The cyclic voltammograms for various molarities: C=0.03833, 0.07170 and 0.08954 mol/dm³ of FeCl₃ in the room temperature ionic liquid——BPBF₄ at GC working electrode referred to Al/Al³⁺ by different scan rates were measured over temperature range 293.15～343.15 K. Analysis of the voltammograms indicates that the Fe³⁺ reduction reaction is a reversible process with one transfer electron. According to Randles-Sevcik's equation, values of diffusion coefficient of Fe³⁺ for various concentrations at different temperatures were estimated. And in terms of Arrenius' equation, values of its diffusion activation energy for various concentrations of Fe³⁺ were obtained. As temperature increases, values of the diffusion coefficient also increase owing to the diminution of the BPBF₄ viscosity. However, as the FeCl₃ molarity increases, values of the diffusion coefficient diminish and the diffusion activation energy increases because of the solute-solvent interaction of FeCl₃ in BPBF₄.

Key words: room temperature ionic liquid, voltammogram, diffusion coefficient, diffusion activation energy, BPBF₄