| Nowadays , Polarography is the most successful electro analytical technique at the liquid/liquid interface in which the working electrode is the dropping mercury electrode (DME). One of the most important advantages of the method is that the surface of every mercury drop is always fresh. The fresh mercury drops can decrease the interference furthest, and improve the reproducibility of experimental results. Since 50's, both the theory research and practical application have been developed dramatically, and polarography has been used widely and effectively in the determination of inorganic ions with very low concentrations. Now, the application of DME has been limited for its toxicity. Therefore, this work aimed at overcoming this disadvantage by constructing a set of effective instrument and selecting a suitable liquid to substitute mercury. So, this work has both theoretical and practical importance in liquid/liquid interface electro -analysis field.In this work, the dropping electrolyte electrode was introduced to the in-situ environmental monitoring in which the high sensitivity and high stability can not be always obtained simultaneously. A new method with good quality/price ratio was expected to meet the need of in-situ environmental monitoring and analysis.The NB/w and 1, 2-DCE/w systems have been commonly used in traditional liquid/liquid interface electrochemistry. Four-electrode equipment is always utilized here to decrease the high impedance and capacitance of organic phase. An experimental system was improved by optimizing the reagent systems. In view of decreasing the pollutants, the aliphatic ketones were selected as reagents to constitute the common toxic ones. By the renovation of reagents and method, a three-electrode system with hanging or dropping electrolyte was used in this work, so that the complex system used before was simplified. A set of novel, simple and practical method was constructed for liquid/liquid interface electro analytical chemistry, which extended the application of electro analysis in in-situ environmental monitoring and analysis. The main experimental results are as follows:1. By using the characters of iodine and its ion, a three-electrode extraction-iodine cyclic voltammetry was constructed to study the charge transfers process at the liquid/liquid interface and determining the concentration of heavy metal ions controlled strictly environmentally, the detail work represents as follow:.(a) A novel method was used to measure the content of copper ion in aqueous solution indirectly by using extraction iodine voltammetry. There are good linear relationship between the peak currents and concentrations of copper ion within the range from 0.025mol/L to 1.25×10-4mol/L, it paves a good way for the in-situ quantitative analysis of Cu(II).(b)An new method was used to measure the concentration of chrome ion(VI)in aqueous solution indirectly by using extraction iodine voltammetry. There are good linear relationship between the peak currents and concentrations of chrome ion(VI)within the range from 3.4×10-4mol/L to 3.4×10-5mol/L, and the work provided a good way for the in-situ quantitative analysis of Cr(VI) in wastewater coming from immovable origin.(c) The charge transfer processes of different iodine origin within liquid/liquid interface formed between various organic solvents (such as methyl isobutyl ketone, acetophenone,nitrobenzene,tetra chloromethane and 1, 2-dichloroethane) and aqueous solution were studied, a possible mechanism was proposed based on the experimental results.2. A three-electrode chelate-cooperating voltammetry was established based on the selectivity of chelates to the heavy metal ion, and the electrochemical character of metal ion transfer across the liquid/liquid interface facilitated by chelating reagent was researched experimentally. A rapid and selective determination of metal ions in water phase was carried out, and the detect sensitivity was improved. The work are as follows:.(a) The transfer process of Pb (II) ion across the water/acetylacetone interface was facilitated by dithizone in water/acetylacetone-dithizone system. The process was irreversible and was controlled by the diffusion of ion. The spike potential appeared at -0.3 V (vs Ag/AgCl), the peak currents are proportional to the concentrations of lead ions within the broad range from 5×10-6mol/L to 0.005mol/L.(b) The transfer process of Cu+ ion across the water/acetylacetone interface was facilitated by 2,9-Dimethy-1,10-phenanthroline in water/ acetylacetone -2,9-Dimethy - 1,10-phenanthroline system. The process was irreversible and was controlled by the diffusion of ion. The spike potential appeared at 0.1 V (vs Ag-AgCl), the peak currents are proportional to the concentrations of copper ions within the range from 5×10-3mol/L to 0.1mol/L.(c)In water-APDC-HAc/MIBK system, Pb(II)-APDC complex was formed in aqueous solution, and the complex was extracted into organic phase by stirring. The complex was transferred from organic phase to aqueous phase within the scanning potential region. The peak potential of transferring appeared at 0.16V (vs.SCE). The transfer process was controlled by diffusion of ion, and it was irreversible. The peak currents are proportional to the concentrations of lead ions within the range from 1.0×10-5mol/L to 9.0×10-5mol/L.3. By using the MIBK as the organic phase, the dropping electrolyte electrode voltammtric analysis method and its stability was studied based on the study of hanging electrode, and the OH- transfer between the liquid/liquid interfaces in some acid-base systems was also discussed. The feasibility of dropping electrolyte electrode voltammtric analysis method was proved here. This work paved a solid way for the further research of dropping oil electrode.
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