Graphene Oxide and Reduced Graphene Oxide as Nanofillers …
135
Table 4 Thermal features and tensile properties of Ps UF and Ps–nRGO composite UF membranes
[105]
Thermal features
Mechanical features
Membrane code
T d (˚C)
Mass loss (%)
TS (MPa)
EB (%)
Ps UF
507.8
57.61
2.94 ± 0.16
36.83
Ps-nRGO UF-1
513.5
51.56
3.33 ± 0.11
32.41
Ps-nRGO UF-2
512.9
53.61
3.42 ± 0.07
30.04
Ps-nRGO UF-3
509.7
54.01
3.12 ± 0.19
34.01
Ps-nRGO UF-4
510.4
52.55
2.84 ± 0.24
38.18
permeability and solute rejection. Measurements were carried out using polyethylene glycol (PEG) with an average molecular weight of 35 kDa and polyethylene
oxide (PEO) with average molecular weight of 100 kDa. The studies showed that an
optimum loading of nRGO (2 w/w%) into the PS matrix leads to membranes with
high solute rejection without comprising the flux reduction as compared with the
PS ultrafiltration membrane. Moreover, the optimum loading of nRGO resulted in a
membrane with better thermal and mechanical stability, which is presented in Table 4.
In another study, TFN membrane was developed by Yin et al. [40]. In this work,
GO was prepared applying a modified Hummers’ method [120] from graphite flakes
and used as nanofiller to produce the TFN membrane. Then, GO nanosheets were
embedded into the ployamide (PA) layer using the in situ interfacial polymerization
process at 0–0.02 wt% of GO. Results indicated that by GO content enhancement,
the contact angle of TFN membranes slightly reduced from 60.4 ± 2.5˚ to 55.4 ±
1.7˚, which led to increasing hydrophilicity of the membrane. The water flux and salt
rejection of the membrane were also investigated. The membrane water permeance
was improved under optimal loaded GO concentration as demonstrated in Fig. 19.
To evaluate the salt rejection of the membrane, 2000 mg/L of Na 2 SO 4 and NaCl
were tested. From Fig. 19, the rejection of Na 2 SO 4 and NaCl reduced slightly, which
shows the negligible effect of incorporated GO into the membrane on salt rejection.
In addition, in order to study the influence of the employed nanofiller, they compared
their results with other studies as shown in Table 5, which indicated relatively good
effect of the added GO. Furthermore, the stability of the synthesized membrane
was investigated by testing selective samples for 72 h filtration time, which showed
acceptable stability under examining conditions.
Fryczkowska et al. [101] reported an innovative technique to incorporate rGO
into the polyacrylonitrile (PAN) membranes. In this work, GO was prepared from
graphite powder by the modified Hummers’ method [120]. Then, GO thermal reduction method was performed to prepare rGO. The phase inversion method was applied
to fabricate the PAN/rGO membranes from the dispersion of rGO in a solution of
PAN dissolved in DMF. Structural studies confirmed the good dispersion of rGO into
PAN membranes. To investigate the effect of rGO concentration on the performance
of fabricated nanocomposite, a wide range of rGO concentrations (from 0.11% to
29.4% w/w) were examined (Table 6). The comparison of the contact angle (Table 6)
135
Table 4 Thermal features and tensile properties of Ps UF and Ps–nRGO composite UF membranes
[105]
Thermal features
Mechanical features
Membrane code
T d (˚C)
Mass loss (%)
TS (MPa)
EB (%)
Ps UF
507.8
57.61
2.94 ± 0.16
36.83
Ps-nRGO UF-1
513.5
51.56
3.33 ± 0.11
32.41
Ps-nRGO UF-2
512.9
53.61
3.42 ± 0.07
30.04
Ps-nRGO UF-3
509.7
54.01
3.12 ± 0.19
34.01
Ps-nRGO UF-4
510.4
52.55
2.84 ± 0.24
38.18
permeability and solute rejection. Measurements were carried out using polyethylene glycol (PEG) with an average molecular weight of 35 kDa and polyethylene
oxide (PEO) with average molecular weight of 100 kDa. The studies showed that an
optimum loading of nRGO (2 w/w%) into the PS matrix leads to membranes with
high solute rejection without comprising the flux reduction as compared with the
PS ultrafiltration membrane. Moreover, the optimum loading of nRGO resulted in a
membrane with better thermal and mechanical stability, which is presented in Table 4.
In another study, TFN membrane was developed by Yin et al. [40]. In this work,
GO was prepared applying a modified Hummers’ method [120] from graphite flakes
and used as nanofiller to produce the TFN membrane. Then, GO nanosheets were
embedded into the ployamide (PA) layer using the in situ interfacial polymerization
process at 0–0.02 wt% of GO. Results indicated that by GO content enhancement,
the contact angle of TFN membranes slightly reduced from 60.4 ± 2.5˚ to 55.4 ±
1.7˚, which led to increasing hydrophilicity of the membrane. The water flux and salt
rejection of the membrane were also investigated. The membrane water permeance
was improved under optimal loaded GO concentration as demonstrated in Fig. 19.
To evaluate the salt rejection of the membrane, 2000 mg/L of Na 2 SO 4 and NaCl
were tested. From Fig. 19, the rejection of Na 2 SO 4 and NaCl reduced slightly, which
shows the negligible effect of incorporated GO into the membrane on salt rejection.
In addition, in order to study the influence of the employed nanofiller, they compared
their results with other studies as shown in Table 5, which indicated relatively good
effect of the added GO. Furthermore, the stability of the synthesized membrane
was investigated by testing selective samples for 72 h filtration time, which showed
acceptable stability under examining conditions.
Fryczkowska et al. [101] reported an innovative technique to incorporate rGO
into the polyacrylonitrile (PAN) membranes. In this work, GO was prepared from
graphite powder by the modified Hummers’ method [120]. Then, GO thermal reduction method was performed to prepare rGO. The phase inversion method was applied
to fabricate the PAN/rGO membranes from the dispersion of rGO in a solution of
PAN dissolved in DMF. Structural studies confirmed the good dispersion of rGO into
PAN membranes. To investigate the effect of rGO concentration on the performance
of fabricated nanocomposite, a wide range of rGO concentrations (from 0.11% to
29.4% w/w) were examined (Table 6). The comparison of the contact angle (Table 6)