Environmental Engineering Reference
In-Depth Information
(a)
(b)
10 µm
10 µm
(c)
10 µm
FIGURE 23.10
SEM images of 0.15 ± 0.05 mm nylon 6 membrane thicknesses after 0.5 μm PS microparticles (125 ppm) separa-
tion: (a) top surface, (b) cross section, and (c) bottom surface. (From Aussawasathien, D. et al.,
J. Membr. Sci.
, 315,
11, 2008.)
23.3.4 Removal of Heavy Metal Ions
Industrial efluents release heavy metals such as lead, chromium, mercury, cadmium, cop-
per, and arsenic, into water streams, and these cause serious problems in aquatic systems.
Adsorption and iltration are the commonly used methods for removal of these contam-
inants. Electrospun nanoiber membranes can offer both adsorption and iltration, and
have proven very effective for the removal of heavy metals from water. In recent work,
Fe
3+
ion-impregnated PVA nanoibers were used for the extraction of As(III) and As(V)
compounds from aqueous media. The maximum capacity was found to be 67 mg/g and
37 mg/g for As(III) and As(V), respectively.
57
Zerovalent iron nanoparticles immobilized
on multiwalled carbon nanotube (MWCNT)-reinforced poly(acrylic acid)/PVA compos-
ite ibers was also found to be an active agent for the removal of Cu(II) ions from water
(Figure 23.11).
58
The presence of MWCNTs improved the mechanical durability of the ilm. Cu
2+
chemi-
sorption occurs via chemical reduction and deposition on the Fe nanoparticle surfaces to
form an Fe/Cu alloy. The uniform Fe NPs on the hybrid nanoibers offer great speciic sur-
face areas that enable very effective, high-capacity, and strong sorption of Cu(II) ions. In
