Practical 5: Building and Testing

Practical 5

Week 11

Teammates Present: Trumann, Shawn, Jovan and Nelly

Written By Trumann

After exams and a break, the team returned to experimenting and improving the prototypes. The first clear prototype and second coloured prototype had leaks and required more sealant glue to be added. To make electrolysis experiments easier to run, a new crude set-up was to be made. The first crude prototype was made using a plastic container as the main body and a pipe on the cap. 

Figure 1: First version of crude prototype

The first version of the crude prototype had leaks and was not air-tight nor fully leakproof which meant that measuring the amount of hydrogen produced during electrolysis is not possible. Attempts to fix the leaks and make the prototype air-tight were made. Sealant glue, blue tack and tape were used but to no avail. This was due to the plastic container used as it did not have an air-tight covering system which meant capping the plastic container did not made the interior of the plastic container air-tight. This 

Thus, the team concluded to made a new prototype from better quality plastic and an inbuilt air-tight system.

Figure 2: Second version of crude prototype

The second version of the prototype was made using a better quality air-tight plastic container and reinforced with a better sealant glue compared to the last sealant glue used. After testing for leaks and whether it was air-tight, the experiments could start. The experimental set-up consists of a water displacement system using a 250ml beaker with the pipe going into, the main body with a plastic stand and a DC transformer to allow for adjust of the voltage and ampere of the current going to the electrodes. 

Figure 3: Electrolysis experimental set-up

Due to a lack of time, only 1 run was done for the electrolysis of KOH. The amount of gas produced to was to be recorded as results and compared with KOH and chitosan together.

Another experiment which was to test for the solubility of chitosan in 15% acetic acid was ran at the same time. The team started by testing using the traditional method which was by stirring the mixture at 200RPM  while heating up the water bath in the ultrasonication machine. However, there was an issue where the water bath would lose heat as the cover could not be properly placed due to the high beaker height. This resulted in the temperature would maintaining at 45°C instead of heating up to 60°C. To overcome this problem, a piece of tin foil was used to cover the ultrasonication machine to reduce heat loss to the surroundings from the exposed top. This method was effective at heating the sonication machine to 60°C.

Figure 4: Ultrasonication Set-up with tin foil as cover

Vacuum filtration was used to determine the amount of chitosan dissolved. This can be done by doing vacuum filtering then drying the filter paper and weighing it to determine the amount of undissolved chitosan. Methods on how to carry out vacuum filtration were tested. The amount of filter paper required was determined to be three to four Size 4 filter papers with a pore size of 20-25 micrometers and pouring the chitosan and acetic acid mixture slowly on to it to prevent pressure build-up on the vacuum side of the paper. Alternatives are to be discussed and researched in the future. 

Figure 5: Vacuum filtration setup sketch

Figure 6: Vacuum filtration process (Pouring Sample)

Chitosan and acetic acid residue was dried at 50°C, Fan speed of 100% and 80% flap for an hour after performing ultrasonication as written earlier in the post and vacuum filtration. The residue was not dry enough so it was further dried for an extra 30 mins. The Size 4 filter paper ran out which led the team to try Size 1 and 6 filter paper as a replacement. Size 1 were too large and had to be cut while Size 6 made filtration too slow.