Carbon-based sorbents and their nanocomposites for the enrichment of heavy metal ions: a review.

This review (with 168 refs) summarizes the progress that has been made on the field of microextraction of heavy metal ions using carbonaceous materials. Following an introduction into the features of such materials, we discuss the various kinds of sorption-based microextraction techniques (like solid phase extraction, micro solid phase extraction, solid phase microextraction, magnetic solid phase extraction, and dispersive solid phase extraction). The next section covers specific methods based on the use of carbon-based adsorbents (with subsections on uses of carbon nanotubes, graphene, fullerenes, activated carbon, carbon nanohorns, carbon nanofibers, graphitic carbon nitride, and their composites). The concluding section addresses current challenges, and gives an outlook on potential future trends. Graphical abstract Schematic of the variety of applications of carbonaceous sorbents in sorptive extraction methods including SPE, SPME, SBSE, DSPE, μSPE, D-μSPE, and MSPE for the extraction and enrichment of different heavy metals.