Highly Efficient Arsenite [As(III)] Adsorption by an [MIL-100(Fe)] Metal–Organic Framework: Structural and Mechanistic Insights

Abstract

The MIL-100­(Fe) metal–organic framework presents a high As­(III) uptake capacity of 120 mg g–1. Mechanistic insights into the role of Fe sites versus carbon sites on As­(III) uptake are provided by a comparative study of a series of MIL-100­(Fe) calcinated at 600, 800, and 900 °C. Using powder X-ray diffraction, TEM, scanning electron microscopy, and N2-porosimetry, we have mapped the morphology evolution of the materials. Fourier transform infrared spectroscopy, thermogravimetric analysis, and electron paramagnetic resonance show that noncalcined MIL-100­(Fe) bears Fe3+ atoms; however, after carbonization, a porous carbon matrix is formed bearing zero-valent iron cores coated with an Fe-oxide layer and iron carbide. The relative proportion of these phases depends on the calcination temperature, that is, 600, 800, and 900 °C. A comprehensive surface complexation model is presented, allowing a quantitative description of the As­(III) adsorption on Fe sites and carbon sites. More specifically, As­(III) uptake can be attributed to specific FeOH sites, located inside the pores and carbon C x OH2 sites located on the surface. Confinement inside the pores is found to be responsible for the lateral interactions among the adsorbed [H3AsO3] species. The As­(III) uptake of MIL-100­(Fe) is 3- to 10-fold higher versus pertinent adsorbent materials, such as graphite/graphite oxide, activated carbon, and pyrolytic carbon, and comparable with that of MIL-101­(Cr).

A Hybrid {Silk@Zirconium MOF} Material as Highly Efficient AsIII-sponge

“…Further analysis of the surface adsorption for the As III species can be done by modeling of the pH-dependent As-uptake on the ZrMOF. This analysis, detailed in our previous works 16,24,67 , is described in Supporting Information, Fig. S4.…”

“…Our systematic efforts during the last decade led to a series of nanomaterials with promising performances, e.g. a mesoporous spinel CoFe 2 O 4 24 with an uptake of 252 mg As III g −1 , magnetic carbon nanocages 22 with a sorption capacity of 264 mg As III g −1 and MIL-100(Fe) 16 showing uptake of 120 mg As III g −1 .…”

“…typical for natural waters, the dominant species is the neutral form H 3 AsO 3 27,28 . Thus -so far -the strategy by all research groups, including us 16,22,29 , was to maximize the number and accessibility of surface sites based on diligent preparation protocols. In this way, it has been achieved a max As III -uptake capacity 320 mg gr −1 by γ-Fe 2 O 3 nanoparticles encapsulated in a macroporous Silica 23 .…”

A new route to triphenylpyridines utilizing ketoximes as building blocks via cascade reactions under iron‐organic framework catalysis

“…In addition to MOFs consisted of a single kind of organic ligand, many frameworks constructed from a mixture of two or more linkers have also been studied . Among a long list of frameworks, iron‐based MOFs have gained considerable interests . Certainly, diverse organic transformations were previously conducted under Fe‐MOF catalysis conditions .…”

“…[29][30][31] Among a long list of frameworks, iron-based MOFs have gained considerable interests. [32][33][34] Certainly, diverse organic transformations were previously conducted under Fe-MOF catalysis conditions. [35][36][37] In this work, we would like to present alternative routes to 2,4,6-triphenylpyridines from ketoximes and dibenzyl ether via cascade reactions in the presence of VNU-20 iron-organic framework catalyst.…”