MPTL Continuous Stirred Tank Reactor (CSTR) SOP

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Standard Operating Procedure

Continuous Stirred Tank Reactor (CSTR)
SOP

Thang Tran 11-2022

Safety

  1. All students must wear safety glasses when working in the lab
  2. Never leave this equipment operating unattended
  3. Mix all chemicals in fume hood
  4. All chemicals, solutions, and standards must be stored in a sealed container. The container must be labeled with: chemical(s) name and concentration, operator name, hazards, and date of storage.
  5. All chemical containers must be sealed when not in use
  6. All unwanted material must be placed in an appropriate container. The container must be labeled “Unwanted Material” the label must include; the chemical(s) name and concentration, the operator name and contact information, and hazards. If you have questions regarding labeling unwanted materials, see the sign posted above the unwanted materials table.
  7. Only pure water can go down the drains

Equipment Description

The CSTR experiment consists of the following equipment

  1. Masterflex peristaltic pumps: These pumps have a switch on the rear panel; it must be set to external in order for the computer system to control the pumps.
  2. Acrylic reactor vessel, maximum volume is about 1 L. The reactor temperature is controlled by the heating/stir plate under the reactor vessel.
  3. Opto22 Control System
    1. Data is sampled every second and stored in an Excel compatible file at C:\User\pfr\Desktop\CSTR Data. See the section on viewing your data for more information. Save your data to a flash drive. The computer is not on the network.
  4. Sensorex conductivity measurement system
    1. Conductivity range = 0 microsiemens to 19.9 millisiemens with a resolution of 0.01 millisiemens. Optional equipment: pH and UV-Vis meters. See lab manager for more information

CSTR Procedure

  1. Determine what chemicals, calibration standards and measurements you will need to make.
  2. Determine the flow rates for your reactants.
  3. Refer to the section on pump specifications and tubing to help determine what tubing is appropriate for your flow rates. Be sure to use only Masterflex tubing, if you are unsure about which tubing to use check with the lab manager. The smaller the inner diameter of the tubing the lower the flow rate.
  4. Pumps may be calibrated using a rotameter or bucket and stopwatch.
  5. Install the tubing in the peristaltic pumps. By using the same size tubing in both heads of one of the dual –head pumps you can achieve two identical flow rates.
  6. Place the reactant feed tubing into the reactor. Ensure that the other end is connected to the fitting on the top of the CSTR reactor.
  7. Ensure that the outlet of the reactor is connected to the conductivity sensor and/or feeds into the proper waste container.
  8. Determine what method you will use to measure the product stream, your options are measuring pH, conductivity or you may measure the transmission of light using a Uv-Vis spectrophotometer. Once you have determined a measurement technique, run the appropriate calibration standards to verify the accuracy of your measuring system.
  9. Power up all equipment:
    1. Switch on the power to the pumps using the grey toggle switch located on the front panel for older pumps or the power switch in the back for newer pumps.
    2. Switch on the Stir plate by pushing the knob controlling stirring.
    3. Switch on the heating element of the plate by pushing the knob on the front
    4. The Sensorex conductivity module does not have a switch, it is always on.
    5. Do not touch the Opto22 control hardware located behind the reactor.
  10. Using the conductivity measurement system:
    1. The conductivity probe is enclosed in a tee fitting which is mounted to the 80/20 next to the reactor vessel. The probe connects to the conductivity transmitter (Sensorex Model CX 100) mounted on the CSTR frame.
    2. Do not adjust the position of the probe within the tee. It is set at the correct depth and angle, adjusting the probe will disrupt data collection.
  11. Calibrating the conductivity system:
    1. This only needs to be done once unless the tubing size or pump is changed
    2. Determine the range of conductivity you want to measure, the specifications for the conductivity system are listed in this document.
    3. Collect the required conductivity standards.
    4. Setup a pump to pump just enough conductivity standard to fill the tubing and the tee, this is typically about 300-500 ml.
    5. Disconnect the tubing that goes from the CSTR to the conductivity sensor
    6. Place the conductivity standard in a beaker, place a small section of tubing into the beaker and then place the tubing in a pump head. Connect the other end of the tubing to the bottom inlet of the tee. This will pump the conductivity standard into the tee / probe assembly, filling it from the bottom.
    7. Now connect another section of tubing to the outlet at the top of the tee. Place the other end of this tubing into the beaker containing the conductivity standard. This completes the pump circuit allowing you to continuously pump conductivity standard solution through the tee/probe assembly.
    8. Once the reading of the CX 100 conductivity meter as well as the corresponding conductivity reading on the computer display are reading the value of the conductivity standard you can stop the pump and disassemble the calibration setup. The reading should be within ~1% of the standard value.
    9. Do not attempt to adjust the calibration setting on the CX100 conductivity meter. Consult the lab manager if you feel that the meter requires calibration.
    10. Once you have confirmed the calibration of the conductivity probe connect the bottom of the tee to the outlet of the CSTR reactor.
  12. See the lab manager for assistance with other measuring devices such as pH and UV-Vis.
  13. Determine the amount of feed stock you will require.
  14. Mix all chemicals / feedstock dilutions in a fume hood.
  15. Place your feedstock in 8 liter Nalgene containers available in the “A” lab on the shelf above the chemical storage cabinets.
  16. Feed the outlet stream of the system into another Nalgene container.
  17. Verify that the feed and drain pumps are connected properly.
  18. There is a floor balance located next to the computer that may be used to weigh your solutions.

How to view and save data in Excel

  1. Do not try to view your data while the system is running, this will cause it to stop data collection
  2. Save data to a flash drive after each trial
  3. If you have any questions, please see the Lab assistant

If you are running one trial:

  1. Once all your required data has been collected, exit the Opto system
  2. Open Excel, click “Open” and navigate to the correct data folder specified in the SOP
  3. In the bottom of the Excel window, click on the drop-down window and select All Files this will display the data files collected organized by date
  4. Double-click on the file you wish to open, the Text Import Wizard will open
  5. Select Delimited then click Next, then select Comma Delimited and click Next. Select the General Data format option and click Finish. The data should now be displayed in Excel
  6. Save your data to the flash drive by clicking Save As and selecting your flash drive as the destination. Ensure you label your data properly and thoroughly to avoid confusion
  7. Eject the flash drive.
  8. Follow the rest of the shutdown procedure specified in the equipment SOP

If you are running several trials in one day:

  1. Leave the Opto system running
  2. Open File Explorer and navigate to the correct data folder specified in the SOP for your equipment
  3. Organize by date if not already done so, your data should appear at the top of the list
  4. Right click on your data file and “cut” the file (or press Ctrl X after clicking once on the file)
    • Note: this will effectively cut the data that was collected up to that point into a file and begin a new data collection (a new file will be created with the same name as the file you cut) as soon as it is cut
  5. Paste the file to a flash drive and rename with the proper label, ensure you are labeling your data thoroughly to avoid confusion
  6. Eject the flash drive and save to your personal device
  7. To open in Excel on your personal device:
    1. Open Excel, click Open and navigate to the saved data on your flash drive or device
    2. In the bottom of the Excel window, click on the drop-down window and select All Files this will display the data files collected organized by date
    3. Double-click on the file you wish to open, the Text Import Wizard will open
    4. Select Delimited then click Next, then select Comma Delimited and click Next. Select the General Data format option and click Finish

Shutdown:

  1. Pump DI water through the system until the conductivity meter reads <100 microSiemens. Store any solution you wish to save in a properly labeled Nalgene container. Consult the lab manager regarding chemical storage.
  2. To empty the CSTR reactor, place a piece of tubing connected to a pump in one of the holes in the top of the reactor and pump the solution/water out
  3. Label all containers.
  4. Properly dispose of any unwanted material, consult the lab manager for guidance.
  5. Switch off the heat/stir plate.
  6. Switch off the power to the pumps. Either place the toggle switch to the center for older pumps or flip the power switch in the back of the pump for newer pumps.
  7. Do not attempt to switch off the Sensorex conductivity module.
  8. Exit the Opto control software, Do Not Shutdown the Computer.
  9. Save your data to a flash drive, the computer is not on the network