阅读说明：本技术 一种电渗析基础实验标准测试方法 (electrodialysis basic experiment standard test method ) 是由 张笑维 楼永通 黄伟平 于 2019-09-27 设计创作，主要内容包括：本发明公开了一种电渗析标准测试方法。本发明中所叠制的标准测试膜堆在阳极处增加一张阳膜,设置两极靠近极膜处均为浓水室,测试膜堆与极膜之间采用双层隔板,确保净电压测量时不易松动。通过精确控制变量法,保证恒定净电压情况下浓水浓度及其他测试条件恒定,在电渗析脱盐过程中,得到不同温度下淡水盐浓度及电流密度的变化关系。该测试方法使测量电渗析净电压为有效膜对净电压,保证其准确性,通过单一变量使结果稳定,重复性良好,可以有效指导实际的工程应用及优化实际生产和实验。(The invention discloses electrodialysis standard test methods.A positive membranes are added at the anode of a stacked standard test membrane stack, concentrated water chambers are arranged at the positions of two electrodes close to polar membranes, and double-layer partition plates are adopted between the test membrane stack and the polar membranes to ensure that net voltage is not easy to loosen during measurement.)

electrodialysis basic experiment standard test method based on electrodialysis standard test device, wherein the test method comprises the following steps:

① standard test membrane stack is fixed on the standard test device to accurately measure the net voltage of the membrane stack, and the variation relation of fresh water salt concentration and current density at different temperatures is obtained by controlling the temperature and net voltage variation by a variable control method, the standard test membrane stack is a membrane stack at least comprising 5 pairs of electrodialysis membranes, anode membranes are added at the anode of the membrane stack, and the two electrodes close to the polar membranes are respectively stacked into concentrated water chambers through partition plates;

② feeding back the net voltage of the two sides of the membrane stack according to the type and quantity of the membrane, measuring the metal wire between the polar membrane and the polar plate in the membrane stack by using a universal meter, reading the net voltage value, the instantaneous voltage value when the universal meter is just connected, and the voltage value after the universal meter reads stably;

③ the material liquid entering the experimental device is analyzed pure salt, the initial concentration of the tested fresh water is 0.5-1 mol, the concentration of the extreme water is the same as that of the fresh water, the equilibrium concentration of the concentrated water is set to 3-4 mol, the corresponding concentration salt is put into the water tank, the volume and the concentration are measured, the experimental process takes the concentration of the fresh water salt set by oneself as the terminal point, container with scales is taken, the pure water is filled into the container, and the container is put into the water suction pipe of the concentrated water metering pump, an air cylinder is put at the concentrated water port, the overflow concentrated water is collected, the concentration of the concentrated water is kept constant, the variable is accurately controlled, a heat exchange pipe is put into each water tank when the device is started, the heat exchange pipe is connected with.

2. The electrodialysis foundation experiment standard test method is characterized in that according to the relationship between the conductivity and the salt concentration, the upper limit value of the conductivity meter is set to be the value based on the conductivity corresponding to the concentration limit salt concentration of the concentrated water, and when the conductivity of the concentrated water is higher than the value, the metering pump is automatically started to supplement pure water.

3. The electrodialysis foundation experiment standard test method as claimed in claim 1, wherein the metal wires connected with a multimeter for measuring the net voltage of the membrane stack are kinds of platinum wires, copper wires or titanium wires.

4. The electrodialysis foundation experiment standard test method is characterized in that samples are taken during the experiment and the salt concentration of fresh water is tested by gravimetric method or titration method, and the measurement error is less than 0.05%.

5. The electrodialysis foundation experiment standard test method as claimed in claim 1, wherein the membrane module of the electrodialysis standard test device is a plate-type module, and the membrane material is or several combinations selected from PVC, PEEK, PET, PES and PVDF.

6. The electrodialysis foundation experiment standard test method as set forth in claim 1, wherein the experimental salt type is selected from types selected from sodium chloride, sodium sulfate, sodium nitrate, potassium chloride and potassium sulfate.

Technical Field

The invention relates to the technical field of basic experiment analysis methods, in particular to electrodialysis basic experiment standard test methods.

Background

Electrodialysis (ED) has found wide application in the fields of environmental protection, seawater desalination, chemical engineering, metallurgy, light industry, paper making, etc., and has been pushed to the field of separation and purification of amino acids, viscose fibers, proteins, etc., which has very good application prospects of in recent years.

In the electrodialysis process, the external electric field is expected to increase the migration speed of ions to the corresponding membrane by increasing the DC electric field, but when the electric field is increased to degrees, a large number of water molecules are ionized and polarized to generate H⁺And OH^-OH ionized in water^-Penetrate the cathode membrane, resulting in a rise in pH on the concentrated water side of the cathode membrane, and H produced by ionization⁺Permeating the anode membrane, enriching the membrane surface at the side of the anode membrane fresh water chamber when Ca exists in the water²⁺、Mg²⁺Therefore, the electrodialysis process has the problem of optimal selection of migration speed and energy consumption of an external electric field, different types of membranes have membrane stack net voltage suitable for operation of the membranes in practical engineering application, namely corresponding to the optimal current density (the size of current on a unit membrane area), and the ion migration speed and the energy consumption in the electrodialysis process are optimal.

At present, standard test methods are passed, the net voltage measurement precision can be guaranteed by accurately controlling variables, the actual process current is fed back under the corresponding membrane operation net voltage, and the engineering application can be better guided and the actual production process can be optimized by the relationship between the fresh water ion migration rate (salt concentration) and the corresponding current density in the experimental process.

Summary of the invention

The research aims to establish electrodialysis standard test methods capable of accurately measuring and accurately controlling variables, and a change relation curve of salt concentration and current density at different constant temperatures is obtained through an electrodialysis standard test experiment, so that the electrodialysis standard test method can be better served for actual engineering and achieve the aim of optimizing production.

In order to achieve the purpose, the invention adopts the following technology:

electrodialysis basic experiment standard test method, wherein a standard test membrane stack is fixed on a standard test device to accurately measure the net voltage of the membrane stack, and the variation relation between the concentration of the fresh water salt and the current density at different temperatures is obtained by controlling the temperature and the net voltage variation through a variable control method.

The standard test membrane stack at least comprises 5 pairs of electrodialysis membranes, anode membranes are added at the anode of the membrane stack, the two electrodes are uniformly stacked to form concentrated water chambers near the polar membranes, and double-layer partition plates are adopted between the test membrane stack and the polar membranes.

The net voltage on the two sides of the membrane stack is fed back according to the type and the quantity of the membranes, a universal meter is used for measuring a metal wire arranged between a polar membrane and a polar plate in the membrane stack, and the net voltage value is read and is used as a variable so as to adjust the output voltage and the current of the high-frequency power supply. The voltage instantaneous value when the universal meter is just connected and the voltage value after the universal meter reading is stable;

the method comprises the steps of adopting pure salt for analysis, testing the initial concentration of fresh water to be 0.5-1 mol, testing the extreme water concentration to be the same as the fresh water concentration, and testing the balanced concentration of concentrated water to be 3-4 mol, placing salt solution with corresponding concentration into a water tank, measuring the volume and the concentration, taking container (A graduated cylinder) with scales as a terminal point in the experiment process when the concentration of the fresh water salt reaches the self-set concentration (corresponding conductance calculation), placing pure water into a water suction pipe of a concentrated water metering pump, placing an empty cylinder (B graduated cylinder) at a concentrated water port, collecting overflow concentrated water, keeping the concentration of the concentrated water constant, and accurately controlling variables.

Preferably, the upper limit value of the conductivity meter is set to the value based on the conductivity corresponding to the concentration limit salt concentration of the concentrated water, and when the conductivity of the concentrated water is higher than the value, the metering pump is automatically started to replenish the pure water.

Preferably, the membrane module is a plate-type module, and the membrane material is at least selected from PVC and PEEK.

Preferably, the metal wires connected with the multimeter for measuring the net voltage of the membrane stack are kinds of platinum wires or titanium wires.

Preferably, samples are taken during the experiment and the sodium chloride concentration of the fresh water is measured by a gravimetric method, and the measurement error is less than 0.05 percent.

Preferably, the experimental salt type is selected from sodium chloride, sodium sulfate or sodium nitrate.

The invention has the beneficial effects that:

(1) according to the electrodialysis standard test method, the concentrated water replenishing device and the concentrated water overflow device are respectively arranged, so that the salt concentration of the concentrated water in the desalting process is ensured to be constant, the variable is accurately controlled, the change relation between the salt concentration and the current density in the actual desalting process at constant temperature is accurately reflected, and a powerful support can be provided for engineering application and production.

(2) In the electrodialysis membrane stack net voltage testing process, positive membranes are added on the basis of the positive membrane (polar membrane) of the anode to form a concentrated water chamber between the two positive membranes, and the cathode is arranged into the concentrated water chamber through a partition plate to ensure that net voltage measurement is relatively stable, meanwhile, an electrode measuring metal wire (connected with a multimeter) is added between the two positive membranes of the anode and between the negative membrane and the polar membrane to measure net voltage, the two partition plates are used for fastening and fixing to reduce the possibility of electrode measurement loosening, therefore, the metal wire measurement voltage is the pure voltage of the membrane stack, and the error caused by the original extra polar membrane net voltage is eliminated.

(3) electrodialysis standard test methods are established, and actual engineering can be guided or membrane performance can be predicted according to electrodialysis basic experiment feedback.

Drawings

Fig. 1 is a schematic structural diagram of an electrodialysis basic experimental device.

Fig. 2 is a membrane stacking method for accurate net voltage measurement in electrodialysis basis experiments according to the present application.

Detailed Description

The invention is further illustrated in by way of example and with reference to the accompanying drawings.