Research Of The Phosphate Detection Based On Ion-selective Electrode

Phosphorus is an indispensable element, but excessive phosphorus discharged into rivers and lakes will lead to water pollution, contributing to eutrophication. Phosphorus content determines the degree of eutrophication. Among the methods of phosphate detection, most of them need to add some chemical reagents, and this will cause secondary pollution to the environment. Compared with other methods, the ion-selective electrode has advantages of simple and rapid analysis, low cost, and high sensitivity, and what is more important is that there is no added chemical reagent in the process of detection, which will not pollute the environment. Therefore, ion-selective electrode is chosen to develop phosphate ion sensor in this paper. The main contents are listed as follows:(1) The phosphate ion-selective electrodes (ISEs) was developed based on poly (vinyl chloride) (PVC)membrane with Mg/Al layered double hydroxides,2-nitrophenyl octyl ether, and tridodecylmethylammonium chloride. The effects of several plasticizers and internal solution, composition ratio of electrode sensitive membrane on the electrode performance were discussed. The results showed that the electrode had a linear potential response in the concentration range of 10-1 to 10-4 mol/L, with a slope of -27.3mV/decade and a detection limit of 9.22×10-5mol/L.(2) A phosphate ion-selective electrode modified by polyaniline/cobalt oxide was studied, which is based on glassy carbon electrode as basal electrode and the cobalt ions doped polyaniline as sensitive film. The influence of polymerization time and the concentration of cobalt ions doped polyaniline on the electrode response was studied. The electrode had a linear potential response in the concentration range of 10-1 to 10-4mol/L, and a detection limit of 9.3×10-5mol/L. The electrode has a shorter response time, good stability and repeatability.(3) A double membrane phosphate ion-selective electrode was developed, with glassy carbon electrode as basal electrode, polyaniline doped cobalt ions as transducer layer, Poly (vinyl chloride) (PVC) as the basal membrane. The results showed that the slope was-32.3 mV/dec, and the detection limit of 7.65×10-5mol/L. The electrode had short response time, stability, high mechanical strength, and longer service life.