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Review
. 2022 Apr 3;8(4):220.
doi: 10.3390/gels8040220.

Hydrogel Adsorbents for the Removal of Hazardous Pollutants-Requirements and Available Functions as Adsorbent

Yoshimi Seida  1 , Hideaki Tokuyama  2
Affiliations
Review

Hydrogel Adsorbents for the Removal of Hazardous Pollutants-Requirements and Available Functions as Adsorbent

Yoshimi Seida et al. Gels. .

Abstract

Over the last few decades, various adsorption functions of polymer hydrogels for the removal of hazardous pollutants have been developed. The performance of hydrogel adsorbents depends on the constituents of the gels and the functions produced by the polymer networks of the gels. Research on hydrogels utilizing the characteristic functions of polymer networks has increased over the last decade. The functions of polymer networks are key to the development of advanced adsorbents for the removal of various pollutants. No review has discussed hydrogel adsorbents from the perspective of the roles and functions of polymer networks in hydrogels. This paper briefly reviews the basic requirements of adsorbents and the general characteristics of hydrogels as adsorbents. Thereafter, hydrogels are reviewed on the basis of the roles and functions of the polymer networks in them for the removal of hazardous pollutants by introducing studies published over the last decade. The application of hydrogels as adsorbents for the removal of hazardous pollutants is discussed as well.

Keywords: adsorbent; adsorption; hazardous pollutant; network function; polymer hydrogel.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Hydrogel for the immobilization support and carrier.
Figure 2
Figure 2
Examples of the adsorption mechanism on the nanoparticles.
Figure 3
Figure 3
Thermoresponsive adsorption control using amphiphilic polymer hydrogel in aqueous systems, (a) adsorption through hydrophobic interaction between the thermoresponsive hydrogel and the molecules with hydrophobic moieties, (b) selective multipoint interaction, (c) solid-phase extraction of metal ions.
Figure 3
Figure 3
Thermoresponsive adsorption control using amphiphilic polymer hydrogel in aqueous systems, (a) adsorption through hydrophobic interaction between the thermoresponsive hydrogel and the molecules with hydrophobic moieties, (b) selective multipoint interaction, (c) solid-phase extraction of metal ions.
Figure 4
Figure 4
Example of metal ion removal by low-molecular-weight gelator (molecular gels).
Figure 5
Figure 5
Schematic diagram of (a) molecular imprint and (b) ion imprint gels.
Figure 5
Figure 5
Schematic diagram of (a) molecular imprint and (b) ion imprint gels.
Figure 6
Figure 6
Reactive adsorption system. (a) Tannin gel redox adsorption system. (b) Hydrolysis of metal cations. (c) Adsorption and catalysis reaction.
Figure 7
Figure 7
Adsorption control via pKa shift in the stimuli-responsive ionic hydrogels.
Figure 8
Figure 8
Application of the hydrogel adsorbents: (a) heat accumulation with light-to-thermal conversion, (b) conservation science: schematic image of the gel cleaning for painting art restoration.
See this image and copyright information in PMC

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