Current location: JICS Archive > Vol. 4 > No. 2 > Articles : 7

Electrochemical Characterization and Application of Ni RuO₂ as a pH Sensor for Determination of Petroleum Oil Acid Number

R. Karimi Shervedani*, H.R. Zare Mehrdjardi and S.H. Kazemi Ghahfarokhi

of Chemistry, University of Isfahan, Isfahan 81746 73441, I.R. Iran

Electrochemical characterization and application of nickel ruthenium dioxide (Ni-RuO₂) as a pH sensor for the determination of petroleum oil acid number is described. The sensor consists of RuCl₃ thermally decomposed onto the upper side of a polycrystalline nickel electrode at 400 °C in an open furnace. The advantages of the sensor are: (i) easy preparation, (ii) fast response in a large pH range, (iii) high physical and chemical stability, and (iv) excellent reproducibility as determined by the reproducible linear variation of charge transfer resistance (R_ct) as a function of overpotential (h) obtained by electrochemical impedance spectroscopy (EIS), and the Nernstian slope of the electrode potential in a wide range of pH (1.5-12.5) obtained by potentiometric measurements. The potentiometric selectivity coefficients of the sensor toward some anions and cations were evaluated in aqueous solution. The characterized Ni-RuO₂ pH sensor was successfully tested for the determination of petroleum oil acid number.

Keywords: pH sensor, Ni-RuO₂, Acid number, Ruthenium dioxide, Petroleum oil