Nanocellulose/Poly(2-(dimethylamino) ethyl methacrylate) Interpenetrating polymer network hydrogels for removal of Pb(II) and Cu(II) ions

Interpenetrating network (IPN) hydrogels based on nanofibrillated cellulose (NFC) and poly(2-(dimethylamino) ethyl methacrylate) (PDMAEMA) were prepared via crosslinking free radical polymerization. Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and thermogravimetric analysis (TGA) confirmed the formation hybrid network of NFC and PDMAEMA. The IPN hydrogels possess uniform pore structure and high porosity (> 97%). The specific surface area and compressive strength were higher than 82 m(2) g(-1) and 1.26 kPa, respectively. Water swelling experiments showed that the IPN hydrogels were both pH-sensitive and temperature-sensitive. The swelling of hydrogels was limited at high temperature and in neutral medium. There was an increase in the swelling ratio as the NFC content increased. Adsorption kinetic and thermodynamics studies of Cu(II) and Pb(II) explained pseudo-second-order equation and Langmuir model (R-2 > 0.99) as the best fit. The maximum adsorption capacities of Cu(II) and Pb(II) according to Langmuir model were 217.39 mg/g and 81.96 mg/g, respectively. The good adsorption performance can be attributed to the chelation of tertiary amine groups and the ion-exchange of carboxyl groups.