Today's objective was to repeat the bead procedure from February 14th, but instead of making a bead composite of 10% bentonite we made beads for 10% charcoal. We also tested our dried film from last week using XRD.
Synthesis of Charcoal beads
The full procedure of the large scale synthesis can be found on Mary's notebook entry.
- A solution of 2. 5g of PVA, 0.25g of activated charcoal, 21.97mL of DI water, and 8.03mL of concentrated HCl (to create 30 mL of a 10% HCl in charcoal solution) was heated and stirred until all PVA beads were dissolved.
- The solution was then transferred to a burette.
- 10mL of the PVA-charcoal solution was added, dropwise, to 100mL of ethyl acetate, while stirring vigorously.
- 2mL of glutaraldehyde was added and the solution was stirred for 7 minutes.
- After 7 minutes, 7mL of sodium bicarbonate solution was added and stirred for 30 seconds.
- The solution was removed and put into 50mL Falcon tubes.
- The solution was centrifuged for 1 minutes at 3000 rpm.
- The liquid was pipetted out of the tubes and replaced with DI water to store.
Protocols are good. Don't forget to include actual masses used. Precision may matter.
Preparing bead columns
A dry column and cap were initially weighed. Then, water was eluted through the column, the outside was patted dry, and the wet column and cap were then weighed again. To pack the beads into the column, the solutions of DI water and 10% clay composite beads were eluted through the column, allowing the beads to catch on the bottom. If air bubbles formed, the columns were inverted and shaken with some water. This was repeated until the level of packed beads came up to about one third to half way up the column. The beads were then dried by allowing all of the water to finish eluting from the column. The column was then patted dry, and weighed once more. This process was epeated with a new column and the charcoal beads. After both columns have been assembled, water was added to the columns so the beads would not dry out and they were stored for next class.
Prepping of XRD samples
To prep the XRD samples, the flat parts of the dried film were cut out and stuck onto a sample holder, held on with silly putty. A sample of just PVOH was also made as a reference, and a sample of just silly putty was made as a blank. All four samples were added to the XRD, and each was measure between the angles of 2 and 35.
When packing the columns, it was easiest to scoop out some of the larger chunks that weren't beads, elute out some water, and pour a more concentrated slurry of beads into the column to save time when packing in the beads.
Table 1: Weight of columns and beads
Excellent! Have matching masses will really help you compare results!