Nanocellulosic fiber-modified carbon paste electrode for ultra trace determination of Cd (II) and Pb (II) in aqueous solution.

In recent years, increasing awareness of the environmental impact of heavy metals has prompted a demand for monitoring and decontaminating industrial wastes prior to discharging into natural water bodies. This paper describes the preparation and electrochemical application of carbon paste electrode modified with nanocellulosic fibers for the determination of cadmium and lead in water samples using anodic stripping voltammetry. First, cadmium and lead were adsorbed on the carbon paste electrode surface at open circuit potential, followed by anodic stripping voltammetric scan from -1 to 0 V. Different factors affecting sensitivity and precision of the electrode, including accumulating solvent, pH of the accumulating solvent, accumulation time, supporting electrolyte, and scan rate were investigated. The proposed method was also applied to the determination of Cd (II) and Pb (II) in the presence of other interfering metal ions and cetyl trimethyl ammonium bromide, sodium dodecyl sulfate, and Triton X-100 as a representative of cationic, anionic, and neutral surfactants. Linear calibration curves were obtained in the concentration ranges of 150-650 μg L(-1) and 80-300 μg L(-1), respectively, for cadmium and lead at an accumulated time of 10 min with limits of detection 88 and 33 μg L(-1). Optimized working conditions are defined as acetate buffer of pH 5 as accumulating solvent, hydrochloric acid as supporting electrolyte, and scan rate 50 mV/s. This technique does not use mercury and therefore has a positive environmental benefit. The method is reasonably sensitive and selective and has been successfully applied to the determination of trace amounts of Cd (II) and Pb (II) in water samples.