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Study On The Determination Of Gallium, Indium, Cobalt And Nickel By Photometric In Microemulsions

Posted on:2003-09-17Degree:MasterType:Thesis
Country:ChinaCandidate:L G YanFull Text:PDF
GTID:2121360095962215Subject:Applied Chemistry
Abstract/Summary:PDF Full Text Request
In this paper, the definition, classes, microstructure, preparation and properties of micromulsion have been reported in detail, as well as its application to analytical chemistry. The structure, dissociation equilibrium of tri-hydroxyl fluorone reagents and the complex structures between fluorone and metallic ions are also summarized. Color reactions of metallic ions (Ga3+, In3+, Co2+, Ni2+) with series of substitution derivates of tri-hydroxyl phenyl fluorone (PF, DBH-PF, TM-PF, o-CPF, o-NPF, w-NPF, p-NPF) were conducted in the presence of micromulsion media. The effects of different conditions such as media, pH value, etc on the color reactions have been researched. The results show that in the micromulsion media the above seven types of color reaction reagents can compound with Ga3+, In3+, Co2+ and Ni2+ stably and the formed complex have highly sensitivity with apparent molar absorptivity of (7.17× 104~3.23×105) L-mol-1cm-1. Reactions with Ga3+ and In3+can be conducted in acidic media (pH 4.94-5.90), which can produce complex with λmax between 560-580 nm. Reactions with Co2+ and Ni2+ can be conducted in alkaline media (pH 9.20-10.38), which can produce complex with X max between 620-650 nm (Co2+) and between 590-606 nm (Ni2+). Above methods have been applied to the determination of metal ions with satisfactory results.The distribution coefficients (KD) of PF (which has lower water solubility) between phases of micelle, microemulsion and water have been determined. The solubilization and sensitization of microemulsion to the reactions are also been validated.In terms of experimental results, the structures of fluorone reagents have important influence on their color reaction abilities. Electron-donating substituting groups make protons of reactive groups dissociate easily, and increase complex ability of fluorone reagents with metallic ions. However, electron-withdrawing groups reduce such complex ability and sensitivity because of its inducement effect. The effect of nitryl substitution group on the color reaction abilities of phenyl fluorone derivates has also been discussed.From the experiment, it is clear that microemulsion media have more excellent solubilization and sensitization effect on the color reactions than other media. In the microemulsion media, consurfactants (straight chain alcohol), which locate on the surface ofmicelle, can effectively improve polarity of micelle interface and increase adsorption amounts of color reaction reagents. Oil (alkane), which lies in the core of micelle, can directly expand the bulk, surface and barrier space of micelle. Hence, color reaction reagents will be easily caught at the places of surface and barrier of micelle. The determination results of KD have indicated that microemulsion media have higher effect on the solubilization and enrichment of color reaction reagents than other media. Highly apparent KD and molar absorptivity proves that solubilization and sensitization are cooperating.
Keywords/Search Tags:Microemulsion, Tri-hydroxyl fluorone, solubilization and sensitization, Distribution coefficients
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