Selective Adsorption of Heavy Metal Cations and Anions from their Aqueous Solution Mixture with Hydrogels

A Possibility of Heavy-Metal Recycling by Utilizing Hydrogels

“…From the standpoint described above, the authors observed high heavy-metal-ion capturing efficiencies of some ionized-hydrogels in the previous studies [17][18][19][20][21][22][23][24]. In the early stage, the authors investigated sodium acrylate/acrylamide (SAlAAm) gel as a heavy-metalcation capturing hydrogel and it is found that the weight ratio of captured Cu to network polymer is estimated ~20wt%, which is very large value compared with other adsorbents (Fig.l) [ 17,18].…”

“…In addition to heavy-metal cations, there are many harmful heavy-metal anions in the environment such as Cr 2 0 7 -2 , namely the hexavalent chromium, and Seol•. Therefore, the authors also developed heavy-metal-anion capturing gels and examined the capturing efficiencies; it was found that almost of the capturing efficiencies of the heavy-metal-anion capturing gels are larger than those of SAlAAm and CMC-Na gels and much larger than those ofzeolites and ion-exchange resins [19][20][21][22][23][24]. The CuCh concentration dependence of the Cu(II) weight adsorbed by the several SA/ AAm gels per 10 g of the respective pre-gel solutions [12,13].…”

A Possibility of Heavy-Metal Recycling by Utilizing Hydrogels

“…From the standpoint described above, the authors observed high heavy-metal-ion capturing efficiencies of some ionized-hydrogels in the previous studies [17][18][19][20][21][22][23][24]. In the early stage, the authors investigated sodium acrylate/acrylamide (SA/AAm) gel as a heavy-metalcation capturing hydrogel and it is found that the weight ratio of captured Cu to network polymer is estimated ~20wt%, which is very large value compared with other adsorbents (Fig.1) [17,18].…”

“…In addition to heavy-metal cations, there are many harmful heavy-metal anions in the environment such as Cr 2 O 7 -2 , namely the hexavalent chromium, and SeO 4 2-. Therefore, the authors also developed heavy-metal-anion capturing gels and examined the capturing efficiencies; it was found that almost of the capturing efficiencies of the heavy-metal-anion capturing gels are larger than those of SA/AAm and CMC-Na gels and much larger than those of zeolites and ion-exchange resins [19][20][21][22][23][24].…”

“…This system can be also utilized when the waste fluid contains the heavy metals of both the polarities; by the usage both of the SA/AAm and DMAPAA/AAm gels simultaneously, the heavy metal with each the polarity can be captured by the corresponding hydrogel as reported in Ref. 24. The proposed heavy-metal recycling system is composed of 4 steps:…”