1. Adsorption techniques for gas purification
Hardy Simgen
Max-Planck-Institute for Nuclear Physics
Heidelberg / GERMANY

2. H. Simgen, MPI for Nuclear Physics / Heidelberg
Outline
Principles of adsorption
Column purification
Adsorption on activated carbon
Single component adsorption
Multi component adsorption
Individual systems
N2/Rn, Ar/Rn, He/Ar
The N2/Kr-system
Summary
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

3. Radioactive noble gases in the atmosphere
Source
Activity concentration (STP)
42Ar
cosmogenic
0.5 µBq/m3 air
50 µBq/m3 Ar
39Ar
17 mBq/m3 air
1.8 Bq/m3 Ar
85Kr
235U fission (nuclear fuel reprocessing plants)
1.4 Bq/m3 air
1.2 MBq/m3 Kr
222Rn
Primordial 238U
10 to >100 Bq/m3 air
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

4. H. Simgen, MPI for Nuclear Physics / Heidelberg
Adsorption in pores
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

5. n = H • p Henrys Law valid for low partial pressures
n = number of moles adsorbed [mol/kg]
p = partial pressure of adsorptive [Pa]
H = Henry coefficient [mol/(kg·Pa)]
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

6. H. Simgen, MPI for Nuclear Physics / Heidelberg
Column purification
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

7. H. Simgen, MPI for Nuclear Physics / Heidelberg
Column purification
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

8. H. Simgen, MPI for Nuclear Physics / Heidelberg
Column purification
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

9. H. Simgen, MPI for Nuclear Physics / Heidelberg
Column purification
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

10. H. Simgen, MPI for Nuclear Physics / Heidelberg
Column purification
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

11. H. Simgen, MPI for Nuclear Physics / Heidelberg
Column purification
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

12. H. Simgen, MPI for Nuclear Physics / Heidelberg
quantitatively …
for large N (many stages):
VRet = HRTmAds
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

13. Pore size distribution
Activated Carbon
pore size [Å]
Pore size distribution
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

14. H. Simgen, MPI for Nuclear Physics / Heidelberg
Single component adsorption model S. Maurer, Ph.D. thesis, TU Munich (2000)
Prediction of Henrys constant for adsorption on activated carbon
Only one gas parameter: TC•pC-0.5
allows to compare adsorption of different components
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

15. for single component adsorption in gas phase !
Maurer formula for H
for single component adsorption in gas phase !
Gas TC PC
TC·PC-0.5
H [mol/(kg·Pa)]
[K]
[bar]
[K·bar-0.5]
T=-100°C
T=-196°C He
5.2
2.3
3.4
1E-7
8E-7 Ar
151 49
21.6
2E-4
6E+1 N2
126 34
CH4
191 46
28.0
3E-3
4E+4 Kr
209 55
28.2 Xe
290 59
37.8
2E-1
7E+8 Rn
377 63
47.6
1E+1
1E+13
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

16. Realization in low-level physics
behaviour at ultralow concentrations?
problem of re-contamination
practical limitations:
column density (troughput)
temperature stability …
at least 2 components
multi-component adsorption
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

17. H. Simgen, MPI for Nuclear Physics / Heidelberg
N2 / Rn - system
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

18. H. Simgen, MPI for Nuclear Physics / Heidelberg
N2 / Rn - system
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

19. MoREx (Mobile Radon Extraction Unit)
-100
-196
-100
-196
-196
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

20. MoREx (Mobile Radon Extraction Unit)
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

21. HD II propor-tional counter
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

22. Noble gas purification line
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

23. H. Simgen, MPI for Nuclear Physics / Heidelberg
N2 purification plant
222Rn <0.3 μBq/m3 N2
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

24. H. Simgen, MPI for Nuclear Physics / Heidelberg
222Rn in argon Ar
-100
-186
-100
-186
222Rn <0.3 μBq/m3 Ar
-186
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

25. H. Simgen, MPI for Nuclear Physics / Heidelberg
He / Ar - system
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

26. H. Simgen, MPI for Nuclear Physics / Heidelberg
He / Ar - system
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

27. H. Simgen, MPI for Nuclear Physics / Heidelberg
Homestake experiment
Raymond Davis jr.
Nobel prize
2002
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

28. H. Simgen, MPI for Nuclear Physics / Heidelberg
N2 / Kr - system
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

29. H. Simgen, MPI for Nuclear Physics / Heidelberg
N2 / Kr - system
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

30. Noble gas mass spectrometer
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

31. H. Simgen, MPI for Nuclear Physics / Heidelberg
Experimental setup
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

32. Kr breakthrough (LN2 cooling)
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

33. H. Simgen, MPI for Nuclear Physics / Heidelberg
Gas phase adsorption
Problem of N2 condensation at 77 K
If pure gas phase, there is higher
mobility of gases
surface diffusion
→ Particles reach appropriate pores faster
But low temperature is required
Liquid argon cooling!
alternatively: pressurized liquid nitrogen
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

34. Kr breakthrough (LAr cooling)
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

35. H. Simgen, MPI for Nuclear Physics / Heidelberg
Adsorption potential
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

36. Potential for Kr adsorption on activated carbon
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

37. H. Simgen, MPI for Nuclear Physics / Heidelberg
H and pore sizes
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

38. Pore size distribution?
Carbon molecular sieve
Activated Carbon
pore size [Å]
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

39. Kr breakthrough (LAr cooling)
Carbon molecular sieve
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

40. H. Simgen, MPI for Nuclear Physics / Heidelberg
Three other systems
N2 / Ar
Impossible
Very
challenging !
Ar / Kr Rn Xe
Should work
 Xmass
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg

41. H. Simgen, MPI for Nuclear Physics / Heidelberg
Summary
Adsorption is powerful tool to produce ultrapure gases.
simple operation / cheap
Activated carbon is well suited for many applications.
Rn purification is very efficient, but problem of re-contamination.
Kr removal from N2/Ar can be done with
optimized adsorbers and
gas phase adsorption
16/11/2018
H. Simgen, MPI for Nuclear Physics / Heidelberg