Tannin-Immobilized Collagen/Cellulose Bead as an Effective Adsorbent for Cu(II) in Aqueous Solutions

Collagen/cellulose bead was prepared by the reconstitution of collagen and cellulose (collagen/cellulose mass ratio = 1/6) from 1-ethyl-3-methylimidazolium acetate. Based on this, a novel bio-adsorbent, bayberry tannin immobilized collagen/cellulose (BT-CC) bead, was obtained via the reaction of collagen with bayberry tannin. The adsorption properties of BT-CC to Cu(II) in aqueous solution were investigated. Results from SEM and XRD indicated the well preservation of structure after the adsorption of Cu(II). Furthermore, the maximum decomposition temperature of BT-CC after the adsorption of Cu(II) was even increased for ∼7 °C, confirming the stability of BT-CC. The adsorption of Cu(II) on BT-CC displayed pH-dependence and the maximum adsorption was obtained at pH = 5.0. Based on the mass content of collagen, the maximum adsorption capacity of BT-CC was 0.73, 0.96 and 1.12 mmol/g at 298, 308 and 318 K, respectively, according to the experimental adsorption isotherms. In kinetics studies, the adsorption equilibrium at both of 298 and 318 K reached within ∼300 min, and the experimental data could be well fitted by the pseudo-first-order rate model. Furthermore, good adsorption properties of BT-CC remained after three cycles of adsorption–desorption. These results indicated that high stability, great adsorption capacity and good reusability of BT-CC as the adsorbent to Cu(II) could be obtained.