Using Adsorbents to Impact Oxidative Stability of Biodiesel and its Influence on Engine Oil Deterioration

This study presents the impact of adsorbents in augmenting the oxidative stability of biodiesel. Engine oil performance is affected by the use of biodiesel as it can accumulate in a vehicle’s sump and impact engine oil durability. Compared with conventional diesel fuel, biodiesel is less likely to evaporate out of engine oil due to its higher boiling range. Biodiesel therefore, accelerates the degradation of engine oil and this result in a short period of oil drain interval. Neat base oil, 80 % blended with biodiesel, 20 % were thermo oxidatively aged. The adsorbents Magnesium aluminum hydroxycarbonate and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene were used and the formation of oligomers in the base oil-RME mixture was monitored. The two adsorbents were used in ratio of 1: 2 respectively as stated above. Various amounts, 0.225 g, 0.45 g and 0.675 g of the combined adsorbent were added to 30 mL of the oil mixture and aged at 170 °C for 80 h. The total acid number, molecular mass distribution, viscosity, density and changes in molecular structure were monitored. The analysis with FTIR showed about 60 % less the formation of oligomers as compared to the samples aged without the adsorbents. About 90 % reduction in the total acid number was recorded. There was 50% reduction in viscosity increment. The adsorbents therefore, have an enhanced impact on the oxidative stability of biodiesel and its blends.