aromatic foulant-induced fouling toward the aromatichydrocarbon-based AEMs could be serious. Figure 6 illustrates the structure of a commercially available hydrocarbontype AEM and a suggested mechanism for fouling by aromatic compounds where two aspects of the fouling mechanism are indicated: affinity between anions and the
oppositely charged fixed groups of the AEM, and affinity as
p–p interactions between the aromatic membrane matrix and
compounds (Tanaka et al. 2011).
According to Allison, organic molecules causing an
irreversible membrane fouling usually have fixed charged
groups and aromatic rings (Allison 2005). Hydrophobic
interactions between benzene rings of organic molecule and
the membrane polymer are the main reason for strong irreversible surface adsorption (Bukhovets et al. 2010).
Accordingly, a promising anti-fouling strategy is to fabricate
an aliphatic polymer backbone matrix (avoiding affinity
interaction between the organic foulants and membrane
surface) and a hydrophilic membrane surface (Liu et al.
2019).
Tanaka et al. (2011) prepared AEM with aliphatic
hydrocarbon matrix and deduced that the permeability
coefficient for sodium dodecyl benzene sulfonate (DBS) of
AEMs with aliphatic matrix was lower than that of aromatic
AEMs in ED system. AEMs with various membrane structures were prepared by introducing various amines:
trimethylamine (TMA), triethylamine (TEA), tri-npropylamine (TPA) and tri-n-butylamine (TBA) into precursor membranes prepared from chloromethylstyrene
(CMS)-divinylbenzene (DVB) and glycidyl methacrylate
(GMA)-DVB. The voltage change through the AEMs during
ED operation using solutions containing DBS as a foulant
indicated that aliphatic AEMs show lower fouling than
aromatic ones (Higa et al. 2014).
Wang et al. (2017) compared the interaction (fouling)
among varying model organics [sodium dodecyl benzene
sulfonate (SDBS), bovine serum albumin (BSA), sodium
humate and sodium alginate (SA)] and the varying AEMs
(TWEDAI and TWEDAII). TWEDAI and TWEDAII are
made by aliphatic monomers and aromatic monomers in a
Table 4 Anti-fouling strategy of AEM
Functional materials
Fabrication
method
Feed solution
Performance
References
SDA
Polymerization
and deposition
0.05 M NaCl and
174 mg/L SDBS
The transition time of SDA-modified AEM
(112 min) showed better anti-fouling
performance than the original AEM (76 min)
Ruan et al.
(2018)
PSS
Electrodeposition
0.05 M NaCl and SDBS
Surface modification of PSS resulted in better
anti-fouling properties at SDBS concentrations
that range from 1 Â 10
4 kg/m
3 to
6 Â 10
4 kg/m
3
Sri Mulyati
et al. (2012)
PSS-PAH
Electrodeposition
0.05 M NaCl, and
52 mg/L SDBS
The transition time increased more than
150 min by seven layers, compared to 0 min
without surface modification
Mulyati et al.
(2013)
PSS-PDADMAC
Electrodeposition
0.1 M NaCl containing
75 mg/L SDS
Modification of AEM showed better
anti-fouling performance than the pristine AEM
with higher SDS (100 mg/L)
Zhao et al.
(2018b)
A-3, NB-8
Chemical
adsorption
0.05 N Na 2 SO 4 and 30–
90 mg/L HA, 0.05 N
Na 2 SO 4 and 30–
100 mg/L DBS
With 30 mg/L DBS, modification of AEM with
A-3 no fouling occurred. Modification of AEM
with NB-8 agent permitted electrodialysis of
solutions containing 100 and 60 mg/L of DBS
and HA, respectively
Grebenyuk
et al. (1998)
GO-PDA
Electrodeposition
0.1 M NaCl and
150 mg/L SDBS
After being fouled by 150 mg/L SDBS for 4 h,
the desalination rate of GO and PDA
surface-modified AEM increased by 39.3%
compared to pristine membrane
Li et al.
(2018b)
PDA
Chemical
adsorption
0.05 M NaCl and SDBS
The transition time for PDA-modified AMX
membrane was extremely longer than that for
the pristine membrane above the critical
micelle concentration of SDBS
Vaselbehagh
et al. (2014)
PDA-PSS-HACC-Ag
Np
Chemical
adsorption and
electrodeposited
0.05 M NaCl and 1.0 g/L
SDBS
The time elapsed until the occurrence of fouling
(transition time) of the modified AEM
(125 min) is much longer than that of the
original one (60 min)
Hao et al.
(2018)
20
L. Han
oppositely charged fixed groups of the AEM, and affinity as
p–p interactions between the aromatic membrane matrix and
compounds (Tanaka et al. 2011).
According to Allison, organic molecules causing an
irreversible membrane fouling usually have fixed charged
groups and aromatic rings (Allison 2005). Hydrophobic
interactions between benzene rings of organic molecule and
the membrane polymer are the main reason for strong irreversible surface adsorption (Bukhovets et al. 2010).
Accordingly, a promising anti-fouling strategy is to fabricate
an aliphatic polymer backbone matrix (avoiding affinity
interaction between the organic foulants and membrane
surface) and a hydrophilic membrane surface (Liu et al.
2019).
Tanaka et al. (2011) prepared AEM with aliphatic
hydrocarbon matrix and deduced that the permeability
coefficient for sodium dodecyl benzene sulfonate (DBS) of
AEMs with aliphatic matrix was lower than that of aromatic
AEMs in ED system. AEMs with various membrane structures were prepared by introducing various amines:
trimethylamine (TMA), triethylamine (TEA), tri-npropylamine (TPA) and tri-n-butylamine (TBA) into precursor membranes prepared from chloromethylstyrene
(CMS)-divinylbenzene (DVB) and glycidyl methacrylate
(GMA)-DVB. The voltage change through the AEMs during
ED operation using solutions containing DBS as a foulant
indicated that aliphatic AEMs show lower fouling than
aromatic ones (Higa et al. 2014).
Wang et al. (2017) compared the interaction (fouling)
among varying model organics [sodium dodecyl benzene
sulfonate (SDBS), bovine serum albumin (BSA), sodium
humate and sodium alginate (SA)] and the varying AEMs
(TWEDAI and TWEDAII). TWEDAI and TWEDAII are
made by aliphatic monomers and aromatic monomers in a
Table 4 Anti-fouling strategy of AEM
Functional materials
Fabrication
method
Feed solution
Performance
References
SDA
Polymerization
and deposition
0.05 M NaCl and
174 mg/L SDBS
The transition time of SDA-modified AEM
(112 min) showed better anti-fouling
performance than the original AEM (76 min)
Ruan et al.
(2018)
PSS
Electrodeposition
0.05 M NaCl and SDBS
Surface modification of PSS resulted in better
anti-fouling properties at SDBS concentrations
that range from 1 Â 10
4 kg/m
3 to
6 Â 10
4 kg/m
3
Sri Mulyati
et al. (2012)
PSS-PAH
Electrodeposition
0.05 M NaCl, and
52 mg/L SDBS
The transition time increased more than
150 min by seven layers, compared to 0 min
without surface modification
Mulyati et al.
(2013)
PSS-PDADMAC
Electrodeposition
0.1 M NaCl containing
75 mg/L SDS
Modification of AEM showed better
anti-fouling performance than the pristine AEM
with higher SDS (100 mg/L)
Zhao et al.
(2018b)
A-3, NB-8
Chemical
adsorption
0.05 N Na 2 SO 4 and 30–
90 mg/L HA, 0.05 N
Na 2 SO 4 and 30–
100 mg/L DBS
With 30 mg/L DBS, modification of AEM with
A-3 no fouling occurred. Modification of AEM
with NB-8 agent permitted electrodialysis of
solutions containing 100 and 60 mg/L of DBS
and HA, respectively
Grebenyuk
et al. (1998)
GO-PDA
Electrodeposition
0.1 M NaCl and
150 mg/L SDBS
After being fouled by 150 mg/L SDBS for 4 h,
the desalination rate of GO and PDA
surface-modified AEM increased by 39.3%
compared to pristine membrane
Li et al.
(2018b)
PDA
Chemical
adsorption
0.05 M NaCl and SDBS
The transition time for PDA-modified AMX
membrane was extremely longer than that for
the pristine membrane above the critical
micelle concentration of SDBS
Vaselbehagh
et al. (2014)
PDA-PSS-HACC-Ag
Np
Chemical
adsorption and
electrodeposited
0.05 M NaCl and 1.0 g/L
SDBS
The time elapsed until the occurrence of fouling
(transition time) of the modified AEM
(125 min) is much longer than that of the
original one (60 min)
Hao et al.
(2018)
20
L. Han