Supported carbon dots serve as high-performance adsorbent for the retention of trace cadmium

Carbon dots were prepared via a one-pot hydrothermal route, and a new solid-phase extraction (SPE) adsorbent was developed by immobilizing the carbon dots on the microcarrier cytopore, shortly termed as C-dots@cytopore. The C-dots@cytopore composites were characterized by means of FT-IR, SEM, XPS and fluorescence spectrometry. The performance of the composites for the adsorption of heavy metals was thoroughly evaluated by using cadmium as a model. The binding of cadmium on C-dots@cytopore fits Langmuir adsorption, and the adsorption dynamic follows pseudo-second-order adsorption kinetics model. The binding of cadmium was pH-dependent, with a maximum adsorption capacity of 2420μgg−1 obtained at pH 4–7. A novel separation and preconcentration procedure was thus developed for trace cadmium using the C-dots@cytopore composites as SPE sorbent. The retained cadmium could be readily eluted and recovered by a 0.1molL−1 HNO3 solution and further quantified with graphite furnace atomic absorption spectrometry (GFAAS). With a sample volume of 1.0mL, an enrichment factor of 17.85 was obtained with a detection limit of 1.8ngL−1 and a RSD value of 2.6% at 0.1μgL−1 (n = 9). The procedure was further validated by analyzing cadmium in certified reference materials and a series of environmental water samples. The unique solid-phase extraction (SPE) adsorbent C-dots@Cytopore composites were prepared by immobilizing the carbon dots on the microcarrier Cytopore for the separation and preconcentration of trace cadmium. [Display omitted] •Supported carbon dots were prepared by modifying hydrosoluble carbon dots on a microcarrier as a novel SPE adsorbent.•The composites merged abundant active sites with great mechanical strength, which was suitable for cadmium preconcentration.•The composites exhibit fast adsorption/desorption dynamics and good adsorption stability against foreign metal species.