A new MOF-based modified adsorbent for the efficient removal of Hg(ii) ions from aqueous media: isotherms and kinetics

Abstract

Herein, a new MOF-based modified adsorbent for the efficient removal of Hg(II) ions from water media was successfully prepared. Initially, a MOF nanocomposite was synthesized and applied as an efficient adsorbent for the removal of the target heavy metal ion. Following the synthesis, the MOF-based modified adsorbent was identified and characterized by SEM, XRD and FT-IR analytical instruments. The impact of several key variables such as pH of aqueous solution, adsorbent dosage, contact time, and initial concentration of the analyte of interest on the adsorption efficiency was also investigated in detail. Under the optimal conditions established (pH, 3; dose of adsorbent, 0.4 g L⁻¹; contact time, 40 min and the analyte's concentration of 1 mg L⁻¹) the removal efficiency of 96.3% for Hg(II) was obtained. The results of the studies on the isotherm and kinetics of adsorption revealed that the adsorption process of Hg(II) matched with the Langmuir isotherm (R² > 0.990) and the pseudo 2nd-order kinetic models (R² > 0.998). Additionally, reuse of the applied adsorbent for five consecutive tests exhibited a small percentage of drop (about 8%) in the removal efficiency of the target ion. Finally, the results indicated that the MOF-based modified compound could be potentially applied as a highly efficacious adsorbent for the discharge of Hg(II) from aquatic media.