Diethyl ether-modified calix[4]pyrrole receptor: thermodynamics of lead cation complexation – lead extraction from water by its polymer

Abstract

A new calix[4]pyrrole-based macrocycle, meso-tetramethyltetrakis-[4-(2-ethoxy)ethoxyphenyl]calix[4]pyrrole, (2) has been prepared and characterized. The binding ability of (2) for metal cations were investigated by ultraviolet–visible spectrophotometry in acetonitrile at 298.15 K. Stability constant and thermodynamic parameters for 1:1 binding interaction between (2) and Pb(II) cation were measured at different temperatures. Ether calix[4]pyrrole polymer, (4) was also synthesized. Solid-phase extraction of Pb(II) cation by (4) from the aqueous media has been studied using the batch method. Various significant extraction parameters (mass, lead concentration, temperature, and time) have been evaluated. Analysis of equilibrium data shows linear fitting with the Langmuir isotherm. Uptake capacity was found to be 80 mg g⁻¹ at 298.15 K. Kinetic studies show a pseudo-second-order reaction mechanism. The thermodynamic parameters of extractions were also calculated.

Keywords:

• Ether calix[4]pyrrole
• Lead cation
• Polymer
• Thermodynamic
• Kinetics
• Extraction
• Isotherm

Acknowledgements

The authors gratefully acknowledge the help of Prof. Angela Danil de Namor at University of Surrey, UK.