Studies And Application Of PVC Membrane Metal Ion-Selective Electrodes And Modified Carbon Paste Electrode Based On Multi-walled Carbon Nanotubes (MWCNTs)

The metal in the human production and life is in a wide range of applications. Metal inappropriate use of metal contamination caused easily, we often say that metal pollution refers to human actiities is because the metal content increased, the environment, and led to a normal range beyond the environmental quality deterioration. This kind of pollution through the food chain into ecological system, causing harm metals have not easy dissolve the characteristics, easy to move in living organisms or ecological system, and metal most enrichment of organisms are toxic. As with wastewater discharge of metal, even concentration small, also can be in algae and sediment accumulation by fish and shellfish, the body surface adsorption, produce the food chain enrichment, causing the public nuisance. ShuiYuBing (such as Japan's mercury pollution), is because of the caustic soda manufacturing industrial emissions contained mercury, in waste water by biological function into organic mercury caused; after And as bone pain disease (cadmium pollution), is refined zinc industry and cadmium by electroplating industry caused by the cadmium emission. Auto emissions by atmospheric diffusion process such as lead into environment, the concentration of surface caused by current lead, which has significantly increased the uptake of modern human body than primitive lead increased almost 100 times, damaged human body health. Therefore, the metal to environmental samples determined the concentration is especially important in environmental analysis. At present, the main methods of detecting metal ions with atomic absorption spectrometry, inductance coupling atomic emission spectrometry, inductively coupled plasma mass spectrometry,etc,but these method involves complex sample processing, need big grassroots organizations and for most analysis laboratory too expensive. As biological medicine, food safety and environmental pollution control of heavy metal ion content to demand more and more, it is urgent to establish an acute economic,convenient quickly, the analysis method, it has important for heavy metal monitoring the economic value and social value. Nowadays, the carrier of ion selective electrode is ion selective electrode study comparing active a direction. This thesis focuses on design, synthesis of different new neutral ligand, it will be as a carrier used in metal ion selective electrode research. Another chosen multi-walled carbon nanotubes functional as sensitive ion carrier construction carbon paste electrodes, the use of new materials reduced ion detection limit, improve the detection sensitivity, is expected to expand selectivity and carrier of optional range.This paper research content as follows:1,Based on acetyl acetone schiff base for the high selectivity neutral carrier of aluminum ion electrodeBecause of good solid geometry and good control of subject and object, schiff base is wildly used in ion selective electrode field. Acetone schiff base is synthesized in this study, and is used as the carrier of ion-selective electrodes, this N, O heteroatoms of schiff base can improve the combining capacity between carrier and metal ions, meanwhile, the required material is cheap and easily obtained, synthetic procedure is simple and feasible. In this experiment, we study the potential of the electrode and the response performance optimized experimental condition, the results show that:compared with other metal ions, electrode can preferred response aluminum, and exhibits an excellent near-Nernstian response for aluminum. Meanwhile, the pH range of electrode is studied and using analytical methods discussed the mechanism of electrode response and exchange impedance behavior, finally, the electrode can be successfully applied to the potential titration and wastewater determination of ion recovery.2,Determination of cerium ion based on newly synthesized nitrogen - sulfur heterocyclic compoundsby polymeric membraneNitrogen - sulfur heterocyclic compound is synthesised. this molecule contains N, S impurity atoms which can provide a solitary pairs of electrons, can strengthen the coordination effect of carriers and metal ions. This study is the first to use this compound as the carrier of PVC membrane electrode, a preliminary study find this electrode can selectively response cerium ion. The simultaneous change carrier content, plasticizer and anion and cation additive method optimization film electrode properties, electrode exhibits an excellent near-Nernstian response for Fe3+ ion ranging from in 3.4×10-7 to 1.0×10-1 mol/L. Under the optimal conditions, pH range, reproducibility, and stability is studied inthe research of the electrode. And the response mechanism is discussed in view of the alternating current impedance technique. In addition, the electrode is successfully used as an indicator electrode in potentiometric titration of cerium ion and in the direct determination of cerium ion in samples.3,Determination of Fe3+ ions by a modified carbon paste electrode based on multi-walled carbon nanotubes (MWCNTs)Carbon nanotubes with large specific surface area and good electrical conductivity, can greatly improve the analysis test selectivity and sensitivity;Carbon paste electrodes due to easy fabrication, do not need inside filling liquid, surface is easily update, mercury-free, no pollution, etc in ion selective electrode field characteristics of attention;and the salicylyl hydrazine contains N, O heteroatoms, can strengthen the coordination effect of carriers and metal ions. In view of the above features, this study use chemical and ultrasonic methods combians salicylyl hydrazine and multi-walled carbon nanotubes, and uses this compound for sensitive ion carrier od modified carbon paste electrodes. In pH range for 2.0～6.0, this electrode presents good selectivity and sensitivity, can responds iron ion in lower concentrations, the limit detection is 1.0×10-8 mol/L, and has good reproducibility and stability. The ac impedance behavior between modified carbon paste electrodes and ion membrane is discussed, and the new electrode is used in water environment and the content of iron ions fast detection of actual samples. The use of multi-walled carbon nanotubes is expected to expand carrier range of ion selective electrode.