Heavy-Metal-Anion Adsorption and Desorption Properties of <i>N,N</i>-Dimethylaminoethylacrylamide/Acrylamide Gels

Abstract

The authors have investigated heavy-metal-anion (hexavalent chromium, Cr(VI)) adsorption and desorption properties of N,N-dimethylaminoethylacrylamide/acrylamide (DMAEAAm/ AAm) gels successively. Though the DMAEAAm/AAm gels show relatively low Cr(VI)-capturing efficiencies, the hydrogels have a possibility of actual use as a heavy-metal-anion recovering material because the DMAEAAm/AAm gels with some compositions show high desorption efficiency of the captured-Cr(VI), which is advantageous to a heavy-metal-anion recycling system with repetitive use of the hydrogel.

Capturing of Positive and Negative Rare-metal Ions by Polarity-Composite Hydrogels

“…Therefore, the authors also carried out a couple of consecutive measurements of adsorption by and desorption from respective positively [14,15,17,18,21] ionized hydrogels and negatively [19][20][21] polarized ones in order to examine the possibility of the reuse of the hydrogel; and it was demonstrated that these hydrogels can be satisfactorily utilized in the heavy-metal and rare-metal recycle. Though the utilization of hydrogels for the recovery of heavy metals and rare metals seems to be promising judging from the previous and present experimental results, however, the assumed conditions in these studies were still too simple compared with those in actual waste processing.…”

“…In the authors' previous studies, measured were the heavy metal capturing efficiencies both of the positively [9,10,17,18,21] and negatively [11][12][13][14][15][16][19][20][21] ionized hydrogels: The heavy-metal cation capturing efficiency of sodium acrylate/acrylamide (SA/AAm) and carboxymethylcellulose (CMC-Na) gels were found to be ~20 wt% of network polymer [9] [10,21]. As for the heavy-metal-anion capturing hydrogels [11][12][13][14][15][16][19][20][21], their capturing efficiencies are larger than those of SA/AAm and CMC-Na gels, which are much larger than those of zeolites and ion-exchange resins.…”

“…As for the heavy-metal-anion capturing hydrogels [11][12][13][14][15][16][19][20][21], their capturing efficiencies are larger than those of SA/AAm and CMC-Na gels, which are much larger than those of zeolites and ion-exchange resins. Such a considerably high capturing efficiency can come from these hydrogels being composed of relatively light elements such as H, C, N and O compared with the adsorbate (heavy metals and rare metals), which are in contrast with the case of inorganic adsorbents made of heavy elements such as zeolites.…”

UV-irradiation Effects on the Properties of <i>poly</i>-Acrylamide/Sodium Acrylate Gel

“…However, the detector was not able to show how much the heavy-metal amount the gel can adsorb. In these circumstances, the authors have been focusing attention on the adsorbable quantity of the heavy-metal-capturing gels aiming at the realizetion of the high-efficient heavy-metal recovery gels [7][8][9][10][11][12][13][14][15][16][17][18].…”

“…In addition to the heavy-metal-cation capturing hydrogels, the authors have been also investigating heavy-metalanion capturing hydrogels because there are many harmful heavy-metal anions in the environment such as Cr 2 O 7 2-; and they found that some heavy-metal-anion adsorbing hydrogels show larger heavy-metal capturing efficiencies than SA/AAm and CMC-Na gels [9][10][11][12][13][14]. Moreover, recently, the authors demonstrated the possibility of the high-efficient heavy-metal-recycle process utilizing these hydrogels [15][16][17][18].…”