Adsorption of Cr(VI) on nano Uio-66-NH₂MOFs in water

Abstract

An efficient adsorbent, nano Uio-66-NH Metal-organic frameworks (MOFs), for the high efficiency removal of Cr(VI) from aqueous solution was successfully synthesized. The adsorbent was characterized and its performance in Cr(VI) removal was evaluated for the first time. Kinetic data reveal that the Cr(VI) adsorption is rapid in the beginning followed by a slower adsorption process; The Cr(VI) adsorption kinetics were well described by the pseudo-second-order kinetics model. The calculated adsorption capacity of this adsorbent for Cr(VI) by Langmuir model was 32.36 mg/g at pH 6.5. The temperature-dependent isotherms indicated that the adsorption reaction of Cr(VI) on the MOFs was a spontaneous process. Filtration experiments revealed that the membranes fabricated by the MOFs could quickly remove Cr(VI) ions from the aqueous solutions. Electrostatic attraction between Uio-66-NH and Cr(VI) should be the mechanism for Cr(VI) adsorption by Uio-66-NH.

Selective Dye Adsorption by Zeolitic Imidazolate Framework-8 Loaded UiO-66-NH2

“…However, the new absorption peaks for the vibration of aromatic ring of MB at 890 cm −1 and 1600 cm −1 could be clearly observed [52], which showed that the MB was immobilized on surface of ZIF-8-loaded UiO-66-NH 2 . The peaks at 1571 cm −1 (C=O), 1257 cm −1 (C–N), and 426 cm −1 (Zn–N) of ZIF-8-loaded UiO-66-NH 2 shifted and showed a significant decrease in intensity after MB adsorption [28,53,54]. This could be explained by the following assumptions: (i) MB, a cationic dye, is more inclined to be absorbed on negatively charged surfaces by electrostatic interaction.…”

Enhanced dispersibility of metal–organic frameworks (MOFs) in the organic phaseviasurface modification for TFN nanofiltration membrane preparation

“…This could be explained by the positively charged character of UiO-66-NH 2 -PC nanoparticles due to the existence of amino groups and zirconium ions in the framework structures. 31,32 3.2.6 Surface roughness of TFC and TFN membranes. The surface roughness of TFC and TFN membranes was studied by AFM measurement.…”

Chromium Speciation in Zirconium‐Based Metal–Organic Frameworks for Environmental Remediation

“…The bifunctionality of the UiO-66 materials has been achieved through:i )the linker defects generation,w hich are known to be efficient adsorption positions for Cr VI ;i i) the electron-donor groups incorporation (i.e.,-(OH) 2 ,-NH 2 )a tt he organic linkers, which work as active functionalitiest hat can directly trigger the Cr VI to Cr III reduction,a nd finally,i ii)the combination of the adsorption and posterior photo-reduction of Cr VI to Cr III for the specific case of photoactive UiO-66-NH 2 material. [57][58][59] After operation, chromium speciation has been fully determined by means of UV/Vis and EPR spectroscopy,q uantifying the Cr VI to Cr III reduction efficiency fore ach material. For comparison purpose, adsorptiona nd posterior speciation analysis have been also studied for trivalent chromium species, in order to understand the possible chromium immobilization mechanismsi na hypothetical case of full Cr VI to Cr III transformation.…”