The Effect of Antioxidants on Corn and Sunflower Biodiesel Properties under Extreme Oxidation Conditions

Abstract

Biodiesel is an alternative to mineral fuels, with advantages such as biodegradability. However, this makes biodiesel unstable to oxidation. In this way, the use of natural or synthetic antioxidants is necessary. Although many studies have paid attention to the effect of these antioxidants on oxidation stability, not much literature about their effect of them on other properties (before and during storage) was found. The aim of this research study was to characterize biodiesel from corn and sunflower by adding two antioxidants, butylated hydroxyanisole (BHA) and tertbutylhydroquinone (TBHQ), in order to improve its oxidation stability. Moreover, the effect of oxidation on the parameters of biodiesel was studied by using extreme oxidation conditions to accelerate the oxidation process. Both antioxidants improved the oxidation stability of biodiesel, whereas some parameters were altered (viscosity and acid number), which could make this biofuel, if high concentrations of antioxidants are used, unsuitable for commercialization according to standards.Keywords BHA Á TBHQ Á Oxidation stability Á Viscosity Á Thermal analysis Á Fatty acid methyl esters J Am Oil Chem Soc (2020) 97: 201-212.

Biodiesel and biolubricant production from different vegetable oils through transesterification

“…Consequently, the use of antioxidant additives (both natural or synthetic) should be necessary. [29][30][31] One of the most important characteristics to be taken into account is the fatty acid profile of the raw materials. Thus, during the two transesterifications, these fatty acids become FAMEs in the case of biodiesel and fatty acid alkyl esters in the case of biolubricants, respectively.…”

“…Many biodiesel samples show high levels of methyl linoleate, as previous studies have pointed out for safflower biodiesel 33 or corn and sunflower biodiesel. 31 Methyl linoleate is di-unsaturated, which makes this molecular structure unstable concerning oxidation.…”

The effect of BHA on oxidative stability of biodiesel from different sources

“…In order to assess the effectiveness of BHA addition, the stabilization factor ratio (or protection factor, expressed in %) was calculated, expressing the increase in oxidative stability (or induction point) for each BHA concentration compared to the control sample. 22 Total FAME content and FAME composition, were determined by using a gas chromatograph (VARIAN 3900, Varian, Palo Alto, CA, USA) coupled to a flame ionization detector (FID). A silica capillary column (Zebron ZB Waxplus, 30 m long, 0.32 mm inner diameter and 0.5 μm film thickness, Phenomenex, Torrance, CA, USA) was used.…”

“…13,[19][20][21] As a consequence, the biodiesel treated with antioxidants becomes more stable to oxidation, implying longer oxidative stability values (that is, induction points, expressed in hours), and keeping its characteristics during storage, as it was observed in previous studies. 22 This way, the FAME composition has an equally strong influence on the optimum antioxidant concentration that is necessary to comply with the standard. In general, the more unstable the biodiesel is, the higher amounts of antioxidant are needed.…”

Babassu Biodiesel Doped with Antioxidants: Assessment of Thermo‐Oxidative Stability by Borchardt and Daniels Method

“…Natural and synthetic compounds may be used, including alkylphenols, such as butylated hydroxytoluene (BHT), butylhydroxyanisole (BHA), unsaturated cardanol (U‐CDN) and 2,4,6‐Tri‐tert‐butylphenol/2,6‐Di‐tert‐butylphenol (IONOL), and amines, such as N , N ′‐di‐sec‐butyl‐p‐phenylenediamine (PDA) and N , N ‐diphenyl‐p‐phenylenediamine (DPD). According to literature reports, these antioxidants improve the biodiesel oxidative stability acting as chain‐breaking or hydroperoxide decomposers (Alberici et al, 2010; Buosi et al, 2016; Kleinberg et al, 2019; Maia et al, 2015; Nogales‐Delgado et al, 2020; Xin et al, 2008).…”