Filtration Membranes Containing Nanoparticles of Hydrated …
761
3 Membrane Test
The diffusion of ions was studied in a two-chamber cell divided with a tested
membrane. The first compartment was filled with 0.1 M solutions of LiCl or NaCl,
deionized water-filled other chambers. The concentration of Li
+ and Na
+ ions was
determined by means of a PFM-U4 flame photometer (Analitpribor, Belarus) and
a Pye Unicam 8800 UV/VIS atomic absorption spectrophotometer (Philips, the
Netherlands).
Preliminarily the membranes were pressurized in deionized water at 1 bar and
298 K, the volume of permeate was monitored. When this volume was constant, tap
water was filtered. Water contained 1 mol dm
−3 Ca
2+ and 0.5 mol dm
−3 Mg
2+ , as
well as organic additions (COD was 15 mg O 2 m
−3 ) and colloidal additions of iron
hydroxide, which were formed as a result of corrosion of water pipes. The permeate
was analyzed with an atomic absorption method.
The experimental stack for filtration included a divided two-chamber cell of
tangential type (the effective membrane area was 3.85 × 10
−3 m
2 ), a fluid supply
line, which provided the liquid circulation through the concentration compartment,
a thermostat and measuring devices (manometer, rotameter) [31, 32]. The filtering
of solutions of ovalbumin (OVA) and bovine serum albumin (BSA) was investigated
(the protein concentration was 1 g dm
−3 ). The molecular mass of OVA and BSA is
40 and 69 kDa, respectively.
Filtration of protein solutions was performed at 1–2 bar. The protein concentration
in the permeate was determined by the Bradford method using Coomassie brilliant
blue G-250 [64]. The selectivity of the membranes (ϕ) was evaluated by the retention
capacity according to:
f =
1 −
C p
C 0
× 100%
(1)
where C p and C 0 are the concentrations of the permeate and initial solution,
respectively.
4 Membrane Morphology
TEM images of the HZD–GO composite are given in Fig. 1a. GO nanosheets
are aggregated through their edges forming a compact coating of primary HZD
nanoparticles, which cannot be recognized.
In the case of composite membrane, the outer surface is a relief, protrusions (up
to several tens of nanometers) are visible indicating a presence of the modifier inside
the active layer. The size of these protrusions corresponds to the possible pore size
of active layer. According to the data of Table 1, the pore size decreases within the
order: PAN-2 < PAN-3 < PAN-4. Large particles of irregular shape, a size of which
761
3 Membrane Test
The diffusion of ions was studied in a two-chamber cell divided with a tested
membrane. The first compartment was filled with 0.1 M solutions of LiCl or NaCl,
deionized water-filled other chambers. The concentration of Li
+ and Na
+ ions was
determined by means of a PFM-U4 flame photometer (Analitpribor, Belarus) and
a Pye Unicam 8800 UV/VIS atomic absorption spectrophotometer (Philips, the
Netherlands).
Preliminarily the membranes were pressurized in deionized water at 1 bar and
298 K, the volume of permeate was monitored. When this volume was constant, tap
water was filtered. Water contained 1 mol dm
−3 Ca
2+ and 0.5 mol dm
−3 Mg
2+ , as
well as organic additions (COD was 15 mg O 2 m
−3 ) and colloidal additions of iron
hydroxide, which were formed as a result of corrosion of water pipes. The permeate
was analyzed with an atomic absorption method.
The experimental stack for filtration included a divided two-chamber cell of
tangential type (the effective membrane area was 3.85 × 10
−3 m
2 ), a fluid supply
line, which provided the liquid circulation through the concentration compartment,
a thermostat and measuring devices (manometer, rotameter) [31, 32]. The filtering
of solutions of ovalbumin (OVA) and bovine serum albumin (BSA) was investigated
(the protein concentration was 1 g dm
−3 ). The molecular mass of OVA and BSA is
40 and 69 kDa, respectively.
Filtration of protein solutions was performed at 1–2 bar. The protein concentration
in the permeate was determined by the Bradford method using Coomassie brilliant
blue G-250 [64]. The selectivity of the membranes (ϕ) was evaluated by the retention
capacity according to:
f =
1 −
C p
C 0
× 100%
(1)
where C p and C 0 are the concentrations of the permeate and initial solution,
respectively.
4 Membrane Morphology
TEM images of the HZD–GO composite are given in Fig. 1a. GO nanosheets
are aggregated through their edges forming a compact coating of primary HZD
nanoparticles, which cannot be recognized.
In the case of composite membrane, the outer surface is a relief, protrusions (up
to several tens of nanometers) are visible indicating a presence of the modifier inside
the active layer. The size of these protrusions corresponds to the possible pore size
of active layer. According to the data of Table 1, the pore size decreases within the
order: PAN-2 < PAN-3 < PAN-4. Large particles of irregular shape, a size of which