Pretreatment of Biodiesel by Esterification of Palmitic Acid in Brønsted–Lowry Acid Based Deep Eutectic Solvents

Abstract

Biodiesel was pretreated by the esterification of palmitic acid over Brønsted–Lowry acid-based deep eutectic solvents. The optimal deep eutectic solvent was synthesized from choline chloride and trichloroacetic acid (1:1), and the methanol to deep eutectic solvent ratio was 10% by mass. The reaction was optimized at a methanol/palmitic acid ratio of 50:1 at 80°C for 120 min. Under the optimized conditions, good calibration curves were obtained at phenolic acid concentrations ranging from 10.0 to 500.0 µg/mL. The recoveries ranged from 99.7% to 104.2%, and the interday and intraday relative standard deviations were less than 5%. The conversion rate was 94.6%, suggesting deep eutectic solvents will find applications in the preparation of biodiesel.

Keywords:

• Biodiesel
• Brønsted–Lowry acids
• Deep eutectic solvents
• Palmitic acid