Dawson-Type Polyoxometalate Incorporated into Nanoporous MIL-101(Cr): Preparation, Characterization and Application for Ultrafast Removal of Organic Dyes

Abstract

In this work, Dawson-type K 6 P 2 W 18 O 62 polyoxometalate salt (abbreviated as P 2 W 18) was successfully encapsulated into mesoporous MIL-101(Cr) metal organic framework. The as-prepared P 2 W 18 @MIL-101(Cr) nanohybrid was characterized by FT-IR spectroscopy, XRD, Raman spectroscopy, EDX, SEM, zeta potential measurements and BET surface area. The results demonstrated the successful loading of K 6 P 2 W 18 O 62 (~36 wt.%) into porous MIL-101(Cr) framework. Compared with the pristine MIL-101(Cr), the encapsulated sample demonstrated a significant decrease in both surface area and pore volume owing to the insertion of large Dowson-type POM into the cages of MOF. The resulting P 2 W 18 @MIL-101(Cr) was applied as a new adsorbent to remove methylene blue (MB), Rhodamine B (RhB) and methyl orange (MO) organic dyes from aqueous solutions. The effect of effective parameters such as adsorbent dosage, dye concentration, pH, and the temperature was studied on the dye removal process. Furthermore, the selective adsorption of the nanohybrid was investigated towards MB/MO, MB/RhB, MO/RhB and MB/MO/RhB mixed dye solutions. The nanohybrid showed rapid and selective adsorption for cationic MB and RhB dyes from mixed dye solutions. The results indicated that the dye adsorption followed Langmuir isotherm. The thermodynamic data showed that the adsorption is an endothermic process. This nanohybrid can function as a recyclable efficien adsorbent for the rapid removal of various cationic textile dyes from aqueous solutions.

The Chemistry and Applications of Metal–Organic Frameworks (MOFs) as Industrial Enzyme Immobilization Systems

“…The nanohybrid was used in an adsorption test with the following organic dyes: methylene blue, rhodamine B, and methyl orange. The results indicated that the material obtained showed fast selective adsorption for systems with different dye concentrations [ 124 ].…”

“…The hydrothermal and solvothermal methods employed are dependent on the solvent used. In general, processes that use water as a solvent are termed hydrothermal processes [ 124 ], while those that use other solvents are classified as solvothermal processes [ 126 ].…”

“…It is worth mentioning that the rate of cooling can influence the properties of the synthesized material [ 109 ]. The main disadvantages of these methods include the processing time and the operating costs, making it difficult to reproduce them on industrial scales [ 111 , 124 , 125 , 126 ].…”

“…The hydrothermal and solvothermal methods employed are dependent on the solvent used. In general, processes that use water as a solvent are termed hydrothermal processes [124], while those that use other solvents are classified as solvothermal processes [126]. In a later work, Yaghi et al [108] discuss that reticular chemistry refers to the arrangement of pre-established coordinate structures through rigid molecular building blocks (the SBUs) that replicate and remain united through metal-ligand bonds [108].…”

“…Generally, processes that use water as a solvent are termed hydrothermal processes, while those that use other solvents are classified as solvothermal processes [124,126] Dye removal MIL-101(Fe)@PDopa@Fe 3 O 4 [144] Lithium-sulfur battery Cu 2 (CuTCPP) [145] Diffusion Diffusion MOF synthesis methods can be subdivided into two strategies: diffusion between two liquids with different densities (no physical barrier) and gradual diffusion that occurs through physical barriers [111] Drug delivery CD-MOF [146] Adsorption of copper ions MOF-5 [112] Electrochemical Electrochemical synthesis is widely used at an industrial scale to produce MOFs [129] Lithium-ion batteries Zn-POMCF [129] Ibuprofen adsorption [Zn(1,3-bdc)0.5…”