Anionic Thermo-Responsive Polymer with High Adsorption Capacity for Heavy Metal Removal

Thermo-responsive adsorbents having high adsorption capacity for heavy metal removal was developed in this paper. The adsorbents were synthesized by free radical copolymerization of N-isopropylacrylamide (NIPAM) as a thermo-responsive element and acrylic acid (AA) as an interactive element with various AA introduction ratios. As a model heavy metal, Cu was used in this study. Experimental results showed that AA content in the resulting copolymer was essentially the same as the ratio in the monomer feed, and AA was successfully introduced in the copolymer up to 61 mol% at maximum. When the AA content was higher than 16.1 mol%, the copolymer lost their thermo-responsive property at pH 5 as expected, however, the copolymer exhibited thermo-response when they adsorbed Cu even when the AA content was 40.8 mol%. High Cu adsorption capacity of 3.0 mmol/g-drypolymer at maximum was obtained due to high AA content in the copolymer.