SALICYLATES AS INHIBITORS OF THE OXIDATIVE PROCESS MEDIATED BY COPPER AND IRON IN BIODIESEL B100

Biodiesel is a renewable fuel produced from vegetable oils and animal fats transesterification. However, due to its chemical characteristics, it is susceptible to oxidation causing losses to its manufacturers and users. In this work a series of salicylates were synthesized and employed as secondary antioxidants in biodiesel B100. The accelerated oxidation tests were carried out against copper and iron. The biodiesel oxidation degree was followed by the acidity index. Among the synthesized compounds, isopropyl salicylate was able to inhibit the oxidation process by 55% when induced by copper and 52% when it was induced by iron after 8 hours exposure. The commercial antioxidant TBHQ was used as a positive control presenting lower inhibition values than isopropyl salicylate. It should be noted that salicylates are accessible molecules in just one reaction step, high yields and low cost, these being desirable characteristics for the biodiesel industry.