User:Melissa Novy/Notebook/CHEM-581/2012/10/03

Objectives

• Crosslink Na-MT films.
• Adjust the pH of CuSO₄ solutions made on 2012/09/28, then take ISE measurements.

CuSO₄ Standard, Na⁺ Standard, and Na-MT Filtrate Solutions

• Please refer to the ISE protocol on 2012/09/28 for how ISE measurements were taken.
  • 3 mL of the solutions were added to 0.1 mL of ionic strength adjuster (4 M solution containing NaOH) to adjust the pH to a value between 8 and 10.
  • The solutions were allowed to equilibrate with the electrode for 2 min.
• Dilutions of 5 mL each of 1, 5, 10, 15, and 20 ppm Na⁺ in pure H₂O were made from a 1000 ppm Na⁺ solution, then ISE measurements were taken.
• Calculations

  5 mL 20 ppm Na+ requires:
  (1000 ppm Na+)V1=(20 ppm Na+)(5 mL)
  V1=100 μL

  5 mL 10 ppm Na+ requires:
  (1000 ppm Na+)V1=(10 ppm Na+)(5 mL)
  V1=50 μL

  5 mL 5 ppm Na+ requires:
  (1000 ppm Na+)V1=(5 ppm Na+)(5 mL)
  V1=25 μL

  5 mL 5 ppm Na+ requires:
  (1000 ppm Na+)V1=(5 ppm Na+)(5 mL)
  V1=25 μL

  5 mL 1 ppm Na+ requires:
  (1000 ppm Na+)V1=(1 ppm Na+)(5 mL)
  V1=5 μL

CuSO₄ Standard Solutions

Na⁺ Standard Solutions

100% CEC (Na-MT)-CuSO₄ Filtrate

50% CEC (Na-MT)-CuSO₄ Filtrate

Unmodified (Na-MT)-CuSO₄ Filtrate

Notes

• The 1 ppm Na⁺ solution gave an ISE value that did not fit the expected calibration curve. This may be because the detection limit of the ISE measurements is above 1 ppm. It was recommended that a solution of higher Na⁺ ppm, such as 25 ppm Na⁺ be tested to generate a more accurate calibration curve.