DESALT EDBM TEST KIT Operating Manual
- Gu Zhouying
- Apr 3
- 6 min read
What is BPED
Bipolar Electrodialysis (BPED) is an advanced form of ED that incorporates bipolar membranes, which can split water into H⁺ (protons) and OH⁻ (hydroxide ions) under an electric field. This process is particularly useful for producing acids and bases from salts.
1.1 Mechanism:
A bipolar membrane consists of a cation-exchange layer and an anion-exchange layer.
When an electric field is applied, water molecules dissociate into H⁺ and OH⁻ ions at the interface of the bipolar membrane.
H⁺ ions migrate to the cathode side, forming an acid, while OH⁻ ions migrate to the anode side, forming a base.
This allows for the conversion of salt solutions into corresponding acids and bases, making BPED ideal for applications like chemical production and pH adjustment.
ABOUT DESALT LAB TEST？
2.1. EDBM LAB TEST EQUIPMENT INTRODUCTION
The DESALT Bipolar Electrodialysis (EDBM) Lab Test Equipment is designed for testing the production of acids and bases from salt solutions. It is particularly useful for applications requiring precise pH control or chemical production.
Key Features:
Bipolar Membrane Integration: Enables the splitting of water into H⁺ and OH⁻ ions for acid and base generation.
Flexible Configuration: Supports testing with various membrane types and stack configurations.
Data Logging: Records key parameters such as voltage, current, and ion concentration for detailed analysis.
Compact and Portable: Suitable for lab-scale testing and pilot studies.
2.2 CUSTOMIZE FOR DIFFERENT BRAND MEMBRANE
The DESALT Lab Test Equipment is highly versatile and can be customized to accommodate membranes from various brands. This ensures compatibility with specific project requirements and allows for comparative testing of membrane performance.
Customization Options:
Membrane type (CEM, AEM, bipolar).
Stack configuration (number of cell pairs, flow distribution).
Integration with existing lab setups.
2.3 SCALE UP ACCORDING TO THE TEST RESULT
The DESALT Lab Test Equipment is designed to provide reliable data that can be directly used for scaling up to industrial systems.
Scaling Process:
Test results from the lab equipment are analyzed to determine optimal operating conditions (e.g., voltage, flow rate, membrane type).
These parameters are used to design larger-scale ED or BPED systems with confidence in their performance.
The DESALT Electrodialysis (ED) Lab Test Equipment is a compact, modular system designed for testing and optimizing ion removal processes. It is ideal for research, pilot studies, and small-scale applications.
3. How to do the test?
3.1. How to install the equipment
Before starting the test, ensure the following preparations are completed:
Equipment Check:
Verify that all components of the DESALT EDBM test kit are present and in good condition.
Inspect membranes, pumps, tubing, and electrical connections for any damage or leaks.
EQUIPMENT CONNECTION
The flow chart below illustrates the steps to connect the DESALT EDBM Lab Test Equipment:
Salt Solution Tank:
Connect the salt solution tank to the salt solution pump (P101).
Salt Solution Pump (P101):
Pump the salt solution into the BPED stack.
BPED Stack:
Connect the salt solution inlet (SND IN) to the BPED stack.
Connect the base outlet (SND OUT) to the base tank.
Connect the acid outlet (SND OUT) to the acid tank.
Electrode Rinse Solution:
Connect the electrode rinse solution tank to the electrode rinse pump (P201).
Pump the electrode rinse solution through the electrode compartments.
Power Supply:
Connect the power supply to the BPED stack and set the desired voltage/current.
Monitoring:
Use sensors (T10, T20, T30, T40) to monitor temperature, conductivity, and pH during the test.
Return to Tank:
Return the acid and base streams to their respective tanks for recirculation or disposal.
Salt Solution → P101 → BPED Stack (SND IN) → Base/Acid (SND OUT) → Tanks.
Electrode Rinse Solution → P201 → Electrode Compartments.
Power Supply → BPED Stack.
3.3 POWER-ON OPERATION
Begin by starting the electrode solution pump, followed by the feed liquid pump, acid liquid pump, and alkali liquid pump. The flow rate in the electrode chamber should generally be maintained at 3–4 cm/sec, while the flow rate in the concentrate and dilute channels should be controlled at 4–6 cm/sec. (The typical pressure drop is around 0.3-0.5 bar for a flow velocity of 3-4 cm/sec. The flow (L/hr) can be calculated based on the flow velocity (3-4cm/sec), spacer thickness (0.55mm), spacer effective width and cell pair numbers)
Adjust the flow rates to ensure the inlet flow and pressure of each feed solution are approximately equal. Circulate each solution for 3–5 minutes to ensure all compartments are filled with liquid and any air bubbles are fully expelled.
Next, connect the positive terminal (red) of the DC power supply to the anode lead of the electro-dialyzer and the negative terminal (black) to the cathode lead. Power the electro-dialyzer using the DC power supply, which can operate in either constant current or constant voltage mode.
Important:
· The recommended applied voltage should be maintained at ≤2.0V per repeating unit;
· The recommended current density should be maintained at ≤750 A/m2;
· For 20 pairs ED stack, the test voltage is 10 pairs * 2V/pair + 5 V (electrolyte room ) = 25V
3.4. POWER-OFF OPERATION
When the treatment reaches the expected results, first gradually reduce the voltage and current of the DC power supply to 0, then turn off the feed pumps, and then replace the feed solutions with deionized water to rinse the membrane stack and equipment components.
3.5. GENERAL MAINTENANCE
If the unit leaks internally or externally, tighten the unit further; if the condition does not improve, the membrane or diaphragm may need to be replaced.
After the experiment, please rinse the feed liquid or electrode liquid in the electro-dialyzer, solution tank and water pump. If the equipment is not used for a long time, please inject 5% NaCl solution to preserve the electro-dialyzer membranes.
3.6. CLEANING PROCEDURES
If a partial blockage occurs in the electro-dialyzer, indicated by a rise in pressure or a drop with flow rate, the equipment must be cleaned. Cleaning involves both backwashing and chemical cleaning.
Note: Ensure the DC power supply is turned off during all cleaning procedures.
Backwashing Procedure:
Reverse the inlet and outlet water pipes of the desalination and concentration chambers of the electro-dialyzer, so the water flows in the opposite direction to the original configuration. If the electro-dialyzer is partially blocked, backwash it with deionized water for at least 30 minutes.
Chemical Cleaning Procedure (if backwashing is insufficient):
Inorganic Salt Deposits:
Rinse the electro-dialyzer with deionized water.
Inject 1% hydrochloric acid and let it sit for more than 30 minutes.
Rinse thoroughly with clean water.
Repeat the process if necessary, depending on the severity of the blockage.
Organic Pollutants:
Rinse the electro-dialyzer with deionized water.
Inject 1% sodium hydroxide and let it sit for more than 10 minutes.
Rinse thoroughly with clean water.
Repeat the process if necessary, depending on the level of contamination.
Bacterial Growth:
Rinse the electro-dialyzer with deionized water.
Inject clean water containing 20 ppm free chlorine and let it sit for more than 10 minutes.
Rinse thoroughly with clean water.
Repeat the process if necessary, depending on the degree of contamination.
4. How to do data analysis
4.1 Expected test results of EDBM
Acid and Base Production:
Generation of acids (e.g., HCl) and bases (e.g., NaOH) from salt solutions (e.g., NaCl).
Typical concentration ranges: 0.1-1.0 M (Max 2 M) for acids and bases, depending on operating conditions.
Current Efficiency:
A measure of how effectively electrical energy is used to produce acids and bases, typically ranging from 60% to 90%.
pH Changes:
Significant pH changes in the acid and base streams (e.g., pH < 2 for acid, pH > 12 for base).
Energy Consumption:
Measured in kWh/kg of acid/base produced, typically ranging from 1.5 to 4.0 kWh/kg.
4.2 What parameters should be recorded during the test?
To ensure accurate analysis, the following parameters should be recorded during the test:
Salt Solution:
Initial salt concentration (e.g., NaCl).
Conductivity and pH.
Temperature
Acid and Base Streams:
Concentration of produced acid (e.g., HCl) and base (e.g., NaOH).
Conductivity and pH.
Temperature
Operating Conditions:
Applied voltage and current.
Flow rates for salt, acid, and base streams.
Current Efficiency:
Calculated based on moles of acid/base produced versus theoretical yield.
Energy Consumption:
Total energy used (kWh/kg of acid/base produced).
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