Preparation of Tannin-immobilized Collagen/Cellulose Bead for Pb(II) Adsorption in Aqueous Solutions

Bayberry tannin-immobilized collagen/cellulose bio-adsorbent (BTcollagen/cellulose) was prepared via the reaction of bayberry tannin with the amino group of collagen in collagen/cellulose blends. Compared with collagen/cellulose beads without tannin, BT-collagen/cellulose had a more compact structure and higher thermal stability. Furthermore, the crystalline structure of cellulose in BT-collagen/cellulose was preserved. The adsorption properties of BT-collagen/cellulose to Pb(II) in aqueous solution were investigated and compared with those of collagen/cellulose. The adsorption of Pb(II) on both of the two bioadsorbents reached the maximum at pH near 5.5. Based on the mass content of collagen, the equilibrium adsorption capacity of BTcollagen/cellulose at 25 °C was 1.352 mmol/g, according to Langmuir isotherms, which was higher than that of collagen/cellulose (0.345 mmol/g). In kinetics studies, both of the two bio-adsorbents reached equilibrium within ~240 min, and the experimental data could be well fitted by the pseudo-second-order rate model. Nevertheless, BTcollagen/cellulose had a better reusability after three cycles of adsorption-desorption.