A Novel Thermosensitive Gel Adsorbent for Phosphate Ions

Summary: A novel thermosensitive gel adsorbent for phosphate ions was developed and its adsorption/desorption properties were investigated. The gel adsorbent was made by the copolymerization of N-isopropylacrylamide (NIPA) and N-3-(dimethylamino)propyl]acrylamide (DMAPAA). The adsorbent has a volume phase transition temperature (VPTT), below which it becomes hydrophilic. The tertiary amino groups of DMAPAA were ionized and showed a cationic state when the gel swelled. Phosphate ions were adsorbed onto the ionized tertiary amino groups in the gel network below the VPTT and were desorbed above the VPTT because of the suppression of the ionization of the tertiary amino groups of gel and the shrinkage of the gel.