Phosphate ion sensor using a cobalt phosphate coated cobalt electrode

• Published in: Electrochimica acta Vol. 282; pp. 242 - 246
• Main Authors: Xu, Kebin, Kitazumi, Yuki, Kano, Kenji, Shirai, Osamu
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 20.08.2018; Elsevier BV
• Subjects: Chromatography; Coated electrodes; Cobalt; Dihydrogenphosphate; Electrochemical sensor; Electrodeposition; Electrodes; Hydroponics; Ion selective electrode; Phosphates; Sensors; Wastewater treatment; Water treatment; Ion selective electrode; Electrodeposition; Electrochemical sensor; Cobalt; Dihydrogenphosphate
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2018.06.021

Phosphorous is one of three major nutritional elements for plants and usually exists as phosphate ions in nature. For hydroponic culturing and wastewater treatment, the development of a high-performance phosphate sensor would be very helpful. A novel phosphate ion-selective electrode was constructed using a cobalt phosphate surface coated cobalt electrode. The potential response seems to be caused by the formation of Co(H2PO4)2 in the coexistence of CoO and Co(OH)2. The sensor exhibited a linear response to H2PO4− in the concentration range from 1.0 × 10−5 to 1.0 × 10−1 mol L−1 at a pH range from 4.0 to 6.5 with a slope of −39 mV dec−1. The sensor was unaffected by common anions, such as chloride, carbonate, and sulfate. The electrode maintained stability for at least 4 weeks in a live hydroponics system when sufficient Co3(PO4)2·8H2O was deposited on the Co electrode. A phosphate ion selective electrode coated with cobalt phosphate hydrate was produced. This electrode responds to the activity of H2PO4−, and it exhibited a linear response to H2PO4− in the concentration range from 1.0 × 10−5 to 1.0 × 10−1 mol dm‒3 at a pH range from 4 to 7 with a slope of −39 mV dec−1. [Display omitted]