Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2020 May 8;9(5):399.
doi: 10.3390/antiox9050399.

Effect of Antioxidants on High-Temperature Stability of Renewable Bio-Oils Revealed by an Innovative Method for the Determination of Kinetic Parameters of Oxidative Reactions

Fabio Mollica  1 , Marco Lucarini  1 , Cinzia Passerini  2 , Claudio Carati  2 , Silvia Pavoni  2 , Lucia Bonoldi  2 , Riccardo Amorati  1
Affiliations

Effect of Antioxidants on High-Temperature Stability of Renewable Bio-Oils Revealed by an Innovative Method for the Determination of Kinetic Parameters of Oxidative Reactions

Fabio Mollica et al. Antioxidants (Basel). .

Abstract

Bio-oils employed for various industrial purposes, such as biodiesel production, undergo extensive oxidation and degradation during transformation processes. Therefore, it is extremely important to predict their stability at high temperature. We report herein a new procedure based on the optically detected profile of headspace O2 concentration during isotherms at 130 °C for evaluating the oxidation kinetic parameters of several bio-oil feedstocks. The slope of O2 consumption and the induction period duration were related to the oil characteristics (molecular structure, acidity, and presence of intrinsic antioxidants or metals). The increase of the induction time caused by a standardized propyl gallate addition yielded a semiquantitative value of radical generation rate. Investigated oils included used cooking oils; mono-, di-, and triglycerides from natural sources; free fatty acids; transesterified oils; and their blends. With respect to other methods, this characterization presents the advantage of disentangling and evaluating the role of both fatty acids composition and naturally occurring antioxidants, and allows the development of rational strategies for antioxidant protection of oils and of their blends.

Keywords: antioxidant; biodiesel; induction period; kinetics; oil mixtures; oxidative stability; oxygen consumption; propyl gallate; radicals.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Figures

Scheme 1
Scheme 1
Mechanism of autoxidation of natural fatty acids. On the top right, the main mechanism of propagation by peroxyl radicals: (a) H-atom transfer; (b) addition; (c) addition–fragmentation; and (d) generation of a hydroperoxyl radical. In the bottom right is the general mechanism of action of chain breaking antioxidants.
Figure 1
Figure 1
(a) Apparatus for measuring oxygen consumption and scheme of the optical O2 probe. (b,c) Experimental oxygen uptake of jojoba oil (BIO86) at 130 °C: (b) results from three open–close cycles; and (c) plot obtained by connecting the traces of plot (b).
Figure 2
Figure 2
O2 uptake measured during the oxidation at 130 °C of raw (BIO19) and purified (BIO73) palm oil.
Figure 3
Figure 3
(a) Induction period of Type B oils. (b) The inset reports the relationship between OSI values and τ, showing that t is in general smaller than OSI, with the exception of BIO61 and BIO68.
Figure 4
Figure 4
Overview of experimental Rst of oils at 130 °C and comparison with the values predicted by the multiple linear regression shown in Equation (2).
Figure 5
Figure 5
(a) Effect of propyl gallate (PG, 500 ppm) on the oxidation of two different oils; and (b) relationship between the PG effect (τPG-τ) and oil composition. Oils showing no PG effect because of high iron or acidity contents were not included. The inset shows the linear relationship between 1/(τPG-τ) and the concentration of bis-allylic groups, white triangles indicate outliers (see text).
Figure 6
Figure 6
O2 uptake measured during the oxidation at 130 °C of oil mixtures. (a) BIO 23 and BIO19, (b) BIO26 and BIO19.
See this image and copyright information in PMC

References

    1. Singh D., Sharma D., Soni S.L., Sharma S., Sharma P.K., Jhalani A. A review on feedstocks, production processes, and yield for different generations of biodiesel. Fuel. 2020;262:116553. doi: 10.1016/j.fuel.2019.116553. - DOI
    1. Liu S., Simonetti T., Zheng W., Saha B. Selective hydrodeoxygenation of vegetable oils and waste cooking oils to green diesel using a silica-supported Ir–ReOx bimetallic catalyst. Chem. Sus. Chem. 2018;11:1446–1454. doi: 10.1002/cssc.201800321. - DOI - PubMed
    1. Li X., Luo X., Jin Y., Li J., Zhang H., Zhang A., Xie J. Heterogeneous sulfur-free hydrodeoxygenation catalysts for selectively upgrading the renewable bio-oils to second generation biofuels. Renew. Sustain. Energy Rev. 2018;82:3762–3797. doi: 10.1016/j.rser.2017.10.091. - DOI
    1. Xin J., Imahara H., Saka S. Kinetics on the oxidation of biodiesel stabilized with antioxidant. Fuel. 2009;88:282–286. doi: 10.1016/j.fuel.2008.08.018. - DOI
    1. Farhoosh R., Nyström L. Antioxidant potency of gallic acid, methyl gallate and their combinations in sunflower oil triacylglycerols at high temperature. Food Chem. 2018;244:29–35. doi: 10.1016/j.foodchem.2017.10.025. - DOI - PubMed

LinkOut - more resources