Green Chemistry and BioKnoT

31 March 2022 | Alessia Belgi, ARC Training Centre for Green Chemistry in Manufacturing

In this post we explain the aims of the BioKnoT project/initiative and how they are linked to the 12 Principles of Green Chemistry.

How are Green Chemistry and BioKnoT connected?

The knowledge transfer that BioKnoT is aiming to achieve around rice straw management, seeks to show farmers and any of the stakeholders involved in the rice production in Vietnam the intrinsic value of rice straw. Rice straw can be turned into high-value products instead of being burnt, which seems to be common practice in Vietnam, with all the deleterious consequences on health and environment.  Rice straw can have multiple uses as composting, animal feed, mushroom production, for example1, all of which are more sustainable than open-field burning which is currently the preferred ‘use’ of rice straw in Vietnam.  Rice straw is primarily composed of cellulose, hemicellulose and lignin. Each of these materials, as well as rice straw as a whole, can be repurposed for the manufacture of everyday products in a sustainable way. This falls under the umbrella of the 7th Principle of Green Chemistry-Use of renewable feedstocks.

Another of the aims of BioKnoT is the utilization of enzymes for the production of biofuel. In particular BioKnoT is looking into the valorization of rice straw specifically as source of bio-ethanol, a high-value product for industry.  This is a practical application of the 8th Principle of Green Chemistry: Reduce derivatives. Enzymes are so specific and selective that they perform a reaction on their substrates without the need of unnecessary steps such as the introduction of protecting groups and their removal at the end.

The 3rd Principle of Green Chemistry: Reduce Toxicity will also play an important role in the BioKnoT project/program. Great attention will be used in the design of protocols for treating rice straw that will use greener chemical compounds and generate waste material that is not toxic to the environment and human health.

How can we repurpose rice straw components?

Rice straw Cellulose Utilization

Once it is recovered from rice straw, or any biomass in general, cellulose can be used in several high value-added applications such as cellulose-based ionic liquids, functional composites, adsorbent materials, carbon dots and nanodots, aerogels2 and superadsorbent hydrogels3. (Figure 1)

Figure 1

Figure 1 Utilization of cellulose from biomass2, 3

Rice straw Hemicellulose utilization

Hemicellulose from biomass can be used in the production of films for food packaging, wound dressing and drug capsules2 and for paper coatings and adhesives4. Hemicellulose-based hydrogels can be used as novel carriers in drug delivery2 as adsorbents for the removal of hazardous compounds and heavy metals from waste water and in the manufacture of contact lenses5. (Figure 2)Figure 2

Figure 2 Utilization of hemicellulose

Rice straw Lignin Utilization

Lignin in biomass can be used for the production of bioethanol, and its aromatic components (phenols in particular) can be used in the manufacture of polymers, fuels and various value-added products6. It can also be used to make carbon/graphene/carbon nanotubes, bioplastics, dye dispersants, aerogels2 as well as adhesives7-9. Lignin can also be added to epoxy resins to make new chemical grouting materials10. (Figure 3)

Figure 3

Figure 3 Utilization of lignin from biomass

If this got you interested in Green Chemistry, find here the 12 reasons why it is important for you

To find out more about the valorization of rice straw and what rice straw exactly are, click on the following links:

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References
1. Gummert, M.; Hung, N. V.; Chivenge, P.; Douthwaite, B., Sustainable rice straw management. Springer Nature: 2020.
2. Liu, Y.; Nie, Y.; Lu, X.; Zhang, X.; He, H.; Pan, F.; Zhou, L.; Liu, X.; Ji, X.; Zhang, S., Cascade utilization of lignocellulosic biomass to high-value products. Green Chemistry 2019, 21 (13), 3499-3535.
3. Barajas-Ledesma, R. M.; Patti, A. F.; Wong, V. N.; Raghuwanshi, V. S.; Garnier, G., Engineering nanocellulose superabsorbent structure by controlling the drying rate. Colloids and Surfaces A: Physicochemical and Engineering Aspects 2020, 600, 124943.
4. Farhat, W.; Venditti, R.; Quick, A.; Taha, M.; Mignard, N.; Becquart, F.; Ayoub, A., Hemicellulose extraction and characterization for applications in paper coatings and adhesives. Industrial Crops and Products 2017, 107, 370-377.
5. Hu, L.; Du, M.; Zhang, J., Hemicellulose-based hydrogels present status and application prospects: A brief review. Open Journal of Forestry 2017, 8 (1), 15-28.
6. Margellou, A.; Triantafyllidis, K. S., Catalytic Transfer Hydrogenolysis Reactions for Lignin Valorization to Fuels and Chemicals. Catalysts 2019, 9 (1), 43.
7. Nasiri, A.; Wearing, J.; Dubé, M. A., The use of lignin in emulsion-based pressure-sensitive adhesives. International Journal of Adhesion and Adhesives 2020, 100, 102598.
8. Wei, C.; Zhu, X.; Peng, H.; Chen, J.; Zhang, F.; Zhao, Q., Facile preparation of lignin-based underwater adhesives with improved performances. ACS Sustainable Chemistry & Engineering 2019, 7 (4), 4508-4514.
9. Zhang, S.; Liu, T.; Hao, C.; Wang, L.; Han, J.; Liu, H.; Zhang, J., Preparation of a lignin-based vitrimer material and its potential use for recoverable adhesives. Green Chemistry 2018, 20 (13), 2995-3000.
10. Zhang, Y.; Pang, H.; Wei, D.; Li, J.; Li, S.; Lin, X.; Wang, F.; Liao, B., Preparation and characterization of chemical grouting derived from lignin epoxy resin. European Polymer Journal 2019, 118, 290-305.