Humin

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Humins are carbon-based macromolecular substances, that can be found in soil chemistry or as a by-product from saccharide-based biorefinery processes.

Humins in Soil Chemistry[edit]

Soil consists of both mineral (inorganic) and organic components. The organic components can be subdivided into fractions that are soluble, largely humic acids, and insoluble, the humins. Humins make up about 50% of the organic matter in soil.[1]

Criticism[edit]

Humic substances, including humin, have not been observed in soils using modern analytical techniques.[2]

Humins from Biomass Sources[edit]

Humins also produced during the dehydration of sugars, as occurs during the conversion of lignocellulosic biomass to smaller, higher value organic compounds such as 5-hydroxymethylfurfural (HMF). These humins can be in the form of either viscous liquids or solids depending on the process conditions used.

Humins Structure and Mechanism of Formation[edit]

Both the structure of humins and the mechanism by which they are synthesized is at present not well defined as the formation and chemical properties of humins will change depending on the process conditions used. Generally, humins have a polymeric furanic-type structure, with hydroxyl, aldehyde and ketone functionalities.[3]

Safety aspects[edit]

Humins are not considered to be a dangerous substance according to officially recognized hazardous material classification systems based on physical-chemical properties such as flammability[4], explosiveness, susceptibility to oxidation, corrosiveness or eco-toxicity.[5]

Potential applications of Humins[edit]

In the past, humins from biomass sources have been mostly considered as combustible materials to supply heat for biorefinery processes. However, high value applications have started to receive more attention, notably the use of humins in the preparation of catalytic materials [6] and in material applications (e.g. plastic reinforcement and construction materials).[7][8][9] Humins can also be subjected to thermal treatments in order to form interesting solid materials, such as lightweight and porous humin foams.[10][11]

See also[edit]

References[edit]

  1. ^ Rice, James A. "Humin" Soil Science 2001, vol. 166(11), pp. 848-857. doi:10.1097/00010694-200111000-00002
  2. ^ Lehmann, J.; Kleber, M. (2015-12-03), "The contentious nature of soil organic matter", Nature, 528, doi:10.1038/nature16069
  3. ^ van Zandvoort, I., "Towards the Valorisation of Humin By-products: Characterisation, Solubilisation and Catalysis", 2015
  4. ^ Muralidhara, A., Tosi, P., Mija, A., Sbirrazzuoli, N., Len, C., Engelen, V., de Jong, E., Marlair, G., ACS Sustainable Chem. Eng., 2018, 6, 16692-16701
  5. ^ Muralidhara, A.,Bado-Nilles, A., Marlair, G., Engelen, V., Len, C., Pandard, P., Biofuels, Bioproducts and Biorefining, 2018, 1-7
  6. ^ Filiciotto, L., Balu, A.M., Romero, A.A, Rodriguez-Castellon, E., van der Waal, J.C., Luque, R., Green Chemistry, 2017, 19, 4423-4434
  7. ^ Mija, A., van der Waal, J.C., Pin, J-M., Guigo, N., de Jong, E., "Humins as promising material for producing sustainable carbohydrate-derived building materials", Construction and Building Materials, 2017, 139, 594 doi:10.1016/j.conbuildmat.2016.11.019
  8. ^ Sangregorio, A., Guigo, N., van der Waal, J.C., Sbirrazzuoli, N., "All 'green' composites comprising flax fibres and humins' resins", Composites Science and Technology, 2019, 171, 70. doi:10.1016/j.compscitech.2018.12.008
  9. ^ Pin, J.M., Guigo, N., Mija, A., Vincent, L., Sbirrazzuoli, N., van der Waal, J.C., de Jong, E., ACS Sustain. Chem. Eng., 2014, 2, 2182-2190
  10. ^ Mija, A., van der Waal, J.C., van Klink, G., de Jong, E., Humins-containing foam, 2016, WO2017074183A8
  11. ^ Tosi, P., van Klink, G.P., Celzard, A., Fierro V., Vincent, L., de Jong, E., Mija, A., ChemSusChem, 2018, 11, 2797-2809

See also[edit]

Singer, Michael J., and Donald N. Munns. Soils An Introduction (6th Edition). Upper Saddle River: Prentice Hall, 2005. ISBN 978-0-13-119019-1