Valorization, Comparison and Characterization of Coconuts Waste and Cactus in a Biorefinery Context Using NaClO2–C2H4O2 and Sequential NaClO2–C2H4O2/Autohydrolysis Pretreatment
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The search for new sources of lignocellulosic raw materials for the generation of energy and new compounds encourages the search for locations not well known and with a high potential for biomass availability as is the case of the Northeast Region of Brazil. Thus, the cactus (CAC), green coconut shell (GCS), mature coconut fibre and mature coconut shell were pretreated by NaClO2–C2H4O2 and sequential NaClO2–C2H4O2/autohydrolysis aiming at the obtention of high added-value compounds in the liquid fraction and solid phase. The yield of the solid phase was between 61.42 and 90.97% and the reduction up to 91.63% of lignin in the materials pretreated by NaClO2–C2H4O2. After NaClO2–C2H4O2/autohydrolysis pretreatment the obtained solids yield was between 43.57 and 52.08%, with a solubilization of the hemicellulose content up to 81.42%. For both pretreatments the cellulosic content remained almost unchanged. The pretreated solids were characterized by SEM, X-ray and crystallinity indexes showing significant modifications when submitted to pretreatments. These results were further confirmed by the enzymatic conversion yields of 81.68–90.03 and 86.97–90.36% of the LCMs pretreated by NaClO2–C2H4O2 and pretreated by NaClO2–C2H4O2/autohydrolysis, respectively. The resulting liquors had a total phenolic compounds content between 0.20 and 3.05 g/L, lignin recovered up to 7.40 g/L (absence of sulphur) and xylooligosaccharides between 16.13 and 20.37 g/L. Thus, these pretreatments showed an efficient fractionation of LCMs, especially in the GCS, being an important requirement for the generation of products and byproducts in the context of the biorefinery.
KeywordsHydrothermal Xylooligosaccharides Phenolic compounds Lignin recovered Enzymatic hydrolysis Biorefinery
The authors gratefully acknowledge the Brazilian research funding agencies CNPq and CAPES for financial support. Financial support from the Energy Sustainability Fund 2014-05 (CONACYT-SENER), Mexican Centre for Innovation in Bioenergy (Cemie-Bio), Cluster of Bioalcohols (Ref. 249564) is gratefully acknowledged. We also gratefully acknowledge support for this research by the Mexican Science and Technology Council (CONACYT, Mexico) for the infrastructure project - INFR201601 (Ref. 269461) and CB-2015-01 (Ref. 254808).
- 8.Matsushita, Y., Jo, E., Inakoshi, S., Yagami, S., Takamoto, N., Fukushima, K., Lee, S.: Hydrothermal reaction of sulfuric acid lignin generated as a by-product during bioethanol production using lignocellulosic materials to convert bioactive agents. Ind. Crops Prod. 42, 181–188 (2013)CrossRefGoogle Scholar
- 15.Sluiter, A., Hames, B., Hyman, D., Payne, C., Ruiz, R., Scarlata, C., Sluiter, J., Templeton, D., Wolfe, J.: Determination of total solids in biomass and total dissolved solids in liquid process samples. National Renewable Energy Laboratory. Golden, Colorado (2008)Google Scholar
- 18.Ruiz, H.A., Ruzene, D., Silva, D.P., da Silva, F.F., Vicente, A.A., Teixeira, J.A.: Development and characterization of an environmentally friendly process sequence (autohydrolysis and organosolv) for wheat straw delignification. Appl. Biochem. Biotechnol. 164(5), 629–641 (2011)CrossRefGoogle Scholar
- 20.Gonçalves, F.A., Ruiz, H.A., dos Santos, E.S., Teixeira, J.A., de Macedo, G.R.: Bioethanol production by Saccharomyces cerevisiae, Pichia stipitis and Zymomonas mobilis from delignified coconut fibre mature and lignin extraction according to biorefinery concept. Renew. Energy 94, 353–365 (2016)CrossRefGoogle Scholar
- 21.Dowe, N., Mcmillan, J.: SSF experimental protocols-lignocellulosic biomass hydrolysis and fermentation. NERL analytical procedure. National Renewable Energy Laboratory, Golden (2001)Google Scholar
- 22.Gonçalves, F.A., Ruiz, H.A., Nogueira, C.C., dos Santos, E.S., Teixeira, J.A., de Macedo, G.R.: Comparison of delignified coconuts waste and cactus for fuel-ethanol production by the simultaneous and semi-simultaneous saccharification and fermentation strategies. Fuel 131, 66–76 (2014)CrossRefGoogle Scholar
- 23.Ding, T.Y., Hii, S.L., Ong, L.G.A.: Comparison of pretreatment strategies for conversion of coconut husk fiber to fermentable sugars. BioResources 7, 1540–1547 (2012)Google Scholar
- 37.Sun, R., Tomkinson, J., Zhu, W., Wang, S.Q.: Delignification of maize stem by peroxymonosulfuric acid, peroxyformic acid, peracetic acid and hydrogen peroxide. 1. Physicochemical and structural characterization of the solubilized lignins. J. Agric. Food Chem. 48, 1253–1262 (2000)CrossRefGoogle Scholar
- 38.Faix, O.: Fourier transform infrared spectroscopy. In: Lin, S.Y., Dence, C.W. (eds.) Methods in lignin chemistry, p. 81. Springer, Berlin (1992)Google Scholar