypothesize that the long-term stabilization of biochar-borne C in the soil systems is not only controlled by its inherent recalcitrance, but also by the cooperative actions of improved soil status and increased microbial CUE. Given that the current knowledge on this specific aspect is still poor, in this feature paper we summarize the state of knowledge and examine the potential impact of biochar on some factors contributing to the whole-soil CUE. We conclude that, beside its inherent recalcitrance, biochar weathering and oxidation in soil create physical and chemical conditions that can potentially increase the microbial CUE. While these processes stabilize the microbial processed C in soil and increase soil fertility, more data from long-term field trials are needed to model the relationship between the CUE and the MRT of biochar-borne C. Based on our hypotheses and relying upon analysis of the available literature, we also suggest possible research approaches that may contribute to filling the gaps in the current knowledge on the topic. Full article
(This article belongs to the Special Issue Preparation and Application of Biochar)
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