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Zhang C, Fang J, Chen WH, Kwon EE, Zhang Y. Effects of water washing and KOH activation for upgrading microalgal torrefied biochar. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 921:171254. [PMID: 38408659 DOI: 10.1016/j.scitotenv.2024.171254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 02/16/2024] [Accepted: 02/23/2024] [Indexed: 02/28/2024]
Abstract
Torrefaction is an effective pathway for microalgal solid biofuel upgrading, and alkali metal activation is also an efficient method to enhance fuel properties. This study explores the comparison of torrefaction alone and KOH activation combined with torrefaction to determine a better operation for biochar production from the microalga Nannochloropsis Oceanica. The results indicate that the HHV ranges of KOH-activated biochar and unactivated biochar are 25.611-32.792 MJ·kg-1 and 25.024-26.389 MJ·kg-1, respectively. Furthermore, KOH-activated biochar is better than unactivated biochar, with less residue, broader pyrolysis and combustion temperature ranges, higher elemental carbon, and less combined carbon. Moreover, KOH-activated biochar is close to the unactivated one from the viewpoint of expense calculation and life cycle assessment and thus possesses a better comprehensive performance. Overall, KOH activation is an efficient method for upgrading microalgal solid biofuel. The results are conducive to exploring further modification of microalgal solid biofuel production with better properties, thus leading to a greener and more efficient approach for upgrading fuel performance.
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Affiliation(s)
- Congyu Zhang
- School of Resources and Environment, Northeast Agricultural University, Harbin 150030, China
| | - Jin Fang
- School of Resources and Environment, Northeast Agricultural University, Harbin 150030, China
| | - Wei-Hsin Chen
- Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan 701, Taiwan; Research Center for Smart Sustainable Circular Economy, Tunghai University, Taichung 407, Taiwan; Department of Mechanical Engineering, National Chin-Yi University of Technology, Taichung 411, Taiwan.
| | - Eilhann E Kwon
- Department of Earth Resources and Environmental Engineering, Hanyang University, Seoul 04763, Republic of Korea
| | - Ying Zhang
- School of Resources and Environment, Northeast Agricultural University, Harbin 150030, China.
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Leong YK, Chang JS. Microalgae-based biochar production and applications: A comprehensive review. BIORESOURCE TECHNOLOGY 2023; 389:129782. [PMID: 37742815 DOI: 10.1016/j.biortech.2023.129782] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Revised: 09/06/2023] [Accepted: 09/11/2023] [Indexed: 09/26/2023]
Abstract
Biochar, a solid carbonaceous substance synthesized from the thermochemical degradation of biomass, holds significant potential in addressing global challenges such as soil degradation, environmental pollution, and climate change. Its potential as a carbon sequestration agent, together with its versatile applications in soil amendments, pollutant adsorption, and biofuel production, has garnered attention. On the other hand, microalgae, with their outstanding photosynthetic efficiency, adaptability, and ability to accumulate carbohydrates and lipids, have demonstrated potential as emerging feedstock for biochar production. However, despite the significant potential of microalgal biochar, our current understanding of its various aspects, such as the influence of parameters, chemical modifications, and applications, remains limited. Therefore, this review aims to provide a comprehensive analysis of microalgae-based biochar, covering topics such as production techniques, pollutant removal, catalytic applications, soil amendments, and synthesis of carbon quantum dots to bridge the existing knowledge gap in this field.
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Affiliation(s)
- Yoong Kit Leong
- Department of Chemical and Materials Engineering, Tunghai University, Taichung 407224, Taiwan; Research Center for Smart Sustainable Circular Economy, Tunghai University, Taichung 407224, Taiwan
| | - Jo-Shu Chang
- Department of Chemical and Materials Engineering, Tunghai University, Taichung 407224, Taiwan; Research Center for Smart Sustainable Circular Economy, Tunghai University, Taichung 407224, Taiwan; Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan; Department of Chemical Engineering and Materials Science, Yuan Ze University, Chung-Li, Taiwan.
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Felix CB, Chen WH, Chang JS, Park YK, Saeidi S, Kumar G. Oxidative torrefaction of microalgae Chlorella sorokiniana: Process optimization by central composite design. BIORESOURCE TECHNOLOGY 2023; 382:129200. [PMID: 37211235 DOI: 10.1016/j.biortech.2023.129200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/14/2023] [Accepted: 05/16/2023] [Indexed: 05/23/2023]
Abstract
Microalgae are currently not viable as solid biofuels owing to their poor raw fuel properties. Torrefaction under oxidative media offers a cost-effective and energy-efficient process to address these drawbacks. A design of experiment was conducted using central composite design with three factors: temperature (200, 250, and 300 °C), time (10, 35, and 60 min), and O2 concentration (3, 12, and 21 vol%). The responses were solid yield, energy yield, higher heating value, and onset temperatures at 50% and 90% carbon conversion determined from thermogravimetric analysis. Temperature and time significantly affected all responses, while O2 concentration only affected higher heating value, energy yield and thermodegradation temperature at 90% conversion. Oxidative torrefaction of microalgae is recommended to be conducted at 200 °C, 10.6 min, 12% O2 where the energy yield and enhancement factor are 98.73% and 1.08, respectively. It is also more reactive under an air environment compared to inert torrefaction conditions.
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Affiliation(s)
- Charles B Felix
- Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan 701, Taiwan; Mechanical Engineering Department, De La Salle University, 2401 Taft Ave, 0922 Manila, Philippines
| | - Wei-Hsin Chen
- Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan 701, Taiwan; Research Center for Smart Sustainable Circular Economy, Tunghai University, Taichung 407, Taiwan; Department of Mechanical Engineering, National Chin-Yi University of Technology, Taichung 411, Taiwan.
| | - Jo-Shu Chang
- Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan; Department of Chemical and Materials Engineering, Tunghai University, Taichung, Taiwan; Research Center for Smart Sustainable Circular Economy, Tunghai University, Taichung, Taiwan
| | - Young-Kwon Park
- School of Environmental Engineering, University of Seoul, Seoul, 02504, Republic of Korea
| | - Samrand Saeidi
- Department of Applied and Environmental Chemistry, Interdisciplinary Excellence Centre, University of Szeged, H-6720, Rerrich Belater 1, Szeged, Hungary; Biotechnology Center, Silesian University of Technology, 8 Krzywousty St., 44-100 Gliwice, Poland
| | - Gopalakrishnan Kumar
- Institute of Chemistry, Bioscience and Environmental Engineering, Faculty of Science and Technology, University of Stavanger, Box 8600 Forus, 4036 Stavanger, Norway
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Yoshimoto S, Luthfi N, Nakano K, Fukushima T, Takisawa K. Effects of potassium on hydrothermal carbonization of sorghum bagasse. BIORESOUR BIOPROCESS 2023; 10:24. [PMID: 38647600 PMCID: PMC10992820 DOI: 10.1186/s40643-023-00645-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 03/22/2023] [Indexed: 04/07/2023] Open
Abstract
Hydrothermal carbonization (HTC) reacts with biomass in water at a high temperature and pressure to produce hydrochar with a higher heating value (HHV) and lower ash content than dry torrefaction. The high potassium content in biomass can promote thermochemical conversion; however, it lowers the melting temperature of the ash, causing slugging and fouling. Therefore, this study, investigated the effect of potassium on the HTC of sorghum bagasse by comparing the removal of potassium by washing with the addition of K2CO3. Consequently, the ash content was the highest in the potassium-added hydrochar and was 3.81% at a reaction time of 2 h. Elemental analysis showed that the lower the potassium content, the higher the carbon content, and the hydrochar with potassium removed by water washing at a reaction time of 3 h had the highest carbon content at 68.3%. Fourier transform infrared spectrometer showed dehydration and decarboxylation reactions due to HTC, but no significant differences were observed between the potassium concentrations. The mass yield decreased with increasing potassium content, and was 27.2% for the potassium-added hydrochar after 3 h. This trend was more pronounced with increasing reaction temperature. On the other hand, HHV was not affected by the potassium content. Therefore, the energy yield was similar to the weight yield. Thermal gravimetry and derivative thermal gravimetry (TG-DTG) analysis showed that higher potassium tended to accelerate the decomposition of lignin and decrease the oxidation temperature.
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Affiliation(s)
- Shuhei Yoshimoto
- Graduate School of Bioresources, Mie University, 1577 Kurimamachiyacho, Tsu, Mie, 514-8507, Japan
| | - Numan Luthfi
- Graduate School of Bioresources, Mie University, 1577 Kurimamachiyacho, Tsu, Mie, 514-8507, Japan
| | - Kanta Nakano
- Graduate School of Bioresources, Mie University, 1577 Kurimamachiyacho, Tsu, Mie, 514-8507, Japan
| | - Takashi Fukushima
- Graduate School of Bioresources, Mie University, 1577 Kurimamachiyacho, Tsu, Mie, 514-8507, Japan
| | - Kenji Takisawa
- Graduate School of Bioresources, Mie University, 1577 Kurimamachiyacho, Tsu, Mie, 514-8507, Japan.
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