Abstract

Graphene, a monolayer of carbon atoms densely packed into a two-dimensional honeycomb crystal lattice, has recently attracted much attention. It possesses an ultrahigh specific surface area, and thus has great potentials for the use as sorbent materials. In this article, we have developed a new method for the preconcentration and determination of trace amounts of cadmium (Cd) prior to its determination by flame atomic absorption spectrometry. It is based on the use of a column packed with graphene as the sorbent. Several effective parameters on the extraction and complex formation were selected and optimized. Under optimum conditions, an enrichment factor of 125 was obtained. The calibration function was linear in the concentration range of 10.0-120.0 µg L^-1 with a detection limit of 0.54 µg L^-1. The relative standard deviation for ten replicate measurements of 10.0 and 80.0 µg L^-1 of Cd were 3.57 and 2.63%, respectively. Comparative studies showed that graphene is superior to other adsorbents including C₁₈ silica, graphitic carbon, and single- and multiwalled carbon nanotubes for the extraction of Cd. The proposed method was successfully applied in the analysis of four real environmental water samples. Good spiked recoveries over the range of 95.4%-100.5% were obtained. This method reveals the large potential of graphene as a sorbent material in separation and preconcentration processes.

Keywords: Cadmium, flame atomic absorption spectrometry, graphene, preconcentration, sodium diethyldithiocarbamate trihydrate, solid-phase extraction.

Graphical Abstract