Influence of Fatty Acid Methyl Ester Composition, Acid Value, and Water Content on Metallic Copper Corrosion Caused by Biodiesel

Abstract

Oxidative stability parameters (OSP), acid value (AV), water content (W), and the metallic copper corrosion rate in biodiesels obtained from eight different vegetable oils were determined. Simple and multiple linear regression models were constructed to explain the influence of the OSP, AV and W variables on the corrosion rate. The corrosion rate was lower in biodiesel with less oxidative stability because, instead of reacting with copper, O 2 reacted preferentially with the unsaturated fatty acid methyl esters (FAME) that could act as "sacrificial molecules" to protect the copper against corrosion. Therefore, the corrosion rate was strongly related to the FAME composition. The AV was an important parameter in the corrosion process because free acids react with passivating agents, increasing the corrosion rate. The predictive capacity of W for corrosion rate was statistically insignificant, although water condensed on a copper surface causes corrosion.

Corrosion Induced on Aluminum by Biodiesel Components in Non-Oxygen Environments

“…No comparative values for these corrosion rates from pure MS, MO, or ML are available, but the effect of the unsaturation C=C on the corrosion rate in the mixtures is evident. Mass loss tests of biodiesel synthesized from several oils in the presence of oxygen have reported a similar tendency in corrosion rates [7,40,41]. Easily oxidizable biodiesel has many unsaturated molecules and is less corrosive.…”

“…mixtures is evident. Mass loss tests of biodiesel synthesized from several oils in the presence of oxygen have reported a similar tendency in corrosion rates [7,40,41]. Easily oxidizable biodiesel has many unsaturated molecules and is less corrosive.…”

Nordic cyanobacterial and algal lipids: Triacylglycerol accumulation, chemotaxonomy and bioindustrial potential

“…For example, high SFA content and a lack of PUFAs (i.e., a lower degree of unsaturation comparative to other strains) resulted in lower IV values. These properties generally indicate superior oxidative stability (Rocha Jr et al, 2019). However, allylic position equivalents (APE) and bis‐allylic position equivalents (BAPE) are better indicators of oxidative stability than IV (Knothe, 2002).…”

“…Allylic sites are where a methylene (CH 2 ) group is located adjacent to one double bond. They are highly susceptible to oxidation, but bis‐allylic sites are even more susceptible due to the location of the methylene group between two double bonds (Rocha Jr et al, 2019). Given the lack of PUFAs in the Synechococcus strains, predicted OS values of zero (Table 3) are surprising.…”

Enhancing Corrosion Resistance in Biodiesel Distribution and Terminal Operations: A Comprehensive Materials Compatibility Review

“…The authors highlighted that the choice of emulsifiers, fuel-water ratio, and other factors were crucial for ensuring the long-term sustainability and performance of equipment that came in contact with diesel emulsion fuels. Rocha et al (2019) investigated the impact of biodiesel properties on the corrosion of metallic copper. The study found that the composition of FAME in biodiesel, as well as the acid value and water content, could significantly influence the corrosion of copper.…”