A rapid method for determination of acid value in transformer oil by PPy modified electrode

Abstract

A polypyrrole-modified glassy carbon electrode (PPy/GC electrode) was prepared and its electrocatalytic behavior towards naphthoquinone in the presence of acid was characterized by linear sweep voltammetry (LSV). A well-defined new reduction peak appeared at a more positive potential than the original reduction peak. The new reduction peak current was linearly related to the acid value (AV) of oil. Based on it, a rapid electrochemical method for determining AV of transformer oil was developed using PPy/GC electrode. A working curve was obtained in the AV range of 0.01 to 0.40 mg(KOH)·g⁻¹, with a sensitivity of 39.42 μA_0.5/(mg(KOH)·g⁻¹) and the detection limit of 0.0014 mg(KOH)·g⁻¹ (signal-to-noise ratio is 3, standard deviation is 2.247%). Moreover, the proposed method has been successfully applied to AV determination of several transformer oil samples with advantages of rapidness, high sensitivity and accuracy compared to the conventional method.

Keywords

acid value / voltammetry / polypyrrole-modified electrode / transformer oil

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