Synthesis of Modified Glassy Carbon Electrode for Electrochemical Detection of Heavy Metals in Water

• Main Authors: LIU, SHANG-LUN, 柳尚倫
• Other Authors: WU, JIUNN-JER
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/d37j6x

碩士 === 逢甲大學 === 環境工程與科學學系 === 107 === Heavy metal ions, such as cobalt, copper, iron, manganese, and zinc, play an important role in living organisms as being essential elements in small amounts for the metabolism maintenance. However, excessive levels or even small doses of very toxic metals (i.e. lead, cadmium, mercury, arsenic, stibium etc.) can cause serious problems on the environment and human health. Accumulation of such metals on the human body can cause severe diseases in our central nervous system, liver and kidneys, or skin, bones, and teeth. In order to be able to detect heavy metals more easily and quickly, the detection and discrimination of heavy metals by the redox reaction of heavy metals were carried out. In this study, the glassy carbon electrode was modified by carboxylation of carbon nanotubes and mixed with polyaniline. The purpose of this study not only effectively enhances the use of electrochemical detection of heavy metal, but also figures out the synthetic parameters and to find the best preparation conditions in the experiment. The optimized conditions of WCNT-COOH/PANI modified glassy carbon electrode were focused in this thesis. In the following, there had different preparation conditions that were tested and discussed. The main focus in this preparing process is the different time in terms of the preparation of functionalization carbon nanotube by ultrasonic irradiation. These four different ultrasonicated periods was tested by characterization to select the optimal parameters. When the optimized electrode was prepared, the next step would determine the best deposition potential and deposition time for heavy metals test. Square wave anodic stripping voltammetry was utilized using MWCNT-COOH/PANI modified glassy carbon electrode in different deposition potential and depositing time. Some modified electrode tests were done to understand their performance availability. The next work is to build a calibration curve for the metal detection. In addition, interference studies were also carried out with different metals. The real sample analysis was used to detect metals in different media, including DI water, tap water, ground water, sea water. In this study, the detection of using MWCNT-COOH/PANI modified glassy carbon electrode was obtained by square wave anodic stripping voltammetry. Both of lead and mercury have good linear regression and the minimum detection limits are 4.34 μM and 8.97 μM, respectively. The functionalized carbon nanotubes can effectively improve the conductivity and sensitivity of the electrode. The Nafion solution can also make the modified coating adhere more firmly on the electrode surface, which provides a better precision for high and low concentration metal measurement and is not easily interfered by different heavy metals. The conductivity range of the natural water body suitable for quantitative detection should be within 4 ms/cm.