Figure 5.

Polyacrylamide cryogel composites. (a) with α-Fe₂O₃ nanoparticles (20 nm) and (b) with activated carbon beads (250–500 mm), produced by the conventional method (left test tube) and produced by pre-freezing the suspension before initiation of polymerization (right test tube). The polyacrylamide cryogel composite with carbon nanotubes (c) and its cross-section (d). α-Fe₂O₃-AAm column produced by the pre-freezing method (140 ml volume) and conventional method (1 ml volume) (e). Adsorption of As(III) by 4 and 140 ml column (f). Pore size distribution (g). See text for discussion.