Abstract
In this work, two magnetic adsorbents Fe3O4@1 and Fe3O4@2 were prepared by combining Fe3O4 nanoparticles and polyoxometalate hybrids [Ni(HL)2]2H2[P2Mo5O23]·4H2O (1), [H2L]5H[P2Mo5O23]·12H2O (2) (HL = 2-acetylpyridine-thiosemicarbazone). The temperature-dependent zero-field-cooled (ZFC) and field-cooled (FC) measurements indicated the blocking temperature at 160 K and 180 K, respectively. The Brunauer–Emmett–Teller (BET) surface area of Fe3O4@1 and Fe3O4@2 is 8.106 m2/g and 1.787 m2/g, respectively. Cationic dye methylene blue (MB) and anionic dye methyl orange (MO) were investigated for selective dye adsorption on Fe3O4@1 and Fe3O4@2. The two adsorbents were beneficial for selective adsorption of cationic dyes. The adsorption efficiency of MB was 94.8% for Fe3O4@1, 97.67% for Fe3O4@2. Furthermore, the two adsorbents almost maintained the same adsorption efficiency after seven runs. The maximum MB adsorption capacity of Fe3O4@1 and Fe3O4@2 is 72.07 and 73.25 mg/g, respectively. The fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) spectra of the adsorbents collected after adsorption of MB are very similar to the initial as-synthesized Fe3O4@polyoxometalates indicating the high stability of the two adsorbents. The adsorption kinetics indicated that the MB removal followed the pseudo-second-order model. These results showed that the two adsorbents had a potential application in treating wastewater.
Highlights
With industrial development, organic dyes have been one of the major water pollutants that cause serious environmental problems and threaten human health due to their toxicity [1,2]
Two magnetic adsorbents Fe3O4@1 and Fe3O4@2 were synthesized by the ultrasonic method with Fe3O4 and polyoxometalate hybrids 1, 2
The two adsorbents were highly efficient for selective removal of cationic dyes from aqueous solution
Summary
Organic dyes have been one of the major water pollutants that cause serious environmental problems and threaten human health due to their toxicity [1,2]. The other strategy is the adsorption process, which is recognized as the most simple, efficient and economic method for dye removal from water [10]. Polyoxometalate hybrid systems provide a new pathway for combining multiple functional groups in a nano structure, which demonstrates great potential for application in selective adsorption [12]. Phosphomolybdates are a unique class of polyoxometalates, which have attracted increasing attention owing to its unique structure and potential application in the removal of dyes [13,14]. Fe3O4@1 and Fe3O4@2 were explored in the adsorption of methylene blue (MB) and methyl orange (MO), and it turned out that the two nanocomposites had high efficiency for selective adsorption of cationic dyes. The two nanocomposites could be isolated from the sample solution by applying an external magnetic field. These results proved that the two magnetic nanocomposites could be of interest in treating wastewater
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