Circular valorization of Argemone ochroleuca seed meal: biomass fractionation, bioethanol production, and hydrothermal carbonization

Abstract

Valorization of waste from the agro-industry is important for the advancement of the circular bioeconomy framework and the establishment of integrated, sustainable biorefineries. This study demonstrates the valorization of Argemone ochroleuca seed meal, a hexane-defatted lignocellulosic biomass, for the simultaneous production of bioethanol, hydrochar, and biopolymer precursor. Compositional analysis shows that 30.2% cellulose, 19.7% hemicellulose, and 22.1% lignin, showing the potential conversion to biofuels and carbonaceous products. Structural characterization confirmed the presence of reactive functional groups, appropriate porosity, moderate crystallinity, and good thermal stability, ideal for hydrothermal process for biomaterial synthesis. Organosolv pre-treatment using acidified ethanol–water mixture enabled effective fractionation with 89.4% cellulose recovery and solubilization of over 86% hemicellulose and lignin. Recovered cellulose was hydrolysed and fermented with Saccharomyces cerevisiae to yield 2.17 g ethanol per 10 g biomass (67.2% theoretical yield). Parallel to this, hydrothermal carbonization of A. ochroleuca seed meal at 180–230 °C for 2–4 h yielded hydrochar with fixed carbon as high as 41.2% and a higher heating value of 27.5 MJ/kg. From the recovered hemicellulose fraction 0.887 g of pentose sugars per gram of hemicellulose obtained. On polymeric content adjustment, pentosan content was 0.781 g g⁻¹ or 78.1% of isolated hemicellulose. Coupling organosolv and hydrothermal valorization processes makes A. ochroleuca seed meal as a suitable feedstock for zero-waste biorefineries to co-produce bioethanol, hydrochar, and biopolymers precursors in a systemic manner. Pilot-scale validation, life-cycle analysis, and techno-economic viability should be targeted in subsequent studies.

Graphical abstract

Keywords

Circular bioeconomy / Seed meal valorization / Organosolv fractionation / Bioethanol / Hydrochar

References

[1] Abdallh ME, Musigwa S, Ahiwe EU, et al. . Replacement value of cottonseed meal for soybean meal in broiler chicken diets with or without microbial enzymes. J Anim Sci Technol, 2020, 62: 159-173.

[2] Adamovic T, Tarasov D, Demirkaya E, Balakshin M, Cocero MJ. A feasibility study on green biorefinery of high lignin content agro-food industry waste through supercritical water treatment. J Clean Prod, 2021, 323129110

[3] Ag M, Yp K, Kg D, Pa S. Physico-chemical characterization of coconut shell (Cocos nucifera). Int J Adv Biochem Res, 2024, 8: 118-122.

[4] Aider M, Martel AA. Bleaching of defatted flaxseed meal to improve its usage as ingredient in food applications. Int J Food Sci Technol, 2011, 46: 2297-2304.

[5] Altınışık S, Nigiz FU, Gürdal S, Yılmaz K, Tuncel NB, Koyuncu S. Optimization of bioethanol production from sugar beet processing by-product molasses using response surface methodology. Biomass Convers Biorefin, 2025, 15(7): 9875-9888.

[6] Álvarez-Castillo E, Felix M, Bengoechea C, Guerrero A. Proteins from agri-food industrial biowastes or co-products and their applications as green materials. Foods, 2021, 10: 981

[7] Anahi M-DA, De AJ, León-Morales JM, et al. . Argemone species: potential source of biofuel and high-value biological active compounds. Environ Eng Res, 2022, 27: 200610-200619.

[8] Ancuţa P, Sonia A. Oil press-cakes and meals valorization through circular economy approaches: a review. Appl Sci, 2020, 10: 7432

[9] Andary J, Ouaini N, Abou-Khalil R. Diluted acid hydrolysate of olive stones: overliming and biomass fermentation. Fermentation, 2025, 11: 100

[10] Anggoro DD, Prasetyaningrum A, Udaibah W, et al. . Effect of ultrasound-advanced oxidation processes for pretreatment of oil palm mesocarp fiber for cellulose extraction. Int J Renew Energy Dev, 2024, 13: 532-538.

[11] Aranda MC, Lourdes M, Cartas M, et al. . Optimisation of sugar and solid biofuel co - production from almond tree prunings by acid pretreatment and enzymatic hydrolysis. Bioresour Bioprocess, 2024, 1130

[12] Arefizadeh M, Behvandi D, Shahhosseini S, Ghaemi A. Efficient CO2 adsorption by deoiled flaxseed hydrochar. Sci Rep, 2024, 14: 28306

[13] Arias A, Feijoo G, Moreira MT. Biorefineries as a driver for sustainability : key aspects, actual development and future prospects biorefineries as a driver for sustainability : key aspects, actual development and future prospects. J Clean Prod, 2023, 418137925

[14] Ashine F, Balakrishnan S, Kiflie Z, Tizazu BZ. Epoxidation of Argemone mexicana oil with peroxyacetic acid formed in-situ using sulfated tin (IV) oxide catalyst: characterization; kinetic and thermodynamic analysis. Heliyon, 2023, 9e12817

[15] Basaglia M, D’ambra M, Piubello G, et al. . Agro-food residues and bioethanol potential: a study for a specific area. Processes, 2021, 9: 344

[16] Başakçılardan Kabakcı S, Baran SS. Hydrothermal carbonization of various lignocellulosics: fuel characteristics of hydrochars and surface characteristics of activated hydrochars. Waste Manag, 2019, 100: 259-268.

[17] Bedru TK, Garuma WB, Meshesha BT. A preliminary investigation of banana pseudo-stem (Musa cavendish) for pulp and paper production: morphology, chemical composition, FTIR, XRD and thermogravimetric analysis. Nord Pulp Pap Res J, 2024, 39: 553-562.

[18] Bedru TK, Meshesha BT, Mohammed SA. Extraction of Argemone ochroleuca seeds oil and parametric optimization for biodiesel and epoxy oil production. Biomass Convers Biorefin, 2024

[19] Bedru TK, Meshesha BT, Mohammed SA, et al. . Efficient biomass fractionation via organosolv for sustainable bioenergy production: a comprehensive review. Int J Chem Eng, 2025, 20253120449

[20] Belewu Ma, Sam R. Solid state fermentation of Jatropha curcas kernel cake : proximate composition and antinutritional components. J Yeast Fungal Res, 2010, 1: 44-46. DOI:

[21] Borand MN, Karaosmanoğlu F. Effects of organosolv pretreatment conditions for lignocellulosic biomass in biorefinery applications: a review. J Renew Sustain Energy, 2018, 10(333104

[22] Brosse N, Sannigrahi P, Ragauskas A. Pretreatment of Miscanthus x giganteus using the ethanol organosolv process for ethanol production. Ind Eng Chem Res, 2009, 48: 8328-8334.

[23] Butnaru E, Stoleru E, Ioniță D, Brebu M. Thermal properties of seed cake biomasses and their valorisation by torrefaction. Polymers, 2024, 16202872

[24] Castro E, Strætkvern KO, Romero-García JM, Martín C. Pretreatment and bioconversion for valorization of residues of non-edible oilseeds. Agronomy, 2023, 13: 2196

[25] Ceriani M, D’Imporzano G, De Nisi P, et al. . Oil cake recovery supports biofuel production sustainability from second-generation non-edible oil-crops. Bioresour Technol Rep, 2024, 25101798

[26] Chaturvedi S, Singh SV, Dhyani VC, Govindaraju K, Vinu R, Mandal S. Characterization, bioenergy value, and thermal stability of biochars derived from diverse agriculture and forestry lignocellulosic wastes. Biomass Conversion Biorefinery, 2023, 132): 879-892.

[27] Chellappan S, Nair V, Sajith V, Aparna K. Experimental validation of biochar based green Bronsted acid catalysts for simultaneous esterification and transesterification in biodiesel production. Bioresour Technol Rep, 2018, 2: 38-44.

[28] Chen Y, Sun Z, Su Y, et al. . Hydrochar derived from spent mushroom substrate ameliorates soil properties and nutrient levels in saline – sodic soil : an incubation study. Sustainability, 2022, 14: 12958

[29] Chi C, Chang H, Li Z, et al. . A method for rapid determination of sugars in lignocellulose prehydrolyzate. BioResources, 2013, 8: 172-181

[30] Chong K, Lu Y, Han Y, et al. . A review on the over-liming detoxification of lignocellulosic biomass prehydrolysate for bioethanol production. Appl Biochem Biotechnol, 2025, 197: 3581-3613.

[31] Costa G dos S, Martinez-Burgos WJ, dos Reis GA, et al (2024) Advances in Biomass and Microbial Lipids Production: Trends and Prospects. Processes 12:1–41. https://doi.org/10.3390/pr12122903

[32] de Barros CR, Ferreira LMM, Fraga I, et al. . Detoxification methods of Jatropha curcas seed cake and its potential utilization as animal feed. Fermentation, 2024, 10: 1-17.

[33] Devnath B, Khanal S, Shah A, Reza T. Influence of hydrothermal carbonization (HTC) temperature on hydrochar and process liquid for poultry, swine, and dairy manure. Environments, 2024, 11: 150.

[34] Dias MC, Zidanes UL, Martins CCN, de Oliveira ALM, Damásio RAP, de Resen JV, Vilas Boas EVdB, Belgacem MN, Tonoli GHD, Ferreira SR. Influence of hemicellulose content and cellulose crystal change on cellulose nanofibers properties. Int J Biol Macromol, 2022, 213: 780-790.

[35] Esteves B, Sen U, Pereira H. Influence of chemical composition on heating value of biomass: a review and bibliometric analysis. Energies, 2023, 16: 4226

[36] Ewunie GA, Morken J, Yigezu ZD. Alkaline and co-digestion pretreatments: process optimization for enhancing the methane yield of Jatropha press cake. Biomass Convers Biorefin, 2021, 11: 971-988.

[37] Ferraz D, Pyka A. Circular economy, bioeconomy, and sustainable development goals: a systematic literature review. Environ Sci Pollut Res Int, 2023

[38] Forfang K, Zimmermann B, Kosa G, Kohler A, Shapaval V. FTIR spectroscopy for evaluation and monitoring of lipid extraction efficiency for oleaginous fungi. PLoS ONE, 2017, 12(1e0170611

[39] García-Vargas MC, Contreras MDM, Castro E. Avocado-derived biomass as a source of bioenergy and bioproducts. Appl Sci, 2020, 10: 8195

[40] Gebreegziabher BW, Dubale AA, Adaramola MS, Morken J. Advancing anaerobic digestion of biodiesel byproducts: a comprehensive review. Bioenerg Res, 2025, 18: 15.

[41] Gek C, Kee M, Rahman A, Teong K. Hydrochar production from high-ash low-lipid microalgal biomass via hydrothermal carbonization : effects of operational parameters and products characterization. Environ Res, 2020, 188109828

[42] Geng W, Narron R, Jiang X, et al. . The influence of lignin content and structure on hemicellulose alkaline extraction for non-wood and hardwood lignocellulosic biomass the influence of lignin content and structure on hemicellulose alkaline extraction for non-wood and hardwood lignocellulos. Cellulose, 2019, 26: 3219-3230.

[43] Ghosh D, Tanner J, Lavoie J-M, et al. . An integrated approach for hemicellulose extraction from forest residue. BioResources, 2021, 16: 2524-2547.

[44] Giannoni T, Gelosia M, Bertini A, et al. . Fractionation of Cynara cardunculus L. by acidified organosolv treatment for the extraction of highly digestible cellulose and technical lignin. Sustainability, 2021, 138714

[45] Gomes TG, Hadi SIIA, Costa Alves GS, Mendonça S, De Siqueira FG, Miller RNG. Current strategies for the detoxification of Jatropha curcas seed cake: a review. J Agric Food Chem, 2018, 6611): 2510-2522.

[46] Gul E, Al Bkoor Alrawashdeh K, Masek O, et al. . Production and use of biochar from lignin and lignin-rich residues (such as digestate and olive stones) for wastewater treatment. J Anal Appl Pyrolysis, 2021, 158105263

[47] D.L. V, Guna V, D. M, et al (2017) Ricinus communis plant residues as a source for natural cellulose fibers potentially exploitable in polymer composites. Ind Crops Prod 100:126–131. https://doi.org/10.1016/j.indcrop.2017.02.019

[48] Guo Y, Liu G, Ning Y, et al. . Production of cellulosic ethanol and value-added products from corn fiber. Bioresour Bioprocess, 2022, 9: 81.

[49] Hamzah MH, Bowra S, Cox P. E ff ects of ethanol concentration on organosolv lignin precipitation and aggregation from Miscanthus x giganteus. Processes, 2020, 8845

[50] Hawrot-Paw M, Drzewicka W. Application of rapeseed oil cake from biodiesel production in methane co-digestion with microalgal biomass. Materials, 2025, 18(194542

[51] He Z, Nam S, Zhang H, Olanya OM. Chemical composition and thermogravimetric behaviors of glanded and glandless cottonseed kernels. Molecules, 2022, 27: 316

[52] He Z, Nam S, Tewolde H, et al. . Morphologic features and thermal characteristics of nine cotton biomass byproducts. Biomass, 2025, 5: 12

[53] Hejna M, ´Swiechowski K, Białowiec A. Study on the effect of hydrothermal carbonization parameters on fuel properties of sewage sludge hydrochar. Materials (Basel), 2023, 166903

[54] Hladnik L, Vicente FA, Novak U, Grilc M, Likozar B. Solubility assessment of lignin monomeric compounds and organosolv lignin in deep eutectic solvents using in situ Fourier-transform infrared spectroscopy. Ind Crops Prod, 2021, 164113359

[55] Hong J-W, Gam D-H, Kim J-H, et al. . Process development for the detoxification of fermentation inhibitors from acid pretreated microalgae hydrolysate. Molecules, 2021, 26: 2435

[56] Ighalo JO, Akaeme FC, Georgin J, et al. . Biomass hydrochar : a critical review of process chemistry, synthesis methodology, and applications. Sustainability, 2025, 17: 1660

[57] Ivanova P, Chalova V, Uzunova G, Koleva L, Manolov I. Biochemical characterization of industrially produced rapeseed meal as a protein source in food industry. Agriculture and Agricultural Science Procedia, 2016, 10: 55-62.

[58] Jagadeesan R, Suyambulingam I, Somasundaram R, et al. . Isolation and characterization of novel microcellulose from Sesamum indicum agro-industrial residual waste oil cake: conversion of biowaste to wealth approach. Biomass Convers Biorefin, 2023, 13: 4427-4441.

[59] Kalifa MA, Habtu NG, Jembere AL, Genet MB. Characterization and evaluation of torrefied sugarcane bagasse to improve the fuel properties. Curr Res Green Sustain Chem, 2024, 8100395

[60] Kaniapan S, Pasupuleti J, Patmanesan K, et al. . A review of the sustainable utilization of rice residues for bioenergy conversion using different valorization techniques, their challenges and techno-economic assessment. Int J Environ Res Public Health, 2022, 19: 3427

[61] Kendra PCK. Potential and utilization of by-products of oilseeds in animal feed industry. Biot Res Today, 2021, 3: 655-657

[62] Khalil HPSA, Aprilia NAS, Bhat AH, Jawaid M, Paridah MT, Rudi D. A jatropha biomass as renewable materials for biocomposites and its applications. Renew Sustain Energy Rev, 2013, 22: 667-685.

[63] Khlifi S, Pozzobon V, Lajili M. A comprehensive review of syngas production, fuel properties, and operational parameters for biomass conversion. Energies, 2024, 17: 1-17.

[64] Khongchamnan P, Wanmolee W, Laosiripojana N. Solvothermal-based lignin fractionation from corn stover : process optimization and product characteristics. Front Chem, 2021, 9697237

[65] Khosravi A, Zheng H, Liu Q, et al. . Production and characterization of hydrochars and their application in soil improvement and environmental remediation. Chem Eng J, 2022, 430133142

[66] Kim TH, Kwak H, Kim TH, Oh KK. Extraction behaviors of lignin and hemicellulose-derived sugars during organosolv fractionation of agricultural residues using a bench-scale ball milling reactor. Energies, 2020, 13: 352

[67] Kim TH, Kwak H, Kim TH, Oh KK. Reaction characteristics of organosolv-fractionation process for selective extraction of carbohydrates and lignin from rice husks. Energies, 2021, 14: 686

[68] Konwar LJ, Mikkola JP, Bordoloi N, et al (2018) Sidestreams from bioenergy and biorefinery complexes as a resource for circular bioeconomy. Elsevier B.V.

[69] Kostyniuk A. Wet torrefaction of biomass waste into value-added liquid product (5-HMF ) and high quality solid fuel ( hydrochar ) in a nitrogen atmosphere. Renew Energy, 2024, 226120450

[70] Krička T, Matin A, Voća N, et al. . Changes in nutritional and energy properties of soybean seed and hull after roasting. Res Agric Eng, 2018, 64: 96-103.

[71] Kumar NV, Sawargaonkar G, Rani CS, et al. . Harnessing the potential of pigeonpea and maize feedstock biochar for carbon sequestration, energy generation, and environmental sustainability. Bioresour Bioprocess, 2024, 11: 5.

[72] Kusumawati N, Sumarlan SH, Zubaidah E, Wardani AK. Isolation of xylose-utilizing yeasts from oil palm waste for xylitol and ethanol production. Bioresour Bioprocess, 2023, 10: 71

[73] Lammers K, Arbuckle-Keil G, Dighton J. Ft-ir study of the changes in carbohydrate chemistry of three New Jersey pine barrens leaf litters during simulated control burning. Soil Biol Biochem, 2009, 41: 340-347.

[74] Lao W, Li G, Zhou Q, Qin T. Quantitative analysis of biomass in three types of wood-plastic composites by FTIR spectroscopy. BioResources, 2014, 9: 6073-6086.

[75] Li J, Zhang M, Dowell F, Wang D. Rapid determination of acetic acid, furfural, and 5-hydroxymethylfurfural in biomass hydrolysates using near-infrared spectroscopy. ACS Omega, 2018, 3: 5355-5361.

[76] Li X, Wei Y, Xu J, et al. . Quantitative visualization of lignocellulose components in transverse sections of moso bamboo based on FTIR macro- and micro-spectroscopy coupled with chemometrics. Biotechnol Biofuels, 2018, 11: 263

[77] Li W, Tan X, Miao C, Zhang Z, Wang Y, Ragauskas AJ, Zhuang X. Mild organosolv pretreatment of sugarcane bagasse with acetone/phenoxyethanol/water for enhanced sugar production. Green Chem, 2023, 253): 1169-1178.

[78] Liang M, Lu W, Lei P, et al. . Physical and combustion properties of binder - assisted hydrochar pellets from hydrothermal carbonization of tobacco stem. Waste Biomass Valorization, 2020, 11: 6369-6382.

[79] Lisseth C, Martinez M, Sermyagina E, et al. . Hydrothermal carbonization of lignocellulosic agro-forest based biomass residues. Biomass Bioenergy, 2021, 147106004

[80] Magdziarz A, Mariusz W. Pyrolysis of hydrochar derived from biomass – experimental investigation. Fuel, 2020, 267117246

[81] Martín–Lorenzo A, Hoyos M, Álvarez–Gómez A. The influence of hydrothermal carbonization parameters on the textural and physicochemical properties of highly porous activated carbons derived from garlic peel biowaste. J Anal Appl Pyrolysis, 2025, 192107280

[82] Matsakas L, Nitsos C, Raghavendran V, et al. . A novel hybrid organosolv: steam explosion method for the efficient fractionation and pretreatment of birch biomass. Biotechnol Biofuels, 2018, 11: 160

[83] Md Salim R, Asik J, Sarjadi MS. Chemical functional groups of extractives, cellulose and lignin extracted from native Leucaena leucocephala bark. Wood Sci Technol, 2021, 55: 295-313.

[84] Melesse EY, Bedru TK, Meshesha BT. Production and characterization of pulp from banana pseudo stem for paper making via soda anthraquinone pulping process. Int J Eng Res Africa, 2022, 58: 63-76.

[85] Mesfun S, Matsakas L, Rova U, Christakopoulos P. Technoeconomic assessment of hybrid organosolv-steam explosion pretreatment of woody biomass. Energies, 2019, 12: 4206

[86] Mignogna D, Szabó M, Ceci P, Avino P. Biomass energy and biofuels: perspective, potentials, and challenges in the energy transition. Sustainability, 2024, 16(167036

[87] Miranda NT, Motta IL, Filho RM, Toscano Miranda N, Lopes Motta I, Maciel Filho R, Wolf Maciel MR. Sugarcane bagasse pyrolysis : a review of operating conditions and products properties. Renew Sustain Energy Rev, 2021, 149111394

[88] Mlombo NT, Makhubu FN, Dube ZP, Tshikalange TE. Potential use of Argemone ochroleuca Sweet and Argemone mexicana Linn as alternative pesticide: a systematic review on their biological activity and phytochemistry. Physiol Mol Plant Pathol, 2025, 136102534

[89] Mohseni NM, Mirzaei HO, Moghimi M. Optimization of producing oil and meal from canola seeds using microwave - pulsed electric field pretreatment. OCL - Oilseeds Fats, Crop Lipids, 2020, 27: 1-12.

[90] Monção M, Hrůzová K, Rova U, et al. . Organosolv fractionation of birch sawdust: establishing a lignin-first biorefinery. Molecules, 2021, 26: 6754

[91] Müller B, Wester-Larsen L, Jensen LS, Salo T, Garrido RR, Arkoun M, D'Oria A, Lewandowski I, Müller T, Bauerle A. Agronomic performance of novel, nitrogen-rich biobased fertilizers across European field trial sites. Field Crops Res, 2024, 316109486

[92] Nair LG, Agrawal K, Verma P. Organosolv pretreatment: an in-depth purview of mechanics of the system. Bioresour Bioprocess, 2023, 10: 50.

[93] Nanda S, Okolie JA, Patel R, et al. . Catalytic hydrothermal co-gasification of canola meal and low-density polyethylene using mixed metal oxides for hydrogen production. Int J Hydrogen Energy, 2022, 47: 42084-42098.

[94] Ndecky A, Tavares PW, Senghor A, et al. . Proximate analysis of alternatives cooking solides fuels in sub Saharan by using Astm Standards. Int J Clean Coal Energy, 2022, 11: 1-12.

[95] Nehmeh M, Rodriguez-Donis I, Cavaco-Soares A, et al. . Bio-refinery of oilseeds: oil extraction, secondary metabolites separation towards protein meal valorisation—a review. Processes, 2022, 10: 841

[96] Nitsos C, Rova U, Christakopoulos P. Organosolv fractionation of softwood biomass for biofuel and biorefinery applications. Energies, 2018, 1150

[97] Nobre C, Alves O, Durão L, Ali S. Characterization of hydrochar and process water from the hydrothermal carbonization of refuse derived fuel. Waste Manag, 2021, 120: 303-313.

[98] Onyeaka H, Mansa RF, Wong CMVL, Miri T. Bioconversion of starch base food waste into bioethanol. Sustainability, 2022, 141811401

[99] Panwar NL, Pawar A, Salvi BL. Comprehensive review on production and utilization of biochar. SN Appl Sci, 2019, 1: 1-19.

[100] Papa AA, Bartolucci L, Cordiner S, Di Carlo A, Mele P, Mulone V, Vitale A. The effect of pyrolysis temperature on the optimal conversion of residual biomass to clean syngas through fast-pyrolysis/steam gasification integration. Int J Hydrogen Energy, 2024, 95: 1316-1327.

[101] Parnthong J, Nualyai S, Kraithong W, Jiratanachotikul A, Khemthong P, Faungnawakij K, Kuboon S. Higher heating value prediction of hydrochar from sugarcane leaf and giant leucaena wood during hydrothermal carbonization process. J Environ Chem Eng, 2022, 106108529

[102] Pasipanodya D, Seedat N, Patel B, Roopchund R. Production of hydrochar from the hydrothermal carbonisation of food waste feedstock for use as an adsorbent in removal of heavy metals from water. Biomass Convers Biorefin, 2025, 15: 11819-11833.

[103] Petrovič J, Ercegovic M, Simic M, et al. . Hydrothermal carbonization of waste biomass: a review of hydrochar preparation and environmental application. Process, 2024, 12: 207

[104] Petrovič A, Cenčič Predikaka T, Vohl S, et al. . Hydrothermal conversion of oilseed cakes into valuable products: influence of operating conditions and whey as an alternative process liquid on product properties and their utilization. Energy Convers Manag, 2024, 313118640

[105] Piasecka I, Brzezińska R, Ostrowska-Ligęza E, Wiktor A, Górska A. Ultrasound-assisted extraction of cranberry seed oil: food waste valorization approach. Eur Food Res Technol, 2023, 24911): 2763-2775.

[106] Piloto-Rodríguez R, Tobío I, Ortiz-Alvarez M, et al. . An approach to the use of Jatropha curcas by-products as energy source in agroindustry. Energy Sources Part A Recover Util Environ Eff, 2020, 00: 1-21.

[107] Portilla-amaguan A, Barraza-burgos J, Guerrero-perez J, et al. . Hydrothermal carbonization of green harvesting residues (GHRs) from Sugar cane: effect of temperature and water / GHR ratio on mass and energy yield. ACS Omega, 2024, 9: 26325-26335.

[108] Predoi D, Groza A, Iconaru SL, Predoi G, Barbuceanu F, Guegan R, Motelica-Heino MS, Cimpeanu C. Properties of basil and lavender essential oils adsorbed on the surface of hydroxyapatite. Materials Basel, 2018, 11(5652

[109] Putro JN, Soetaredjo FE, Lin S, et al. . RSC advances pretreatment and conversion of lignocellulose biomass into valuable chemicals. RSC Adv, 2016, 6: 46834-46852.

[110] Redda ZT, Laß-Seyoum A, Yimam A, et al. . Characterization of hexane-defatted Brassica carinata oilseed meals to explore their potential for valorization towards a sustainable circular bioeconomy. Waste Biomass Valoriz, 2024, 15: 1185-1197.

[111] Reza MT, Mumme J, Ebert A. Characterization of hydrochar obtained from hydrothermal carbonization of wheat straw digestate. Biomass Conv Bioref, 2015, 5: 425-435.

[112] Roslan SZ, Zainudin SF, Aris AM, Mohd Aris A, Chin KB, Musa M, Mohamad Daud AR, Syed Hassan SSA. Hydrothermal carbonization of sewage sludge into solid biofuel : influences of process conditions on the energetic properties of hydrochar. Energies, 2023, 1652483

[113] Salapa I, Katsimpouras C, Topakas E, Sidiras D. Biomass and bioenergy organosolv pretreatment of wheat straw for ef fi cient ethanol production using various solvents. Biomass Bioenergy, 2017, 100: 10-16.

[114] Salem KS, Kasera NK, Rahman MA, et al. . Comparison and assessment of methods for cellulose crystallinity determination. Chem Soc Rev, 2023, 52: 6417-6446.

[115] Sari YW, Syafitri U, Sanders JPM, Bruins ME. How biomass composition determines protein extractability. Ind Crops Prod, 2015, 70: 125-133.

[116] Sari DN, Rois MF, Widiyastuti W, Setyawan H. Organosolv lignin from Coconut coir as potential biomaterials for sunscreen. AIP Conf Proc, 2022, 2470040008

[117] Sarkar N, Chakraborty D, Dutta R, et al. . A comprehensive review on oilseed cakes and their potential as a feedstock for integrated biorefinery. J Adv Biotechnol Exp Ther, 2021, 4: 376-387.

[118] Sarker TR, Azargohar R, Dalai AK, Meda V. Enhancement of fuel and physicochemical properties of canola residues via microwave torrefaction. Energy Rep, 2021, 7: 6338-6353.

[119] Satira A, Paone E, Bressi V, Iannazzo D, Marra F, Calabrò PS, Mauriello F, Espro C. Hydrothermal carbonization as sustainable process for the complete upgrading of Orange Peel Waste into value-added chemicals and bio-carbon materials. Appl Sci, 2021, 112210983

[120] Sezer AY. Investigation of the structural characteristics of seed surfaces of some soybean genotypes by using scanning electron microscopy (SEM). Selcuk J Agric Food Sci, 2024, 38: 553-560.

[121] Shokri A, Larki MA, Ghaemi A. Retrieval of carbon and inorganic phosphorus during hydrothermal carbonization : ANN and RSM modeling. Heliyon, 2024, 10e40999

[122] Shrivastava P, Kumar A, Tekasakul P, et al. . Comparative investigation of yield and quality of bio-oil and biochar from pyrolysis of woody and non-woody biomasses. Energies, 2021, 14: 1092

[123] Shukla A, Kumar D, Girdhar M, Kumar A, Goyal A, Malik T, Mohan A. Strategies of pretreatment of feedstocks for optimized bioethanol production: distinct and integrated approaches. Biotechnol Biofuels Bioprod, 2023, 16144

[124] Sindhu R, Binod P, Á PÁL (2012) Organosolvent pretreatment and enzymatic hydrolysis of rice straw for the production of bioethanol. World J Microbiol Biotechnol 28:473–483. https://doi.org/10.1007/s11274-011-0838-8

[125] Sisuthog W, Attanatho L, Chaiya C. Conversion of empty fruit bunches (EFBs) by hydrothermal carbonization towards hydrochar production. Energy Rep, 2022, 8: 242-248.

[126] Smit A, Huijgen W. Effective fractionation of lignocellulose in herbaceous biomass and hardwood using a mild acetone organosolv process. Green Chem, 2017, 19: 5505-5514.

[127] Takano M, Hoshino K. Bioethanol production from rice straw by simultaneous saccharification and fermentation with statistical optimized cellulase cocktail and fermenting fungus. Bioresour Bioprocess, 2018, 5: 16.

[128] Tao A, Wang J, Luo B, Liu B, Wang Z, Chen X, Zou T, Chen J, You J. Research progress on cottonseed meal as a protein source in pig nutrition: an updated review. Anim Nutr, 2024, 18: 220-233.

[129] Temporim RBL, Petrozzi A, Coccia V, et al. . A prototype plant for oilseed extraction: analysis of mass and energy flows. Sustainability, 2020, 12: 9786.

[130] Thanasi V, Caldeira I, Santos L, et al. . Simultaneous determination of ethanol and methanol in wines using FTIR and PLS regression. Foods, 2024, 13: 2975

[131] Thawornprasert J, Somnuk K. Optimization of oil extraction from cocoa bean shells using three solvents with solvent reusability. ACS Omega, 2024, 9: 5995-6004.

[132] Tofani G, Jasiukaitytė-Grojzdek E, Grilc M, Likozar B. Organosolv biorefinery: resource-based process optimisation, pilot technology scale-up and economics. Green Chem, 2024, 26: 186-201.

[133] Usman I, Saif H, Imran A, Afzaal M, Saeed F, Azam I, Afzal A, Ateeq H, Islam F, Shah YA, Shah MA. Innovative applications and therapeutic potential of oilseeds and their by-products: an eco-friendly and sustainable approach. Food Sci Nutr, 2023, 116): 2599-2609.

[134] Vassilev SV, Baxter D, Andersen LK, Vassileva CG. An overview of the chemical composition of biomass. Fuel, 2010, 89: 913-933.

[135] Venkata K, Rama T, Doddapaneni KC, et al. . Critical review on production, characterization and applications of microalgal hydrochar : Insights on circular bioeconomy through hydrothermal carbonization. Chem Eng J, 2023, 473145059

[136] Viegas C, Nobre C, Correia R, et al. . Optimization of biochar production by co-torrefaction of microalgae and lignocellulosic biomass using response surface methodology. Energies, 2021, 14: 7330

[137] Waheed MA, Akogun OA, Enweremadu CC. An overview of torrefied bioresource briquettes: quality-influencing parameters, enhancement through torrefaction and applications. Bioresour Bioprocess, 2022, 9: 122

[138] Wang X, Duo J, Jin Z, et al. . Effects of hydrothermal carbonization conditions on the characteristics of hydrochar and its application as a soil amendment : a review. Agronomy, 2025, 15: 327

[139] Wei D, Chin K, Lim S, et al. . Effects of organic solvents on the organosolv pretreatment of degraded empty fruit bunch for fractionation and lignin removal. Sustainability, 2021, 13: 6757

[140] Wolf M, Berger F, Hanstein S, et al. . Hot-water hemicellulose extraction from fruit processing residues. ACS Omega, 2022, 7: 13436-13447.

[141] Xu F, Sun D, Wang Z, et al. . Highly efficient production of cellulosic ethanol from poplar using an optimal C6/C5 co-fermentation strain of Saccharomyces cerevisiae. Microorganisms, 2024, 12: 1174

[142] Yahya AM, Adeleke AA, Nzerem P, et al. . Comprehensive characterization of some selected biomass for bioenergy production. ACS Omega, 2023, 8: 43771-43791.

[143] Yáñez-Barrientos E, Barragan-Galvez JC, Hidalgo-Figueroa S, et al. . Neuropharmacological effects of the dichloromethane extract from the stems of Argemone ochroleuca Sweet (Papaveraceae) and its active compound dihydrosanguinarine. Pharmaceuticals, 2023, 16: 1175

[144] Yang J, Ching YC, Chuah CH. Applications of lignocellulosic fibers and lignin in bioplastics: a review. Polymers (Basel), 2019, 11: 751

[145] Yeasmin S. Characteristics of sesame (Sesamum indicum l.) seed meal grown in the Northern region of Bangladesh. Biomedical Journal of Scientific & Technical Research, 2021, 38: 29944-29949.

[146] Yin C-Y, El-Harbawi M, Jiang Z-T. Life cycle assessment of production of hydrochar via hydrothermal carbonization of Date Palm Fronds Biomass. Materials (Basel), 2023, 16: 6653

[147] Young K, Lee K, Kim D. Characterized hydrochar of algal biomass for producing solid fuel through hydrothermal carbonization. Bioresour Technol, 2018, 258: 119-124.

[148] Zhan H, Zhang S, Song Y, Chang G, Wang X, Zeng Z. Hydrothermal co-carbonization of industrial biowastes with lignite toward modified hydrochar production : Synergistic effects and structural characteristics. J Environ Chem Eng, 2022, 103107540

[149] Zhang J, Ying Y, Li X, Yao X. FTIR and thermogravimetric analysis of three kinds of nutshells. Nat Resour, 2018, 09: 313-325.

[150] Zhang L, Tan J, Xing G, et al. . Cotton stalk - derived hydrothermal carbon for methylene blue dye removal : investigation of the raw material plant tissues. Bioresour Bioprocess, 2021, 8: 10.

[151] Zhang Y, Wang H, Sun X, et al. . Separation and characterization of biomass components (cellulose, hemicellulose, and lignin) from corn stalk. BioResources, 2021, 16: 7205-7219.

[152] Zhang Y, Wan Y, Zheng Y, et al. . Hydrochar loaded with nitrogen-containing functional groups for versatile removal of cationic and anionic dyes and aqueous heavy metals. Water, 2024, 16: 3387

[153] Zhu W, Theliander H. Precipitation of lignin from softwood black liquor: an investigation of the equilibrium and molecular properties of lignin. BioResources, 2015, 10: 1696-1714.

[154] Zhu G, Yang L, Gao Y, et al. . Characterization and pelletization of cotton stalk hydrochar from HTC and combustion kinetics of hydrochar pellets by TGA. Fuel, 2019, 244: 479-491.

[155] Zhuang J, Li M, Pu Y, Ragauskas A, Yoo C. Observation of potential contaminants in processed biomass using fourier transform infrared spectroscopy. Appl Sci, 2020, 10124345

Funding

Addis Ababa University(Ph.D. RG-GSR/7444/14)

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The Author(s)