Surface functionalization of cellulose nanocrystals derived from waste newspaper for highly efficient Mn (VII) sorption

This study aims to produce functionalized cellulose nanocrystals (FCNCs) by preparing and functionalizing cellulose nanocrystals (CNCs) from eco-friendly newspapers utilizing a straightforward two-step reaction with an anionic polymer (poly hydrex 6161). FCNCs' structure is described using FTIR, XRD, and SEM. A pseudo-second-order model was used to describe the sorption kinetics of Mn(VII) onto FCNCs, and the results of the linear and nonlinear regression analyses agreed well (R2 > 0.999). Additionally, a number of intervening diffusion types, including intra-particle diffusion, were linked to the regulating phase in the Mn(VII) sorption process. The linear versions of the Freundlich, DR, and Langmuir isotherms were also used to examine the Mn(VII) equilibrium data; the results showed that the Langmuir fits the data better, with an R2 value of 0.9981. This validates the uniform properties of Mn(VII) sorption on the surface of FCNCs with exceptional removal capacities (qmax = 384.615) in both linear and nonlinear modes, in an orderly mode. The spontaneous and endothermic nature of the Mn(VII) sorption process at 288–328 K was confirmed by the thermodynamic parameters ΔH°, ΔS°, and ΔG°. On the other hand, the E value of 1461 kJ mol⁻¹according to D-R isotherm calculation, which was greater than 8 kJ mol⁻¹, indicated chemisorption. To ascertain the adsorption mechanism on the FCNCs, techniques such as ion exchange, pore filling, complexation interaction, and electrostatic interaction can be employed. The hybrid FCNCs were able to easily execute at least six adsorption–desorption recycles. The hybrid composite's unique characteristics make it a very promising enhanced adsorbent with great promise for heavy metal removal in wastewater treatment on an industrial scale.