CN110907520B - Device for detecting ion concentration in soil leaching solution and using method thereof - Google Patents
Device for detecting ion concentration in soil leaching solution and using method thereof Download PDFInfo
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Abstract
The invention relates to the field of electrochemical detection, and provides a device for detecting the concentration of ions in soil leachate and a using method thereof. The device comprises a controller, a vacuum pump, a sampling bottle, a detection cavity, a liquid distribution cavity, a deionized water liquid storage tank and an ionized water liquid storage tank; the sampling bottle is communicated with the detection cavity through a first valve, a plurality of seepage holes are formed in the wall surface of the sampling bottle, and the sampling bottle is buried in soil; the ionic water liquid storage tank and the deionized water liquid storage tank are respectively communicated with the liquid preparation cavity through a second valve and a third valve, and the liquid preparation cavity is communicated with the detection cavity through a fourth valve; the detection cavity is communicated with the vacuum pump, the bottom of the detection cavity is provided with a liquid discharge port which can be opened and closed, the detection cavity is internally provided with an ion selective electrode and a reference electrode, and the ion selective electrode, the reference electrode and the vacuum pump are respectively and electrically connected with the controller. The invention does not need any pretreatment operation on the soil sample, obviously simplifies the operation process, greatly reduces the labor intensity of experimenters and improves the experimental efficiency.
Description
Technical Field
The invention relates to the technical field of electrochemical detection, in particular to a device for detecting the concentration of ions in soil leachate and a using method thereof.
Background
At present, three major problems of grain safety, resource consumption and environmental protection exist in China, and particularly the problems of land impoverishment, underground water pollution and the like caused by excessive fertilization exist. Taking a nitrogen fertilizer as an example, the nitrogen fertilizer is the fertilizer with the largest application amount in agricultural production in China, the fertilizer consumption per mu of crops in China is 21.9 kilograms, and the average level in the world is only 8 kilograms per mu, which is 2.6 times of that in the United states and 2.5 times of that in European Union. However, excessive use of chemical fertilizers not only pollutes the soil, but also causes soil hardening and influences the growth of crops.
The main component of the nitrogen fertilizer is nitrate nitrogen, and the dosage of the nitrogen fertilizer per mu can be obtained by detecting the concentration of nitrate ions in soil, so that the improvement of the detection level of the nitrate ions has a vital effect on the improvement of the use efficiency of the nitrogen fertilizer. However, the conventional nitrate ion concentration detection apparatus is large in size and difficult to move freely, and therefore, the detection process can be performed only in a laboratory. In addition, the whole experiment process is very complex, and a plurality of pretreatment operations are required to be carried out on the soil sample before detection, so that the labor intensity of experimenters is greatly increased.
Disclosure of Invention
The invention aims to provide a device for detecting the concentration of ions in soil leaching solution, which is simple in structure and convenient and fast to operate, and a using method thereof.
In order to achieve the aim, the invention provides a device for detecting the concentration of ions in soil leachate, which comprises a controller, a vacuum pump, a sampling bottle, a detection cavity, a liquid distribution cavity, and a deionized water liquid storage tank and an ionized water liquid storage tank which are arranged above the liquid distribution cavity; the sampling bottle is communicated with the detection cavity through a first valve, a plurality of seepage holes are formed in the wall surface of the sampling bottle, and the sampling bottle is buried in soil to provide soil leachate for the detection cavity; the ionic water liquid storage tank and the deionized water liquid storage tank are respectively communicated with the liquid preparation cavity through a second valve and a third valve, and the liquid preparation cavity is communicated with the detection cavity through a fourth valve and used for providing a standard solution formed by mixing ionic water and deionized water for the detection cavity; the detection cavity is communicated with the vacuum pump, the bottom of the detection cavity is provided with an openable liquid discharge port, the detection cavity is internally provided with an ion selective electrode and a reference electrode, and the ion selective electrode, the reference electrode and the vacuum pump are respectively electrically connected with the controller.
The vacuum sampling device comprises a vacuum pump, a detection cavity, a sampling bottle, a three-way joint, a sampling bottle, a liquid distribution cavity, a vacuum pump, a sampling bottle, a sampling tube, a liquid inlet pipe, a liquid outlet pipe, a liquid inlet pipe; the first liquid inlet pipe and the second liquid inlet pipe are respectively provided with the first valve and the fourth valve, and the inner diameters of the first liquid inlet pipe and the second liquid inlet pipe are smaller than the inner diameter of the main pipeline.
The liquid mixing device is characterized by further comprising a stirring rod and a driving motor, wherein the bottom end of the stirring rod is inserted into the liquid mixing cavity, and the top end of the stirring rod is electrically connected with the driving motor.
Wherein the ion-selective electrode is any one of a nitrate ion-selective electrode, an ammonium ion-selective electrode, a potassium ion-selective electrode, and a calcium ion-selective electrode.
The controller comprises an ion meter and a vacuum pump control module, the ion selection electrode and the reference electrode are respectively electrically connected with the ion meter, and the vacuum pump is electrically connected with the vacuum pump control module.
The ion selective electrode and the reference electrode are arranged in the upper cavity; the upper surface of the diaphragm plate is provided with two grooves sunken downwards, the bottom ends of the ion selective electrode and the reference electrode are respectively suspended in the two grooves, the bottom of each groove is communicated with the lower cavity through a fifth valve, and the bottom of the lower cavity is provided with the liquid discharge port.
The middle part of the upper surface of the diaphragm is provided with a liquid storage tank which is sunken downwards, and the two grooves are respectively arranged at two ends of the bottom surface of the liquid storage tank.
The first valve, the second valve, the third valve, the fourth valve and the fifth valve are all electromagnetic valves, and each electromagnetic valve is electrically connected with the controller.
In order to achieve the above object, the present invention further provides a method for using the device for detecting ion concentration in soil leachate, which comprises the following steps:
s1, filling deionized water with the concentration of a and ionized water with the concentration of b into a deionized water liquid storage tank and an ionized water liquid storage tank in advance respectively, and embedding a sampling bottle in a pre-dug soil pit;
s2, opening the second valve and the third valve until the concentration of the standard solution in the liquid preparation cavity reaches x, wherein a < x < b;
s3, starting a vacuum pump until the vacuum degree of the liquid distribution cavity reaches a specified value;
s4, opening a fourth valve;
s5, the controller acquires and stores the calibration electromotive force signals generated by the ion selection electrode and the reference electrode;
s6, after the time T1 elapses, the liquid discharging port and the third valve are opened;
s7, after the time T2 elapses, the liquid discharge port, the third valve and the fourth valve are closed;
s8, repeating the steps S2-S7N times, and replacing x in the step S2, wherein N > 2;
s9, drawing a calibration curve by the controller according to the acquired N +1 calibration electromotive force signals;
s10, starting a vacuum pump until the vacuum degree of the liquid distribution cavity reaches a specified value;
s11, opening the first valve;
s12, after the time T3 elapses, the controller obtains the sample electromotive force signals generated by the ion selection electrode and the reference electrode, and calculates the corresponding ion concentration in the soil solution according to the Nernst formula, the sample electromotive force signals and the calibration curve;
s13, after a time T4 elapses, the first valve is closed, the fourth valve, the drain port, and the third valve are opened, and the step S7 is repeatedly performed.
Wherein before executing the step S1, the method further comprises the following steps:
and S0, paving the quartz sand in the pre-dug soil pit.
The invention has simple structure and convenient operation, and can provide standard solutions with different concentrations for the detection cavity by controlling the opening time of the second valve and the third valve, so that the controller can draw a calibration curve according to the calibration electromotive force signals generated when the ion selective electrode and the reference electrode are immersed in the standard solutions with different concentrations, and further, when the vacuum pump pumps the leaching solution of the soil to be detected into the detection cavity, the controller can calculate the concentration of the specified ions according to the sample electromotive force signals generated by the ion selective electrode and the reference electrode, the Nernst formula and the calibration curve. Therefore, the method does not need any pretreatment operation on the soil sample, thereby obviously simplifying the operation process, greatly reducing the labor intensity of experimenters and improving the experimental efficiency.
Drawings
FIG. 1 is a schematic view showing the structure of an apparatus for detecting the concentration of ions in a soil leachate according to example 1 of the present invention;
FIG. 2 is a schematic view of the structure of a detection chamber in embodiment 1 of the present invention;
FIG. 3 is a schematic structural view of a liquid-dispensing chamber in embodiment 1 of the present invention.
Reference numerals:
1. a detection chamber; 1-1, ion selective electrode; 1-2, a reference electrode; 1-3, a liquid outlet;
1-4, a diaphragm plate; 1-5, a fifth valve; 1-6, T-shaped bracket; 1-7, a wiring piece;
2. a liquid preparation cavity; 2-1, stirring rods; 3. sampling a bottle; 4. an ionic water reservoir;
5. a deionized water storage tank; 6. a first valve; 7. a second valve;
8. a third valve; 9. a fourth valve; 10. a vacuum pump; 11-1, an ion meter;
11-2, a vacuum pump control module; 12. a main pipeline; 13. a first liquid inlet pipe;
14. a second liquid inlet pipe;
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, unless otherwise specified, the terms "upper", "lower", "top", "bottom", and the like, as used herein, refer to an orientation or positional relationship based on that shown in the drawings, which is for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the system or element being referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, should not be construed as limiting the present invention.
It is to be understood that, unless otherwise expressly stated or limited, the term "coupled" is used in a generic sense as defined herein, e.g., fixedly attached or removably attached or integrally attached; may be directly connected or indirectly connected through an intermediate. Specific meanings of the terms in the invention can be understood in specific cases by those skilled in the art.
Example 1
As shown in fig. 1 to 3, the present invention provides an apparatus for detecting ion concentration in soil leachate, which comprises a controller, a vacuum pump 10, a sampling bottle 3, a detection chamber 1, a solution preparation chamber 2, and a deionized water storage tank 5 and an ionized water storage tank 4 disposed above the solution preparation chamber 2; the sampling bottle 3 is communicated with the detection cavity 1 through a first valve 6, a plurality of liquid seepage holes are formed in the wall surface of the sampling bottle 3, and the sampling bottle 3 is buried in soil to provide soil leachate for the detection cavity 1; the ionized water liquid storage tank 4 and the deionized water liquid storage tank 5 are respectively communicated with the liquid preparation cavity 2 through a second valve 7 and a third valve 8, and the liquid preparation cavity 2 is communicated with the detection cavity 1 through a fourth valve 9 and is used for providing a standard solution formed by mixing ionized water and deionized water for the detection cavity 1; the detection cavity 1 is communicated with a vacuum pump 10, the bottom of the detection cavity 1 is provided with an openable liquid outlet 1-3, the detection cavity 1 is internally provided with an ion selection electrode 1-1 and a reference electrode 1-2, and the ion selection electrode 1-1, the reference electrode 1-2 and the vacuum pump 10 are respectively and electrically connected with a controller. The ion-selective electrode 1-1 may be any one of a nitrate ion-selective electrode, an ammonium ion-selective electrode, a potassium ion-selective electrode, and a calcium ion-selective electrode. For example, when it is desired to detect the concentration of nitrate ions in soil, a nitrate ion selective electrode may be used. The sensitive film material of the nitrate ion selective electrode can be polypyrrole, and meanwhile, the base electrode of the nitrate ion selective electrode can be a glassy carbon electrode with the length of 7 cm.
The following description will be made of a method of using the apparatus for detecting the concentration of nitrate ions in soil, by way of example:
during the experiment: firstly, embedding a sampling bottle 3 in soil to be detected, and respectively filling water and a sodium nitrate solution with the concentration of 1mol/L into a deionized water liquid storage tank 5 and an ionic water liquid storage tank 4;
next, a calibration curve is obtained: first step, preparation of a concentration of 10-7Specifically, the second valve 7 and the third valve 8 are opened, the sodium nitrate solution and the water in the ionized water liquid storage tank 4 and the deionized water liquid storage tank 5 automatically flow into the liquid preparation chamber 2 under the action of gravity, and when the concentration of the diluted sodium nitrate solution formed by mixing the sodium nitrate solution and the water, namely the concentration of the standard solution reaches a specified value, the second valve 7 and the third valve 8 are closed; it should be noted that the respective opening times of the second valve 7 and the third valve 8 are related to the concentration of the standard solution to be prepared, that is, the opening times of the second valve 7 and the third valve 8 may be the same or different. Step two, the standard solution in the liquid preparation cavity 2 is pumped into the detection cavity 1 for detection, specifically: (1) starting the vacuum pump 10, and closing the vacuum pump 10 when the vacuum degree in the detection cavity 1 reaches-85 to-75 mbar; (2) and the fourth valve 9 is opened, and the liquid preparation cavity 2 is communicated with the detection cavity 1 through the fourth valve 9, so that the standard solution in the liquid preparation cavity 2 can be sucked into the detection cavity 1 under the action of pressure difference when the fourth valve 9 is opened. Since the potential of the reference electrode 1-2 is a constant value and is not affected by the composition of the standard solution, but the potential of the nitrate ion selective electrode is affected by the composition of the standard solution, that is, the potential of the nitrate ion selective electrode is affected by the concentration of nitrate ions, the magnitude of the electromotive force of the galvanic cell formed by the nitrate ion selective electrode and the reference electrode 1-2 is related to the concentration of nitrate ions. When the standard solution passes through the bottoms of the nitrate ion selective electrode and the reference electrode 1-2, the primary battery formed by the nitrate ion selective electrode and the reference electrode 1-2 generates electromotive force, and the controller can store the electromotive force signals generated by the nitrate ion selective electrode and the reference electrode 1-2 as calibration electromotive force signals. Step three, cleaning the detection cavity 1, specifically, opening a liquid discharge port 1-3 and a third valve 8 after 60-90 seconds; at this time, the fourth valve 9 is still open, and the water in the deionized water reservoir 5 is directly pumped into the detection chamber 1 after flowing into the dispensing chamber 2. Since the liquid discharge port 1-3 at the bottom of the detection chamber 1 is in an open state, waste liquid is generated by washingCan be directly discharged out of the detection cavity 1 through the liquid discharge ports 1-3. And step four, after 30 seconds, closing the liquid discharge ports 1-3, the third valve 8 and the fourth valve 9. Step five, continuously preparing according to the steps from the step one to the step four in sequence and detecting the concentration to be 10-6mol/L、10-5mol/L、10-4mol/L、10-3mol/L、10-2mol/L、10-1mol/L standard solution. And sixthly, drawing a calibration curve by the controller according to the obtained 7 calibration electromotive force signals.
And then, acquiring the concentration of nitrate ions in the soil to be detected, specifically: the method comprises the following steps that firstly, a vacuum pump 10 is started, and when the vacuum degree in a detection cavity 1 reaches-85-, -75mbar, the vacuum pump 10 is closed; secondly, opening a first valve 6; because the wall surface of the sampling bottle 3 is provided with a plurality of liquid seepage holes, and the detection cavity 1 is communicated with the sampling bottle 3 through the first valve 6, when the first valve 6 is opened, the soil leachate to be detected can be sucked into the detection cavity 1 under the action of pressure difference. When the soil leachate to be measured is submerged at the bottoms of the nitrate ion selective electrode and the reference electrode 1-2, an original battery formed by the nitrate ion selective electrode and the reference electrode 1-2 generates electromotive force, and the controller can calculate the concentration of nitrate ions in the soil solution according to electromotive force signals generated by the nitrate ion selective electrode and the reference electrode 1-2, namely sample electromotive force signals, an Nernst formula and a calibration curve.
Finally, cleaning the detection cavity 1, specifically, closing the first valve 6, and opening the liquid discharge port 1-3, the third valve 8 and the fourth valve 9 after 60-90 seconds; thus, the water in the deionized water reservoir 5 is drawn into the detection chamber 1 directly after flowing into the dispensing chamber 2. Since the liquid discharge port 1-3 at the bottom of the detection chamber 1 is in an open state, waste liquid generated by washing can be directly discharged out of the detection chamber 1 through the liquid discharge port 1-3.
Therefore, the device is simple in structure and convenient to operate, standard solutions with different concentrations can be provided for the detection cavity 1 by controlling the opening time of the second valve 7 and the third valve 8, so that the controller can draw a calibration curve according to the calibration electromotive force signals generated when the ion selective electrode 1-1 and the reference electrode 1-2 are immersed in the standard solutions with different concentrations, and further, when the vacuum pump 10 pumps the leaching solution of the soil to be detected into the detection cavity 1, the controller can calculate the concentration of the specified ions according to the sample electromotive force signals generated by the ion selective electrode 1-1 and the reference electrode 1-2, the Nernst formula and the calibration curve. Therefore, the device does not need to carry out any pretreatment operation on the soil sample, so that the operation flow is obviously simplified, the labor intensity of experimenters is greatly reduced, and the experiment efficiency is improved.
Preferably, the device also comprises a three-way joint, wherein a first port of the three-way joint is respectively communicated with the detection cavity 1 and the vacuum pump 10 through a main pipeline 12, a second port of the three-way joint is communicated with the sampling bottle 3 through a first liquid inlet pipe 13, and a third port of the three-way joint is communicated with the liquid distribution cavity 2 through a second liquid inlet pipe 14; the first liquid inlet pipe 13 and the second liquid inlet pipe 14 are respectively provided with a first valve 6 and a fourth valve 9, and the inner diameters of the first liquid inlet pipe 13 and the second liquid inlet pipe 14 are smaller than the inner diameter of the main pipe 12. The advantages of such an arrangement are: on one hand, the pipeline is simplified and the installation is convenient; on the other hand, since the inner diameters of the first liquid inlet pipe 13 and the second liquid inlet pipe 14 are smaller than the inner diameter of the main pipe 12, when the first valve 6 or the fourth valve 9 is opened, the capillary phenomenon occurring in the sampling bottle 3 or the liquid distribution cavity 2 can assist the vacuum pump 10 to pump the liquid in the sampling bottle into the detection cavity 1.
Preferably, in order to enable the deionized water and the ionized water to be uniformly mixed in the liquid preparation cavity 2, the device further comprises a stirring rod 2-1 and a driving motor, wherein the bottom end of the stirring rod 2-1 is inserted in the liquid preparation cavity 2, and the top end of the stirring rod is electrically connected with the driving motor. More preferably, the bottom end of the stirring rod 2-1 is spiral-shaped. It should be noted that the stirring rod 2-1 can be manually operated, besides being directly driven by the driving motor. In addition, the time for each stirring in the experiment cannot be less than 30 seconds.
Preferably, the controller includes an ion meter 11-1 and a vacuum pump control module 11-2, the ion selective electrode 1-1 and the reference electrode 1-2 are electrically connected to the ion meter 11-1, respectively, and the vacuum pump 10 is electrically connected to the vacuum pump control module 11-2.
More preferably, the top of the detection cavity 1 is provided with a wiring hole, and wiring pieces 1-7 are inserted into the wiring hole; the wiring pieces 1-7 comprise wiring tubes and wiring covers which are respectively arranged at the inner side and the outer side of the detection cavity 1, external threads are arranged on the outer wall of the top end of each wiring tube, internal threads which are matched and connected with the external threads are arranged on the inner wall of each wiring cover, and an electric connecting column is arranged at the top of each wiring cover; the top end of the wiring tube passes through the wiring hole to be matched with the wiring cover in a threaded manner, the ion selection electrode 1-1 and the reference electrode 1-2 are electrically connected with the ion meter 11-1 through an electric wiring column, namely, a lead connected to the bottom end of the electric wiring column passes through the wiring tube and then is electrically connected with the ion selection electrode 1-1 and the reference electrode 1-2, and the lead connected to the top end of the electric wiring column is directly electrically connected with the ion meter 11-1. In addition, considering that the lead wire connecting the ion meter 11-1 and the electric terminal is exposed to the outside and is easily damaged, the lead wire is also sleeved with a hose.
Furthermore, a T-shaped support 1-6 for suspending the ion selective electrode 1-1 and the reference electrode 1-2 is arranged in the detection cavity 1, one end of the T-shaped support 1-6 is fixed on the side wall of the junction tube, two jacks are formed in the other end of the T-shaped support 1-6, and the ion selective electrode 1-1 and the reference electrode 1-2 are respectively fixed in the corresponding jacks through rubber rings.
Preferably, in view of the fact that it takes a lot of time to collect the soil leachate, in order to improve the experimental efficiency and reduce the amount of the soil leachate required for the detection, a transverse partition plate 1-4 for dividing the detection chamber 1 into an upper chamber and a lower chamber is provided in the detection chamber 1, and the ion selective electrode 1-1 and the reference electrode 1-2 are both provided in the upper chamber; the upper surface of the diaphragm plate 1-4 is provided with two grooves which are sunken downwards, the bottom ends of the ion selective electrode 1-1 and the reference electrode 1-2 are respectively suspended in the two grooves, the bottom of each groove is communicated with the lower cavity through a fifth valve 1-5, and the bottom of the lower cavity is provided with a liquid discharge port 1-3. Therefore, during the experiment, the soil leaching liquid provided by the sampling bottle 3 to the detection cavity 1 only needs to overflow two grooves, that is, the volume of the soil leaching liquid provided by the sampling bottle 3 to the detection cavity 1 is slightly larger than the volume of the two grooves. Similarly, the volume of the standard solution provided by the solution preparation chamber 2 to the detection chamber 1 only needs to be slightly larger than the volume of the two grooves. Therefore, the arrangement reduces the using amount of the soil leachate, obviously reduces the collecting time of the soil leachate, reduces the using amount of the standard solution and reduces the volumes of the deionized water liquid storage tank 5 and the ionized water liquid storage tank 4.
More preferably, in order to further reduce the amount of the soil leachate, a sump is formed in the middle of the upper surface of the diaphragms 1 to 4 to be depressed downward, and two grooves are formed at both ends of the bottom of the sump, respectively. Therefore, during the experiment, the volume of the soil leaching liquid provided by the sampling bottle 3 to the detection cavity 1 only needs to be equal to the sum of the volumes of the liquid storage tank and the two grooves. Similarly, the volume of the standard solution provided by the solution preparation chamber 2 to the detection chamber 1 only needs to be equal to the sum of the volumes of the liquid storage tank and the two grooves.
In addition, for the convenience of automatic control, the first valve 6, the second valve 7, the third valve 8, the fourth valve 9 and the fifth valves 1 to 5 are all electromagnetic valves, and each electromagnetic valve is electrically connected with the controller.
Example 2
The invention also provides a using method of the device for detecting the ion concentration in the soil leaching solution, which comprises the following steps:
and S0, paving the quartz sand in the pre-dug soil pit. For example, quartz sand having a particle size of 2um can be uniformly spread over a radius of 2cm from the sampling bottle 3 as a center.
S1, filling deionized water with the concentration of a and ionized water with the concentration of b into the deionized water liquid storage tank 5 and the ionized water liquid storage tank 4 in advance respectively, and embedding the sampling bottle 3 in a pre-dug soil pit; for example, when the nitrate ion concentration is to be detected, water and a sodium nitrate solution having a concentration of 1mol/L may be filled in advance in the deionized water liquid storage tank 5 and the ionic water liquid storage tank 4, respectively.
S2, opening the second valve 7 and the third valve 8 until the concentration of the standard solution in the liquid preparation cavity 2 reaches x, wherein, a<x<b; when the second valve 7 and the third valve 8 are opened, the sodium nitrate solution and the water in the ionized water tank 4 and the deionized water tank 5 automatically flow into the solution preparing chamber 2 under the action of gravity, and when the concentration of the low-concentration sodium nitrate solution formed by mixing the sodium nitrate solution and the water, namely the concentration of the standard solution reaches 10-7mol/L, i.e. x is equal to 10-7At mol/L, the second valve 7 and the third valve 8 are closed.
S3, starting the vacuum pump 10 until the vacuum degree of the liquid distribution cavity 2 reaches a specified value; for example, after the vacuum pump 10 is started, when the vacuum degree in the detection chamber 1 reaches-85 to-75 mbar, the vacuum pump 10 is closed.
S4, opening the fourth valve 9; because the liquid distribution chamber 2 is communicated with the detection chamber 1 through the fourth valve 9, when the fourth valve 9 is opened, the standard solution in the liquid distribution chamber 2 can be sucked into the detection chamber 1 under the action of pressure difference.
S5, the controller acquires and stores the calibration electromotive force signals generated by the ion selection electrode 1-1 and the reference electrode 1-2; since the potential of the reference electrode 1-2 is a constant value and is not affected by the composition of the standard solution, while the potential of the nitrate ion selective electrode is affected by the composition of the standard solution, that is, the potential of the nitrate ion selective electrode is affected by the concentration of nitrate ions, the magnitude of the electromotive force of the galvanic cell formed by the nitrate ion selective electrode and the reference electrode 1-2 is related to the concentration of nitrate ions. When the standard solution passes through the bottoms of the nitrate ion selective electrode and the reference electrode 1-2, the primary battery formed by the nitrate ion selective electrode and the reference electrode 1-2 generates electromotive force, and the controller can store the electromotive force signals generated by the nitrate ion selective electrode and the reference electrode 1-2 as calibration electromotive force signals.
S6, after the time T1, namely the detection time lasts for T1, opening the liquid discharging ports 1-3 and the third valve 8; at this time, the fourth valve 9 is still open, and the water in the deionized water reservoir 5 is directly pumped into the detection chamber 1 after flowing into the dispensing chamber 2. Since the liquid discharge port 1-3 at the bottom of the detection chamber 1 is in an open state, waste liquid generated by washing can be directly discharged out of the detection chamber 1 through the liquid discharge port 1-3. Among them, T1 is preferably 60 to 90 seconds.
S7, after the time T2, namely the flushing time lasts for T2, closing the liquid discharging ports 1-3, the third valve 8 and the fourth valve 9; among them, T2 is preferably 30 seconds or more.
S8, repeating the steps S2-S7N times, and replacing x in the step S2, wherein N is>2; of these, N is preferably 6 times, that is, the sequential preparation and detection of the concentration are continuedDegree of 10-6mol/L、10-5mol/L、10-4mol/L、10-3mol/L、10- 2mol/L、10-1mol/L standard solution.
S9, drawing a calibration curve by the controller according to the acquired N +1 calibration electromotive force signals;
s10, starting the vacuum pump 10 until the vacuum degree of the liquid distribution cavity 2 reaches a specified value; for example, after the vacuum pump 10 is started, when the vacuum degree in the detection chamber 1 reaches-85 to-75 mbar, the vacuum pump 10 is closed.
S11, opening the first valve 6; because the wall surface of the sampling bottle 3 is provided with a plurality of liquid seepage holes, and the detection cavity 1 is communicated with the sampling bottle 3 through the first valve 6, when the first valve 6 is opened, the soil leachate to be detected can be sucked into the detection cavity 1 under the action of pressure difference.
S12, after the time T3, namely the collection time lasts for T3, the controller obtains the sample electromotive force signals generated by the ion selective electrode 1-1 and the reference electrode 1-2, and calculates the corresponding ion concentration in the soil solution according to the Nernst formula, the sample electromotive signal and the calibration curve. Among them, T3 is preferably 1 to 12 hours.
S13, after the time T4 elapses, that is, after the detection time lasts for T4, the first valve 6 is closed, the fourth valve 9, the drain ports 1 to 3, and the third valve 8 are opened, and the step S7 is repeatedly executed. Among them, T4 is preferably 60 seconds. Therefore, under the action of the pressure difference, the water in the deionized water liquid storage tank 5 is directly pumped into the detection cavity 1 after flowing into the solution distribution cavity 2. Since the liquid discharge port 1-3 at the bottom of the detection chamber 1 is in an open state, waste liquid generated by washing can be directly discharged out of the detection chamber 1 through the liquid discharge port 1-3. After the time T2, namely the flushing time lasts for T2, the liquid discharging ports 1-3, the third valve 8 and the fourth valve 9 are closed; among them, T2 is preferably 30 seconds or more.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the invention, but not to limit it; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (9)
1. The device for detecting the concentration of ions in the soil leachate is characterized by comprising a controller, a vacuum pump, a sampling bottle, a detection cavity, a liquid distribution cavity, a deionized water liquid storage tank and an ionic water liquid storage tank, wherein the deionized water liquid storage tank and the ionic water liquid storage tank are arranged above the liquid distribution cavity; the sampling bottle is communicated with the detection cavity through a first valve, a plurality of seepage holes are formed in the wall surface of the sampling bottle, and the sampling bottle is buried in soil to provide soil leachate for the detection cavity; the ionic water liquid storage tank and the deionized water liquid storage tank are respectively communicated with the liquid preparation cavity through a second valve and a third valve, and the liquid preparation cavity is communicated with the detection cavity through a fourth valve and used for providing a standard solution formed by mixing ionic water and deionized water for the detection cavity; the detection cavity is communicated with the vacuum pump, the bottom of the detection cavity is provided with an openable liquid discharge port, an ion selective electrode and a reference electrode are arranged in the detection cavity, and the ion selective electrode, the reference electrode and the vacuum pump are respectively and electrically connected with the controller; a transverse partition plate for dividing the detection cavity into an upper cavity and a lower cavity is arranged in the detection cavity, and the ion selective electrode and the reference electrode are both arranged in the upper cavity; the upper surface of the diaphragm plate is provided with two grooves sunken downwards, the bottom ends of the ion selective electrode and the reference electrode are respectively suspended in the two grooves, the bottom of each groove is communicated with the lower cavity through a fifth valve, and the bottom of the lower cavity is provided with the liquid discharge port.
2. The apparatus according to claim 1, further comprising a tee joint, wherein a first port of the tee joint is respectively communicated with the detection chamber and the vacuum pump through a main pipeline, a second port of the tee joint is communicated with the sampling bottle through a first liquid inlet pipe, and a third port of the tee joint is communicated with the liquid distribution chamber through a second liquid inlet pipe; the first liquid inlet pipe and the second liquid inlet pipe are respectively provided with the first valve and the fourth valve, and the inner diameters of the first liquid inlet pipe and the second liquid inlet pipe are smaller than the inner diameter of the main pipeline.
3. The apparatus according to claim 1, further comprising a stirring rod and a driving motor, wherein the stirring rod is inserted into the solution preparation chamber at a bottom end thereof and electrically connected to the driving motor at a top end thereof.
4. The apparatus according to claim 1, wherein said ion-selective electrode is any one of a nitrate ion-selective electrode, an ammonium ion-selective electrode, a potassium ion-selective electrode, and a calcium ion-selective electrode.
5. The apparatus according to claim 1, wherein the controller comprises an ion meter and a vacuum pump control module, the ion selective electrode and the reference electrode are electrically connected to the ion meter, respectively, and the vacuum pump is electrically connected to the vacuum pump control module.
6. The apparatus according to claim 1, wherein a liquid reservoir is formed at a central portion of an upper surface of the diaphragm, and two of the grooves are formed at opposite ends of a bottom surface of the liquid reservoir.
7. The apparatus according to claim 1, wherein the first valve, the second valve, the third valve, the fourth valve and the fifth valve are all solenoid valves, and each solenoid valve is electrically connected to the controller.
8. A method of using an apparatus for detecting the concentration of ions in a soil leachate according to any of claims 1 to 7, comprising the steps of:
s1, filling deionized water with the concentration of a and ionized water with the concentration of b into a deionized water liquid storage tank and an ionized water liquid storage tank in advance respectively, and embedding a sampling bottle in a pre-dug soil pit;
s2, opening the second valve and the third valve until the concentration of the standard solution in the liquid preparation cavity reaches x, wherein a < x < b;
s3, starting a vacuum pump until the vacuum degree of the liquid distribution cavity reaches a specified value;
s4, opening a fourth valve;
s5, the controller acquires and stores the calibration electromotive force signals generated by the ion selection electrode and the reference electrode;
s6, after the time T1 elapses, the liquid discharging port and the third valve are opened;
s7, after the time T2 elapses, the liquid discharge port, the third valve and the fourth valve are closed;
s8, repeating the steps S2-S7N times, and replacing x in the step S2, wherein N > 2;
s9, drawing a calibration curve by the controller according to the acquired N +1 calibration electromotive force signals;
s10, starting a vacuum pump until the vacuum degree of the liquid distribution cavity reaches a specified value;
s11, opening the first valve;
s12, after the time T3 elapses, the controller obtains the sample electromotive force signals generated by the ion selection electrode and the reference electrode, and calculates the corresponding ion concentration in the soil solution according to the Nernst formula, the sample electromotive force signals and the calibration curve;
s13, after a time T4 elapses, the first valve is closed, the fourth valve, the drain port, and the third valve are opened, and the step S7 is repeatedly performed.
9. The method for using the apparatus for detecting ion concentration in soil leachate of claim 8, further comprising the following steps before performing step S1:
and S0, paving the quartz sand in the pre-dug soil pit.
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| CN203224384U (en) * | 2013-04-19 | 2013-10-02 | 中国水稻研究所 | Special soil percolate extracting device for rice field |
| KR101519359B1 (en) * | 2014-11-03 | 2015-05-13 | 길주형 | On-Line Multipurpose Chloride Analyzer |
| CN204346761U (en) * | 2015-01-19 | 2015-05-20 | 轻工业环境保护研究所 | A kind of buried holard collection system |
| CN108088885B (en) * | 2017-11-10 | 2020-06-30 | 中国农业大学 | Soil heavy metal electrochemical in-situ detection system and detection method |
| CN107884465B (en) * | 2017-12-08 | 2023-09-22 | 自然资源部第二海洋研究所 | Online monitoring system and method for early warning of red tide |
| CN207541017U (en) * | 2017-12-08 | 2018-06-26 | 国家海洋局第二海洋研究所 | A kind of on-line monitoring system for red tide early warning |
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