Graphite powder derivatized with poly-L-cysteine using "building-block" chemistry - a novel material for the extraction of heavy metal ions

Graphite powder derivatized with 4-nitrophenyl moieties (NPcarbon) can be used to successively attach other chem. species to the graphite surface in a controlled and selective manner. Characterization of these novel materials was undertaken using electrochem. and x-ray photoelectron spectroscopic (XPS) techniques. The authors demonstrate the proof of concept of this building-block chem. by 1st reducing the nitro groups on the NPcarbon using a Sn-HCl redn. to the corresponding aniline-like moieties, and then coupling p-nitrobenzoic acid to these via an amide-linkage. Next the authors demonstrate the utility of this novel derivatization method by coupling poly-S-benzyl-L-cysteine to the reduced NPcarbon in an analogous manner. After deprotection of the thiol groups using Na in liq. NH3, the poly-L-cysteine derivatized C (PCcarbon) was found to complex Cd(II) ions. Quant. anal. of the uptake of Cd2+ from aq. solns. at pH 5.0 by PCcarbon was carried out using stripping-voltammetry at a B doped diamond (BDD) electrode and revealed that PCcarbon complexed 137 ± 20 mg of Cd2+ per g of modified PCcarbon. [on SciFinder(R)]