Abstract

A novel and green adsorbent based on sulfobetaine-modified magnetic Fe3O4 nanoparticles (SBMNPs) was successfully synthesized via a convenient one-step chemical coprecipitation method and applied to the removal of the anionic dyes methyl blue (MB) and amaranth (AM) from aqueous solution. The morphology and properties of the SBMNPs were characterized using various methods, including Fourier-transform infrared spectroscopy, X-ray powder diffraction, transmission electron microscopy, and vibrating-sample magnetometry. The obtained SBMNPs were easily dispersible in water and exhibited excellent superparamagnetic behavior. For the adsorption process, four experimental parameters, namely, the solution pH, initial dye concentration, reaction time, and adsorbent dosage, were optimized. The adsorption process was remarkably fast and reached equilibrium within 15 min. The isotherm data were consistent with the Langmuir model, and the maximum adsorption capacities of the SBMNPs were 127.06 mg·g−1 and 57.01 mg·g−1 for MB and AM, respectively, which exceed those reported for other adsorbents. The adsorption kinetics were well fitted by a pseudo-second-order model, which indicated chemical adsorption. Furthermore, the SBMNPs displayed good recyclability, removing 80.92% of MB and 77.49% of AM in the fifth cycle. Owing to their rapid adsorption properties and facile synthesis from green and inexpensive starting materials, the SBMNPs may represent a promising new adsorbent for the removal of anionic dyes from aqueous solution.

Highlights

  • Organic dyes are extensively used in cosmetics, paper, leather, textiles, plastics, medicine, and other sectors owing to their numerous advantages, such as variety, color stability, and low cost.[1]

  • A characteristic Fe–O stretching vibration band was observed at 578 cm−1 in the spectrum of the sulfobetaine-modified magnetic Fe3O4 nanoparticles (SBMNPs), which is the same as that of pure Fe3O4.30 The Fourier-transform infrared (FT-IR) spectra confirmed the presence of sulfobetaine on the SBMNP surface owing to the observation of a C=O stretching vibration band at 1631 cm−1,31 C–H stretching vibration and bending vibration bands scitation.org/journal/adv scitation.org/journal/adv of the alkyl group at 2927 cm−1 and 1396 cm−1,32 and a C–S stretching vibration band at 1238 cm−1

  • The absorption band at 3433 cm−1 was ascribed to water molecules adsorbed on the SBMNP surface

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Summary

INTRODUCTION

Organic dyes are extensively used in cosmetics, paper, leather, textiles, plastics, medicine, and other sectors owing to their numerous advantages, such as variety, color stability, and low cost.[1]. A variety of adsorbents have been widely used to remove organic dyes, including activated carbon, montmorillonite clay, fuller’s earth, kaolin, etc.[11–13]. We reported that betaine-modified Fe3O4 nanoparticles (BMNPs) could serve as a novel adsorbent for the rapid removal of MB from aqueous samples at room temperature.[27]. To the best of our knowledge, there have been no previous reports concerning the use of sulfobetaine-modified Fe3O4 nanoparticles as an adsorbent for removing organic dyes. We successfully synthesized the novel green adsorbent of sulfobetaine-modified magnetic Fe3O4 nanoparticles (SBMNPs), characterized them using various techniques, including Fourier-transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and vibrating-sample magnetometry (VSM), and applied them to the removal of the anionic dyes MB and AM from aqueous solution. The isotherms, kinetics, and recyclability were comprehensively examined to demonstrate the adsorption ability and recycling capacity of the SBMNPs

Materials
Instrumentation
Synthesis of the SBMNPs
Adsorption experiments
Morphology and structure of as-prepared SBMNPs
Optimization of experimental parameters
Adsorption equilibrium
Adsorption isotherms
Adsorption kinetics
CONCLUSION

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