Page 475 - Polymer-based Nanocomposites for Energy and Environmental Applications

428 Polymer-based Nanocomposites for Energy and Environmental Applications

For water purification, membrane filtration has been an extensively used
method; based on the suspended particle size, various filtration techniques are differ-
entiated and can separate, namely, microfiltration (0.1–10 mm), ultrafiltration
(0.01–0.10 mm), NF (order of nanometers), and RO that can remove monoionic salts
in solution.
Compared with other treatment techniques, these techniques are useful owing to
the high-quality water produced, simpler module design, little amount of chemicals
used, and small energy consumption [167]. However, fouling and concentration
polarization are the two major problems associated with membrane filtration. Fouling
is the deposition of ingredients on the surface and/or inside the membrane pores,
thereby reducing the performance of the membrane [168], while in concentration
polarization, a layer near the membrane surface generates when the components per-
meate increasingly or not at all gather. To overcome these problems, proper modifi-
cation of the membrane is possibly the best choice to obtain fouling-resistant
membranes [169]. This needs the incorporation of hydrophilic groups into a polymeric
structure, so that the overall material becomes more hydrophilic and consequently less
prone to (organic) fouling [170]. For this purpose, poly(vinyl alcohol) (PVA), which is
a water-soluble biodegradable polymer accessible with different degrees of hydroly-
sis, is an ideal candidate because of its hydrophilicity and film forming characteristics
[171,172]. Generally, membrane selectivity can be improved via modification of the
chemical structure of the polymer by cross-linking and joining [173].
Likewise, for oil-containing wastewater remediation, Maphutha et al. [174] indus-
trialized a CNT-integrated polymer composite membrane using a PVA barrier layer to
separate oil from water. The CNTs were synthesized by chemical vapor deposition,
and a phase inversion method was employed for the blending of the CNTs in the poly-
mer composite solution for casting of the membrane. For a concentration of 7.5%
CNTs in the polymer composite, an increase of 119% in the tensile strength, 77%
in the Young’s modulus, and 258% in the toughness was found comparative to the
baseline polymer. The permeate through the membrane displayed oil concentrations
below the acceptable 10 mg/L limit with an excellent throughput and oil rejection of
over 95%.

15.12 ZrO microfiltration membrane
2

The separation of dispersed materials in the size range 0.1–10 μm by means of porous
polymeric or inorganic fences is termed as “microfiltration.” Microfiltration earlier
finds industrial application worldwide, but its usage would be enabled by means of
supposing the performance of such processes. Microfiltration membrane process
property estimation mainly depends on the development of operative methods for
their characterization. For measuring the physical properties of membranes, a variety
of methods such as porosity, pore-size distribution, and pore structure are explored.
Microfiltration membranes cannot be assumed simply as filters. But some other
properties also affect their separation capabilities. In particular, the electrochemical
properties of membrane surfaces can have a considerable effect on the nature and