Facile Synthesis of Cross-linked Hyperbranched Polyamidoamines Dendrimers for Efficient Hg(Ⅱ) Removal From Water.

Xue Geng,Shengnan Geng,Ying Zhang,Xiangyu Kong,Rongjun Qu,Chunnuan Ji,Changmei Sun

doi:10.3389/fchem.2021.743429

Abstract

Dendrimers as commonly used metal ions adsorption materials have the advantages of good adsorption performance and high reuse rate, but the high cost limits its extensive use. Compared with dendrimers, hyperbranched dendrimers have similar physical and chemical properties and are more economical. Therefore, hyperbranched dendrimers are more suitable for industrial large-scale adsorption. The hyperbranched polyamidoamine (HPAMAM) gels were prepared by cross-linking hyperbranched polyamidoamine (HPAMAM-ECH-x and HPAMAM-EGDE-x) with different amounts of epichlorohydrin (ECH) and ethylene glycol diglycidyl ether (EGDE), respectively. The as-synthesized adsorbents were characterized by FT-IR, SEM and XPS. The prepared adsorbents were used to adsorb Hg(Ⅱ) in aqueous solution, and the effects of solution pH, contact time, temperature and initial concentration of metal ion on the adsorption capacity were investigated. The effect of solution pH indicated that the optimum condition to Hg(Ⅱ) removing was at pH 5.0. The adsorption kinetic curves of the two kinds of materials were in accordance with the pseudo-second-order model. For the HPAMAM-ECH samples, the adsorption thermodynamic curves fitted the Langmuir model, while for the HPAMAM-EGDE samples, both Langmuir and Freundlich equations fitted well. The maximum adsorption capacity of HPAMAM-ECH-3 obtained from Langmuir model toward Hg(Ⅱ) was 3.36 mmol/g at pH 5.0 and 35°C.

Highlights

Pollution prevention and control has always been a serious problem with social development
It can be observed that the absorption peaks around 3284 and 1640 cm−1 in hyperbranched polyamidoamine (HPAMAM), which correspond to the N-H stretching vibration of amino and C O stretching vibration of amide (Oliveira et al, 2021), respectively
After crosslinking with ECH, the stretching vibration peak of C O were weakened and the C-O-C stretching vibration appeared at 1073 cm−1 (Abdulhameed et al, 2019), which indicated the successful crosslinking between HPAMAM and ECH

Summary

Introduction

Pollution prevention and control has always been a serious problem with social development Heavy metal ions such as Hg(II), Cu(II), Cd(II) and Pb(II) are one of the most discharged pollutants, which cause great harm to water body, soil and human health (Zamora-Ledezma et al, 2021). Hg(II) pollution mainly comes from the mining industry, battery production, electroplating and textile industries (Fan et al, 2019). When it is discharged into water, it will be absorbed by aquatic plants and animals, and infiltrate into the soil and affect crops, causing great harm to human health (Li et al, 2019).

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