Kinetic and Thermodynamic Study of Magnetic Separable β-Cyclodextrin Inclusion Complex with Organic Phosphoric Acid Applied to Removal of Hg2+.

Magnetic β-cyclodextrin inclusion complex with phosphonobutanetricarboxylic acid (MNP-CD-PBTCA) was synthesized via step-by-step method to applied in removal of Hg2+ for the first time. TEM, SEM, XRD, TGA, FTIR, and BET proved the successful synthesis of core-shell structure of MNP-CD-PBTCA whose particle size ranged from 20 to 200 nm. In the single-factor experiments for adsorption of Hg2+, the maximum uptake capacity of MNP-CD-PBTCA attained was 77.59 mg·g-1 after 150 min of adsorption while the pH was 4 and the temperature was kept at 55 °C. Langmuir isotherm study indicated the adsorption of MNP-CD-PBTCA for Hg2+ was in agreement with monolayer theory and was rate controlled by chemisorption; chelation interaction between phosphoric acid group and Hg2+ was suggested to be the main bonding effect in adsorption. Calculated thermodynamic results demonstrated that the adsorption process was a spontaneous and endothermic reaction with entropy-production; reusability study suggested that application of MNP-CD-PBTCA would be convenient, efficient, and economic. [ABSTRACT FROM AUTHOR]