Removal of Cd(II) from Micro-Polluted Water by Magnetic Core-Shell Fe3O4@Prussian Blue.

Xinxin Long,Tijun Huang,Yifeng Lu,Rongzhi Chen,Huanyu Chen,Jihua Tan,Yajing Zhang

doi:10.3390/molecules26092497

Abstract

A novel core-shell magnetic Prussian blue-coated Fe3O4 composites (Fe3O4@PB) were designed and synthesized by in-situ replication and controlled etching of iron oxide (Fe3O4) to eliminate Cd (II) from micro-polluted water. The core-shell structure was confirmed by TEM, and the composites were characterized by XRD and FTIR. The pore diameter distribution from BET measurement revealed the micropore-dominated structure of Fe3O4@PB. The effects of adsorbents dosage, pH, and co-existing ions were investigated. Batch results revealed that the Cd (II) adsorption was very fast initially and reached equilibrium after 4 h. A pH of 6 was favorable for Cd (II) adsorption on Fe3O4@PB. The adsorption rate reached 98.78% at an initial Cd (II) concentration of 100 μg/L. The adsorption kinetics indicated that the pseudo-first-order and Elovich models could best describe the Cd (II) adsorption onto Fe3O4@PB, indicating that the sorption of Cd (II) ions on the binding sites of Fe3O4@PB was the main rate-limiting step of adsorption. The adsorption isotherm well fitted the Freundlich model with a maximum capacity of 9.25 mg·g−1 of Cd (II). The adsorption of Cd (II) on the Fe3O4@PB was affected by co-existing ions, including Cu (II), Ni (II), and Zn (II), due to the competitive effect of the co-adsorption of Cd (II) with other co-existing ions.

Highlights

Water pollution caused by heavy metals is of great concern due to their bioaccumulation, non-biodegradation, and high toxicity [1,2]
This work described the removal of Cd (II) from micro-polluted water using novel magnetic core-shell Fe3 O4 @Prussian blue (PB) composites as adsorbents
The adsorption characteristics and mechanisms of Cd (II) on Fe3 O4 @PB were studied in detail

Summary

Introduction

Water pollution caused by heavy metals is of great concern due to their bioaccumulation, non-biodegradation, and high toxicity [1,2]. A growing body of evidence shows that long-term exposure to cadmium may cause adverse effects on human health [5]. The maximum carcinogenic risk of Cd was suggested at the level of 10−7 μg/L for the individual through different exposure pathways [6]. In the past few years, drinking water resources that have been subjected to heavy metal micro-pollution, such as Cd micropolluted water, have generated various concerns. Chakrabarty and Sharma reported that higher levels of Cd (an average of 25 μg/L) in wells were caused by geogenic contamination in Assam, India [7]. Stricter legislation on pollution emissions and concentrations in the environment has been enforced.

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Conclusion