# User:Karlena L. Brown/Notebook/PVOH Research/2012/09/21

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## OBJECTIVES

1. Prepare 2000ppm SO42- solution from Na2SO4
2. Prepare 2000ppm SO42- solution from CuSO4
3. Prepare fixant solution for glutaldehyde film crosslinking

## 2000ppm SO42- Solutions

In order to prepare a 2000ppm SO42- solution from Na2SO4, the following calculations were completed:

MW Na2SO4: 142.04 g/mol

MW SO42-: 90.06 g/mol

``` 0.001 g SO42- × (1 mol SO42-/90.06 g SO42-) × (1 mol Na2SO4/1 mol SO42-) × (142.04 g Na2SO4/1 mol Na2SO4) = 0.001479 g Na2SO4
Actual mass Na2SO4: 0.00150 g
0.00150 g Na2SO4 × (1 mol Na2SO4/142.04 g Na2SO4) × (1 mol SO42-/1 mol Na2SO4) × (96.06 g SO42-/1 mol SO42-) = 0.00101 g SO42-
```
``` Actual concentration: (0.00101 g SO42-/0.5 L) × 106 = 2020 ppm SO42-
```
• Weigh out ~0.00150g Na2SO4

(Actual Na2SO4 Mass: 0.00150g)

• Within the 500mL volumetric flask, add ~500mL of H2O; however, do not exceed the dilution mark
• Next, stir solution until all the solid dissipate into solution

(Repeat procedure above again for CuSO4.5H2O)

MW CuSO4.5H2O: 249.69 g/mol

``` 0.001 g SO42- × (1 mol SO42-/90.06 g SO42-) × (1 mol CuSO4.5H2O/1 mol SO42-) × (249.68 g CuSO4.5H2O/1 mol CuSO4.5H2O) = 0.00256 g CuSO4.5H2O
Actual mass CuSO4.5H2O: 0.00252 g CuSO4.5H2O
0.00252 g CuSO4.5H2O × (1 mol CuSO4.5H2O/249.68 g CuSO4.5H2O) × (1 mol SO42-/1 mol CuSO4.5H2O) × (96.06 g SO42-/1 mol CuSO4.5H2O) = 0.00097 g SO42-
```
``` Actual concentration: (0.00097 g SO42-/0.5 L) × 106 = 1939 ppm SO42-
```

(Actual CuSO4.5H2O Mass: 0.00252g)

## Fixant Solution Preparations

• Weigh out ~200g Na2SO4

(Actual Na2SO4 Mass: 200.1459g)

• Add the Na2SO4 solids to a 1000mL closed cap plastic bottle
• Next, add ~1000mL of H2O to the bottle along with large magnetic stir bar
• Place container with the solution on a stir plate and stir solution for ~20 minutes or until all solids dissipate into solution
• Add 20mL of concentrated H2SO4 to solution and continue stirring for ~10 minutes more

1. After allowing the glutaldehyde PVOH films to completely dry in a Teflon dish, remove the film from the dish
2. Add prepared fixant solution to a 150mL beaker along with a stir bar and a Buchner funnel top
3. Heat the solution to ~70°C on a hot plate and use a thermometer to measure solution temperature at all times
4. Place film in fixant solution for ~1 hour while keeping the temperature around 70°C
5. Next, prepare a 100mL 1% HCl solution in a 150mL beaker by adding 1mL of concentrated HCl to 100mL of H2O
6. Heat 1% HCl solution to ~70°C as well
7. Next, remove film from the fixant solution and rinse thoroughly with H2O
8. Place a stir bar in the 1% HCl solution and add a new Buchner funnel top to the beaker
9. Add rinsed PVOH film to the 1% HCl solution
10. Allow film to remain in the 1% HCl solution for ~30 minutes at a constant temperature of 70°C
11. Finally, prepare a 0.2M NaHCO3 solution by adding ~1.6g of NaHCO3 to 100mL of H2O

(Actual Mass NaHCO3: 1.6801g)

1. After ~30 minutes, remove the film from the 1% HCl solution to place into the 0.2M NaHCO3 solution for ~15 minutes
2. Finally, after 15 minutes remove from the NaHCO3 solution and rinse with H2O
3. Dry the film thoroughly with a paper towel (dabbing gently) and weigh new mass of the PVOH film

## Notes

• H2SO4 is a highly corrosive substance, care and safety should be taken at all times
• After treatment with varied solutions, the glutaldehyde film mass changed

(New Mass: 0.5126g)

• New glutaldehyde film after treatment appeared to be more flexible and less transparent