High-Content Hydroxyapatite Carbon Composites for the Electrochemical Detection of Heavy Metal Cations in Water

The great performance of nanostructured hydroxyapatite (Hap) in adsorbing heavy metal cations with the good electrical conductivity of high-surface carbon materials was here combined for the crafting of high-content hydroxyapatite electrodes (Hap 84-96 wt.%) endowed with the synergistic capability of detection and adsorption of heavy metal cations by water solutions. To improve the sustainability of the sensor, a mesoporous carbon (derivable by bio-waste) was selected as scaffold for depositing Hap by simply co-precipitation. The composite with 92 wt.% of Hap, which exhibited ca. 1 : 1 ratio between the exposed area of Hap and carbon (by Brunauer-Emmett-Teller method), invariably showed an average stripping oxidation peak intensity of ca. 250 mu A cm(-2) and 150 mu A cm(-2) for a 50 mu M Pb2+ and Cu2+ solution, respectively. Control experiments showed that the above sensor outperformed the sensibility of two low-content Hap electrodes (4 and 8 wt.%), representative of the best performing Hap-carbon composites available in literature.