Why is the Antimony Electrode of pH Meter Used in Oilfield Wastewater?
The poor reproducibility of pH measurement for oilfield wastewater using industrial pH meters has long been a tough problem. This paper summarizes and analyzes a large amount of research data. Using antimony electrodes to detect the pH value of wastewater is an effective solution. Conventional glass electrodes can hardly meet the measurement requirements under such working conditions, so metal antimony electrodes are selected. Why choose antimony electrodes? Why cannot glass electrodes be applied? The reasons are analyzed as follows.
I. Analysis of Ions in Oilfield Wastewater
Oilfield wastewater contains abundant calcium, potassium, sulfur and other ions, together with unknown suspended crude oil, well-washing water and other substances. These contaminants tend to foul electrodes, resulting in stringent requirements for wastewater measurement.
Reasons why glass electrodes cannot be used: ① Glass electrodes are vulnerable to oil fouling and scaling in alkaline solutions containing oil and substantial suspended solids, which impairs measurement accuracy. ② At high temperatures (above 50℃), their service life is only about one month. ③ The glass bulb at the tip of the glass electrode for ion exchange is merely 0.2 mm thick. It is fragile and easy to break. ④ Glass electrodes feature high internal impedance, which imposes strict requirements on signal connections. Slight contamination or condensation will immediately cause signal distortion. ⑤ Glass electrodes will crack when operated below 0℃.
