Adsorption of lead ions from aqueous solutions by porous cellulose nanofiber–sodium alginate hydrogel beads

Herein we report a new type of adsorbent for the efficient removal of Pb(II), which is prepared from cellulose nanofiber (CNF) and sodium alginate (SA) via a simple cross-linking method. During this process, the porous structure of the hydrogel beads was formed by the disintegration of calcium phosphate . The performance and structure of the prepared beads were systematically examined by X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, zeta potential measurements, and scanning electron microscopy. Investigations revealed that the adsorption equilibrium was attained after approximately 120 min. In addition, 82% of Pb(II) ions were absorbed in the initial 40 min at 297 K. The adsorption process was consistent with a pseudo-second order kinetic model and the Langmuir adsorption isotherm model, and the limit adsorption capacity reached 318.47 mg g −1 . Acid treatment and regeneration experiments verified that the adsorption capacity of Pb(II) on the beads was satisfactory, and the adsorption rate remained at >80% after 5 cycles. These results indicate that the prepared beads are potential adsorbents for water treatment.