Electrochemical Detection Of Total Phosphorus In Water Based On Cobalt-modified Graphene Electrodeetection

With the rapid socio-economic growth,scientific and technological progress and industrial development,the discharge of sewage from industry,agriculture and people’s daily life is gradually increasing,and the pollution problems of rivers and lakes are also increasing.Phosphorus is a nutrient that is indispensable in all kinds of natural water bodies.While phosphorus promotes the normal growth of aquatic organisms,excessive phosphorus in water bodies can cause eutrophication of rivers and lakes,plankton and freshwater algae blooms,decreased oxygen content in water,and water quality deterioration and turbidity,making it difficult for aquatic animals and aquatic plants to survive.Therefore,among the 9 indicators for environmental water quality monitoring,total phosphorus is one of the 4 most important indicators.Accurate detection and monitoring of total phosphorus is a prerequisite for the scientific management of total phosphorus in excess of the standard.On this premise,phosphorus-containing organisms in the water environment must be more strictly monitored,which poses a great challenge to existing detection methods.The most commonly used method for detecting total phosphorus is the GB11893-89 ammonium molybdate spectrophotometry,as well as many modified versions of this method,such as flow injection of ammonium molybdate spectrophotometry and microwave digestion-ammonium molybdate spectrophotometry.However,these methods are subject to digestion and spectrophotometric steps and are therefore limited by the location of the test site,making water quality testing in remote areas particularly difficult.These methods are also used in water quality monitoring stations in China,where the large number of water samples,cumbersome testing steps,and long duration are persistent problems that increase the workload of testing personnel.Therefore,it is of great practical significance to explore the possibility of online portable high-precision detection of total phosphorus,to significantly reduce the time and workload of continuous and batch detection of total phosphorus in water quality monitoring stations,to improve the detection range and stability,and to establish a new low-cost,rapid and highly sensitive total phosphorus detection method to improve the efficiency of existing water quality total phosphorus detection.In this paper,an electrochemical total phosphorus detection method based on a cobalt-modified graphene working electrode was developed to electrochemically oxidize the phosphorus in various valence states to orthophosphate by high oxygen removal,and then to quantitatively measure the total phosphorus in the water environment using electrochemical impedance spectroscopy（EIS）.The effects of p H,ionic strength,and digestion time on the detection efficiency were systematically investigated,and a linear calibration curve from 0.013 to 1.2 mg L^-1with a limit of detection（LOD）of 0.013 mg L^-1and a detection time of 9～11 minutes was obtained under optimal conditions with an accuracy of over 90%compared to the national standard method.Compared with the national standard method,the electrochemical total phosphorus detection method in this study exhibits a wider detection range and better stability,with fast detection speed,low cost and high sensitivity.Therefore,the electrochemical total phosphorus detection method in this paper has certain application value in the detection of total phosphorus in water.