- Finish film synthesis
- Start new film synthesis
- 1.0028g PVA, 0.1102g clay
- 1.0534g PVA
- UV-vis of Malachite Green solution to make calibration curves for Malachite green solutions
- Using Calibration curves find equilibrium of remaining malachite green solution that have films soaking in them.
- Calibration Curves
- Take UV Vis spectra for Malachite green concentrations: 0ppm, 0.20ppm, 0.50ppm, 1.1ppm, 1.4ppm, 1.7ppm, and 2.0ppm Malachite Green
- Find the two absorbance maxima in the spectra. Plot the absorbance value vs concentration at each ppm for each maximum you find.
- For each absorbance max, determine the slope of your A vs concentration plots. This will give you the extinction coefficient for the wavelengths you are analyzing
- Malachite Green Equilibrium
- We will use UV-Vis spectroscopy to determine the amount of Malachite green absorbed into a film
- Upon determining the amount of Malachite green in the film, we can determine the equilibrium of free Malachite green vs bound malachite green by creating an I.C.E. table. (Remember those from Gen Chem II??)
- We can also determine the mass of malachite green absorbed per mass of film
- To properly determine MG concentration, we will need to dilute our samples so that their absorbance is similar to the absorbance of our calibration curve samples.
- You can see from the intense color of your MG/film solutions that they are much darker (and will absorb more light) than those you used for your calibration curves (except for the 2ppm).
- Before you get to lab, figure out how you are going to need to make your dilutions.
- Hint 1: Use a 10mL volumetric flask (only 1 per each group)
- Hint 2: Transfer your dilutions to a glass test tube and label (you'll only need 3mL for your absorbance measurement)
- Hint 3: The two groups who are running UV Vis should take turns running 1 sample at a time. (At the end of the day, each group will have run 6 calibration samples and 8 diluted samples)
- Hint 4: Delegate responsibility among your group members for:
- Running Spectra
- Cleaning Cuvettes
- Making Dilutions
- Analyzing Spectra and making calibration curves
- Hint 5: Acetone is fantastic for really cleaning MG out of volumetric flasks and cuvettes.
- UV-vis of malachite green standard solutions
These graphs display the standard concentrations of malachite green versus the wavelengths. The second graph includes the solution at 8 ppm but is disregarded to make a calibration curve because its peak surpasses 1.
- Calibration curves for Malachite green
The following graphs plot the absorbance versus the concentration of the standard malachite green solutions. The first graph shows the absorbance at 425 nm. The second graph shows the absorbance at 615 nm. Both graphs have r-squared values close to one. The higher the concentration, the higher the absorbance.
- Absorbance of Malachite Green solutions after absorption of polymer films
The absorbance of these solutions are much higher which indicate what we know that the polymer films absorb less malachite green leaving more freely floating in solution. This explain the peak difference between this data and that of the solutions that where the polymer-clay films absorbed malachite green.
- Absorbance of Malachite Green Solutions after absorption of polymer-clay films
This shows how effectively the polymer-clay films were able to absorb the malachite green solutions. The lower intensity as well as the flattened shape especially of the 2ppm demonstrate how effectively the malachite green was absorbed into the film.
- Polymer film mass absorption
||mass of orginal film
||Mass ratio of malachite gree and film
- Polymer-Clay film mass absorption
|concentration of original solution
| mass of malachite green absorbed (g)
| mass of original film (g)
| mass ratio of malachite green:film