Adsorption of lead(II) and chromium(VI) from aqueous environment onto metal-organic framework MIL-100(Fe): Synthesis, kinetics, equilibrium and thermodynamics

• Published in: Journal of solid state chemistry Vol. 291; p. 121636
• Main Authors: Forghani, Mojtaba, Azizi, Asghar, Livani, Milad Jamal, Kafshgari, Leila Asadi
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01-11-2020
• Subjects: Adsorption; Chromium(VI); Lead(II); Metal organic frameworks; MIL-100(Fe); Adsorption; Metal organic frameworks; MIL-100(Fe); Lead(II); Chromium(VI)
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2020.121636

In present research, MIL-100(Fe) was efficiently synthesized by hydrothermal strategy applying HF as mineralizing agent and its ability was examined for lead(II) and chromium(VI) adsorption from an aqueous environment. Structural, chemical and morphological properties of the synthesized MOF were specified by different experimental techniques including XRD, FTIR, SEM, EDS and adsorption isotherms of N2 at 77 ​K (BET). D-spacing was measured with Debye–Scherrer’s formula as 7.98 ​Å. Also, the analyses confirmed relatively high BET surface area (1843.9 ​m2 ​g−1) and an octahedral-shaped structure for MIL-100(Fe) synthesized. Additionally, the adsorption behavior of lead(II) and chromium(VI) onto the MIL-100(Fe) was investigated using kinetics, equilibrium and thermodynamic parameters. Equilibrium analysis exhibited that the maximum uptake capacity for lead(II) was 23.46 ​mg ​g−1 based on sips model and for chromium(VI) was 30.45 ​mg ​g−1 ​by Langmuir isotherm. The sorption kinetics of lead(II) followed the pseudo 1st order model, while for chromium(VI) followed both pseudo 1st order and pseudo 2nd order models. Thermodynamic conclusions indicated a non-spontaneous nature for the sorption of each two metals and an exothermic reaction for lead(II) and endothermic nature for chromium(VI). Meanwhile, chemical ion-exchange and physisorption were distinguished as dominant adsorption mechanisms for lead(II) and chromium(VI), respectively.
Overall flowchart of MIL-100(Fe) fabricated for Pb(II) and Cr(VI) adsorption. [Display omitted]
•MIL-100(Fe) was efficiently synthesized by a facile hydrothermal route and HF mineralizing agent.•BET analysis proved a relatively high specific surface area (1843.9 ​m2 ​g−1) for fabricated MOF.•Adsorption behavior implied a good affinity for Pb(II) and the decreased affinity for Cr(VI).•Chemical ion exchange and physisorption were found as adsorption mechanism for Pb(II) and Cr(VI), respectively.