CN202903673U - Full-automatic quick water quality measuring system with hexavalent chromium - Google Patents

Abstract

The utility model relates to a full-automatic rapid measurement system for hexavalent chromium in water quality. The first electromagnetic valve is connected with the standard solution of hexavalent chromium and the second electromagnetic valve, and is connected to the first interface of the six-way valve through a peristaltic pump. The valve is connected to the standard sample, the second port of the six-way valve is connected to the fifth port through a quantitative loop, the sixth port of the six-way valve is connected to waste liquid, and the third port of the six-way valve is connected to the carrier liquid through a peristaltic pump. The fourth port of the through valve is respectively connected with one end of the reaction tube and the color developer through the peristaltic pump through the three-way mixer, the third solenoid valve is respectively connected with the other end of the reaction tube and the air, and the third solenoid valve is connected with the photoelectric detection device. to waste. This system has the advantages of simple flow path design, pure digital photoelectric detection, and elimination of air bubble interference. At the same time, the use of PLC programmable controllers greatly reduces the failure rate of the instrument control system, making the instrument truly unattended and fully automated measurement.

Description

Water quality hexavalent chromium automatic rapid measurement system

technical field

The utility model relates to a measurement system for hexavalent chromium in environmental water samples, in particular to a fully automatic rapid measurement system for hexavalent chromium in water quality.

Background technique

Hexavalent chromium is highly toxic and is easily absorbed and accumulated by the cells of many tissues and organs in the human body. It can interfere with the activity of many important enzymes in the human body and damage the liver and kidneys. It is a recognized carcinogen. Excessive (more than 10ppm) hexavalent chromium has a lethal effect on aquatic organisms. The industrial pollution sources of chromium mainly come from wastewater from ore processing, metal surface treatment, leather tanning, printing, dyeing and printing industries, which has been listed as one of the indicators for total amount control by the environmental protection department. It can be seen that it is necessary to strictly monitor the content of hexavalent chromium in the surface water and the discharge water of related enterprises, so as to take corresponding countermeasures in time for the water body with hexavalent chromium exceeding the standard and avoid harm.

At present, the instruments for determining hexavalent chromium mainly include spectrophotometry, chemiluminescence, atomic spectroscopy, polarography, flow injection analysis, electrochemical method, neutron activation method, isotope dilution mass spectrometry, etc. Some of these methods have high sensitivity and good selectivity, but expensive instruments and reagents greatly limit the scope of application; some instruments are large in size and inconvenient to carry, so they are not suitable for online real-time monitoring.

Relatively speaking, as a new rapid analysis technology, the flow injection analysis method has the characteristics of simplicity, speed, high degree of automation and saving indicators. It has developed rapidly in recent years and is currently used by most automatic water quality monitoring systems. . However, there are generally disadvantages such as complex flow path design, high failure rate, air bubble interference, and low measurement accuracy.

Utility model content

The main purpose of the utility model is to provide a fully automatic rapid measurement system for hexavalent chromium, which has the advantages of simple flow path design, pure digital photoelectric detection, elimination of air bubble interference, and full automation. The detection results of the system are accurate and reproducible. , It can be used for automatic rapid detection of hexavalent chromium in fresh water and sea water.

In order to achieve the above object, the technical solution proposed by the utility model is:

A fully automatic rapid measurement system for hexavalent chromium in water quality, the water sample is connected to one port of solenoid valve V1, one of the other two ports of solenoid valve V1 is connected to one port of solenoid valve V2, and the other is connected to a port of six-way valve through a peristaltic pump The first interface, the other two interfaces of the solenoid valve V2 are respectively connected to the hexavalent chromium standard solution B1 and the hexavalent chromium standard solution B2, the second interface of the six-way valve is connected to the fifth interface through the quantitative loop, and the third interface is connected through the said The peristaltic pump is connected to the carrier liquid, the fourth port is connected to one end of the reaction tube and the chromogen through the peristaltic pump respectively through the three-way mixer, the sixth port is connected to the waste liquid W1, and the other end of the reaction tube is connected to the solenoid valve V3 One port of the solenoid valve V3, the other two ports of the solenoid valve V3 are respectively connected to the air and the photoelectric detection device, and the other end of the photoelectric detection device is connected to the waste liquid W2;

The conversion of the connection relationship between the interfaces of the six-way valve is controlled by the PLC programmable controller:

When the system is in sampling mode, the first port of the six-way valve is connected to the second port, the third port is connected to the fourth port, and the fifth port is connected to the sixth port;

When the system is in the measurement mode, the first port of the six-way valve is connected to the sixth port, the third port is connected to the second port, and the fifth port is connected to the fourth port.

The communication is all communicated through the PTFE pipeline of polytetrafluoroethylene material.

The peristaltic pump is made of corrosion-resistant material and has a 4-channel hose.

The photoelectric detection device includes a single light source, a flow cell and a digital photosensitive IC;

The flow cell is a container for circulating mixed solutions;

The light emitted by the single light source is irradiated onto the mixed solution in the flow cell;

The digital photosensitive IC receives the light signal reflected by the mixed solution, converts the light signal into a digital signal, and communicates with the PLC programmable controller through the I ² C digital communication protocol.

The PLC programmable controller receives and stores the data sent by the digital photosensitive IC.

All reagents are stored using reagent bags.

It also includes a touch screen, which is connected to a PLC programmable controller, provides control operation keys and displays the control process.

The utility model has the following beneficial effects and advantages:

1. The utility model combines flow injection technology with single light source detection technology, and cleverly solves the difficult problem of air bubbles in flow injection;

2. The digital photosensitive IC adopted for the first time in this utility model greatly reduces the noise interference generated by the existing digital-to-analog conversion and photoelectric amplification, and improves the detection accuracy and stability of the instrument;

3. The utility model adopts the quantitative loop Ls to accurately quantify the water sample, and the four-channel peristaltic pump ensures the constant flow rate of each pipeline. Therefore, the dispersion state of the sample in the carrier liquid within a certain retention time is highly reproducible , so as to ensure the high reproducibility of the measurement results;

4. The utility model adopts a PTFE pipeline with an inner diameter of 0.8mm, which greatly saves the amount of reagents;

5. The utility model adopts programmable controller PLC to realize automatic and data processing, which greatly reduces the failure rate of the instrument control system;

6. The utility model has the advantages of simple flow path design and flow injection unsteady state reaction, so that the time to complete a water sample detection and analysis is only 2 minutes, realizing real-time online monitoring in the true sense;

7. The utility model is used for regular or random on-line monitoring of hexavalent chromium on water bodies such as rivers, lakes, source water of water plants, industrial discharge water, sea water, etc., to obtain instant analysis data simply and quickly, and to prevent water pollution accidents. Discover in time, deal with in time, won precious time for eliminating hidden danger.

Description of drawings

Figure 1 is a schematic diagram of the connection of the flow collection mode of the system;

Figure 2 is a schematic diagram of the measurement mode connection of the system.

Among them, C—carrier liquid, S—water sample, B1, B2—hexavalent chromium standard solution, R—chromogen, V1, V2, V3—solenoid valve, P—peristaltic pump, V4—six-way valve, Ls – quantitative loop, X – three-way mixer, Lc – reaction tube, A – air, D – photoelectric detection device, W1, W2 – waste liquid.

Detailed ways

As shown in Figure 1, it is a schematic diagram of the flow collection mode connection of this system. The fully automatic measurement system for hexavalent chromium consists of a peristaltic pump, a six-way valve, a solenoid valve, a three-way mixer, a photoelectric detection device, a programmable controller PLC, It is composed of touch screen, reagent bag, PTFE pipeline, etc.

In this system, the sample injection quantitative module is composed of a peristaltic pump P, a six-way valve V4, and a quantitative loop Ls, and the length of the quantitative loop is 45 cm. Port 4 is connected to the three-way mixer X, port 6 is the waste liquid outlet, and port 2 and port 5 are connected to each other to form a quantitative loop Ls. Solenoid valve V1 is provided with ports 1~3, solenoid valve V2 is provided with ports 4~6, and solenoid valve V3 is provided with ports 7~9; port 3 is the inlet of water sample S, port 4 and port 6 are standard samples B2, B1 inlet, port 9 is air A inlet, port 1 is connected to port 5, port 2 is connected to port 1 of six-way valve V4, port 7 is connected to reaction tube Lc, port 8 is connected to photoelectric detection device D. The six-way valve V4 is provided with 6 ports, wherein the first port is connected to the water sample source S through the peristaltic pump P, the third port is connected to the carrier liquid C through the peristaltic pump P, and the fourth port is connected to the three-way mixer X. The sixth interface is a waste liquid outlet, and the second interface and the fifth interface are connected to each other to form a quantitative loop Ls.

The first port of the six-way valve communicates with the second port, the third port communicates with the fourth port, the fifth port communicates with the sixth port, the sample is pumped into the quantitative loop Ls from the first port, and the excess sample is pumped from the It is discharged from the sixth interface.

Figure 2 is a schematic diagram of the measurement mode connection of the system.

The first port of the six-way valve is connected to the sixth port, the second port is connected to the third port, and the fourth port is connected to the fifth port. At this time, the carrier liquid C pushes the sample in the quantitative loop Ls to be in the third port. It is mixed with the chromogenic agent in the mixer, and then the mixed solution enters the reaction tube, and finally the photovoltage is detected in the photoelectric detection device.

This system adopts flow injection technology, and by adding a solenoid valve in front of the flow cell, the solution in the flow cell is emptied before each measurement, which solves the problem that the tiny bubbles that often remain in the flow cell are difficult to be discharged, namely Solve the problem of air bubbles that flow injection technology is difficult to overcome.

The main components of the photoelectric detection device are a 540nm single light source, a 10mm optical path flow cell and a digital photosensitive IC. The use of single light source detection technology avoids the interference of miscellaneous peaks; for the first time, digital photosensitive IC is used to directly convert optical signals into digital signals, realizing the pure digitalization of photoelectric detection in the true sense. It directly communicates with the CPU through the ^I2C digital communication protocol The realization of communication greatly reduces the noise interference produced by the existing digital-to-analog conversion and photoelectric amplification, thereby greatly improving the detection accuracy and stability.

The peristaltic pump has 4 channels to ensure the consistency of the flow rate of each flow path, and the pump tube is made of corrosion-resistant material hose.

Programmable controller PLC is mainly to realize automatic and data processing, with stable performance and low failure rate.

The touch screen can conveniently control the system, which is convenient, simple and fast.

The reagent storage method adopts reagent bags instead of the existing reagent bottles, which can completely prevent external air bubbles from entering the pipeline and ensure the reliability of the flow injection technology.

All pipelines are polytetrafluoroethylene material tubes with an inner diameter of 0.8 mm.

The chemical principle can react at room temperature without heating.

The system uses a six-way valve to change the two state positions of sampling and measurement. Driven by the carrier liquid, the cut-in water sample is mixed with the chromogen in the three-way mixer, and the two diffuse and react in the carrier liquid. The generated purple-red compound is detected by a photoelectric detection device, and the photoelectric data is received and processed by a programmable controller PLC, and finally the content of hexavalent chromium is automatically displayed on the touch screen.

The system can not only detect the content of hexavalent chromium in fresh water, but also detect the content of hexavalent chromium in seawater by simply changing the reagent formula.

Automatic measurement process of hexavalent chromium measurement system:

1. Preparation of required reagents

(1) Carrier liquid

Measure 25ml of concentrated sulfuric acid, slowly add 500ml of deionized water, stir and cool, add 25ml of phosphoric acid, and then add distilled water to make up to 1000ml.

(2) Color developer

Weigh 1g of diphenylcarbohydrazide (molecular formula C13H14N4O), dissolve in 180ml of acetone, add water to make up to 500ml, and store in the dark.

(3) Hexavalent chromium standard stock solution

Accurately weigh 0.2829±0.0001g of potassium dichromate (K2Cr2O7) dried at 105°C for 2 hours, dissolve it in water, transfer it into a 1000ml volumetric flask, dilute with water to the marked line, and shake well. This solution contains 100mg/L of hexavalent chromium.

(4) Hexavalent chromium standard solution B1 (0μg/L): deionized water.

Hexavalent chromium standard solution B2 (1000μg/L): Take 10ml of 100mg/L hexavalent chromium standard stock solution, add it to 1000ml, dilute with water to the marked line and shake well, store in a brown glass bottle (2～5℃ Save below).

If this system measures hexavalent chromium in seawater, it only needs to use 3% NaCl solution to make up the volume when preparing the carrier liquid and standard solution.

2. Specific steps of system operation

The system can be operated fully automatically, and the action of each component is controlled by the programmable controller PLC, and the data of the flow cell is received and stored. The sampling method can be selected through the touch screen, and operations such as instant sampling, periodic sampling, and timing sampling can be selected. The following are the specific steps for a single automatic sampling to detect hexavalent chromium:

(1) Sampling process

The port selection 2 and 3 in the solenoid valve V1 are connected; the port selection 8 and 9 in the solenoid valve V3 are connected, and the liquid in the flow cell is emptied under the action of gravity and atmospheric pressure; the six-way valve V4 is turned to the left position, that is, the first port It communicates with the second port, the third port communicates with the fourth port, and the fifth port communicates with the sixth port; after that, the ports 7 and 8 in the solenoid valve V3 are connected; the peristaltic pump P rotates to pump the actual water sample S into the quantitative In the loop Ls, the excess water sample is discharged into the waste liquid W1; at the same time, the carrier liquid C and the chromogenic agent R are also mixed in the three-way mixer X driven by the peristaltic pump P, and passed through the reaction tube Lc and the solenoid valve V3 enter the photoelectric detection device D, and after the photovoltage stabilizes, the PLC records and saves the base value I0; the peristaltic pump P stops rotating.

(2) Measurement process

The states of solenoid valves V1 and V3 remain unchanged; the six-way valve V4 is turned to the right position, that is, the first port communicates with the sixth port, the second port communicates with the third port, and the fourth port communicates with the fifth port; the peristaltic pump P Rotate again, the water sample in the quantitative loop Ls is cut into the carrier liquid, and distributed in the order of "carrier liquid‖water sample‖carrier liquid", the chromogenic agent R is always pushed by the peristaltic pump P and mixed in the three-way The container meets the carrier liquid carrying the quantitative water sample, and enters the photoelectric detection device D through the reaction tube Lc and the solenoid valve V3, and the peak value I1 is recorded and saved by the PLC.

(3) Cleaning process

The states of solenoid valves V1, V3 and six-way valve V4 remain unchanged, and the peristaltic pump P continues to rotate until the photovoltage value returns to the base value I0, indicating that the pipeline is flushed and the peristaltic pump P is stopped.

(4) Calculation process

Based on the data I0 and I1 obtained above, the PLC calculates the absorbance value of the water sample according to Lambert-Beer's law, compares it with the standard curve obtained from the two-point calibration of B1 and B2, calculates the concentration of hexavalent chromium in the water sample and automatically displayed on the touch screen.

Table 1 is the detection data of three standard samples and three water samples detected by this measurement system.

Table 1 water sample determination results and standard addition recovery experiment (n=8)

The above experiments show that the error between the sample concentration measured by this system and the actual concentration is small, indicating that this system has high accuracy. In terms of performance, the system also has the advantages of fast determination (30 samples/h), saving reagents, good stability and reproducibility; Automatic real-time online monitoring has a good application prospect.

Claims (7)

1. full-automatic Fast measurement system of water quality sexavalent chrome, it is characterized in that, water sample is communicated with the interface of solenoid valve V1, one of two other interface of solenoid valve V1 is communicated with the interface of solenoid valve V2, two be communicated with the first interfaces of six-way valve by peristaltic pump, two other interface of solenoid valve V2 is communicated with respectively sexavalent chrome mark liquid B1 and sexavalent chrome mark liquid B2, the second interface of six-way valve is communicated with by quantitatively encircling with the 5th interface, the 3rd interface is communicated with current-carrying liquid by described peristaltic pump, the 4th interface by the threeway mixer respectively with an end of reaction tube, developer by described peristaltic pump is communicated with, the 6th interface is communicated with waste liquid W 1, the other end of reaction tube is communicated with the interface of solenoid valve V3, two other interface of solenoid valve V3 is communicated with respectively air and photoelectric detection system, and the other end of photoelectric detection system is communicated with waste liquid W 2;

The PLC Controlled by Programmable Controller is passed through in the conversion of connected relation between the interface of six-way valve:

When system was in sampling pattern, the first interface of six-way valve was communicated with the second interface, and the 3rd interface is communicated with the 4th interface, and the 5th interface is communicated with the 6th interface;

When system was in measurement pattern, the first interface of six-way valve was communicated with the 6th interface, and the 3rd interface is communicated with the second interface, and the 5th interface is communicated with the 4th interface.

2. by the full-automatic Fast measurement system of water quality sexavalent chrome claimed in claim 1, it is characterized in that described connection all is communicated with by the PTFE tube road of polytetrafluoroethylmaterial material.

3. by the full-automatic Fast measurement system of water quality sexavalent chrome claimed in claim 1, it is characterized in that described peristaltic pump is the flexible pipe that 4 passages were made and had to resistant material.

4. by the full-automatic Fast measurement system of water quality sexavalent chrome claimed in claim 1, it is characterized in that described photoelectric detection system comprises single light source, flow cell and digital sensitization IC;

Described flow cell is for being used for the container of circulation mixed solution;

The illumination that described single light source sends is mapped on the mixed solution in the flow cell;

Described digital sensitization IC receives the light signal of mixed solution reflection, light signal is converted into digital signal, and passes through I ²C digital communication agreement is communicated by letter with the PLC Programmable Logic Controller.

5. by the full-automatic Fast measurement system of water quality sexavalent chrome claimed in claim 4, it is characterized in that described PLC Programmable Logic Controller receives and store the data that digital sensitization IC sends.

6. by the full-automatic Fast measurement system of water quality sexavalent chrome claimed in claim 1, it is characterized in that described all reagent all utilize the storage of reagent bag.

7. by the full-automatic Fast measurement system of water quality sexavalent chrome claimed in claim 1, it is characterized in that, also comprise touch-screen, connect the PLC Programmable Logic Controller, the control operation button is provided and shows the control process.

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