*3.10. Relationship between the Adsorption and Swelling*

For the investigation of the correlation between the swelling of GT-cl-poly(DMA)/RGO hydrogel composite and adsorption of the Hg2<sup>+</sup> and Cr6<sup>+</sup> onto GT-cl-poly(DMA)/RGO hydrogel composite, the adsorption percentage was determined using aqueous metal solution (20 mg L<sup>−</sup>1) and the swelling experiments were performed in distilled water. The relationship between the adsorption values versus swelling values is presented in Figure 10. It is clear from Figure 10 that the adsorption percentage is directly proportional to the swelling percentage of the adsorbent. The adsorption percentages for Hg2<sup>+</sup> and Cr6<sup>+</sup> were increased from 78.9% to 90.7% and 29.8% to 38.4% respectively when the swelling percentage of GT-cl-poly(DMA)/RGO rise from 834.6% to 971.9%.

**Figure 10.** Adsorption percentage and swelling percentage of reduced graphene oxide incorporated gum tragacanth-cl-*N,N*-dimethylacrylamide (GT-cl-poly(DMA)/RGO) hydrogel composite.
