Preparation of Hydroxyapatite/Ionic Liquid Composite Film Modified Electrode and Its Application to the Highly Selective Determination of Trace Cadmium in Water

Stick-like hydroxyapatite particles were synthesized using cetyltrimethylammonium bromide as template and characterized with SEM, XRD and LR. The hydroxyapatite/ionic liquid modified electrode was prepared by coating the mixture of hydroxyapatite particles and the ionic liquids ([BMIM]PF6) on the glassy carbon electrode surface. The accumulative and electrochemical behavior of Cd(II) on the modified electrode was investigated and the results showed that Cd(II) could be accumulated on the hydroxyapatite surface and reduced to Cd by the ionic liquid at the open-circuit. When the potential was scanned to positive direction, a sensitive stripping peak was obtained. Therefore, a novel method was developed for the highly selective determination of trace cadmium in water samples based on the oxidative stripping. The interferences from lead, mercury, silver and other common metal ions were not found in this method. There was a good liner relationship between the stripping peak current and Cd(II) concentration in the range of 4.0 X 10(-8) similar to 2.2 X 10(-7) mol.L-1 with the detection limit of 2.0 X 10(-8) mol.L-1 Cd(II). This study should have potential application to environmental monitoring and environmental treatment.