Amine-functionalized copper-coordinated cryogels for efficient removal of Acid Blue 113 from water

A macroporous Poly(2-Hydroxyethyl methacrylate-glycidyl methacrylate) [Poly(HEMA-GMA)] cryogel functionalized with Poly(L-lysine) (PLL) and Cu(II) ions was developed for the efficient removal of the anionic dye Acid Blue 113 from water. The cryogel was synthesized via free-radical cryopolymerization of HEMA and GMA at - 20 °C, followed by covalent grafting of PLL through epoxy ring-opening reactions and subsequent coordination of Cu(II) ions with PLL amine groups. SEM analysis confirmed a highly interconnected macroporous structure, while BET analysis revealed specific surface areas ranging from 6.45 to 7.85 m² g^-1 and average pore diameters between 36 and 41 nm. Batch adsorption experiments demonstrated strong pH dependence, with maximum adsorption at pH 4.0. The Poly(HEMA-GMA)-PLL-Cu(II) cryogel exhibited a high adsorption capacity of 501.6 mg g^-1 and reached equilibrium within 30 min, indicating rapid adsorption kinetics. Kinetic data were best described by the pseudo-second-order model, while equilibrium data fitted well to the Langmuir isotherm, suggesting monolayer adsorption on homogeneous active sites. Additionally, the Cu(II)-containing cryogel exhibited notable antibacterial activity against several Gram-positive and Gram-negative bacteria. These findings demonstrate that the developed cryogel combines high adsorption capacity, rapid kinetics, and antimicrobial functionality, making it a promising material for advanced wastewater treatment applications.