Metrohm Inline-Ultrafiltration - Manual (Page 25)

￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭
4 Operation and maintenance
IC equipment: Inline-Ultrafiltration
￭￭￭￭￭￭￭￭ 19
Table 1 Filtration of various samples
Sample designation Number of samples per filter
Orange juice with fruit pulp 40
Surface water 500
Drinking water 1,000
Ground water 500
Waste water 1 1,000
Waste water 2 130
Waste water 3 40
Waste water 4 80
NaCl solution (1%) 5,000
Schöniger absorption solution 100
Acidic earth extracts 1,000
Aqueous earth extracts 200
4.1.2 Selecting the filtration membrane
You can apply existing sample preparation procedures to the Metrohm
ultrafiltration cell (6.2729.110). If you wish to use a different filtration
membrane than the one supplied, please note that, even if the particle
size is known, selecting a membrane with a suitable pore size does not
automatically yield the desired results.
Our investigations have shown that the retention capacity of conventional
filtration membranes does not always correspond to their specified pore
size. The following table shows the qualitative filtration action of filtration
membranes with different nominal pore sizes. Aqueous solutions contain-
ing silica particles with particle sizes of 1.5 µm and 5 µm were used in the
test.
Table 2 Selection of the filtration membrane
Test solutions: silica
particles in water Pore size of the
filtration membrane
1
Effect
0.5%, 5 µm 0.15 µm no permeation
0.5%, 5 µm 3 µm no permeation
0.5%, 5 µm 8 µm no permeation
0.5%, 5 µm 10 µm permeation 2
0.5%, 5 µm 12 µm no permeation
0.5%, 1.5 µm 0.15 µm no permeation
0.5%, 1.5 µm 3 µm permeation