High-strength hydrogel as a reusable adsorbent of copper ions.

A mechanically strong hydrogel was prepared by photoinitiated polymerization of oligo(ethylene glycol) methacrylate (OEGMA), 2-vinyl-4,6-diamino-1,3,5-triazine (VDT) and cross-linker N,N'-methylenebisacrylamide (MBAA). Introduction of the monomer VDT considerably strengthened the mechanical properties of the hydrogel by self-hydrogen bonding of diaminotriazine, and enhanced the adsorption of copper ion onto the hydrogel by chelation between amino groups and metal ion. Adsorption studies were carried out by varying the OEGMA/VDT ratio, contact time, pH value, counterion and initial concentration of Cu(2+) ions. The evaluation of adsorption properties showed that the hydrogel exhibited better correlation with Langmuir isotherm model. This adsorbent could be used repeatedly with little loss in adsorption capacity.