The synthesis of nanocellulose-based nanocomposites for the effective removal of hexavalent chromium ions from aqueous solution

The present study reports the synthesis of a polydopamine (PDA)/nanocellulose (NC) nanocomposite for the effective removal of chromium ions from water. PDA was used to modify NC surface producing a nanocomposite namely PDA/NC, by in situ polymerization of dopamine on the surface of NC. Thereafter, the as-synthesized nanocomposite was characterized using familiar techniques such as Fourier transform infrared, X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, and transmission electron microscopy. All results indicated the successful combination of PDA and NC in one nanocomposite. The PDA/NC nanocomposite was evaluated for the removal of hexavalent Cr(vi) ions from an aqueous solution. The adsorption conditions, such as pH, contact time, and initial Cr(vi) concentration, were optimized. Adsorption kinetic studies revealed that Cr(vi) removal on the surface of PDA/NC nanocomposite followed the pseudo-second-order kinetic model. Furthermore, isotherm studies revealed that Cr(vi) removal followed the Langmuir isotherm model with a maximum adsorption capacity (q (m)) of 210 mg/g. The adsorption mechanism study indicated that the Cr(vi) removal was reached via complexation, adsorption, and chemical reduction. The reusability of a PDA/NC nanocomposite for the removal of Cr(vi) ions was studied up to five cycles with acceptable results. The high adsorption capacity and multiple removal mechanisms validated the effective applicability of PDA/NC nanocomposite as a useful adsorbent for the removal of Cr(vi) ions from aqueous solution.