Capability of magnetic functional metal-organic nanocapsules for removal of mercury(II) ions

In this study, a magnetic infinite coordination polymer with the morphology of nanocapsule, as an efficient adsorbent for removal of Hg2+ ions has been introduced. This infinite coordination polymer was synthesized from Zn2+ ion and a ditopic organic ligand (1,3-bis(tetrazol-5-ylmethyl)benzene (btb)) and its efficiency as an adsorbent was studied in view of adsorption isotherms, kinetics and thermodynamics. The adsorption capacity of mercury(II) ions was impressed by pH value and adsorption time and the optimal adsorption conditions were pH value of 8, adsorption time of 75 min. The adsorption isotherm was analyzed by Freundlich and Langmuir equations and was fitted with Langmuir model better. Outcomes indicated that the adsorption was an endothermic process. Moreover, this adsorption process was fitted with pseudo-second order model kinetically. Finally, the magnetic properties of nanocapsules synthesized in high and low concentration of initial reagents were investigated. Studies showed that the saturation magnetization of nanocapsules synthesized in low concentration of initial reagent is higher.