Effective lead removal from aqueous solutions using cellulose nanofibers obtained from water hyacinth

In this paper, the removal of Pb(II) ions from aqueous solutions using cellulose nanofibers (NFC) and crystalline nanocellulose (CNC) was studied. These adsorbents were obtained from water hyacinth (Eichhornia crassipes) by the Kraft process. Characterization was carried out to NFC and CNC by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), showing excellent structural properties and high availability of surface functional groups. The influence of different parameters on the adsorption process was evaluated through batch-type adsorption experiments. The results showed effective lead removal reaching adsorption equilibrium at 180 min. Isotherms results showed maximum adsorption capacities (Qmax) of 80.02, 84.64, and 87.10 mg/g for NFC at 25, 30 and 45 °C, respectively. Results of Pb(II) adsorption isotherms by CNC showed a Qmax of 17.90, 28.20, and 30.36 mg/g at 25, 30 and 45 °C, respectively. Isotherm data were best described by the Langmuir–Freundlich model for NFC, and the Freundlich model best-described CNC isotherm. Lead adsorption mechanisms were different for both biosorbents. The thermodynamic parameters of the process were calculated. Endothermic reactions were observed for both materials. NFC and CNC materials have great potential as biosorbents for the removal of lead ions from water.