Fabrication, calibration and evaluation of a phosphate ion-selective microelectrode

To conduct the micro-environment study of flocs in an enhanced biological phosphorus removal (EBPR) process, a phosphate ion-selective microelectrode was developed. The cobalt-based microelectrodes have tip diameters of 5–20 μm and respond to all the three forms of phosphate ions, namely, H2PO4−, HPO42−, and PO43−. The calibration curve at pH 7.5 had a slope of 31.5 mV per decade change of concentration and a R2 value of 0.99. Other characteristics of this microelectrode, such as response time, interferences from pH, ion strength, DO and other anions were also evaluated.