Isotherm sorption of Cd2+, Co2+, and Ni2+ onto high-yield kraft fibers

The sorption capacity of high-yield kraft fibers for Cd2+, Co2+, and Ni2+ increased with pH and concentration of the cations in the liquid phase. Within the concentration range for the experiments, which was less than 2 mM, the experimental results fitted the Langmuir, Freundlich, and Sips models with regression coefficient greater than 0.97. Of the three cations investigated, Ni2+ had the highest sorption affinity, followed by Cd2+ and Co2+. The effect of the hydrated radius on the sorption affinity was discussed. Thermodynamically, the sorption was spontaneous and exothermic in the temperature range 283–308 K.

Graphical abstractThe sorption capacity of kraft fibers for Cd2+ increases with pH due to increased degree of ionization of lignocellulosic fiber components. The sorption capacity also increased with the Cd2+ concentration.Figure optionsDownload full-size imageDownload high-quality image (26 K)Download as PowerPoint slide