Host-Guest Extraction of Heavy Metal Ions with p-t-Butylcalix[8]arene from Ammonia or Amine Solutions.

Md Hasan Zahir,Shakhawat Chowdhury,Md Abdul Aziz,Mohammad Mizanur Rahman

doi:10.1155/2018/4015878

Md Hasan Zahir, Shakhawat Chowdhury + Show 2 more

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https://doi.org/10.1155/2018/4015878

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Abstract

The capacities of the p-t-butylcalix[8]arene (abbreviated as H8L) host to extract toxic divalent heavy metal ions and silver from aqueous solution phases containing ammonia or ethylene diamine to an organic phase (nitrobenzene, dichloromethane, or chloroform) were carried out. When the metal ions were extracted from an aqueous ammonia solution, the metal ion selectivity for extraction was found to decrease in the order Cd2+> Ni2+> Cu2+> Ag+> Co2+> Zn2+. When the aqueous phase contained ethylene diamine, excellent extraction efficiencies of 97% and 90% were observed for the heavy metal ions Cu2+ and Cd2+, respectively. Under the same conditions the extraction of octahedral type metal ions, namely, Co2+ and Ni2+, was suppressed. The extraction of transition metal cations by H8L in ammonia and/or amine was found to be pH dependent. Detailed analysis of extraction behavior was investigated by slope analysis, the continuous variation method, and by loading tests.

Highlights

Host–guest chemistry has attracted great attention in the field of separation and/or extraction of alkaline, rare earth, and divalent heavy metal ions with calixarenes and their ester derivatives
Calix[6]arenes can be modified with a carboxylic acid as host in the host–guest extraction of immunoglobulin G (IgG) [6]
The logD value increases linearly with an increasing initial concentration of ammonia with a slope of 2. These findings suggest that a 2:1 (H8L: metal) complex was extracted into the organic phase by releasing an equimolar amount of protons from H8L along with two ammonia molecules

Summary

Introduction

Host–guest chemistry has attracted great attention in the field of separation and/or extraction of alkaline, rare earth, and divalent heavy metal ions with calixarenes and their ester derivatives. Calixarenes are macrocyclic phenolic oligomers with phenolic hydroxyl groups, which are able to coordinate the metal ions very tightly. Yusof et al reported that the heavy metal ions could be included into the host calix[4]resorcinarenes cavity in water-chloroform extraction systems [4, 5]. A precise affinity can be created for specific ions and/or molecules by modification the hydroxyl functional group and/or by creating a new cavity size [7]. The cavity size, position and type of donor groups, and molecular flexibility lead to their high potential for the complexation and extraction of metal ions. Ludwig et al reported the impact of calixarenes in analytical chemistry and chemical separation technology in a review article [8]

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