Environmental Engineering Reference
In-Depth Information
dispersion (i.e., to achieve smaller ZrP NPs). ZrP-N and ZrP-S had higher capacity than ZrP-cl for lead removal. As
compared to ZrP-N, ZrP-S exhibits higher preference toward lead ion at high calcium levels as a result of the potential
Donnan membrane effect. On the other hand, nano ZrP immobilization would simultaneously reinforce both the compressive
strength and the wear performance of the resulting nanocomposites with the ZrP loadings up to 5 wt%.
The organic-inorganic hybrid of poly(acrylic acid-acrylonitrile)/attapulgite, P(A-N)/AT nanocomposites, were prepared by
in situ polymerization and composition of acrylic acid (AA) and acrylonitrile (AN) onto modified AT NPs [48]. The resulting
P(A-N)/AT nanocomposites were transformed into a novel nanoadsorbent of poly(acrylic acid-acryloamidoxime)/AT by
further functionalization, that is, P(A-O)/AT nanoadsorbent. The adsorption properties of P(A-O)/AT toward metal ions were
determined, and the results indicated that the adsorbents with nanocomposite structure held a good of selectivity to Pb(II)
among numerous metal ions. The maximum removal capacity of Pb(II) was up to 109.9 mg/g, and it was notable to see that the
adsorption removal of P(A-O)/AT nanoadsorbent for Pb(II) was more than 96.6% when the initial concentration of Pb(II) was
120.0 mg/l. Besides the nanoadsorbents mentioned, several other materials have also been examined as nanoadsorbents for the
removal of different aquatic pollutants [49-75]. Table 15.1 lists some of the nanoadsorbents used to for the removal of different
aquatic pollutants.
15.3
conclusions
In the past few decades, various types of nanoadsorbents have been developed and tested for the removal of different types of
aquatic pollutants. Nanoadsorbents present a potent alternative to conventional treatment methods due to increased adsorption
capacity and substance specificity. However, most applications are not yet ready for the market due to technical challenges
(e.g., scale-up, system setup), environmental concerns, and cost-effectiveness, and only a few commercial products are avail-
able in the market. Another important aspect that needs to be considered is the selection of the most suitable nanoadsorbent
in removing target pollutants depending on the characteristics of effluents to be treated, technical applicability, discharge
standards, cost-effectiveness, regulatory requirements, and long-term environmental impacts. Although the amount of avail-
able literature data for the application of nanoadsorbents in water and wastewater treatment is increasing at a tremendous
pace, there are still several gaps that need more attention, such as investigation of these materials with real industrial effluents,
regeneration studies, and continuous flow studies. Despite various drawbacks and challenges that currently exist, widespread
and significant progress in this area can be expected in the future.
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