Thermal condensation drives molecular evolution of biochar-derived dissolved organic matter for heavy metal immobilization
-
GRAPHICAL ABSTRACT
DownLoad:
Full size image
-
PUBLIC SUMMARY
-
BDOM was identified as an important determinant of biochar-mediated Cd binding in soils.
Thermal reorganization shifted BDOM from heterogeneous humic aggregates into phenolic O-coordinating domains.
This reorganization enhances Cd immobilization and limits the transfer from the soil to the biosphere, here ryegrass.
-
-
ABSTRACT
Biochar-derived dissolved organic matter (BDOM), the soluble fraction of biochar, plays an important yet underrecognized role in environmental chemistry, here exemplified by heavy metal mobilization/immobilization. Current studies largely emphasize biochar as a beneficial additive to soil, but neglect the specific role of the highly functional BDOM. In an integrated approach combining spectroscopic analysis, ultrahigh-resolution mass spectrometry, and reaction network modeling, we show that BDOM is the overlooked reactive fraction in biochar application. The complex condensation-derived molecular structures of BDOM across a range of typical pyrolysis temperatures (300-700°C) was analyzed, and molecular transformations changed by metal coordination were elucidated. We demonstrate that higher pyrolysis temperatures facilitate decomposition of humic aggregates and form tyrosine-like phenolic ligands. Using cadmium (Cd) binding as a model metal-interaction process, we show that low temperature pyrolysis produces soluble condensation products which mobilize Cd, while Cd mobility is strongly reduced by the high temperature pendants. This transformation occurs via coordinative mechanisms involving rearrangement of functional groups, conformational changes in polymer structures, and hydrophobic microencapsulation. Finally, we demonstrate that the optimized coordination structure significantly suppresses Cd mobility in the environment and especially minimizes plant uptake. Our thermally controlled synthesis sheds a new light on the role of BDOM and provides a rationale for the controversial reports on different biochars in soil applications. -
-
REFERENCES
[1] Yang H., Huang X. and Thompson J. R. (2015). Biochar: Pros must outweigh cons. Nature 518:483. DOI:10.1038/518483f [2] Cernansky R. (2015). Agriculture: State-of-the-art soil. Nature 517:258−260. DOI:10.1038/517258a [3] Niu X., He Y., Musl O., et al. (2024). Bark extractives as sources of carbon-efficient functional precursors and materials. Innov. Mater. 2:100074. DOI:10.59717/j.xinn-mater.2024.100074 [4] Yu P., Zhang B., Zhang Y., et al. (2026). What’s next in materials science. Innov. Mater. 4:100196. DOI:10.59717/j.xinn-mater.2026.100196 [5] Yu S., Lu Z., Chen L., et al. (2026). Electrically conductive wood-based materials beyond biochar: Modifications, functions, and environmental impact. Matter 9:102528. DOI:10.1016/j.matt.2025.102528 [6] Kleber M., Bourg I. C., Coward E. K., et al. (2021). Dynamic interactions at the mineral–organic matter interface. Nat. Rev. Earth Environ. 2:402−421. DOI:10.1038/s43017-021-00162-y [7] Yang F., Wang C. and Sun H. (2021). A comprehensive review of biochar-derived dissolved matters in biochar application: Production, characteristics, and potential environmental effects and mechanisms. J. Environ. Chem. Eng. 9:105258. DOI:10.1016/j.jece.2021.105258 [8] Peng B., Li T., Guo Y., et al. (2025). The key components of biochar's environmental behavior and potential ecological risks: Biochar-derived dissolved organic matter. J. Water Process Eng. 72:107499. DOI:10.1016/j.jwpe.2025.107499 [9] Smith C. R., Sleighter R. L., Hatcher P. G., et al. (2013). Molecular characterization of inhibiting biochar water-extractable substances using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Environ. Sci. Technol. 47:13294−13302. DOI:10.1021/es4034777 [10] Sun Y., Xiong X., He M., et al. (2021). Roles of biochar-derived dissolved organic matter in soil amendment and environmental remediation: A critical review. Chem. Eng. J. 424:130387. DOI:10.1016/j.cej.2021.130387 [11] Lyu H., Zhang H., Dong J., et al. (2024). Pyrolysis temperature matters: Biochar-derived dissolved organic matter modulates aging behavior and biotoxicity of microplastics. Water Res. 250:121064. DOI:10.1016/j.watres.2023.121064 [12] Wang W., Nie M., Yan C., et al. (2024). Effect of pyrolysis temperature and molecular weight on characterization of biochar derived dissolved organic matter from invasive plant and binding behavior with the selected pharmaceuticals. Environ. Pollut. 348:123867. DOI:10.1016/j.envpol.2024.123867 [13] Masud M. A. A., Samaraweera H., Mondol M. M. H., et al. (2025). Iron biochar synergy in aquatic systems through surface functionalities electron transfer and reactive species dynamics. npj Clean Water 8:46. DOI:10.1038/s41545-025-00471-5 [14] Fan T., Yao X., Sun Z., et al. (2023). Properties and metal binding behaviors of sediment dissolved organic matter (SDOM) in lakes with different trophic states along the Yangtze River Basin: A comparison and summary. Water Res. 231:119605. DOI:10.1016/j.watres.2023.119605 [15] Huang M., Li Z., Wen J., et al. (2021). Molecular insights into the effects of pyrolysis temperature on composition and copper binding properties of biochar-derived dissolved organic matter. J. Hazard. Mater. 410:124537. DOI:10.1016/j.jhazmat.2020.124537 [16] Fu H., Liu H., Mao J., et al. (2016). Photochemistry of dissolved black carbon released from biochar: Reactive oxygen species generation and phototransformation. Environ. Sci. Technol. 50:1218−1226. DOI:10.1021/acs.est.5b04314 [17] Kind T. and Fiehn O. (2007). Seven golden rules for heuristic filtering of molecular formulas obtained by accurate mass spectrometry. BMC Bioinformatics 8:105. DOI:10.1186/1471-2105-8-105 [18] Bramer L. M., White A. M., Stratton K. G., et al. (2020). ftmsRanalysis: An R package for exploratory data analysis and interactive visualization of FT-MS data. PLoS Comput. Biol. 16:e1007654. DOI:10.1371/journal.pcbi.1007654 [19] Koch B. P. and Dittmar T. (2006). From mass to structure: An aromaticity index for high-resolution mass data of natural organic matter. Rapid Commun. Mass Spectrom. 20:926−932. DOI:10.1002/rcm.2386 [20] LaRowe D. E. and Van Cappellen P. (2011). Degradation of natural organic matter: A thermodynamic analysis. Geochim. Cosmochim. Acta 75:2030−2042. DOI:10.1016/j.gca.2011.01.020 [21] Patel S. A. and Erickson L. E. (1981). Estimation of heats of combustion of biomass from elemental analysis using available electron concepts. Biotechnol. Bioeng. 23:2051−2067. DOI:10.1002/bit.260230910 [22] Battley E. H. (1998). The development of direct and indirect methods for the study of the thermodynamics of microbial growth. Thermochim. Acta 309:17−37. DOI:10.1016/S0040-6031(97)00357-2 [23] Popovic M. (2019). Thermodynamic properties of microorganisms: Determination and analysis of enthalpy, entropy, and Gibbs free energy of biomass, cells and colonies of 32 microorganism species. Heliyon 5:e01950. DOI:10.1016/j.heliyon.2019.e01950 [24] Liu L., Yang X., Ahmad S., et al. (2023). Silicon (Si) modification of biochars from different Si-bearing precursors improves cadmium remediation. Chem. Eng. J. 457:141194. DOI:10.1016/j.cej.2022.141194 [25] Chen W.-H., Wang C.-W., Ong H. C., et al. (2019). Torrefaction, pyrolysis and two-stage thermodegradation of hemicellulose, cellulose and lignin. Fuel 258:116168. DOI:10.1016/j.fuel.2019.116168 [26] Liu N., Dou C., Yang X., et al. (2025). Effects of pretreatment procedure, compositional feature and reaction condition on the devolatilization characteristics of biomass during pyrolysis process: A review. J. Energy Inst. 118:101943. DOI:10.1016/j.joei.2024.101943 [27] Zheng J., Kwak K., Chen X., et al. (2006). Formation and dissociation of intra–intermolecular hydrogen-bonded solute–solvent complexes: Chemical exchange two-dimensional infrared vibrational echo spectroscopy. J. Am. Chem. Soc. 128:2977−2987. DOI:10.1021/ja0570584 [28] Xu S., Yang J., Su P., et al. (2024). Identifying key intermediates for the oxygen evolution reaction on hematite using ab-initio molecular dynamics. Nat. Commun. 15:10411. DOI:10.1038/s41467-024-54796-9 [29] Wang S., Dai G., Yang H., et al. (2017). Lignocellulosic biomass pyrolysis mechanism: A state-of-the-art review. Prog. Energy Combust. Sci. 62:33−86. DOI:10.1016/j.pecs.2017.05.004 [30] Wang N., Zhi Y., Wei Y., et al. (2020). Molecular elucidating of an unusual growth mechanism for polycyclic aromatic hydrocarbons in confined space. Nat. Commun. 11:1079. DOI:10.1038/s41467-020-14493-9 [31] Ciccone V., Lin E., Prieto Kullmer C. N., et al. (2026). Double deoxygenative coupling of carboxylic acids and alcohols. ACS Catal. 16:12645−12652. DOI:10.1021/acscatal.6c02684 [32] Grandbois M., Beyer M., Rief M., et al. (1999). How strong is a covalent bond. Science 283:1727−1730. DOI:10.1126/science.283.5408.1727 [33] Gunina A. and Kuzyakov Y. (2022). From energy to (soil organic) matter. Glob. Change Biol. 28:2169−2182. DOI:10.1111/gcb.16071 [34] Freeman L. A., Walley J. E. and Gilliard R. J. (2022). Synthesis and reactivity of low-oxidation-state alkaline earth metal complexes. Nat. Synth. 1:439−448. DOI:10.1038/s44160-022-00077-6 [35] Liu X., Xi S., Kim H., et al. (2021). Restructuring highly electron-deficient metal-metal oxides for boosting stability in acidic oxygen evolution reaction. Nat. Commun. 12:5676. DOI:10.1038/s41467-021-26025-0 [36] Noda I. (2016). Two-dimensional correlation spectroscopy (2DCOS) analysis of polynomials. J. Mol. Struct. 1124:53−60. DOI:10.1016/j.molstruc.2016.01.091 [37] Yang H., Yang S., Kong J., et al. (2015). Obtaining information about protein secondary structures in aqueous solution using Fourier transform IR spectroscopy. Nat. Protoc. 10:382−396. DOI:10.1038/nprot.2015.024 [38] Wünsch U. J., Murphy K. R. and Stedmon C. A. (2017). The one-sample PARAFAC approach reveals molecular size distributions of fluorescent components in dissolved organic matter. Environ. Sci. Technol. 51:11900−11908. DOI:10.1021/acs.est.7b03260 [39] Tiwari J., Ramanathan A. L., Bauddh K., et al. (2023). Humic substances: Structure, function and benefits for agroecosystems—a review. Pedosphere 33:237−249. DOI:10.1016/j.pedsph.2022.07.008 [40] Deng J.-H., Luo J., Mao Y.-L., et al. (2020). π-π stacking interactions: Non-negligible forces for stabilizing porous supramolecular frameworks. Sci. Adv. 6:eaax9976. DOI:10.1126/sciadv.aax9976 [41] Ellerbrock R. H. and Gerke H. H. (2021). FTIR spectral band shifts explained by OM–cation interactions. J. Plant Nutr. Soil Sci. 184:388−397. DOI:10.1002/jpln.202100056 [42] Mackie A. L., Park Y. and Gagnon G. A. (2022). Calibration of high performance size exclusion chromatography (HPSEC) for molecular weight estimation of aquatic humic substances. J. Environ. Chem. Eng. 10:108913. DOI:10.1016/j.jece.2022.108913 [43] Terkhi M. C., Taleb F., Gossart P., et al. (2008). Fourier transform infrared study of mercury interaction with carboxyl groups in humic acids. J. Photochem. Photobiol. A Chem. 198:205−214. DOI:10.1016/j.jphotochem.2008.03.018 [44] Hughey C. A., Hendrickson C. L., Rodgers R. P., et al. (2001). Kendrick mass defect spectrum: A compact visual analysis for ultrahigh-resolution broadband mass spectra. Anal. Chem. 73:4676−4681. DOI:10.1021/ac010560w [45] Cheng Z., Hu Q., Guo H., et al. (2024). Long-term straw return enhanced the chlorine reactivity of soil DOM: Highlighting the molecular-level activity and transformation trade-offs. Sci. Total Environ. 951:175485. DOI:10.1016/j.scitotenv.2024.175485 [46] Cai S., Zhang Y., Hu A., et al. (2023). Dissolved organic matter transformation mechanisms and process optimization of wastewater sludge hydrothermal humification treatment for producing plant biostimulants. Water Res. 235:119910. DOI:10.1016/j.watres.2023.119910 [47] Homoki-Farkas P., Örsi F. and Kroh L. W. (1997). Methylglyoxal determination from different carbohydrates during heat processing. Food Chem. 59:157−163. DOI:10.1016/S0308-8146(96)00273-7 [48] Sulis D. B., Lavoine N., Sederoff H., et al. (2025). Advances in lignocellulosic feedstocks for bioenergy and bioproducts. Nat. Commun. 16:1244. DOI:10.1038/s41467-025-56472-y [49] Ren W., Zhang D., Zhou Y., et al. (2024). Lignin's complex role in lignocellulosic biomass recalcitrance: A case study on bamboo. Chem. Eng. J. 490:151422. DOI:10.1016/j.cej.2024.151422 [50] Mohan V., Naske C. D., Britten C. N., et al. (2020). Hydroxide-catalyzed cleavage of selective ester bonds in phosphatidylcholine: An FTIR study. Vib. Spectrosc. 109:103055. DOI:10.1016/j.vibspec.2020.103055 [51] Ma H., Wei M., Wang Z., et al. (2020). Bioremediation of cadmium polluted soil using a novel cadmium immobilizing plant growth promotion strain Bacillus sp. TZ5 loaded on biochar. J. Hazard. Mater. 388:122065. DOI:10.1016/j.jhazmat.2020.122065 [52] Mahmud J. A., Hasanuzzaman M., Nahar K., et al. (2018). Insights into citric acid-induced cadmium tolerance and phytoremediation in Brassica juncea L. : Coordinated functions of metal chelation, antioxidant defense and glyoxalase systems. Ecotoxicol. Environ. Saf. 147:990−1001. DOI:10.1016/j.ecoenv.2017.09.045 [53] Ke T., Guo G., Liu J., et al. (2021). Improvement of the Cu and Cd phytostabilization efficiency of perennial ryegrass through the inoculation of three metal-resistant PGPR strains. Environ. Pollut. 271:116314. DOI:10.1016/j.envpol.2020.116314 [54] Hu T., Li H.-y., Zhang X.-z., et al. (2011). Toxic effect of NaCl on ion metabolism, antioxidative enzymes and gene expression of perennial ryegrass. Ecotoxicol. Environ. Saf. 74:2050−2056. DOI:10.1016/j.ecoenv.2011.07.013 [55] Li Q., Xing Y., Huang B., et al. (2022). Rhizospheric mechanisms of Bacillus subtilis bioaugmentation-assisted phytostabilization of cadmium-contaminated soil. Sci. Total Environ. 825:154136. DOI:10.1016/j.scitotenv.2022.154136 [56] Liu R., Liu G., Yousaf B., et al. (2022). Novel investigation of pyrolysis mechanisms and kinetics for functional groups in biomass matrix. Renew. Sustain. Energy Rev. 153:111761. DOI:10.1016/j.rser.2021.111761 -
ABOUT THIS ARTICLE
Cite this article:
Li Y., Meng X., Ai S., et al. (2026). Thermal condensation drives molecular evolution of biochar-derived dissolved organic matter for heavy metal immobilization. The Innovation Materials 4:100236. https://doi.org/10.59717/j.xinn-mater.2026.100236
Welcome!
To request copyright permission to republish or share portions of our works, please visit Copyright Clearance Center's (CCC) Marketplace website at marketplace.copyright.com.
Export File
Citation
Li Y., Meng X., Ai S., et al. (2026). Thermal condensation drives molecular evolution of biochar-derived dissolved organic matter for heavy metal immobilization. The Innovation Materials 4:100236. https://doi.org/10.59717/j.xinn-mater.2026.100236
Format
Content
-
Figure 1.
Comparative analysis of molecular characteristics in BDOM across thermal gradients
-
Figure 2.
Thermal reorganization reshapes BDOM molecular networks and Cd coordination pathways
-
Figure 3.
Structural analysis of BDOM-Cd
-
Figure 4.
Molecular transformations during Cd coordination (A-C)
-
Figure 5.
Molecular and thermodynamic pathways during Cd coordination
-
Figure 6.
Possible transformation pathways of BDOM during Cd chelation and the effect of pyrolysis temperature on BDOM formation.
-
Figure 7.
BDOM immobilizes soil Cd and limits its uptake by ryegrass
