Fabrication of attapulgite/magnetic aminated chitosan composite as efficient and reusable adsorbent for Cr (VI) ions.

Abdelazeem S Eltaweil,Eman M Abd El-Monaem,Ahmed M Omer,Mohamed S Mohy-Eldin

doi:10.1038/s41598-021-96145-6

Abdelazeem S Eltaweil, Eman M Abd El-Monaem + Show 2 more

Open Access

https://doi.org/10.1038/s41598-021-96145-6

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Abstract

An efficient composite was constructed based on aminated chitosan (NH2Cs), attapulgite (ATP) clay and magnetic Fe3O4 for adsorptive removal of Cr(VI) ions. The as-fabricated ATP@Fe3O4-NH2Cs composite was characterized by Fourier Transform Infrared Spectroscopy (FTIR), Thermal Gravimetric Analyzer (TGA), Scanning Electron Microscope (SEM), Zeta potential (ZP), Vibrating Sample Magnetometer (VSM), Brunauer–Emmett–Teller method (BET) and X-ray photoelectron spectroscope (XPS). A significant improve in the adsorption profile was established at pH 2 in the order of ATP@Fe3O4-NH2Cs(1:3) > ATP@Fe3O4-NH2Cs(1:1) > ATP@Fe3O4-NH2Cs(3:1) > Fe3O4-NH2Cs > ATP. The maximum removal (%) of Cr(VI) exceeded 94% within a short equilibrium time of 60 min. The adsorption process obeyed the pseudo 2nd order and followed the Langmuir isotherm model with a maximum monolayer adsorption capacity of 294.12 mg/g. In addition, thermodynamics studies elucidated that the adsorption process was spontaneous, randomness and endothermic process. Interestingly, the developed adsorbent retained respectable adsorption properties with acceptable removal efficiency exceeded 58% after ten sequential cycles of reuse. Besides, the results hypothesize that the adsorption process occurs via electrostatic interactions, reduction of Cr(VI) to Cr(III) and ion-exchanging. These findings substantiate that the ATP@Fe3O4-NH2Cs composite could be effectively applied as a reusable adsorbent for removing of Cr(VI) ions from aqueous solutions.

Highlights

An efficient composite was constructed based on aminated chitosan (NH2Cs), attapulgite (ATP) clay and magnetic Fe3O4 for adsorptive removal of Cr(VI) ions
Fourier Transform Infrared Spectroscopy (FTIR) spectrum of NH2Cs points out absorption bands at 2901, 2216 and 1619 cm−1 which correspond to C H2, COH stretching and N–H bending vibrations, r espectively[46]
Batch adsorption experiments clarified that the best adsorption capacity values were attained at pH 2 and achieved by ATP@Fe3O4-NH2Cs(1:3)

Summary

Introduction

An efficient composite was constructed based on aminated chitosan (NH2Cs), attapulgite (ATP) clay and magnetic Fe3O4 for adsorptive removal of Cr(VI) ions. The magnetization loops of both Fe3O4 and ATP@Fe3O4-NH2Cs composite reveal a ferromagnetic behavior as the coericivity values were 198.76 and 90.68 G, respectively. It was obvious that the incorporation of ATP clay greatly enhanced the removal efficiency of F e3O4-NH2Cs. the increase in the adsorption capacity with increasing the Fe3O4-NH2Cs dosage in the adsorption medium is most likely due to increasing the surface positive charges resultant from the extra amine groups of aminated chitosan (NH2Cs).

Results

Conclusion