Capturing Cadmium(II) Ion from Wastewater Containing Solid Particles and Floccules Using Ion-Imprinted Polymers with Broom Effect

Cavities and adsorption sites in adsorption materials can be easily blocked in complex media containing solid particles and floccules, which limit the applicability of these materials. This study demonstrates the synthesis of cadmium(II) ion-imprinted polymers (Cd-IIPs) and non-ion-imprinted polymers (NIPs) via reversible addition fragmentation chain transfer precipitation polymerization (RAFTPP). Microspheres of IIPs and NIPs were modified by grafting bicomponent polymer brushes with different ratios of a hydrophilic component, hydroxyethyl methacrylate (HEMA), and a rigid component, styrene. The maximum adsorption capacities of the IIPs and NIPs in pure water are 65.5 and 24.5 mg/g, respectively. Specifically, the 9:1-TIP exhibits excellent antiblockage and anti-interference performance, with an adsorption capacity considerably higher than those of UPs in simulated wastewater including SiO2 solid particles and floccules. This higher performance suggests that the has the rigidity to resist chaff interference from different aqueous media and also possesses good water-compatibility. The 9:1-IIP has a high recognition ability and high selectivity (alpha > 5.9) to Cd(II) although the surface is grafted with bicomponent polymer brushes. Furthermore, the steric hindrance due to the styrene on the bicomponent polymer brushes, in addition to van der Waals interactions with the interfering chaff, was confirmed to result in a "broom effect". The developed sorbents demonstrate the expected adsorption capacities when applied to environmental samples from factories, which indicate that IIP microspheres grafted with polymer brushes have significant potential for application in complex wastewater treatment.