Designed Construction of 2D Honeycomb Cationic MOF Materials for Selective Removal of Sulfonic Anionic Dyes

Abstract

Various carcinogenic dyes in water bodies are difficult to degrade due to their stability to light and oxidants, causing extended pollution. In this study, MOF 1 ({[Co(tib)2]·(H2O)2·SO4} n ) and MOF 2 ({[Cu(tib)2]·(H2O)2·SO4} n ) (tib = 1,3,5-tirs(1-imidazolyl)benzene) were synthesized by the solvothermal method. MOFs 1 and 2 were successfully characterized by single-crystal X-ray diffraction (XRD) and powder X-ray diffraction (PXRD). Based on the structural characteristics of MOFs 1 and 2, we designed two cationic MOF material skeletons, namely, MOFs I and II ([Co(tib)2 2+] n and [Cu(tib)2 2+] n ), which were obtained by calcination in combination with the thermogravimetric curve to remove the free components in the lattice. As expected, MOFs I and II showed an excellent adsorption effect on sulfonic anionic dyes. Notably, the adsorption capacity of MOF I can reach 2922.8 mg g–1 for Congo Red (CR) at room temperature (RT). The adsorption process fits the pseudo-second-order kinetic model and Freundlich isotherm model. Moreover, zeta potential tests and quantum chemical calculations indicate that electrostatic interactions and hydrogen bond between the hydroxyl group on the sulfonic acid group and the N atom on the imidazole ring mainly promote the adsorption of CR dyes on MOF I. MOFs I and II are revealed as a promising novel adsorption material to remove hazardous organic aromatic pollutants with high efficiency in future endeavors.

Cationic Europium–Organic Framework for Chromatographic Column Separation of Ionic Dyes and Stimuli-Responsive Chromic Properties

“…To efficiently remove anionic pollutants from the aqueous system, cationic MOFs are highly sought after, representing the next generation of ion-exchange chromatographic materials that surpass conventional ion-exchange resins. Due to their positively charged networks with precisely defined pores, cationic MOFs could seamlessly integrate ion-exchange and size-exclusion effects, making them exceptional hosts for the targeted capture of anionic contaminants. − However, achieving precise control over the synthesis of cationic MOFs proves challenging during the one-pot bottom-up synthetic process, as the positive charge of metal or metal clusters is typically balanced by negatively charged organic linkers or anions.…”

Bells and Whistles on Fertilizers: Molecular Hands to Hang Nanoporous Foliar Fertilizer Reservoirs

“…In its quick phase of growth, various molecules have been tested as modulators to stabilize the structure; in this line, biomolecules, viz., amino acids, exhibit a mosaic of structures . MOF applications in catalysis, energy storage, water filtration, and gas adsorption have been explored. − Also, transition-metal-based MOFs have also been explored for ion-sensing and photocatalytic water splitting. − Further, in biology, the porous architecture has been used for sustained drug delivery.…”

Robust High-performance Bifunctional Porous Cobalt MOF-Based Catalysts for Overall Water Splitting

“…Nevertheless, their high cost and scarcity limit their large-scale application. It is worthwhile to investigate the use of organic framework materials, including nonprecious metals, in the overall water splitting process. − Metal-organic framework (MOF) materials, being extensively studied catalysts, have garnered a lot of interest because of their abundant metal active sites and tunable framework structure. − For example, Chen et al synthesized a FeMn bimetallic MOF which exhibits good electrocatalytic performance for electrocatalytic total water decomposition . MOFs are currently used primarily to enhance electrocatalytic activity by their derivatives, such as various oxides, , phosphides, − sulfides, , or single-atom catalysts. , However, this can damage the original active sites in MOFs or even cause their structural collapse .…”