Molecules, Vol. 30, Pages 4198: Iron-Based Metal–Organic Frameworks for the Removal of Different Organic and Inorganic Arsenic Species from Water: Kinetic and Adsorption Studies

Molecules doi: 10.3390/molecules30214198

Authors:
Afef Azri
Khaled Walha
Claudia Fontàs
José-Elias Conde-González
Eladia M. Peña-Méndez
Andreas Seubert
Victoria Salvadó

Basolite® F300 and synthetic nano-{Fe-BTC} MOFs, two iron-trimesate MOFs, have been investigated, demonstrating broad pH range adsorption for monomethylarsenate (MMA), cacodylic acid (DMAA), 4-aminophenylarsonate (ASA), and arsenate, while arsenite adsorption was notable at pH > 9.5. A similar uptake trend was found for both MOFs, with Basolite® F300 being the more effective given its higher porosity and greater surface area. Pseudo-second-order kinetic models were followed by MMA, DMAA, ASA, and As(V), suggesting a chemisorption mechanism with arsenic species diffusion into MOF pores as the controlling step. Equilibrium data for DMAA and ASA fit the Langmuir model whereas MMA adsorption fits the Redlich–Peterson model. The uptake of MMA, DMAA, and ASA by both Fe-MOFs is mainly attributed to their coordination with Fe(III). Aromatic units in ASA enhance adsorption through П-П stacking interactions. The competition between all arsenic species for the sorption sites of the Fe-MOFs led to an uptake decrease of 10% for MMA and ASA and higher than 30% for DMAA and As(V) with respect to the individual uptakes. The Fe-MOFs can be reused for four cycles by washing with acidic methanol. Basolite® F300 and synthetic nano-{Fe-BTC} effectively removed organic and inorganic arsenic species, exhibiting rapid adsorption, selective uptake, stability, and easy regeneration.

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