Poly(Amidoamine) Dendrimer Modified Superparamagnetic Nanoparticles as an Efficient Adsorbent for Cr(VI) Removal: Effect of High-Generation Dendrimer on Adsorption Performance

Can Cui,Hai-Liang Hu,Sen Lin,Jiao-Jiao Niu,Ya-Dian Xie

doi:10.1007/s10904-021-02222-8

Abstract

In this work, three different generations of Poly(amidoamine) dendrimers (PAMAM) decorated on magnetic Fe3O4 composites (Fe3O4@SiO2–G1, Fe3O4@SiO2–G3, Fe3O4@SiO2–G5) were fabricated and characterized by FTIR, XRD, TEM, TGA, VSM and XPS. The obtained composites were used for Cr(VI) removal. Batch adsorption studies showed that the adsorption reached equilibrium within 60 min, and the optimal pH was 3.0. The result of adsorption kinetics was simulated by the pseudo-second-order model. The adsorption equilibrium isotherm was well fitted with the Langmuir adsorption model. Furthermore, thermodynamics calculations revealed that the adsorption process was endothermic and spontaneous. Importantly, adsorption capacity of Cr(VI) obeyed the sequence of Fe3O4@SiO2–G1 < Fe3O4@SiO2–G5 < Fe3O4@SiO2–G3, 3 generation of PAMAM (G3) was the optimal for adsorption capacity of Cr(VI). The maximum theoretical Cr(VI) adsorption capacity (qm) of Fe3O4@SiO2–G3 was 334.45 mg/g, and removal ration remained above 89.5% after five cycles of adsorption–desorption. Thus, Fe3O4@SiO2–G3 is predicted to be an efficient adsorbent for the adsorption of Cr(VI) from aqueous solution, and the obtained results can help in the generation optimization during fabrication of dendrimer modified adsorbents.

Highlights

Water contamination arises from heavy metal ions has attracted great attention due to its high toxicity, non-degradability, carcinogenicity, and ecological unbalance [1–3]
After decoration of Fe3O4 with different generations of Poly(amidoamine) dendrimers (PAMAM) dendrimer, the characteristic peaks of the above crystal planes still exist and do not change the position and intensity, suggesting the crystal structure of Fe3O4 is not destroyed during the functionalization
Interestingly we found that the adsorption capacity of Fe3O4@SiO2–G5 is relatively poor than that of Fe3O4@SiO2–G3, this may be due to excessively high generation causes the large sterically hindered, which hinders the contact of Cr(VI) with the amine groups located within the interior of PAMAM, and causes serious surface defects of PAMAM, that decreasing amine groups on the surface of Fe3O4@SiO2–G5

Summary

Introduction

Water contamination arises from heavy metal ions has attracted great attention due to its high toxicity, non-degradability, carcinogenicity, and ecological unbalance [1–3]. Chromium is widely used in the fields of electroplating, cement production, paper processing and textile industry [4]. Chromium ion is harmful to the environment and human health because of its biological build-up and tremendous toxicity. Cr(III) and Cr(VI) are the primary Cr ion states in aqueous solution. The latter is more toxic and carcinogenic [5]. The development of low cost materials and effective techniques for the removal of Cr(VI) is imperative

Methods

Results

Conclusion