Ionic Liquid Antioxidant [X][C6H2(OH)3COO] of Biodiesel and Its Theory Antioxidant Mechanism

ABSTRACT

In this study, three ionic liquid antioxidants were synthesized using a one-step method from gallic acid (C₆H₇O₅) and choline, 1-methylimidazole (MI), and 1-ethylimidazole (EI). The antioxidant activity of ionic liquid antioxidants, corrosion, and oil solubility properties of Jatropha biodiesel were also studied. The results show that the three ionic liquid antioxidants improved the oxidation resistance of Jatropha biodiesel. In addition, 3‰ [MI] [C₆H₂(OH)₃COO] increased the induction period of Jatropha biodiesel by 238%. The solubility of three antioxidants decreases in the following order: [MI] [C₆H₂(OH)₃COO] > [EI] [C₆H₂(OH)₃COO] > [Ch] [C₆H₂(OH)₃COO] > C₆H₇O₅. The surface corrosion of copper sheet decreases in the following order: Jatropha Biodiesel > [Ch] [C₆H₂(OH)₃COO] + Jatropha Biodiesel > [EI] [C₆H₂(OH)₃COOC₆H₅COO] + Jatropha Biodiesel > [MI] [C₆H₅COO] + Jatropha Biodiesel. The infrared absorption spectra, NBO charge, and frontier orbital of three ionic liquids were calculated using density functional theory, B3LYP/6-311G(d,p). The antioxidant mechanism of three antioxidants was elucidated.

KEYWORDS:

• Biodiesel
• ionic liquid
• antioxidant activity
• quantum chemistry
• oxidation resistance

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [51766007];Natural Science Foundation of Yunnan Province [2015FB128,2018FB092];Research Fund from State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization of Kunming University of Science and Technology [CNMRCUTS1704];NSFC-Yunnan Joint Fund Project [U1602272].

Notes on contributors

Yu Chen

Yu Chen Kunming University of Science and Technology, School of Chemical Engineering, is committed to the theoretical study of chemical reaction kinetics; master's degree

Fashe Li

Fashe Li Kunming University of Science and Technology, School of Metallurgy and Energy Engineering, is committed to the research and development of biomass energy conversion; professor.

Meng Sui

Meng Sui Kunming University of Science and Technology, School of Metallurgy and Energy Engineering, is committed to the research and development of biomass energy conversion; master's degree.

Bican Wang

Bican Wang Kunming University of Science and Technology, School of Metallurgy and Energy Engineering, is committed to computational fluid dynamics research; master's degree.