Adsorption of cationic dyes within spherical particles of poly(N-isopropylacrylamide) hydrogel containing smectite

Spherical particle of poly(N-isopropylacrylamide) hydrogel containing smectite clay (a synthetic saponite) was prepared by the polymerization of N-isopropylacrylamide in aqueous clay suspension. The diameter of the gel particle is 800–1300 nm and the clay content is 11 wt.% (clay/poly(N-isopropylacrylamide)). The gel particle was shown to be useful adsorbent of cationic species from water as a result of strong electrostatic interactions between smectites and the cationic species. Due to the fact that the cation adsorption capacity to the present hybrid hydrogel particles is determined by the cation exchange capacity of clay, the hydrogel particles containing clay are a useful scaffold to immobilize various cationic species to construct functional hybrid gel particles.