A novel cartoon crosslinked β-cyclodextrin (C-β-CD) polymer for effective uptake of Hg from aqueous solutions: Kinetics, equilibrium, thermodynamics, and statistical physics approach

Abstract

A novel cartoon crosslinked β-cyclodextrin (C-β-CD) polymer was obtained by crosslinking β-CD unities and cellulosic fibers of paper towel cardboard via esterification using citric acid. C-β-CD polymer was used as an adsorbent to uptake Hg from aqueous matrices, and kinetics, equilibrium, thermodynamics, and statistical physics were evaluated. It was found that the C-β-CD polymer was successfully synthesized and was a promising adsorbent to remove Hg from aqueous solution, achieving a removal percentage higher than 90 % and a maximum adsorption capacity of 211.3 mg g−1. The best operational adsorption conditions were a pH of 5.0, an adsorbent dosage of 0.5 g/L, 270 min, and 328 K. Besides, the pseudo-second-order model well-described the adsorption kinetics, and the Langmuir model better represented the equilibrium. The thermodynamic studies pointed to spontaneous and endothermic adsorption. The positive effect of the temperature on the process was also confirmed by the statistical physics approach, where the number of ions adsorbed per site increased with increasing temperature. It was suggested that electrostatic interaction was the main interaction mechanism responsible for the good performance of the novel C-β-CD polymer. In addition, the adsorbent proved to be effective for three adsorption cycles. Finally, it can be concluded that a novel C-β-CD adsorbent was prepared using an easy and green technique, and the obtained material is promising to separate Hg from contaminated waters.