Water-Stable Nanoscale Zirconium-Based Metal–Organic Frameworks for the Effective Removal of Glyphosate from Aqueous Media

Abstract

Two water-stable zirconium-based metal–organic frameworks (MOFs) (NU-1000 and UiO-67) have been synthesized in various size scales (100–2000 nm) for the adsorptive removal of glyphosate from the aqueous media. Both NU-1000 and UiO-67 possess a three-dimensional structure; NU-1000 consists of triangular micropores and wide mesoporous channels (31 Å), whereas UiO-67 has cage-like pores [octahedral (16 Å) and tetrahedral (14 Å) cages]. NU-1000 comprises Zr 6 (μ 3 -O) 4 (μ 3 -OH) 4 (H 2 O) 4 (OH) 4 , and UiO-67 contains Zr 6 O 4 (OH) 4 as secondary building units. These units act as Lewis acid nodes and can interact with the Lewis base phosphate group of the glyphosate. The time taken for reaching equilibrium is found to be reduced considerably as the size of the MOF decreases. The smaller the particle size, the lesser is the diffusion barrier for the analyte, which enhances the interaction between Lewis acidic metal nodes and the Lewis basic center of the glyphosate molecule. NU-1000 was found to be better compared to UiO-67, both in terms of efficiency and reusability. This might be due to the larger pore diameters of the NU-1000. Theoretical calculations revealed that the interaction energy of glyphosate with the nodes of NU-1000 is higher (−37.63 KJ mol –1 ) compared to UiO-67 (−17.37 KJ mol –1 ), which might be the possible reason for the higher efficiency of NU-1000.

Pyrene-based metal organic frameworks: from synthesis to applications

“…Another organic pollutant resulting from the use of herbicides is glyphosate, which causes damage to human cells and increases the risk of erosion and contamination of surface and groundwater sources. Pankajakshan et al 208 studied the adsorption of glyphosate using NU-1000 and UiO-67. The selection of these MOFs were because of the higher affinity of Lewis acid Zr metal nodes for the phosphate functional group of glyphosate, which is a Lewis base.…”

Liquid‐Phase Quasi‐Epitaxial Growth of Highly Stable, Monolithic UiO‐66‐NH2 MOF thin Films on Solid Substrates

“…Because of the high oxidation state of Zr 4 + , the strength of carboxylate-Zr 4 + -bonds result in a pronounced stability of the UiO (and also NU1000) bulk compound in boiling water and even in strongly basic conditions. [21] Unfortunately, the rather complicated secondary building unit (SBU) required for the fabrication of such UiO-type materials has prohibited the straightforward application of the liquid-phase epitaxy method.…”

Synthesis and Functionalization of Porous Zr-Diaminostilbenedicarboxylate Metal–Organic Framework for Storage and Stable Delivery of Ibuprofen

“…Among MOFs, zirconium-MOFs (Zr-MOFs) usually possess excellent chemical, thermal, and water stability because of strong Zr–O bonds and a stable secondary building unit. 25,26 For example, an amino-functionalized Zr-MOF, Zr-diaminostilbenedicarboxylate (Zr-DASDCA, also known as JLU-Liu36 or UBMOF-8 and composed of robust Zr 6 O 4 (OH) 4 clusters), is stable and contains large pores, 27,28 rendering it suitable for PSM. Moreover, functionalized Zr-MOFs are very attractive because of their potential applications, especially in biomedical fields and drug delivery.…”