Practical 1: Replication

 Practical 1

Week 2

Teammates Present: Trumann, Shawn, Jovan, Nelly

Written By Shawn
The team's overall goal was to: Replicate of the Previous Prototype, conduct 3D Printer Filament Test in KOH & 1% Acetic Acid and Test of Chitosan's Dissolving ability in 1% Acetic Acid Solution.

Goals:

  1. Rough Replication of previous group's prototype
    • To understand the previous group's challenges when building their electrolysis prototypes
    • To understand the electrolysis of water 
    • Test Chitosan's dissolvability in 1% acetic acid based on literature review
    • To test and verify the practicality of dissolving chitosan into 1% acetic acid to make it more soluble in water 
  2. Testing of 3D printer's filament (PLA) in different solutions
    • To test before prototyping whether 3D printing materials are viable to be used as MOC for the future prototypes


Replication of previous team's prototype

Preparation of 1L of  2M Potassium Hydroxide Solution, KOH


Calculation to produce 1L of 2M KOH using pure KOH powder:

Mr, KOH = 56.11g/mol

2M = 2 mol/L

To produce 1 L of 2M, 

Moles of KOH required = 2M × 1L = 2 mol

Mass of KOH required = 2mol × 56.11g/mol = 112.22g


Materials & Equipment Required:

  1. Weighing Boat × 1
  2. 1L measuring cylinder × 1
  3. Weighing Scale 
  4. Glass stirrer × 1
  5. KOH powder (112.22g)
  6. DI Water (1L)
  7. 1L Blue screw cap laboratory bottle, to store KOH solution (with SDS Label & Project Group Reagent Label) × 1

Figure: Blue screw cap laboratory bottle (100mL to 1000mL) 


Steps to prepare 1L of 2M KOH solution:

  1. Measure 1L of DI water using a 1L measuring cylinder
  2. Weigh 112.22g of KOH powder in weighing boat
  3. Slowly add the KOH powder into the DI water, stirring the solution before adding more powder
  4. Transfer & store KOH using 1L blue screw cap laboratory bottle with SDS Label & Project Group Reagent Label pasted on it.
    • Purpose of SDS Label: Safety hazard warning for all users
    • Purpose of  Project Group Reagent Label: For easy traceability of chemicals prepared and stored in the lab
Improvements for KOH preparation process:
  • Volumetric Flasks could be used instead of beakers to combine DI water with KOH powder to ensure solution is more accurate (at 2M).
    • As the lab only has 500mL volumetric flasks, 2 × 500mL of 2M KOH solution could be measured instead and combined in the storage container

Preparation of 1g of Chitosan with 1% v/v Acetic Acid

Calculation to produce 50mL of 1% Acetic Acid using 100% Acetic Acid solution:

Volume of solution required = 50mL
Volume of 100% Acetic Acid solution required = 50mL × 1% = 0.5mL 
Volume of DI water required = 50mL - 0.5mL = 49.5mL

Materials & Equipment Required:
  1. Plastic Pipette × 3
  2. 100mL measure cylinder × 1
  3. Glass Stirrer × 2
  4. 500 mL beaker × 1
  5. 50mL beaker × 2
  6. Weighing boat × 1
  7. Weighing scale × 1
  8. Stop watch × 1
  9. Chitosan (1g)
  10. 100% Acetic Acid (0.5mL)
  11. DI water (139.5mL)
Steps to prepare 50mL 1% v/v Acetic Acid solution using 100% acetic acid:
  1. Measure 49.5mL of DI water using the 100mL measuring cylinder and transfer to 50mL beaker
  2. Using a dropper, drop 0.5mL of 100% acetic acid into the 50mL beaker
  3. Use a glass stirrer to stir the solution

Steps to prepare 1g of chitosan with 1% Acetic Acid:
  1. Measure 10mL of 1% Acetic Acid Solution using 100mL measuring cylinder and transfer to 50mL beaker
  2. Weigh 1g of chitosan using the weighing boat and transfer to 50mL beaker and stir using a glass rod
  3. Start timer and wait for 30minutes 
  4. Measure 90mL of DI water using 100mL measuring cylinder 
  5. Transfer chitosan mixture into 500mL measuring cylinder, use DI water from 90mL DI water measured in the measuring cylinder to flush out the chitosan mixture into the beaker
  6. After all chitosan mixture is flushed into the 500mL measuring cylinder, pour remaining DI water of the 90mL measured into the 500mL measuring cylinder and stir with the glass rod used to stir the chitosan in step 2.
Figure A: Chitosan mixture with 10mL 1% Acetic Acid (Step 2)

Figure B: Chitosan mixture after dissolving using 1% Acetic Acid
Testing method (to determine how much chitosan was dissolved):
Visual comparison of chitosan in Figure A against Figure B.

Results:
Majority of the chitosan was dissolved in water based on the comparison with some large chunks floating on top.

Discussion of results:
The chitosan mixture looks viscous (similar to mucus viscosity) visually with 
Based on using the 1% acetic acid, it is shown(visibly) that most of the chitosan was dissolved in water, however there are still clumps of chitin that remains undissolved.
An improvement made could be to increase the volume of 1% acetic acid used (in step 1 and 2) or increase the concentration of acid used to make chitosan be more soluble in water.


Improvements for Chitosan preparation process:
  • Volumetric Flasks could be used instead of beakers to combine DI water with 100% Acetic Acid solution to ensure solution is more accurate (at 1% v/v)
  • While preparing the 1g of chitosan with 1% Acetic Acid, the 50mL beaker can be forgone and the 500mL beaker used to mix 10mL of 1% acetic acid with 1g of chitosan.
    • This eliminates the glassware used and the possibility of chemicals lost during transferring of chitosan into the 500mL beaker
Notes:
The chitosan mixture could not be filtered using conventional gravity filtration with coffee bag filter as the solution is too viscus, a mesh filter may possibly work (testing required). 



Setting up of prototype
As the previous team's prototype was already constructed, the team only had to assemble the prototype and prepare the necessary equipment. 
The team used the marine glue to add an additional layer of glue to the Electrode rods to reduce the possibility of solution leaking during electrolysis as the rods were connected through the base of the container. We also cut a hole for the bottom plastic container to allow easier connection from the converter to the Electrode rod without having the prototype squish the wire to increase the structural stability of the set up.

Figure: Base support plastic container with additional cut for wires

Materials Required:
  1. Previous Team Prototype (with Electrode rod, plastic container & PVC tubing connected) × 1
  2. Styrofoam Board (with holes predrilled) × 1
  3. Plastic Base support container × 1
  4. Retort Stand × 1
  5. 500mL glass beaker × 1
  6. Green tray × 2 
  7. Tap water 
  8. Alligator Clips × 2
  9. Syringe (with elongated tip tubing) × 1
  10. DC to AC power converter × 1
  11. 2M KOH solution (500mL)
  12. Dissolved Chitosan (100mL, 1g of Chitosan)
Steps to set up the prototype:
  1. Place the prototype on top of the Styrofoam board(Middle) and plastic container(Bottom) as shown on Figure C. Ensure the Electrode rods are placed in the drilled holes of the Styrofoam board and plastic container
  2. Connect the 2 alligator clips to the bottom of the Electrode rods (one alligator clip on one rod)
  3. Connect the 2 alligator clips connected to each Electrode rod to the DC to AC converter on the negative charge and positive charge (as shown in figure D & Figure E)
  4. Place the current set up (Steps 1-3) in the fume hood in a green tray.
  5. Fill prototype with 500mL 2M KOH solution and Dissolved Chitosan.
  6. Fill another green tray with tap water to about half full .
  7.  Place green tray with tap water to the side of the green tray with the prototype.
  8. Place retort stand beside the green tray.
  9. Place 500mL beaker (face down) in the tap water, ensure at least 1-2cm of tap water on the walls.
  10. Use the retort stand to secure the 500mL beaker at that position.
  11. Place the tubing from the prototype into the beaker, ensure tubing is secured to the top of the beaker.
  12. Use the syringe to extract air from the beaker, to allow water to rise. Stop when air is at 100mL, to prevent water from leaking into the PVC tubing, blocking Hydrogen gas from entering the water displacement measuring set up.
  13. Turn on DC to AC converter and set Volts to 4.0, the Ampere will automatically adjust depending on the current strength. 
Figure C: Electrolysis set up, Step 1 ( Top: Prototype, Middle: Styrofoam Board, Bottom: Plastic Base)

Figure D: Electrode rod connection diagram

Figure E: Electrode Rod connection (Actual, Step2&3)


Notes:
While setting up the displacement of water to measure hydrogen gas produced, the team faced a challenge.
Challenge faced: How to place water in the beaker to measure hydrogen gas produced.
Solution: Use DI rubber bottle to compress, place the head of the bottle into the beaker and allow the bottle to suck the air from the beaker. (or Syringe with elongated tubing tip to suck out the air)
Challenge faced 2nd: As air is being sucked, due to the container air being open in the container, the pressure difference causes the water to get sucked in and water to be displaced back to its original height.
Solution: place KOH solution into electrolysis prototype before displacing the water to measure hydrogen gas.
Challenge face 3rd: When tall measuring cylinder is used, while displacing the air for water to enter the measuring cylinder, the KOH solution would also get sucked into the tube due to the pressure difference the suction produces.
Solution: Use a wider beaker and suck the air away from the tube to prevent KOH from back flowing into the tubing for hydrogen.

Figure: Removal of air using empty DI bottle (first compress then place into cylinder and allow to decompress)

Video: Using DI bottle to extract air from hydrogen measuring using water displacement
Video: Using syringe to extract air from hydrogen measuring using water displacement

Videos of Electrolysis of water:
Video: Electrolysis set up after starting
Video: Time-lapse of electrolysis reaction (20minutes)

Identified areas of improvement:
  • As not the entire Electrode rod is submerged, there is less surface area for electrons to be transferred.
  • There was a minor leak in the set up, to prevent future leaks the prototype has to be water tight sealed with the correct glues to prevent loss of solution during electrolysis.
 
Overall Lab Safety Notes
  • To handle 100% acetic acid, 3 gloves have to be worn as acetic acid can dissolve the gloves if split. After handling of 100% acetic acid, 2 layer of gloves must be thrown away before touching any other materials / equipment. 
  • For preparation of 2M KOH, DI water should be prepared first as KOH powder is highly hydrophilic, thus it will react and draw moisture from the surrounding air if left out for too long, creating a highly basic solution which could be dangerous.
  • When handling of electricity (DC to AC converter), the voltage and ampere must always be monitored and ensure hands and equipment are dry before touching any switches or electric parts.
  • Perform all handling, diluting and preparation of solutions in the fume hood to prevent inhalation of harmful chemicals.
  • Perform all preparation of chemicals in a spill tray (green tray) as means of containment in case of spillage. 
  • Perform electrolysis prototype test in fume hood as Hydrogen gas produced is highly flammable and dangerous.
Procedures prepared before the experiment

Solution Preparation 


Preparation of 1.0L of 2.0M Potassium Hydroxide Solution

Material: 112.2grams of Potassium Hydroxide pellets Procedure 

1) 112.2 grams of Potassium Hydroxide pellets has been weighed by using an electronic scale to produce 1.0L of 2.0M liquid potassium hydroxide. 

2)The Potassium Hydroxide pellets are transferred into a 500 ml beaker. 

3) 500 ml of water has been added into the beaker and stirred to allow the potassium hydroxide pellets to dissolve in the water. 

4) 500 ml of the Potassium Hydroxide solution has been transferred into 1 litre glass chemical bottle. 

5) Add water into the bottle to the 1L mark to dilute and produce 1 litre of 2.0M Potassium Hydroxide.

 

Construction of the prototype 

1) The bottom of the container with a smaller base area is drilled with 2 holes using a hand drill. 

2) Using a file, the hole is filled to a size that can fit the graphite electrode. 

3) The graphite electrode is then inserted into the holes, ensuring enough length at the bottom to allow connection of the wire.

4) The cover of the container is drilled with 2 holes using a hand drill. 

5) Using a file, one of the holes is filled to a size that can fit the transparent PVC tube. 

6) The transparent PVC tube is cut into 1 piece, with a length of 1.0m. 

7) The transparent PVC tube is then inserted into the hole at the cover of the container. 

8) The orange plastic hose tube is cut into 1 piece, with a length of 0.15m. 

9) The orange plastic hose tube is inserted and attached to the PVC tube on the cover. 

10) A piece of Styrofoam with dimensions of 0.17m x 0.16m is cut out and 2 holes are cut out of the Styrofoam to fit the graphite electrode. Refer to figure 9. 

11) Referring to figure 10, a plastic container is cut to act as the base collection container to contain leakage.


Set-Up Procedure

1) Measure 500ml of the required electrolyte in a 1.0L measuring beaker. 

2) Transfer the electrolyte solution into the container of the setup. 

3) Insert the bottom electrode into the Styrofoam and place the container above the base collection container. 

4) Connect the alligator clips to the graphite electrode. 

5) Cover the container, ensuring that the tube covers the electrode to allow collection of gas produced. The tube is to cover the negative charge electrode. 

6) Fill a secondary container and measuring cylinder with water and using a clamp, clamp the measuring cylinder above the container with water to set up the water displacement. 

7) Insert the other end of the longer tube into the measuring cylinder. 

8) Connect the wire to the generator and turn it on. 

9) Set the voltage to that required and visually inspect that the gas is being produced at the electrodes. 

10) After waiting for the 3rd bubble to rise up the measuring cylinder to ensure that the hydrogen produce can displace the water properly, start the stopwatch for 10minutes and take the initial reading on the measuring cylinder. 

11) The reading is taken every 30 seconds for 10 minutes.


Hydrogen fuel car 

1) Cap the O2 opening using a stopper. 

2) Fill the H2 side of the fuel cell with water before lowering it below the water level of the water displacement setup from the previous sections. 

3) Fill both the top openings with water to prevent the gas collected from escaping. 

3) Bubble the H2 gas produced from the electrolysis into the fuel cell similar to that of the water displacement test. 

4) Cap the H2 side without lifting it above the water surface level to prevent it from escaping to the atmosphere. 

5) Attach the fuel cell to the fuel cell car. 

6) Connect the wires to the appropriate connections with the same colour for the hydrogen fuel cell car to start.


Chitin Set Up

Undissolved chitin The required mass of chitin is measured using an electronic scale and added into the 1.0L measuring beaker containing the electrolyte before adding it into the container of the setup. 


Dissolved chitin using ultrasonication The required mass of chitin is measured using an electronic scale and transferred into a 100ml conical flask and add 50ml of water into the conical flask. The conical flask is then placed in an ultrasonicator and then added into the 1.0L measuring beaker before adding the electrolyte solution to 500ml. 


Dissolved chitin using H2SO4 The required mass of chitin is measured using an electronic scale and transferred into a 250ml measuring beaker and 50ml of H2SO4 is added into the measuring cylinder. The mixture is then stirred and transferred into the 1.0L measuring beaker before adding the electrolyte solution to 500ml