English abstract
Availability and access to clean water have become a global issue of concern as
human populations grow, industrial and agricultural activities expand. Both
desalination and reuse wastewater represent a major opportunity to reduce water
scarcity. Seawater desalination by reverse osmosis (RO) is a costly process and
requires reliable pre-treatment techniques such as ultrafiltration (UF) processes to
make the process much more economically attractive.
In view of this, the main objective of this study is to fabricate and characterize
low-biofouling UF nanocomposite membranes by incorporating different weight
percentages of silver nanoparticles (AgNPs) loadings (0.5, 1.0, 2.0 wt.%) by in
situ blending method for seawater desalination pre-treatment and surface water
treatment applications. The nanocomposite membranes were fabricated via phase
inversion method using a dope solution containing 15 wt.% polyethersulfone
(PES) as the base polymer dissolved in 82 mL of 1-Methyl-2-pyrrolidinone
(NMP).
All membrane types were characterized using scanning electron microscopy
(SEM), energy dispersive spectroscopy (EDS), fourier transform infrared
radiations spectroscopy (FTIR), x-ray diffraction (X-RD), water contact angle
(WCA), membranes porosity (ɛ %), mechanical strength and inductively coupled
plasma-optical emission spectroscopy (ICP-OES) were studied as well.
Membrane performance was tested using a dead-end unit to evaluate the effect of
AgNPs on membrane pure water flux and filtration performance using two model
foulants humic acid (HA) and bovine serum albumin (BSA). The antifouling
property of the membrane was analyzed by calculating the fouling resistance
parameters of BSA. The antibacterial activity of membranes was tested using two
types of bacteria which are Bacillus subtilis (B. subtilis) and Escherichia coli (E.
coli).
The results showed that the WCA was reduced from 68˚ for the unmodified PES
membrane to 58˚ for PES-0.5 AgNPs membrane. The PES-0.5 AgNPs membrane
displayed improved water flux by 65.55% and both HA and BSA rejections were
90.04% and 82.41% respectively. Although the WCA of the membrane was
further reduced when a higher AgNPs amount (1.0 and 2.0 wt.%) was used, the
results of membranes suffered from decreased ultimate strength and significant
nanoparticles leaching. A high flux BSA recovery of about 97.29% was achieved
for the modified membrane with 2.0% AgNPs compared to 71.12% for the neat
membrane. In terms of the antibacterial performance evaluation, modified PES
membranes showed the excellent property in biofouling mitigation and E. coli
results show more sensitive to AgNPs than B. subtilis due to their thinner cell
walls structure compared to B. subtilis.
