Mercury Free Anodic Stripping Voltammetric Determination of Pb(II) Using a Low Cost Cocos nucifera Shell Modified Carbon Paste Electrodes

A metal sensor based on the incorporation of fibrous tissues of coconut shell in carbon paste matrix is presented for the determination of lead ions in aqueous solution. Cyclic voltammetry and electrochemical impedance study were used to characterize the electrochemical parameters of the coconut shell modified carbon paste electrode. Lead ions were pre-concentrated on the modified electrode surface at open circuit potential and the determination was carried out by stripping voltammetry in anodic direction. Various factors affecting the sensitivity and precision of the determination of lead, including accumulating solvent, pH of accumulating solvent, accumulation time and stripping solvent were optimized. The effect of the surface active macro molecules was also studied using Triton X-100, cetyl trimethyl ammonium bromide and sodium dodecyl sulfate as representative for neutral, cationic and anionic surfactants. Interference with other metals on the determination of lead was studied. Under optimum experimental conditions i.e., acetate buffer of pH 5 as an accumulating solvent, 0.1 M HCl as stripping solvent and 15 min accumulation time linear calibration curve was obtained in the concentration range 120-400 mu g l(-1) with limit of detection 80 mu g l(-1).