Structural characteristics of lignin extracted from Jordanian olive cake using different fractionation conditions

ABSTRACT

The chemical structure and properties of lignin-derived from lignocellulosic olive mill waste (Jeft) were investigated. Alkali and dioxane lignins were evaluated regarding the achieved high delignification and high purity of the extracted lignins. The results declared that the major constituents of olive cake are extractives, cellulose, hemicelluloses, and lignin. Furthermore, the olive cake has low relative crystallinity and the ash content does not exceed 2%. The yields of Alkali and Dioxane lignins were 15.3 ± 0.34, and 1.4 ± 0.43%, respectively. For the elucidation of structural features of lignin molecules, lignins samples were also subjected to UV spectroscopy and ¹HNMR analysis. The analysis showed that the treatment under acidic condition did not significantly attack the β-aryl ether structure (β-O-4), while the alkali treatment shows an extensive cleavage of the β-aryl-ether linkage with the degradation of ester resulting in a structural alteration of lignin. High Delignification is achieved by dioxane process through progressive enrichment of carboxylic acid group in isolated lignin; also dioxane isolation has little influence on the structure of isolated lignin. Moreover, the results confirmed that Alkali and Dioxane lignin were guaiacyl-syringyl lignin, typical of hardwood lignins.

KEYWORDS:

• Lignin extraction
• olive cake
• spectroscopic analysis
• alkali lignin
• dioxane lignin

Additional information

Notes on contributors

Arwa Sandouqa

Arwa Sandouqa is Engineer at the chemical engineering laboratory/the University of Jordan since 2006. She obtained her B.Sc in Chemical Engineering from Al-Balqa` Applied University in 2000. She has completed her M.Sc in Renewable Energy in 2017 from the Mechanical Engineering Department/ The University of Jordan-Amman-Jordan. Currently, she supervises undergraduate as well as graduate chemical engineering students during their work in the chemical engineering laboratories. She is interested in research work related to biomass valorization and biofuels.

Zayed Al-Hamamre

Zayed Al-Hamamre is a Professor of Chemical Engineering at the University of Jordan-Amman-Jordan. He received his B.Sc. in Chemical Engineering in 2000 from The Jordan University of Science and Technology – Jordan and the M.Sc. in 2003 from Friedrich-Alexander Universität Erlangen – Nürnberg, Germany. He received his doctorate in Chemical Engineering from TU Bergakademie Freiberg – Freiberg, Germany. His research interests include the transformation of biomass into fuels, chemicals, and high added value materials.

Jamil Asfar

Jamil Asfar received his Ph. D in Mechanical Engineering from the University of Jordan in 2007, from which he also obtained his M. Sc. in 1996. He received his B.Sc. in Mechanical Engineering in 1985 from Yarmouk University in Jordan. He began his career as a sales and specifications engineer in 1986. He then worked for the Jordanian Ministry of Trade and Industry (Jordan Investment Board) from 1995 to 2007. Currently, he works as Professor at the University of Jordan-School of Engineering/ mechanical engineering Department. His current research interests include CFD, Energy, Combustion, Hybrid renewable energy systems, Energy and Renewable Energy, Alternative Fuel.