User:Douglas M. Fox/Notebook/AU CHEM-581 F2012 Lab Support/2012/09/18: Difference between revisions

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Revision as of 10:12, 24 September 2012

Project 2: Instrumentation <html><img src="/images/9/94/Report.png" border="0" /></html> Main project page
<html><img src="/images/c/c3/Resultset_previous.png" border="0" /></html>Previous entry<html>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</html>

Atomic Absorption Flame Spectroscopy

AA Standards

  • 10 mL total solution stored in 15 mL centrifuge tubes
  • Used CuSO4 stock solution (13.30 ppm Cu2+ as CuSO4)
  • Diluted with 16.7 MΩ DI
  • 100 - 1000 μL pipetters were sticking, so precision of solutions likely to be low
  • Prepared 10:0, 5:5, 2:8, & 1:9 dilutions


Cu exchange of NaMT

  1. 10 min exchange, 1:5 salt to clay
    • 0.100 g CuSO4 in 20 mL DI
    • Added 0.500 g NaMT
    • Stirred 10 min ± 5 sec and filtered through 41 Whatman paper into dried filter flask
    • filtrate stored in 20 mL vial & clay air-dried overnight
  2. 30 min exchange, 1:5 salt to clay
    • 0.100 g CuSO4 in 20 mL DI
    • Added 0.500 g NaMT
    • Stirred 30 min ± 1 min and filtered through 41 Whatman paper into dried filter flask
    • filtrate stored in 20 mL vial & clay air-dried overnight
  3. 60 min exchange, 2:2 salt to clay
    • 0.200 g CuSO4 in 20 mL DI
    • Added 0.200 g NaMT
    • Stirred 60 min ± 2 min and filtered through 41 Whatman paper into dried filter flask
    • filtrate stored in 20 mL vial & clay air-dried overnight


AA Clay Exchange Solutions

  • 10 mL total solution stored in 15 mL centrifuge tubes
  • Used clay exchange filtrate solutions
  • Diluted with 16.7 MΩ DI
  • 100 - 1000 μL pipetters were sticking, so precision of solutions likely to be low
  • Mixed 50 μL filtrate and 9.950 mL DI
  • 2:5 salt to clay (10 min, 30 min, 2 hr, & 24 hr) and 1:1 (1 hr)


AA Flame Spectroscopy

  • Cu lamp, 0.2 cm slit
  • AA Wizard, single measurement per sample
     Sample [Cu2+] (ppm, measured) [Cu2+] (ppm, solution) [Cu2+] (ppm, adsorbed)
Stnd 0       -0.0101 (abs)           0.0000
Stnd 1       -0.0028 (abs)           1.3300
Stnd 2       +0.0019 (abs)           2.6600
Stnd 3       +0.0080 (abs)           6.6400
Stnd 4       +0.0290 (abs)         13.3000
Water           -0.2536
1-5_24h           1.9010           380           1906
1-5_2h           2.4853           497           1789
1-5_30m           3.7270           745           1541
1-5_10m           4.0556           811           1475
1-5_ctrl           11.4324           2286              0
2-2_1h           25.6748           5135           -563


NOTE 1: Based on AA absorbance of Ctrl soln, 0.18 g CuSO4 added
NOTE 2: Theoretical maximum [Cu2+] exchanged in interlayer of 0.5 g NaMT = 763 ppm. Surface adsorption taking place!
NOTE 3: Higher concentration solution outside calibration. Absorbance may not be linear here, as noted by neg. exchange.

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