A Ca2+ MOF combining highly efficient sorption and capability for voltammetric determination of heavy metal ions in aqueous media

Anastasia D. Pournara, Antigoni Margariti, Georgios D. Tarlas, Andreas Kourtelaris, Valeri Petkov, Christos Kokkinos, Anastasios Economou, Giannis S. Papaefstathiou, Manolis J. Manos

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

We recently discovered that a Ca2+ two-dimensional framework, namely [Ca(H4L)(DMA)2]·2DMA (Ca-MOF), was capable of exchanging the Ca2+ ions with Cu2+ almost quantitatively in a matter of seconds in aqueous solution. Herein, we report that Ca-MOF exhibits the capability of both removal and voltammetric determination of heavy metal ions in aqueous media. Ca-MOF shows one of the highest Pb2+ sorption capacities (∼522 mg g-1) reported for MOFs. More importantly, a column filled with Ca-MOF (1% wt) particles dispersed in silica sand (99% wt) can quantitatively remove traces of Pb2+ (∼100 ppb) from a relatively large volume of a wastewater simulant solution (containing a large excess of competitive ions). Ca-MOF is also highly efficient for sorption of Cd2+, Ni2+ and Zn2+, even in the presence of several competitive cations. Actually, the Cd2+ sorption capacity (∼220 mg g-1) of Ca-MOF is one of the largest reported for MOFs. Furthermore, detailed Ni2+ and Zn2+ sorption studies of MOFs have not been described prior to this work. The mechanism of the M2+ (M2+ = Pb2+, Cd2+, Ni2+, Zn2+) exchange process was elucidated based on a series of spectroscopic, analytical and X-ray diffraction methods. In addition, a simple ready-to-use electrochemical sensor based on modified graphite paste with Ca-MOF was fabricated and successfully utilized for the determination of Pb2+, Cd2+, Cu2+ and Zn2+ at μg L-1 levels in aqueous solutions by anodic stripping voltammetry (ASV). Overall, this work demonstrates, for the first time, a dual function of a MOF as a sorbent and as an electrochemical sensor for heavy metal ions, thus opening a new window for materials with application in both environmental remediation and monitoring.

Original languageEnglish
Pages (from-to)15432-15443
Number of pages12
JournalJournal of Materials Chemistry A
Volume7
Issue number25
DOIs
StatePublished - 2019

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