Е-Публикации
Технически университет - София

Abstract: This paper proposes a valorization approach for solid lavender residue, a by-product of the essential oil industry. The biomass residue was carbonized at atmospheric pressure and two temperatures (450 °C and 650 °C), followed by solvothermal modification with zinc ions (Zn2+, 3 and 5 mmol). The effects of temperature and Zn2+ incorporation on the elemental composition and morphology of the resulting biochar were examined using X-ray Fluorescence (XRF), Fourier Transform Infrared (FTIR) spectroscopy, and Scanning Electron Microscopy/Energy-Dispersive X-ray Spectroscopy (SEM/EDS) analyses. The applied Zn2+ modification was effective at both concentrations for the biochar obtained at both carbonization temperatures. However, a more uniform metal ion distribution was observed at 3 mmol, while at 5 mmol, a partial particle agglomeration occurred. Progressive degradation of the O–H, C=O, and C–O groups with increasing temperature and the presence of Zn–O-related interactions was observed. The results demonstrated consistent and reproducible trends, suggesting that controlled carbonization combined with Zn2+ incorporation can convert lavender residues into modified carbonaceous materials.

References

1. Van Nguyen T.T. Phan A.N. Nguyen T.A. Nguyen T.K. Nguyen S.T. Pugazhendhi A. Phuong H.H.K. Valorization of Agriculture Waste Biomass as Biochar: As First-Rate Biosorbent for Remediation of Contaminated Soil Chemosphere 2022 307 135834 10.1016/j.chemosphere.2022.135834
2. Slavov A.M. Karneva K.B. Vasileva I.N. Denev P.N. Denkova R.S. Shikov V.T. Ivanova V.N. Valorization of Lavender Waste—Obtaining and Characteristics of Polyphenol Rich Extracts Food Sci. Appl. Biotechnol. 2018 1 11 18 10.30721/fsab2018.v1.i1.5
3. Khiri S. Ullah N. Boubal Z. Janati W. Amalich S. Lgaz H. Elmaaiden E. Transforming essential oil extraction Wastes: Sustainable valorization approaches for agricultural, industrial, and cosmetic applications Biomass Bioenergy 2023 201 108109 10.1016/j.biombioe.2025.108109
4. Crisan I. Ona A. Vârban D. Muntean L. Varban R. Stoie A. Morea A. Current trends for lavender (Lavandula angustifolia Mill.) crops and products with emphasis on essential oil quality Plants 2023 12 357 10.3390/plants12020357
5. Khatri P.K. Paolini M. Larcher R. Ziller L. Magdas D.A. Marincas O. Roncone A. Bontempo L. Validation of gas chromatographic methods for lavender essential oil authentication based on volatile organic compounds and stable isotope ratios Microchem. J. 2023 186 108343 10.1016/j.microc.2022.108343
6. Chilev C. Simeonov E. Dimitrova B. Yonkova V. Pietsch S. Heinrich S. Peshev D. Valorization of waste lavender residue from the essential oil industry for production of rosmarinic acid—A study on the solid-liquid extraction J. Chem. Technol. Metall. 2022 57 522 532
7. Pech-Rodríguez W.J. Meléndez-González P.C. Hernández-López J.M. Suarez-Velázquez G.G. Sarabia-Castillo C.R. Calles-Arriaga C.A. Pharmaceutical Wastewater and Sludge Valorization: A Review on Innovative Strategies for Energy Recovery and Waste Treatment Energies 2024 17 5043 10.3390/en17205043
8. Tang K.H.D. Valorization of organic waste as biosorbents for wastewater treatment Water Emerg. Contam. Nanoplastics 2024 3 25 10.20517/wecn.2024.53
9. Ţurcanu A.A. Matei E. Râpă M. Predescu A.M. Coman G. Predescu C. Biowaste Valorization Using Hydrothermal Carbonization for Potential Wastewater Treatment Applications Water 2022 14 2344 10.3390/w14152344
10. Mukome F.N. Six J. Parikh S.J. The effects of walnut shell and wood feedstock biochar amendments on greenhouse gas emissions from a fertile soil Geoderma 2013 200 90 98 10.1016/j.geoderma.2013.02.004
11. Alfattani R. Shah M.A. Siddiqui M.I.H. Ali M.A. Alnaser I.A. Bio-char characterization produced from walnut shell biomass through slow pyrolysis: Sustainable for soil amendment and an alternate bio-fuel Energies 2021 15 1 10.3390/en15010001
12. Zhang N. Xing J. Wei L. Liu C. Zhao W. Liu Z. Wang Y. Liu E. Ren X. Jia Z. et al. The potential of biochar to mitigate soil acidification: A global meta-analysis Biochar 2025 7 49 10.1007/s42773-025-00451-5
13. Wang G.X. Xia L.S. Zhu X.S. Wu J.X. Liu X. Study on electrochemical supercapacitor performance of modified lavender biochar J. Phys. Conf. Ser. 2023 2639 012002 10.1088/1742-6596/2639/1/012002
14. Li Y. Xu R. Wang H. Xu W. Tian L. Huang J. Liang C. Zhang Y. Recent advances of biochar-based electrochemical sensors and biosensors Biosensors 2022 12 377 10.3390/bios12060377
15. Hu H. Sun L. Wang T. Lv C. Gao Y. Zhang Y.F. Wu H. Chen X. Nano-ZnO functionalized biochar as a superhydrophobic biosorbent for selective recovery of low-concentration Re (VII) from strong acidic solutions Miner. Eng. 2019 142 105885 10.1016/j.mineng.2019.105885
16. Vassilev S.V. Baxter D. Andersen L.K. Vassileva C.G. An overview of the chemical composition of biomass Fuel 2010 89 13 33 10.1016/j.fuel.2009.10.022
17. Semenova E. Kurakov A.V. Nazarov V. Presnyakova V. Markelova N. Karaseva E. Rajput V.D. Biotransformation of Wastes of Essential Oil Industry by Strains Agaricus bisporus (JE Lange) Imbach, Lentinula edodes (Berk.) Pegler, and Pleurotus ostreatus (Jacq.) P. Kumm Horticulturae 2022 9 450 10.3390/horticulturae9040450
18. Solomakou N. Fotiou D. Tsachouridou E. Goula A.M. Valorization of Waste from Lavender Distillation Through Optimized Encapsulation Processes Foods 2025 14 2684 10.3390/foods14152684
19. Zeidabadi Z.A. Bakhtiari S. Abbaslou H. Ghanizadeh A. Synthesis Characterization and Evaluation of Biochar from Agricultural Waste Biomass for Use in Building Materials Constr. Build. Mater. 2018 181 301 308 10.1016/j.conbuildmat.2018.05.271
20. Susilawati A. Maftuah E. Fahmi A. The Utilization of Agricultural Waste as Biochar for Optimizing Swampland: A Review IOP Conf. Ser. Mater. Sci. Eng. 2020 980 012065 10.1088/1757-899X/980/1/012065
21. Yaashikaa P.R. Kumar P.S. Varjani S. Saravanan A.A. Critical Review on the Biochar Production Techniques, Characterization, Stability and Applications for Circular Bioeconomy Biotechnol. Rep. 2020 28 e00570 10.1016/j.btre.2020.e00570
22. Cordero T. Marquez F. Rodriguez-Mirasol J. Rodriguez J.J. Predicting heating values of lignocellulosics and carbonaceous materials from proximate analysis Fuel 2001 80 1567 1571 10.1016/S0016-2361(01)00034-5
23. Ronsse F. Nachenius R.W. Prins W. Recent Advances in Thermo-Chemical Conversion of Biomass Chapter 11—Carbonization of Biomass Pandey A. Bhaskar T. Stöcker M. Sukumaran R.K. Elsevier Amsterdam, The Netherlands 2015 293 324 10.1016/B978-0-444-63289-0.00011-9 9780444632890
24. Ferreira A.F. Ribau J.P. Costa M. A decision support method for biochars characterization from carbonization of grape pomace Biomass Bioenergy 2021 145 105946 10.1016/j.biombioe.2020.105946
25. Barszcz W. Lozynska M. Molenda J. Impact of Pyrolysis Process Conditions on the Structure of Biochar Obtained from Apple Waste Sci. Rep. 2024 14 10501 10.1038/s41598-024-61394-8
26. Lee Y. Park J. Ryu C. Gang K.S. Yang W. Park Y.K. Hyun S. Comparison of Biochar Properties from Biomass Residues Produced by Slow Pyrolysis at 500 °C Bioresour. Technol. 2013 148 196 201 10.1016/j.biortech.2013.08.135 24047681
27. Gaskin J.W. Steiner C. Harris K. Das K.C. Bibens B. Effect of Low-Temperature Pyrolysis Conditions on Biochar for Agricultural Use Trans. ASABE 2008 51 2061 2069 10.13031/2013.25409
28. Luo Q. Deng Y. Li Y. He Q. Wu H. Fang X. Effects of Pyrolysis Temperatures on the Structural Properties of Straw Biochar and Its Adsorption of Tris-(1-Chloro-2-Propyl) Phosphate Sci. Rep. 2024 14 25711 10.1038/s41598-024-77299-5 39468241
29. Liu X. Lin J. Zhao Z. Min Y. Song J. Li B. Huang J. Advances in functional applications of biomass-derived carbon composites for phase change materials Microstructures 2025 5 2025039 10.20517/microstructures.2024.109
30. Zhang N. Ye X. Gao Y. Liu G. Liu Z. Zhang Q. Zhang P. Environment and Agricultural Practices Regulate Enhanced Biochar-Induced Soil Carbon Pools and Crop Yield: A Meta-Analysis Sci. Total Environ. 2023 905 167290 10.1016/j.scitotenv.2023.167290
31. Naydenova I. Radoykova T. Petrova T. Sandov O. Valchev I. Utilization Perspectives of Lignin Biochar from Industrial Biomass Residue Molecules 2023 28 4842 10.3390/molecules28124842
32. Tadesse A.W. Huang M. Zhou T. Biochar for Wastewater Treatment: Preparation, Modification, Characterization, and Its Applications Molecules 2025 30 4288 10.3390/molecules30214288 41226249
33. Monga D. Shetti N.P. Basu S. Reddy K.R. Badawi M. Bonilla-Petriciolet A. Aminabhavi T.M. Engineered biochar: A way forward to environmental remediation Fuel 2022 311 122510 10.1016/j.fuel.2021.122510
34. Fakhar A. Canatoy R.C. Galgo S.J.C. Rafique M. Sarfraz R. Advancements in modified biochar production techniques and soil application: A critical review Fuel 2025 400 135745 10.1016/j.fuel.2025.135745
35. Díaz B. Sommer-Márquez A. Ordoñez P.E. Bastardo-González E. Ricaurte M. Navas-Cárdenas C. Synthesis Methods, Properties, and Modifications of Biochar-Based Materials for Wastewater Treatment: A Review Resources 2024 13 8 10.3390/resources13010008
36. Kumari A. Yadav M. Bhatia A. Sharma M. Bhateria R. A review and bibliometric analysis on recent modification of biochar for effective and sustainable remediation of heavy metals in aqueous medium Discov. Chem. Eng. 2025 5 21 10.1007/s43938-025-00088-7
37. Wang X. Guo Z. Hu Z. Zhang J. Recent advances in biochar application for water and wastewater treatment: A review PeerJ 2020 8 e9164 10.7717/peerj.9164
38. Nanda S. Dalai A.K. Berruti F. Kozinski J.A. Biochar as an Exceptional Bioresource for Energy, Agronomy, Carbon Sequestration, Activated Carbon and Specialty Materials Waste Biomass Valorization 2016 7 201 235 10.1007/s12649-015-9459-z
39. Han R. Gao Y. Jia Y. Wang S. Heterogeneous precipitation behavior and mechanism during the adsorption of cationic heavy metals by biochar: Roles of inorganic components J. Hazard. Mater. 2024 480 136322 10.1016/j.jhazmat.2024.136322 39486330
40. Sizmur T. Fresno T. Akgül G. Frost H. Moreno-Jiménez E. Biochar modification to enhance sorption of inorganics from water Bioresour. Technol. 2017 246 34 47 10.1016/j.biortech.2017.07.082
41. Patwa D. Bordoloi U. Dubey A.A. Ravi K. Sekharan S. Kalita P. Energy-efficient biochar production for thermal backfill applications Sci. Total Environ. 2022 833 155253 10.1016/j.scitotenv.2022.155253
42. Zhao F. Shan R. Li W. Zhang Y. Yuan H. Chen Y. Synthesis, Characterization, and Dye Removal of ZnCl2-Modified Biochar Derived from Pulp and Paper Sludge ACS Omega 2021 6 34712 34723 10.1021/acsomega.1c05142
43. Qian T. Wang Y. Fan T. Fang G. Zhou D. A New Insight into the Immobilization Mechanism of Zn on Biochar: The Role of Anions Dissolved from Ash Sci. Rep. 2016 6 33630 10.1038/srep33630 27641899
44. Alves Z. Ferreira N.M. Figueiredo G. Mendo S. Nunes C. Ferreira P. Electrically Conductive and Antimicrobial Agro-Food Waste Biochar Functionalized with Zinc Oxide Particles Int. J. Mol. Sci. 2022 23 8022 10.3390/ijms23148022 35887369
45. Lourenco M.A. Zeng J. Jagdale P. Castellino M. Sacco A. Farkhondehfa M.A. Pirri C.F. Biochar/Zinc Oxide Composites as Effective Catalysts for Electrochemical CO2Reduction ACS Sustain. Chem. Eng. 2021 9 5445 5453 10.1021/acssuschemeng.1c00837
46. Bhakta A.K. Tang M. Snoussi Y. Khalil A.M. Mascarenhas R.J. Mekhalif Z. Chehimi M.M. Sweety, Salty, Sour, and Romantic Biochar-Supported ZnO: Highly Active Composite Catalysts for Environmental Remediation Emergent Mater. 2023 8 2647 2661 10.1007/s42247-023-00599-5
47. Liu Y. Ji X. Wang Y. Zhang Y. Zhang Y. Li W. Yuan J. Ma D. Sun H. Duan J. A Stable Fe-Zn Modified Sludge-Derived Biochar for Diuron Removal: Kinetics, Isotherms, Mechanism, and Practical Research Molecules 2023 28 2868 10.3390/molecules28062868
48. Sayed M.H. Dilova T. Atanasova G. Avdeev G. Boshta M. Dikovska A.O. Gomaa M.M. Enhanced gas sensing performance of sprayed ZnO–ZnWO4toward CO gas Mater. Adv. 2024 5 5140 5147 10.1039/D4MA00121D
49. Plum L.M. Rink L. Haase H. The essential toxin: Impact of zinc on human health Int. J. Environ. Res. Public Health 2010 7 1342 1365 10.3390/ijerph7041342 20617034
50. Inoue M. Solvothermal Synthesis. Chapter 2 Chemical Processing of Ceramics 2nd ed. Lee B. Komarneni S. Taylor & Francis Group, LLC. Boca Raton, FL, USA 2005 13:978-1-4200-2733-4
51. Ye H. Chen J. Hu Y. Li G. Fu X.-Z. Zhu P. Sun R. Wong C.-P. One-pot synthesis of two-dimensional multilayered graphitic carbon nanosheets by low-temperature hydrothermal carbonization using the in situ formed copper as a template and catalyst Chem. Commun. 2020 56 11645 11648 10.1039/D0CC03010D
52. Ndlwana L. Raleie N. Dimpe K.M. Ogutu H.F. Oseghe E.O. Motsa M.M. Msagati T.A. Mamba B.B. Sustainable hydrothermal and solvothermal synthesis of advanced carbon materials in multidimensional applications: A review Materials 2021 14 5094 10.3390/ma14175094
53. Hu H. Sun L. Gao Y. Wang T. Huang Y. Lv C. Wu H. Synthesis of ZnO nanoparticle-anchored biochar composites for the selective removal of perrhenate, a surrogate for pertechnetate, from radioactive effluents J. Hazard. Mater. 2020 387 121670 10.1016/j.jhazmat.2019.121670
54. Dumbrava A. Matei C. Diacon A. Moscalu F. Berger D. Novel ZnO-biochar nanocomposites obtained by hydrothermal method in extracts of Ulva lactuca collected from Black Sea Ceram. Int. 2023 49 10003 10013 10.1016/j.ceramint.2022.11.178
55. Petrova T. Naydenova I. Ribau J. Ferreira A.F. Biochar from Agro-Forest Residue: Application Perspective Based on Decision Support Analysis Appl. Sci. 2023 13 3240 10.3390/app13053240
56. Peçanha D.A. Freitas M.S.M. Cunha J.M. Vieira M.E. Jesus A.C. Mineral composition, biomass and essential oil yield of french lavender grown under two sources of increasing potassium fertilization J. Plant Nutr. 2023 46 344 355 10.1080/01904167.2022.2068430
57. Fertilizer for Lavender Available online: https://agrecol.pl/en/produkt/fertilizer-for-lavender-2/ (accessed on 14 January 2026)
58. Buss W. Wurzer C. Manning D.A. Rohling E.J. Borevitz J. Masek O. Mineral-enriched biochar delivers enhanced nutrient recovery and carbon dioxide removal Commun. Earth Environ. 2022 3 67 10.1038/s43247-022-00394-w
59. Grafmüller J. Schmidt H.-P. Kray D. Hagemann N. Root-Zone Amendments of Biochar-Based Fertilizers: Yield Increases of White Cabbage in Temperate Climate Horticulturae 2022 8 307 10.3390/horticulturae8040307
60. Puri L. Hu Y. Naterer G. Critical Review of the Role of Ash Content and Composition in Biomass Pyrolysis Front. Fuels 2024 2 1378361 10.3389/ffuel.2024.1378361
61. Luo S. Yang M. Wu Y. Li J. Qin J. Feng F. A Low Cost Fe3O4–Activated Biochar Electrode Sensor by Resource Utilization of Excess Sludge for Detecting Tetrabromobisphenol A Micromachines 2022 13 115 10.3390/mi13010115
62. Zhao J. Jiang Y. Chen X. Wang C. Nan H. Unlocking the Potential of Element-Doped Biochar: From Tailored Synthesis to Multifunctional Applications in Environment and Energy Biochar 2025 7 77 10.1007/s42773-025-00467-x
63. Grafmüller J. Böhm A. Zhuang Y. Spahr S. Muller P. Otto T.N. Hagemann N. Wood Ash as an Additive in Biomass Pyrolysis: Effects on Biochar Yield, Properties, and Agricultural Performance ACS Sustain. Chem. Eng. 2022 10 2720 2729 10.1021/acssuschemeng.1c07694
64. Li J. Li Y. Wu Y. Zheng M. A comparison of biochars from lignin, cellulose and wood as the sorbent to an aromatic pollutant J. Hazard. Mater. 2014 280 450 457 10.1016/j.jhazmat.2014.08.033
65. Wang Y. Hu Y. Zhao X. Wang S. Xing G. Comparisons of biochar properties from wood material and crop residues at different temperatures and residence times Energy Fuel 2013 27 5890 5899 10.1021/ef400972z
66. Alamdari S. Sasani Ghamsari M. Lee C. Han W. Park H.-H. Tafreshi M.J. Afarideh H. Ara M.H.M. Preparation and Characterization of Zinc Oxide Nanoparticles Using Leaf Extract of Sambucus ebulus Appl. Sci. 2020 10 3620 10.3390/app10103620
67. Hitkari G. Singh S. Pandey G. Structural, optical and photocatalytic study of ZnO and ZnO–ZnS synthesized by chemical method Nano-Struct. Nano-Objects 2017 12 1 9 10.1016/j.nanoso.2017.08.007
68. Liu M. Ran B. Hu P. Fang J. Sun J. Bai Y. Duan H. Room-Temperature Trimethylamine Gas Sensor with Enhanced Performance Using Biomass-Derived Carbon Quantum Dot Modified Biochar J. Environ. Chem. Eng. 2025 13 118427 10.1016/j.jece.2025.118427
69. Ngambia A. Masek O. Erastova V. Development of Biochar Molecular Models with Controlled Porosity Biomass Bioenergy 2024 184 107199 10.1016/j.biombioe.2024.107199
70. Bayoka H. Snoussi Y. Bhakta A.K. El Garah M. Khalil A.M. Jouini M. Chehimi M.M. Evidencing the Synergistic Effects of Carbonization Temperature, Surface Composition and Structural Properties on the Catalytic Activity of Biochar/Bimetallic Composite J. Anal. Appl. Pyrolysis 2023 173 106069 10.1016/j.jaap.2023.106069
71. Zaitun Z. Halim A. Sa’dah Y. Cahyadi R. Surface Morphology Properties of Biochar Feedstock for Soil Amendment IOP Conf. Ser. Earth Environ. Sci. 2022 951 012034 10.1088/1755-1315/951/1/012034
72. Abyaneh M.R. Aliasghar A. Bidhendi G.N. Zand A.D. Moazeni K. Importance of Pyrolysis Temperature and Particle Size on Physicochemical and Adsorptive Properties of Urban Wood-Derived Biochar Sustain. Chem. Pharm. 2024 40 101631 10.1016/j.scp.2024.101631
73. Tshoko S. Mulaudzi-Masuku T. Iwuoha E. Ngece-Ajayi R.F. Electrochemical and biosensing applications of biochar and biochar-based composites Front. Sens. 2025 6 1552969 10.3389/fsens.2025.1552969
74. Saikrithika S. Kim Y.-J. Biochar-Derived Electrochemical Sensors: A Green Route for Trace Heavy Metal Detection Chemosensors 2025 13 278 10.3390/chemosensors13080278
75. Adamu N. Umar K. Oh W.D. Parveen T. Lawal A. Application of Biochar-Based Metal Catalyst and Their Uses Biochar-Based Catalysts: Preparation, Sustainable Materials and Technology Bhawani S.A. Umar K. Mohamad Ibrahim M.N. Alotaibi K.M. Spinger Singapore 2024 75 107 10.1007/978-981-97-6544-7_5
76. Saif A. Rizvi S.I. Shaukat Z. Saif M. Tabassum S. Khalid R. Javed F. Rebouh N.Y. Hassan F. Zaman Q.U. Development of composite catalyst containing renewable biochar blended with zinc oxide and copper diphenyl amine for visible light photocatalytic degradation of methylene blue Front. Sustain. Food Syst. 2025 9 1500907 10.3389/fsufs.2025.1500907
77. Zhang L. Zhang Q. Wang Y. Cui X. Liu Y. Ruan R. Wu X. Cao L. Zhao L. Zheng H. Preparation and application of metal-modified biochar in the purification of micro-polystyrene polluted aqueous environment J. Environ. Manag. 2023 347 119158 10.1016/j.jenvman.2023.119158 37804638
78. Gusiatin M.Z. Rouhani A. Application of Selected Methods to Modify Pyrolyzed Biochar for the Immobilization of Metals in Soil: A Review Materials 2023 16 7342 10.3390/ma16237342 38068085
79. Yan L. Liu Y. Zhang Y. Liu S. Wang C. Chen W. Liu C. Chen Z. Zhang Y. ZnCl2modified biochar derived from aerobic granular sludge for developed microporosity and enhanced adsorption to tetracycline Bioresour. Technol. 2020 297 122381 10.1016/j.biortech.2019.122381 31740243
80. ISO 16559:2022 Solid Biofuels—Terminology, Definitions and Descriptions International Organization for Standardization Geneva, Switzerland 2022
81. ISO 14780:2017 Solid Biofuels—Sample Preparation International Organization for Standardization Geneva, Switzerland 2017
82. ISO 18123:2023 Solid Biofuels—Determination of the Content of Volatile Matter International Organization for Standardization Geneva, Switzerland 2023
83. ISO 18122:2022 Solid Biofuels—Determination of Ash Content International Organization for Standardization Geneva, Switzerland 2022
84. ISO 18134-3:2023 Solid Biofuels—Determination of Moisture Content—Oven Dry Method—Part 3: Moisture in General Analysis Sample International Organization for Standardization Geneva, Switzerland 2023
85. Naydenova I.I. Sandov O.L. Petrova T.S. Thermal Analysis and PM Emissions of Lavender Residue Proceedings of the 2023 58th International Scientific Conference on Information, Communication and Energy Systems and Technologies (ICEST) Nis, Serbia 29 June–1 July 2023 183 186 10.1109/ICEST58410.2023.10187327

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