Electrochemical Detection Of COD And Triclosan Based On The Enhancement Effect Of Nano-Cu And Carbon Nanotubes

With the rapid development of industry and agriculture, environmental pollution and food safety problems are getting worse and have obtained increasing attention. As an important indicator of the extent of water pollution, COD (Chemical Oxygen Demand) is defined as the amount of oxygen equivalents consumed in the oxidation of organic compounds by strong oxidizing agents. Triclosan is an antimicrobial which is widely used in household products. However, recent studies show that triclosan can form toxic dioxin-type derivatives. Thus, it is of great importance to establish a rapid, simple and sensitive analytical method for COD and triclosan. In this work, novel electrochemical methods were investigated based on the remarkable enhancement effect of nano-materials. Main work is as follows:1. The nano-Cu film was electrodeposited on the surface of Cu disk electrode by potentiostatic method to construct a nano-Cu modified electrode. The enhancement effect of nano-Cu to the oxidation behavior of glycine, a standard compound for evaluating the COD, was investigated. Meanwhile, the influences of electrolyte, deposition potential and deposition time on the enhancement effect of nano-Cu were studied. As a result, a simple and rapid electroanalytical method was developed for COD using amperometric detection. The linear range was from 4.8 to 600 mg/L, and the limit of detection was as low as 3.6 mg/L. Finally, this method was successfully applied to detect the COD values of different water samples, and the results were testified by the standard dichromate method.2. Based on the large surface area, high adsorption capacity and numerous reaction sites of multi-walled carbon nanotubes (MWNT), a new modified electrode was prepared for triclosan. The electrochemical behavior of triclosan was studied. The results show that MWNT exhibits considerable enhancement effect to the oxidation of triclosan, and then significantly increases the oxidation signal of triclosan. The electrochemical oxidation mechanism of triclosan was also examined, and a one-electron irreversible oxidation process was obtained. The detection medium, amount of MWNT and accumulation time were optimized. So, a sensitive, rapid and convenient electrochemical method was developed for triclosan. The linear range is from 50μg/L to 1.75 mg/L, and the limit of detection is 16.5μg/L (about 57 nmol/L). The relative standard deviation (RSD) was 4.4% for 11 parallel measurements, indicating good reproducibility.The method was successfully applied to determine triclosan in different toothpaste samples, and the results consisted with the values that obtained by high-performance liquid chromatography (HPLC).