Abstract
In this work, Dawson-type K6P2W18O62 polyoxometalate salt (abbreviated as P2W18) was successfully encapsulated into mesoporous MIL-101(Cr) metal organic framework. The as-prepared P2W18@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 K6P2W18O62 (~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 P2W18@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.
Highlights
Metal organic frameworks (MOFs) are crystalline porous materials whose structures are defined by metal ions or metallic clusters that are connected to bi- or multipodal organic linkers.[1]
The results showed that the P2W18@MIL-101(Cr) hybrid is an effective adsorbent for ultrafast removal of cationic dyes such as methylene blue (MB)and rhodamine B (RhB) from aqueous solutions
During the formation of the MIL-101 (Cr) framework, K6P2W18O62 molecules are encapsulated into the MIL-101 (Cr) framework to create a new hybrid with the formula of P2W18@ MIL-101(Cr).[36]
Summary
Metal organic frameworks (MOFs) are crystalline porous materials whose structures are defined by metal ions or metallic clusters that are connected to bi- or multipodal organic linkers.[1]. Polyoxometalates (POMs) are a class of compounds formed by bulky clusters of transition metal oxide anions and have attracted intensive attention due to their earth-abundant source, rich topology and versatility, controllable shape and size, oxo-enriched surfaces, highly electronegative etc, with various applications in many fields, such as catalysis, optics, magnetism, biological medicine as well as dye adsorption.[20] The disadvantages of low surface area (
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