In other words, if auto manufacturers had to make some alterations to accommodate ethanol, so what? Take a look. Follow the hashtag FuelChat. Fuel Freedom is a non-profit with a simple mission: break America's oil addiction by bringing competition to the U. We'd like to hear from you. If you have any questions, ideas or feedback, please send all inquiries to: [email protected].
While weight loss mitigated in 10 M ethanol, corrosion rate was still much higher than in lower ethanol concentration solutions. Figure 3 shows the surface profiles of samples immersed in acid ferric chloride solution with series of ethanol contents for 24 h.
With the increase of ethanol concentrations from 0 to 5 M, the quantities of pits increased, and the surface area of the single pit changed little. For samples in 10 M ethanol, the surface of samples was densely covered with pits, and the areas of pits were much smaller, which was quite different from the pits pattern under 0 M ethanol to 5 M ethanol.
As shown in Figure 4 , the logarithm of the number of pits on the sample surface has a linear relationship with the concentration of ethanol. Such phenomenon can also be observed in methanolic solutions.
In methanolic solutions, the change in pit density could be attributed to the oxidation from methanol to formic acid Szklarska-Smialowska and Mankowski, However, similar mechanism cannot hold in ethanolic solution, since the oxidation from ethanol to acetic acid in acid medium takes place at 1. The mechanism of the effect of ethanol on the pits density will be discussed in section Discussion.
Figure 3. Pits pattern of the L samples after h immersion tests in 0. Figure 4. Effect of ethanol on number of pits initiated on the surface of L samples after immersion tests in 0. The breaking potential gradually decreased from to mV with the addition of ethanol. In methanolic solutions, the dissolution of metal matrix in pits slows down due to the lower diffusion coefficient of metal cations Ramgopal and Amancherla, Similar phenomenon occurred in the ethanolic solutions.
At the rear stage after pits break down, the climb of current density got stuck in the ethanolic solutions. In 10 M ethanol, the current density fell obviously during climbing, which shared the same climb behavior in multiple tests.
Figure 5. The derived corrosion potential E corr , breakdown potential E b and the average passive current density i pass values are listed in Table 3. E b decreased significantly while E corr and i pass changed slightly as the concentration of ethanol increased. It proved that the pitting resistance of L did deteriorate with no obvious change in passivation film. In addition, the dispersion of E b decreased with the increased ethanol content.
Table 3. Corrosion potential E corr , breakdown potential E b and average passive current density i pass of L stainless steel samples in solutions with different ethanol content.
The pits pattern on the surface of L samples after potentiodynamic polarization tests was similar to the pattern in immersion tests. As shown in Figure 6 , pits density increased as concentration of ethanol increased, but no exponential growth as in immersion tests occurred. Since the number of precursor sites on the surface of stainless steel is finite Chen et al. Figure 6. As shown in Figure 7 , panoramic optical micrographs of samples were taken and stitched after polarization tests.
Considering Figure 5 , the dissolution charge after broken in 0 M ethanol was contributed by the single pit on the surface, which developed rapidly and generated higher current density. In 10 M ethanol case, the dissolution charge was formed by the joint contribution of several pits. While most of the pits failed to grow up to the size of the main pits, several pits developed to scale, which suggested that single pit failed to generate sufficient current density, and instead, more pits were initiated at a higher overvoltage to climb to the specified current density.
Figure 7. No ultrasound treatment was conducted. As shown in Figure 8 , pits on the surface of L samples were limited to single. This confirms the previous assumption for first single stable pit at E b. It is noteworthy that the lacy cover occurred in 10 M ethanol.
Lacy cover is generally considered to be affected by the aggressiveness of the solution in the pits. Distribution of metal cations in hemispherical pits controlled the dissolution of matrix near the surface of samples in aqueous environment Ernst et al. In environment less aggressive, the inner surface of pits near matrix surface tends to oscillate between diffusion-control process and reaction-control process, and forms lacy cover.
Figure 8. The 3D plots in Figure 9 , shows that the edge of the pits on the surface of stainless steel owned a lower contrast in ethanolic solution where the dissolved surfaces were steeper. It reveals that the bottom of it. The ratio of width and depth of pits in different concentrations of ethanol was calculated and summarized in Figure Once ethanol was present, the depth of the pits would be significantly deeper than in non-ethanolic environment.
Figure 9. Figure Based on the experiment results above, the effect of ethanol on the pitting behavior of stainless steel was clear. In ethanolic solutions, the initiation of pitting was simplified, the development was suppressed, and the pits tended to be deeper. Since the development of stable pits is an electrochemical process controlled by metal cation diffusion Frankel et al.
However, the influence on pits initiation is not caused by the deterioration of the passivation film on the surface of L and the theory of alcohol electro-oxidation does not apply to ethanolic systems. Interpretations more suitable for this system need to be proposed. Ferrous ions are much less soluble in ethanol than in pure water Pound, In addition, pH of solution has changed at the same metal cation concentration as the ethanol content increased.
Ho et al. Based on those two works, schematic pH curves are illustrated as Figure 11 , where pH crit is the pH dissolves iron under a specified potential in the pourbaix diagrams for iron Beverskog and Puigdomenech, According to the schematic pH curves, schematic diagram of pitting initialization in ethanolic solutions and non-ethanolic solutions is described as Figure 12A.
The metastable pits start with the injection of chloride ions and come into a void Frankel et al. Since the performance of passive films changed slightly and ethanol does not affect the puncture behavior of chloride ions, the probabilities of this event are the same whether ethanol is introduced. Along with the expansion of the void, solutions inflow and contact the substrate and the difference of hydrolysis influences the result of pits initiation.
The medium in ethanolic solutions have stronger acidity while pH of the medium in non-ethanolic solution failed to dissolve the matrix and the pits annihilated. As a result, pits are more easily activated in ethanolic solutions. Therefore, during the immersion tests, more pitting occurred on the surface of stainless steel in the ethanolic environment. The schematic diagram of a pitting initialization, b pH distribution in pits, in ethanolic solutions and non-ethanolic solutions.
In addition, the synergy effect of metal cation solubility drop and hydrolysis enhancement is also ascribed to the morphology difference in ethanolic solutions. In stable pitting, a salt film forms on the inner surface of pits due to saturation of metal cations Frankel, According to the yellow curve in Figure 11 , the pH at the bottom of pits is higher in ethanolic solutions.
As shown in Figure 12B , the concentration of metal cations at the bottom of pits is lower in high ethanol content than in non-ethanolic solution, resulting in dissatisfaction of pH to pH crit near the surface. The effect of bioethanol addition on density and water content of gasohol. Pleyer , J. Corrosion and corrosion inhibition in an environment of ethanol — gasoline blends. Koroze a ochrana materialu , 63 3 , Energies , 12 20 , Atmosphere , 10 7 , Chemical Engineering Research and Design , , Sajdl , V.
In-situ electrochemical impedance measurements of corroding stainless steel in high subcritical and supercritical water. Giorgetti , E. Santos , J. Marcomini , V. Stress corrosion cracking and fatigue crack growth of an API 5L X70 welded joint in an ethanol environment. International Journal of Pressure Vessels and Piping , , On the characteristics and reactivity of soot particles from ethanol-gasoline and 2,5-dimethylfuran-gasoline blends.
Pair your accounts. Do not store in that little red container more than a month, especially not over the winter or summer months. If it is older than that, dump it into a car or truck that uses gas frequently where it will mix with the fresh gasoline. If possible, run any tank containing ethanol dry before putting any engine away for a season or more. There are some additives, such as Sta-Bil that promote safer long-term storage.
I don't know of any scientific studies to back up these claims but do believe them and use the products myself. Since , a Canadian Federal Renewable Fuel Regulation has required an annual volume-weighted average of 5 per cent renewable fuel ethanol in gasoline, excluding that sold into colder areas like the Yukon, Northwest Territories, Newfoundland and much of Quebec.
The Regulation applies to refiners and importers. There are similar regulations in place regarding gas stations in Ontario and all provinces to the west. None of the four Atlantic provinces have regulations in place requiring ethanol, so many of their storage facilities have not been set up to handle fuel containing ethanol. Here is where it gets tricky. Generally speaking, refineries will add ethanol to regular and a lesser amount to mid-grade gasoline to meet federal and provincial regulations.
Because these grades make up the bulk of sales, it is not necessary to add ethanol to premium grades to achieve the required average.
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