PEO with octylphenol or polypropylene
oxide head group
cost savings by surface modification
Decline in flux relative to untreated
membrane, only T-X 100 improved rejection significantly, P-F87 was the only
treatment that resulted decline in rejection after fouling, surfactant cause decrease
in roughness without a large change in zeta potential after fouling.
Polyether-polyamide block copolymer
To see effect on membrane fouling and
Coating reduced surface roughness
without significant change in CA, enhanced fouling resistance against a model
oil/surfactant/water emulsion feed, the coating reduced water flux whithout
change salt rejection, coating remained on the surface of the membranes after
106 days of filtration.
To improve antifouling properties
Coating reduced pure water permeability
by 37%, by
increase in the PEI concentration,
flux decreased (from 23.5 L/m2 h to 15 L/m2 h), salt rejection improved from 77.9%
to 82.2% for NaCl and from 72.2% to 91.2% for MgCl2, improved fouling
resistance and the increased surface hydrophilicity.
PEG based coating (poly ethylene
glycol diacrylate + poly ethylene glycol acrylate, 2-hydroxyethyl acrylate,
or acrylic acid)
To increase fouling resistance.
Coating reduced the water flux of
membrane, salt rejection of both coated and uncoated membranes is 99.0% or
higher, coating caused small reduction in the negative charge of membranes,
negatively charged membranes fouled extensively in the presence of positively
foulant and minimal fouling in the presence of negatively foulant, more
resistant of coated membranes to fouling in surfactant feed solutions and in
an oil/ water emulsion made with DTAB
Polyethylene glycol acrylate (PEGA) followed
by Glutaraldehyde (GA) crosslinking
To increase fouling resistance.
Reduction in Contact Angle (from 49.2 for
bare membrane to 45.6) and surface roughness by coating, The pure water flux
decreased with increasing the PEGA concentration and increasing GA concentration,
exhibited better antifouling properties, recovered 100% of their initial
water flux after physical cleaning.
To check performance of modified
roughness by coating (from 87 nm to
106), decrease in CA from about> 55 for the unmodified membrane, increase
in CA by increasing environmental temperature, little influence of coating on
salt rejection (between 97% and 98% as that of the original membranes), decreases
of water flux by increasing coating concentration, good durability and high performance
stability of coating layer.
Polydopamine (PDA) deposition followed
by PEG-NH2 grafting
Effect on flux and foulant adhesion
coating exhibited a small decrease in
flux with increasing PDA deposition, PEG grafting reduced RO flux, PDA
deposition reduced BSA adhesion and more BSA adhesion reduction was observed when
Polyamidoamine (PAMAM) and PAMAM– polyethylene
Reduce contact angle and increase
biofoulants and organic pollutants resistance.
Coated membranes had reduced flux
(from 0.11 mL/cm2 min for uncoated membranes to 0.08 mL/cm2 min for coated
membranes) without salt rejection (about 99%), reduction in CA (from 60° to
polyether-polyamide block copolymer
(PEBAX): 1 wt% in
n-butanol or 1:1
ethanol: water (mass
To enhance water flux
Ethanol re-soaking of PEBAX-coated
membranes increased the water flux of membranes by almost 70%, from 2.6 L/(m2
h) to 4.5 L/(m2 h) and decrease salt rejection from 96.8% to 95.4%.
Triethylene glycol dimethyl ether (Triglyme)
To improve anti-fouling performance.
By increasing the time of plasma
polymerization, CA reduced and surface roughness increased, lower
organic fouling, a little reduction of
salt rejection (97.9–98.1%), more reversibility of the fouling
P(NIPAM-co-Am) – N-isopropylacrylamide
To improve acid stability and chlorine
By increasing copolymer from 0 to 200
ppm, the CA decreased from 62.5° to 36.6°, and then leveled off, both the
water flux and salt rejection of membrane slightly increased at lower coating
concentration and then gradually decreased, both of the acid stability and
chlorine resistance of the modified membrane increased with increasing the
P(NIPAm-co-AAc) – N-isopropylacrylamide-co-acrylic
To increase NaCl and Na2SO4
rejection and fouling resistance.
Coating increased membrane surface hydrophilicity
and surface charge at neutral pH, decreased the salt
permeability of NaCl and Na2SO4,
fouling resistance to BSA, enhanced cleaning
P(NIPAM-co-Am) – poly(N-isopropylacrylamide-co-acrylamide)
To improve fouling resistance and
Reduction of CA from about 58.6° to
40.5°with increasing the coating concentration, the pure water permeability slightly
increased and then gradually decreased by increasing deposition time, increase
in water permeability by 12% and the salt rejection slightly (from 98.5% to
98.9%), improved fouling resistance of membrane to BSA, enhanced cleaning efficiency.
For antifouling coating.
Slight increase in the surface
roughness and increase in CA with increasing PFDA content, flux decline (13%)
for 20 nm coatings with 40% PFA content for short term permeation tests with
Methyl methacrylate- hydroxyl poly
(oxyethylene) methacrylate (MMA-HPOEM)
To introduce hydrophilicity and
Slower flux decline of modified
membrane than the virgin membrane for BSA (37% and 44%) and seawater,
antifouling property against reversible and irreversible fouling of E. coli,
durability of coating layer to chemical cleaning.
Ring-opening by DMAP followed by SPGE
and glycerol coating
To improve chlorine resistance.
SPGE membranes were more hydrophilic
and smoother, improved chlorine stability, with increasing DMAP concentration,
water flux increased and salt rejection decreased, by increasing SPGE
concentration water flux decreased and salt rejection increased.
PDA deposition followed by PEG-NH2
To improve bioinspired fouling
PDA increased 30–50% water flux and
oil/water fouling resistance, the
PD-g-PEG coating exhibited no flux decline and no fouling, modified membranes
exhibited an increase in irreversible fouling resistance.
3-(3,4-dihydroxyphenyl)- L alanine
To increase flux and fouling
No change in zeta potential after
modification, reduction of CA from 55 to 15, intact salt rejection intact
(about 97%), increased water flux with increasing the coating duration (1.27
times of original membrane), improved the BSA adhesion resistance, enhanced
the organic and surfactant fouling resistance, high water flux recovery ratio
PEG acrylate multilayers (containing
PAA-Alk, PEG-Az or PEG-Alk)
To make high flux and fouling
fouling resistance and CA reduction
for coated membranes, for seawater membranes, the flux decline 9–17% and salt
rejection increase small and for brackish water, no reduction in the flux and
slight increase in salt rejection relative of the uncoated value
Coating with sericin followed by GA crosslinking
To improve fouling resistance.
Sericin coating improved surface
hydrophilicity, smoothed surface morphology, enhanced negative charge, lower
pure water permeability, enhanced salt rejection, improved fouling resistance
Polyvinylalcohol (PVA) polyhexamethylene
guanidine hydrochloride (PHMG)
To enhance anti-biofouling performance
Smoothening the membrane surface with
all coatings (67.8 nm for uncoated and lowest RMS for PVA by the value42.5
nm), reduction in CA (from 53.2 for uncoated to15.9 for PHMG), Lower number
of adhered bacteria on all coated membranes, membranes with higher PHMG
percentage had higher antimicrobial performance, reduced water permeability
and salt rejection after modification.
To increase flux and fouling
No change in CA with modification of
membranes (about 19), decreasing pure water flux and salt rejection with increasing
dopamine concentration and deposition time, more resistant of modified membranes
to in oil/water emulsion fouling (as judged by higher permeate flux), little
effect of variations in dopamine concentration, deposition times, and alkaline
pH on the fouling resistance of coated membranes.
Polydopamine (PDA) and polydopamine-g-PEG
To increase fouling resistance.
The PDA-coated RO membranes did not enhance
water flux or depress transmembrane pressure difference relative to the
unmodified module due to the cleanliness of the RO feed after UF pretreatment,
salt rejection was higher and more stable in the modified membrane.
Hydroxyethyl methacrylate and
To reduce attachment of bacterial
Increasing the PFDA content in the
films leaded to increase the CA (from 38 for bare membrane to 64) and surface
roughness, increasing the thickness of the coatings increased the surface
roughness and decreased the permeation rates (from 170 L/m2 h for bare
membrane to 80 L/m2 h for 100 nm coating thickness), by increase
the PDFA content the permeation rates of the coated membranes decrease,
reduction in cell attachment on the coated surface.
P(MDBAC-r-Am-r-HEMA) coating followed
by GA crosslinking
To improve chlorine resistance and antifouling
Coating decreased flux, increased salt
rejection, more tolerance chlorine exposure (7–10 times the pristine
membrane), better wettability, fouling resistance, antimicrobial properties.
phosphorylcholine (MPC)-co-2-amino ethylmethacrylate (AEMA)
For high resistance to bacterial adhesion
The coating reduced CA (from 36 of
bare membrane to 18.6) and change the surface charge from a negative to a neutral
value, decline in water permeability about 20% an increase in salt rejection
(from 94.7 to 96.9), high resistance
to bacterial adhesion
To improve antibiofouling potential
PDA did not affect the hydrophilicity,
surface charge and salt rejection, PDA enhanced the biofouling resistance of membranes,
improvement in the bacterial adhesion resistance
PDA coating followed by
AEMA) as the PZ
To improve antibiofouling potential
No change of hydrophilicity with PDA
and/or PZ modification, changing surface charge from negative to neutral by
PZ immobilization, permeability and rejection were not affected by modification,
enhanced biofouling resistance and lower bacterial attachment of with PZ
deposition followed by reaction with
PS to obtain pyridine-based sulfobetaine
For prevention of biofouling.
Coating decreased surface roughness
(from 1.3 nm to 0.8 nm), with the 30-nm coating thickness, the water flux is
reduced only by ~14% compared to untreated membranes whiteout changing the
salt rejection, the addition of 4% DVB produces a major increase in the
resistance to chlorine, whereas additions beyond 4% result in minor
additional resistance, good fouling resistance against BSA and bacterial attachment.
Hydroxyethyl methacrylate (HEMA) and
the hydrophobic perfluoro decylacrylate (PFDA)
To reduce attachment of bacteria.
By increasing PFDA content, the
roughness of surface (< 5 nm) and static contact angle increased, coatings was very smooth and conformal, the intermediate chemistry (40% PFDA) showed less alginate adsorption and highest resistance to bacterial adhesion (2 orders of magnitude). 59 2014 Hydroxyethyl methacrylate (HEMA) and the hydrophobic perfluoro decylacrylate (PFDA) To enhance the biofouling resistance without much affecting permeate flux and salt rejection Deposited film were smooth and conformal, modified surface were initially very hydrophobic but quickly assumed a hydrophilic character within few minutes, modification caused flux decline about 10% of the original value and negligible change in rejection. 60 2014 Atomic layer deposition trimethylaluminium (AlMe3) – (ALD-Al2O3) To reduce Pseudomonas aeruginosa bacterial cells and to optimize process parameter of coating. Coating caused membranes surface tightening, decreasing the roughness, the most hydrophilic surface was obtained with 10 and 50 ALD cycles at temperature 70 °C (16 and 27) and 10 ALD cycles at 100 °C (27), improved antifouling performance of the membrane, the lowest number of bacteria cells was adhered to surface. 61 2014 BaSO4-deposition To increase membrane performance and antifouling property. Mineralized membranes became smoother, more hydrophilic (from 65 of raw membrane to 38.5), more negatively charged, enhanced water flux and salt rejection (from 24.7 L/m2 h and 96.8% for raw membranes to 29.5 L/m2 h and 98.2% of mineralized membranes), improved antifouling property. 62 2015 P(4-VP-co-EGDA) deposition followed by reaction with 3-BPA to obtain zwitterionic pCBAA To increase fouling resistance. 85% 4-VP is the optimal chemistry for copolymer, zwitterionic coatings reduce CA (from 60.4° for bare membrane to 29°), enhanced resistance against bacterial adhesion, decline in permeate flux (about 17%) and increase in salt rejection (about 2%), stability of copolymer in DI water 63 2015 HPOEM or PEI coating followed by GA crosslinking, then dipping GA-treated PEI membranes in aqueous bromoacetic acid to obtain carboxylated PEI coating To introduce fouling resistance in SWRO membrane. By surface coating, roughness decreased slightly, HPOEM coating made the membrane less negative and PEI coating made it more neutral, for HPOEM coating, the CA increase from 30.6 to 40.2 and for PEI coating the CA decrease from 57.8 to 43, PEI coating improved fouling resistance in SW feed and HPOEM coating have better fouling resistance under BW feed. 64 2015 p(4-VP-co-EGDA) deposition followed by reaction with 3-BPA to obtain zwitterionic pCBAA To control biofouling. Significant enhancement in resisting biopolymers (BSA and HA) adsorption, reduced attachment of seawater bacterial species. 65 2016 2- acrylamido-2-methyl propanesulfonic acid, acrylamide and 1-vinylimidazole (P(AMPS-co-Am-co-VI)) To improve chlorine resistance. Coated membrane became more hydrophilic (decreased CA to 15), neutral, and smoother, with increasing the coating concentration, the water flux increased and then decreased, the salt rejection increased monotonically, strong chlorine tolerance. 66 2016 2-hydroxyethyl methacrylate-co-perfluorodecyl acrylate (HEMA-co-PFDA) To reduce sodium alginate fouling with low flux decline and unaltered salt rejction. Continuous and dense foulant layer on uncoated membrane while porous and discontinuous one on coated membrane, lower flux decline for coated membrane (10.51% vs. 19.82% for uncoated membrane) without change the salt rejection, better resistance to foulant adsorption, reduction in CA of coated membrane after the deposition of SA (~20) significant decrease (~20°) in the CA of the coated membrane. 67