The effect of foaming additives on acrylic acid/acrylamide hydrogels

The physical and chemical properties of hydrogels are greatly dictated by their composition. In this study, modifications were brought to the macroscopic structure of hydrogels using foaming additives, and their effects on the swelling capacity and heavy metal adsorption were investigated. Significant differences in swelling capacities were found for hydrogels synthesized with a foaming agent and a foam stabilizer (257 g/g), with a foaming agent without foam stabilizer (195 g/g), or without any additives (182 g/g). The study compared the ion removal capacity for copper (II), cadmium (II), and nickel (II) under competitive and non-competitive conditions. The use of a foaming agent significantly increased the ion removal capacity of the hydrogels, from 54 to 93 mg/g cadmium, from 75 mg/g to 104 mg/g copper, and from 48 mg/g to 80 mg/g nickel. Under competitive conditions, the hydrogels preferentially removed cadmium > copper > nickel. However, maximum removal decreased for individual heavy metals under competitive conditions.