A Novel Chitosan Nanoparticle-Schiff Base Modified Carbon Paste Electrode as a Sensor for the Determination of Pb(II) in Waste Water

This paper describes the preparation and electrochemical application of a modified carbon paste electrode with a new kind of chitosan nanoparticle-Schiff base for the determination of Pb(II) ions in waste water using differential pulse anodic stripping voltammetry (DPASV). Firstly a new kind of chitosan nanoparticle-Schiff base (CNSB) was synthesized by chitosan nanoparticle reaction with 2,4-dihydroxybenzaldehyde. CNSB structure was characterized by FT-IR spectroscopy, elemental analysis, particle size and zeta potential. Afterwards, a novel, simple and effective chemically modified carbon paste electrode with CNSB was prepared and characterized using scanning electronic microscopy (SEM-EDX) and anodic stripping voltammetry. The modified electrode showed only one oxidation peak in the anodic scan at -0.35 V (vs. Ag/AgCl) for the oxidation of Pb(II). The electrochemical properties and applications of the modified electrode, including the pH, supporting electrolyte, preconcentration time, reduction potential and time, and percentage of modifier were investigated. The best voltammetric response was observed for a paste composition of 73.7% (w/w) of graphite powder, 5.3% (w/w) of chitosan and 21% (w/w) of paraffin oil, with 0.2 mol L-1 NaAc solution at pH 6.0 as supporting electrolyte, preconcentration time of 600 s, a reduction potential of -0.1 V and reduction time of 10 s. The new electrode displays excellent response to Pb(II) which is linear in the range from 1x10(-6) to 1x10(-4) mol L-1, with a correlation coefficient of 0.998 and a detection limit of 7.24x10(-7) mol L-1.