Page 543 - Polymer-based Nanocomposites for Energy and Environmental Applications

496 Polymer-based Nanocomposites for Energy and Environmental Applications

dioxide (HMO) onto a porous polystyrene cation-exchanger resin (D-001), provided
a nice example [126]. As compared with D-001, HMO-001 showed highly selective
2+
+
2+
lead retention from waters in the presence of competing Na ,Mg , and Ca ,at
much higher levels than the target toxic metals. The exhausted adsorbent particles
were amenable to regeneration by the binary NaAc-HAc solution for repeated use
without any noticeable capacity loss. Additional example is hydrated ferric oxides,
which can selectively bind anionic ligands (e.g., phosphate and arsenate) through
inner-sphere complex formation [127,128]. They are also cost-effective and environ-
mentally benign. Like HMO, they cannot be directly employed in fixed-bed columns
or any other flow-through systems due to the fine or ultrafine particles. Polymer-
supported hydrated ferric oxides (D201-HFO) were then fabricated by using a
strongly basic anion-exchanger D201 as the host material to overcome its inherent
defect [36]. D201-HFO was found to exhibit higher capacity for arsenic or phosphate
removal than the host exchanger and a commercial sorbent Purolite Arsen X. Addi-
tionally, it also presented fast kinetics, which was particularly crucial for deep
removal of trace pollutants. Fixed-bed column experiments exhibited that arsenic
sorption on D201-HFO could result in a concentration of this toxic metalloid ele-
ment, which is lower than 10 g/L, the new maximum concentration limit set recently
by the European Commission and imposed by USEPA and China.
There are many PNC used in the pollutant removal process base on the pollutant
removal types. Several pollutant removal types are the following.

Arsenic removal
The main pollutant in the industrial waste that toxic and cause the human health
and environment problems is arsenic (As). Polymeric anion-exchanger-based
nanocomposites are very common as a PNC for arsenic removal. Ferric oxide is usu-
ally used as a nanoparticle in this type. The preparation methods influence the removal
capacity pollutants especially arsenic. The preparation method involves the precipi-
tation of iron(III) hydroxides from FeCl 3 that could remove As(V) approximately
from 50 to 10 ppb within 4000 BV and As(III) removed from 100 to <10 ppb within
2000 BV [35–38].
The other nanoparticles used in polymer-based nanocomposite are iron oxides with
alginate as polymer matrix. Alginate beads were dispersed into hydrated ferric oxide
(HFO) solution to produce polymer-based nanocomposite (PNCs). This alginate-
based iron oxide composite successfully reduced arsenic from 50 to <10 ppb within
230 BV for As(V) [45] and 400 BV for As(III) [37].
Polystyrene-based nanocomposite also developed with hydrated ferric oxide as
nanoparticle. These PNCs reduced the arsenic content in the waste from 100 to
10 ppb within 60 BV [43].

(Pb, Cu, Cd, and Zn) removal
These ion pollutants were also found in the environment waste, and these metal ions
are very dangerous for our health and of course cause environment problems.