Magnetic carboxylated cellulose nanocrystals as adsorbent for the removal of Pb(II) from aqueous solution

•A magnetic carboxylated cellulose nanocrystal composite (CCN-Fe3O4) was prepared.•The reusable CCN-Fe3O4 was characterized by TEM, VSM, FT-IR, and XPS.•The CCN-Fe3O4 was applied the adsorption of Pb(II) from aqueous solution.•The thermodynamics and kinetics of the adsorption process were evaluated.•The adsorption mechanism was considered by adsorption isotherm studies.

A novel magnetic carboxylated cellulose nanocrystal composite (CCN-Fe3O4) was prepared as an adsorbent for the adsorption of Pb(II) from aqueous solution. The new adsorbent was characterized by transmission electron microscopy, vibrating sample magnetometry, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Batch experiments were carried out to investigate the effects of contact time, adsorbent dose, pH, and temperature on adsorption capacity. Pb(II) adsorption onto CCN-Fe3O4 reached equilibrium in 240 min, and the maximum adsorption capacity of Pb(II) was 63.78 mg g−1 at 298.2 K. The equilibrium data fitted the Langmuir isotherm model better than the Freundlich isotherm model, and they were well explained in terms of pseudo-second-order kinetics. Thermodynamics studies indicated that the adsorption of Pb(II) onto CCN-Fe3O4 was spontaneous and endothermic in nature. The adsorbent could also be regenerated with acid treatment and successfully reapplied.