Robust Al3+ MOF with Selective As(V) Sorption and Efficient Luminescence Sensing Properties toward Cr(VI)

Dimitrios Evangelou; Anastasia Pournara; Charikleia Tziasiou; Evangelos Andreou; Gerasimos S Armatas; Manolis J Manos

doi:10.1021/acs.inorgchem.1c03199

Robust Al³⁺ MOF with Selective As(V) Sorption and Efficient Luminescence Sensing Properties toward Cr(VI)

Inorg Chem. 2022 Jan 31;61(4):2017-2030. doi: 10.1021/acs.inorgchem.1c03199. Epub 2022 Jan 19.

Authors

Dimitrios Evangelou¹, Anastasia Pournara¹, Charikleia Tziasiou¹, Evangelos Andreou², Gerasimos S Armatas², Manolis J Manos^{1

3}

Affiliations

¹ Department of Chemistry, University of Ioannina, GR-45110 Ioannina, Greece.
² Department of Materials Science and Technology, University of Crete, GR-70013 Heraklion, Greece.
³ Institute of Materials Science and Computing, University Research Center of Ioannina, GR-45110 Ioannina, Greece.

PMID: 35044748
DOI: 10.1021/acs.inorgchem.1c03199

Abstract

Herein, we report the synthesis and characterization of a new robust Al³⁺ metal-organic framework MOF, [Al(OH)(PATP)]·solvent (Al-MOF-1, with PATP^2- = 2-((pyridin-2-ylmethyl)amino)terephthalate). Al-MOF-1 exhibits excellent stability from highly acidic (pH = 2) to basic (pH = 12) aqueous solutions or in the presence of oxoanionic species [As(V) and Cr(VI)]. On the contrary, the related MIL-53(Al) MOF (Al(OH) (BDC), with BDC^2- = terephthalate) shows a partial structure collapse under these conditions, signifying the superior chemical robustness of Al-MOF-1. Al-MOF-1 was proved to be an effective sorbent toward As(V) with efficient sorption capacity (71.9 ± 3.8 mg As/g), rapid sorption kinetics (equilibrium time ≤1 min), and high selectivity in the presence of various competing anions. Furthermore, Al-MOF-1 revealed high sorption capacities for Cr(VI) species in both neutral (124.5 ± 8.6 mg Cr/g) and acidic (63 ± 2 mg Cr/g) aqueous media, combining fast kinetics and relatively good selectivity. The limited porosity (BET = 38 m²/g) and small pores (2-3 Å) of the material indicate that the sorption process occurs exclusively on the external surface of Al-MOF-1 particles. The driving force for the capture of oxoanions by Al-MOF-1 is the strong electrostatic interactions between the oxoanionic species and the positively charged surface of MOF particles. Aiming at a practical wastewater treatment, we have also immobilized Al-MOF-1 on a cotton substrate, coated with polydopamine. The fabric sorbent exhibited highly effective removal of the toxic oxoanionic species from aqueous media under either batch or dynamic (continuous flow) conditions. In addition, Al-MOF-1 was found to be a promising luminescence sensor for detecting trace amounts of Cr(VI) in real water samples, with Cr(VI) being successfully detected at concentrations well below the acceptable limits (<50 ppb). Moreover, Al-MOF-1 was demonstrated to be a sufficient water sensor in organic solvents (LOD ≤0.25% v/v). All the above indicate that Al-MOF-1 represents a multifunctional material with a multitude of potential applications, such as environmental remediation, industrial wastewater treatment, chemical analysis, and water determination in biofuels.