Removal of Cu(II) ions from water by ion-imprinted magnetic and non-magnetic cryogels: A comparison of their selective Cu(II) removal performances

2-Hydroxyethylmethacrylate (HEMA) based ion-imprinted cryogel membranes (IIP) were synthesized using histidine containing functional monomer, N-methacryloyl-L-histidine (MAH) as complexing/chelating agent, Cu(II) ions as template, methylene bisacrylamide as cross-linker, TEMED and APS as redox pair in both magnetic and non-magnetic forms through free radical polymerization method for selective Cu(II) ion removal. A control non-imprinted cryogel (NIP) was also prepared for comparison. The matrices were characterized by swelling tests, scanning electron microscopy (SEM), BET, and FTIR. Effect of several parameters (pH, temperature, contact time, etc.) on adsorption capacities was examined in batch mode. The maximum adsorption capacities of cryogel membranes under optimized conditions were 77.2 mg/g and 182.7 mg/g for non-magnetic and magnetic IIP cryogels, respectively. The adsorption process best fitted to Langmuir isotherm while pseudo-second-order kinetic model was well suited to explain controlling step in adsorption kinetics. The reusability of matrices was tested for three successive cycles. Competitive adsorption studies were finally performed to prove the selectivity of resulting matrices for Cu(II) ions in binary and multi-ion containing synthetic water samples. (C) 2016 Elsevier Ltd. All rights reserved.