Continue synthesis of the polymer and polymer-clay films for experimentation. The creation of a calibration curve via the UV-Vis for malachite green absorbance will be used to determine the equilibrium of their malachite green/dye samples.
- Synthesis of new films was started. The procedure may be viewed here.
- Finish the synthesis of clay films started on 08/29. The procedure may be viewed here.
- 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. The stock solution concentrations may be found here.
- 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.
- 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.
- Dilutions were determined before arrival at lab. Dilution information can be viewed below.
- Use a 10mL volumetric flask.
- Transfer your dilutions to a glass test tube and label. Only 3mL is necessary for an absorbance measurement.
- 6 calibration samples and 8 diluted samples were run.
- The only sample solutions that required dilution were the 80ppm PVA film and the 200ppm PVA-Clay film.
- PVA 80ppm → 200μL into 10 mL (50x dilution)
- PVA-Clay 200ppm → 100μL into 10mL (100x dilution)
- New Film Synthesis
- 1.0256g PVA
- 107272g PVA + 0.1176g Clay
Absorbance of Malachite Green Solutions
- This is a calibration curve of the Malachite Green at various concentrations. This graphic was made by collecting data from the UV-vis. A quartz cuvette was utilized.
Absorbance of Malachite Green in Sample Films
- This is a curve of Malachite Green absorbance after the solution was treated with either a PVA or a PVA-clay film.
Interpretation of Curves
Calibration Curve of 423nm and 617nm peaks
Initially the graphs created from the Uv-vis were only saved up to the 700nm wavelength. The files were resaved and no data was lost, but in the future make sure the parameter extends to 800nm.