Design And Key Technology Research Of On-line Monitoring Instrument Of Total Nitrogen Based On Wide Spectrum Of Microreagents

The indicators of total nitrogen means that nitrogen-containing compound existed as different forms chemically converted into nitrate,by oxidant under high temperature and high pressure,and total nitrogen value obtained by measurement.If total nitrogen content over the standard values too much,it would influent the water environment directly,and it is a very important indicator for judging water eutrophication.Referring to the water quality system pollution report of our country in previous years,water eutrophication caused by high total nitrogen levels has already affected sustainable development of society and the safety of people using water.So it is a vital of meaningful to achieving full-time on-line monitoring of total nitrogen parameters.At present,monitoring the total nitrogen there are mainly ways: continuous flow analytical method,using ion and chromatography to analyze method,using the gas phase molecular is aborted by spectrometry method,and then the way of monitoring the total nitrogen,the alkaline potassium persulfate digestion of water samples,and make use of ultraviolet spectrophotometry(GB11894-89),etc,counting GB11894-89 total nitrogen determination method in be used actually has the characteristics of good repeatability,high reliability,is commonly used by all the people,consist of abroad and our country,at present,meanwhile monitoring equipment on-line of water quality of total nitrogen equipment has a large range,poor stability,high reliability,low detection limit,detection cycle is long.Based on wide spectrum technology,combined with sequential injection method,and according to HJ/T102-203 Mechanical Necessities for Online Programmed Monitoring equipment for Total Nitrogen and GB1894 49 the way of detecting total nitrogrn,this paper designed a highly integrated online monitoring system for total nitrogen.On the basis of criterion authorizing by government for the monitoring total nitrogen,within the criterion of surface water and underground water,the testing process which conform to all the standards is planned,the quality of water of the total nitrogen in sequential injection as control reagent order into the basis of the method,using the quartz digestion tank designed by ourselves,which can withstand high temperature and pressure,to provide a guarantee for the full digestion of water samples,under the condition of continuous spectrum scanning solution,total nitrogen of water parameters is analyzed.The least square fitting method was used to establish the regression model for the purpose of total nitrogen,at the same time,to optimize the measurement procedure and the exposure system.Using the self-designed water quality total nitrogen monitor to make many experiments,and at the same time,using the method proclaimed by our government to make the same experiments,Comparing the results of two ways,and that attested the self-designed equipment possess better permanency,accuracy,reliability,in the meantime the time of the test cycle is shortened significantly.Analyzing a mass of empirical data got by tests,which made clear of that the total nitrogen recognition assortment of the equipment was 0-10 μg/m L,the minutest finding limit was 0.01μg/m L,the waste liquid discharge was less than 20 m L,the total nitrogen standard working curve fitting function coefficient was greater than or equal to 0.998,the determination of total nitrogen,the range of repetitive the relative standard RSD was0.16～0.88%,the fault of comparing the real water sample was less than 0.4%,the whole of the indicator correspond to the requirements of the total nitrogen water quality automatic monitor.The method of using wide spectrum technology combined with sequential injection technology to monitor total nitrogen for the quality of water,it is a vital of meaningful for strengthening the ability of online total nitrogen monitor,meanwhile it is also proper for real-time online monitoring the water,including surface water,underground-water and industrial wastewater,due to the development of science,it is not only systematic but also networked.