PH MEASURING INSTRUMENT FOR HIGH-TEMPERATURE HIGH-PRESSURE AQUEOUS SOLUTION

摘要

PURPOSE:To calculate Efb of a metal oxide in a sample and to measure pH by previously forming an Efb-pH calibration curve by utilizing the phenomenon that the flat band potential difference Efb of the metal oxide having semiconductor-like properties changes linearly at a prescribed ratio with the pH and absolute temp. T(K) of a soln. CONSTITUTION:A measuring part attached together with a TiO2 sensing electrode 1, a Pt counter electrode 3, and a reference electrode 2 to a holder 4 is immersed into a high-temp. high-pressure oil well. An arithmetic unit 8 measures 1/CS2 for the capacity CS of impedance from the impedance and current voltage phase difference measured by an AC generator 8 and a potentiometer 7 at specified intervals from the initial period to the final potential difference and sends the same to a memory 10. Said unit makes linear regression with 1/CS2 as the linear function of the potential difference E-Efb and calculates Efb from the potential difference intercept of the straight line. The pH and Efb pair is stored 10 at the time of forming the calibration curve. The pH is calculated by substituting the calibration curve with the measured Efb at the time of measurement. One of pH, Efb and T is displayed in a window 11.