Calix[4]pyrrole for the removal of arsenic (III) and arsenic (V) from water

Abstract

Although extensive research has been carried on anion complexation reactions involving calix[4]pyrrole, nothing has been reported regarding this receptor and its interaction with arsenic species. The fact that a single step reaction is required for the synthesis of this receptor, calls upon the need to explore its removal ability for these species from water as a starting point for the development of a new technological approach for water remediation purposes based on Supramolecular Chemistry. This paper reports a detailed study on the interactions involving calix[4]pyrrole with As(III) and As(V). The interaction of As species and calix[4]pyrrole was assessed by 1H NMR using a phase transfer approach aided by molecular simulation studies. The X-ray spectrum confirms the presence of arsenic species in the solid receptor.

Optimal conditions for removing As(III) and As(V) from water were established. The kinetics of extraction is fast and calix[4]pyrrole is able to remove 15.28 and 14.29 mg/g of arsenate and arsenite respectively.

Material was tested for removing arsenic species from real samples collected from different contaminated sites in Argentina. Percentages of arsenate, arsenite and organic arsenic removed from these samples are higher than 85%.