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Development Of Soil Nitrate Nitrogen Rapid Detection Equipment Based On Ion Selective Electrode

Posted on:2024-08-25Degree:MasterType:Thesis
Country:ChinaCandidate:H R WangFull Text:PDF
GTID:2531307121965259Subject:Mechanics
Abstract/Summary:PDF Full Text Request
Soil nitrate nitrogen is an important plant nutrient element and plays an important role in agricultural production.However,excessive nitrogen application can lead to the accumulation of nitrate nitrogen in the soil,which not only causes waste,but also has a negative impact on the environment.Therefore,rapid and accurate detection of soil nitrate nitrogen concentration is of great significance for scientific and reasonable fertilization.At present,commonly used soil nitrate nitrogen detection methods include chemical analysis,spectral analysis,etc.,which require a lot of time and effort and are difficult for on-site detection.The ion selective electrode is a sensor that can selectively detect specific ions,which has the advantages of fast detection speed,high accuracy,and easy operation.Therefore,the use of ion selective electrode to develop soil nitrate nitrogen rapid detection equipment has important application value.In this study,ion selective electrodes were used to detect nitrate nitrogen ions in soil,and a rapid detection equipment for nitrate nitrogen in soil was designed and manufactured.The device consists of an ion selective electrode,a microprocessor,a signal acquisition module,and a display module.The ion-selective electrode selectively adsorbs nitrate nitrogen ions,converts them into electrical signals,and feeds them into a microprocessor via a signal acquisition module.The microprocessor processes the collected signal and calculates the soil nitrate nitrogen concentration according to the relationship curve between the nitrate ion concentration and the electrical signal intensity established in advance.In turn,it provides a feasible solution for the rapid detection of soil nitrate nitrogen content and scientific and precise fertilization.The main research contents and conclusions of this paper are as follows:(1)The overall design of testing equipment and embedded hardware design have been completed.This design builds a rapid detection platform for soil nitrate nitrogen content based on ion selective electrode,and designs the overall structure of the equipment,which is mainly divided into external frame,leachate delivery module connected to the inlet pipeline,upper end cover for ion selective electrode and reference electrode fixing and control circuit board,motor and power supply arrangement,liquid cylinder for soil stirring,leaching and detection,and lower end cover for pressure sensor and waste liquid discharge and solenoid valve fixation.The hardware circuit design mainly includes the solid state3-selection electrode and reference electrode filled with saturated KCl solution as the signal acquisition circuit design of soil nitrate nitrogen front-end detection equipment,analysis of the function relationship between the response potential of the half-cell system and the concentration of NO3-and the amplification filter circuit that regulates the response potential,the design of the display control circuit,and the design of the power supply circuit.(2)A soil nitrate nitrogen concentration prediction model based on ion selective electrode was constructed.The detection platform for NO3-concentration is designed according to the working principle of the ion-selective electrode:the ion-selective permeability membrane only produces a specific response to the corresponding specific ion in solution.When there is a concentration difference between the analytical ions in the sample solution and the analytical ions in the reference solution of the filled solution,ion exchange occurs at the interface of the ion-sensitive membrane sample solution and the interface of the ion-sensitive membrane-filled solution,thereby forming a membrane potential.The membrane potential is the response potential of the two-electrode system,and the3-concentration prediction model based on the ion-selective electrode is constructed for the correspondence between the response potential and the membrane potential,and its R2 is 0.9807.Combined with the weight information of the prediction model and the pressure sensor,the formula for calculating the concentration of soil nitrate nitrogen based on ion selective electrode can be obtained.(3)The soil pretreatment parameter standard was determined and the control software design of the testing equipment was completed.The optimal soil leaching treatment process of soil nitrate nitrogen rapid detection equipment based on ion selection electrode is to use tap water as the soil leaching agent,take the soil sample and extract according to the soil liquid ratio around 1:5,detect the supernatant obtained after standing stratification of the suspension after stirring treatment,and read the data 30s after the electrode starts detection.The designed equipment software process is that the weigh module measures and converts the weight signal after adding soil sample and leachate into an electrical signal,the analog-to-digital conversion chip converts it into a digital signal,and the ion selective electrode generates a response voltage signal according to the NO3-concentration,and transmits the two signals to the operation control module.The operation control module transmits the calculated data to the core processor module through the serial port,and the core processing module calls the ion concentration prediction model and the corresponding calculation formula of soil content to calculate the nitrate nitrogen content in the soil sample to be measured,and feeds it back to the user through the display screen of the human-computer interaction module.(4)The construction and performance verification of soil nitrate nitrogen rapid detection equipment were completed.The whole equipment is mainly composed of a two-electrode system composed of ion selective electrode and reference electrode,detection data acquisition system,soil leaching system,data processing calculation system and interactive display system.Through the actual detection of soil with different nitrate nitrogen content in the field,and the detection results were verified with the national standard method,the consistency between the measurement results and the national standard method was very good,and the measured values of both were within the 95%consistency interval.KCl crystalline powder and Mg SO4 crystalline powder were added to the KNO3 solution at a determined concentration to detect the influence of interfering ions on the detection stability of the device.Through the equipment test results,it can be seen that within the scope of soil nitrate nitrogen content detection applicable to the equipment,the interference ions are far from the extent that affects the detection accuracy of the equipment,and the soil nitrate nitrogen rapid detection equipment based on ion selection electrode fully meets the accuracy and stability requirements of the equipment application.Therefore,the soil nitrate nitrogen rapid detection equipment based on ion selective electrode developed in this design has the advantages of low cost,high detection accuracy and fast detection speed,and has important application value for the development of precision agriculture and formula fertilization technology,as well as in improving fertilizer utilization rate and reducing fertilizer pollution.
Keywords/Search Tags:Ion selective electrode, Soil nitrate nitrogen, Precise fertilization, Real-time detection
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