Investigation on the electro-oxidation of iodide in the room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate at platinum electrode

The oxidation behavior of iodide has been investigated by linear sweep voltammetry and cyclic voltammetry at a platinum electrode in the room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]). The experimental results showed that iodide yielded two oxidation peaks Pa1 and Pa2 in [C4mim][BF4], and both of Pa1 and Pa2 are diffusion-controlled. Pa1 yielded from iodide to triiodide at +0.58 V is a two-electron oxidation wave, and Pa2 yielded from triiodide to iodine at +1.00 V is one-electron oxidation wave. Linear relationships between Ipa1 and the concentration of iodide can be established from 0.45 to 7.2 mmol L−1 with a detect limit of 0.3 mmol L−1 by linear sweep voltammetry, and from 0.30 to 7.8 mmol L−1 with a detect limit of 0.2 mmol L−1 by differential pulse voltammetry. These methods can be used for simple, rapid determination of iodide in the crude [C4mim][BF4].