8 research outputs found
Antifouling Double-Skinned Forward Osmosis Membranes by Constructing Zwitterionic Brush-Decorated MWCNT Ultrathin Films
Pressure
retarded osmosis (PRO) process is hindered by severe fouling occurring
within the porous support of the forward osmosis (FO) membranes. We
designed a novel double-skinned FO membrane containing a polyamide
salt-rejecting layer and a zwitterionic brush-decorated, multiwalled
carbon nanotube (MWCNT/PSBMA) foulant-resisting layer on the back
side. Our results demonstrated that the coating of the MWCNT/PSBMA
layer on the porous polyketone (PK) support imparted enhanced hydrophilicity
and smaller membrane pore size, thereby providing excellent resistance
toward both protein adhesion and bacterial adsorption. We also further
evaluated this resultant double-skinned membrane (i.e., TFC-MWCNT/PSBMA)
in dynamic PRO fouling experiments using protein and alginate as model
organic foulants. Compared to the pristine TFC-PK and hydrophobic
TFC-MWCNT membranes, the TFC-MWCNT/PSBMA membrane exhibited not only
the lowest water flux decline but also the highest water flux recovery
after simple physical flushing. These results shed light on fabrication
of antifouling PRO membranes for water purification purposes
Comparison of Hydrophilicity and Mechanical Properties of Nanocomposite Membranes with Cellulose Nanocrystals and Carbon Nanotubes
The inherent properties of hydrophilicity
and mechanical strength of
cellulose nanocrystals (CNCs)
make them a possible alternative to carbon nanotubes (CNTs) that may
present fewer objections to application water-treatment membranes.
In this work, the hydrophilicity and mechanical properties of CNCs
and CNTs nanocomposite polyÂ(ether sulfone) (PES) membranes were characterized
and compared. Membrane pore geometry was analyzed by scanning electron
microscopy (SEM). Overall porosity and mean pore radius were calculated
based on a wet–dry method. Results showed that PES polymers
were loosely packed in the top layer of both the CNC- and CNT-composite
membranes (CNC-M and CNT-M). The porosity of the CNC-M was greater
than that of the CNT-M. Membrane hydrophilicity, measured by water-contact
angle, free energy of cohesion, and water flux, was increased through
the addition of either CNCs or functionalized CNTs to an otherwise
hydrophobic polymer membrane. The hydrophilicity of the CNC-M was
greater than the CNT-M. In addition, the Young’s modulus and
tensile strength was enhanced for both the CNC-M and CNT-M. While
smaller concentrations of CNTs were required to achieve an equal increase
in Young’s modulus compared with the CNCs, the elasticity of
the CNC-composite membranes was greater