The Role Of Metal Ions And 8 - Hydroxy Quinoline Reagent Complex Polarographic Wave Nature And Surface Active Agents

The polarographic behaviors of metal ion-8-hydroxyquinaldine complex and the enhancement effect of the anionic surfactant of mentioned were investigated. The main points were summarized as follows:1. In the buffer solution of Na2CO3-NaHCO3(pH 8.6), a sensitive oscillopolarographic method for the determination of trace palladium based on the complex adsorptive current of the palladium (II)-8-hydroxyquinoline-5-sulfonic acid (8-OXSA) system with a anionic surfactant, sodium dodecyl sulfate (SDS), was developed. With SDS the current response was increased about 30 times compared to that obtained without SDS and the peak potential was at -0.72V (vs. SCE). Under the optimum experimental conditions the peak current was directly proportional to the concentration of Palladium in the range from 0.8 ng/mL to 300ng/mL and the detection limit was 2.8+10"9mol/L (0.3ng/mL). The method was applied to determination of palladium in catalyst and industrial waste water with satisfactory results. The experiment results demonstrated that the peak current of Pd(II)-8-OXSA behaved an adsorptive character and an irreversible process of electrode reaction, the number of electron (n), the transfer coefficient (a) and the amount of saturated adsorption (fs) were 2, 0.46 and 2. 2+10-9mol/cm2, respectively. It was shown that Pd(II) formed a complex with 8-OXSA with the mole ratio of 1:2, the conditional stability constant was calculated to be 8. 73+107. Ternary complex does not form after adding SDS. Because SDS and superoxide anion radical adsorbed on the electrode surface, the reactive intermediate of Pd(I) -8-OXSA was oxidied by superoxide anion radical and the peak current of the complex was enhanced.2. In the medium of H3BO3-NaOH at pH9 containing sodium dodecyl benzene sulfonate(SDBS), a sensitive peak current of lead(II)-8-hydroxy- quinoline complex was observed at -0.55V (vs SCE) . With SDBS the current response was increased about 9 times compared to that obtained without SDBS. Under the optimum experimental conditions, there is an excellent linearity between peak of current and concentration of lead(II) in the range from 1 ng/mL to 60ng/mL. Thedetection limit is 0.01ng/mL. The linear regression equation is ip=0.24+0.090x[Pb2+] (ng/mL), r=0.9964. Ternary complex does not form after adding SDS. It was shown that lead (II) formed a complex with 8-OX with the mole ratio of 1:2, the conditional stability constant was calculated to be 3.5+1013. The experiment results demonstrated that the peak current of complex behaved an adsorptive character and the enhancement effect of the anionic surfactant is directly related to the superoxide anion radical in the solution.3. In potassium hydrogen phthalate medium at pH4.3 containing Perron and SDBS, a sensitivy current of vanadium ( V ) in second derivative oscillopolarography was observed at -0.60 V (vs. SCE). With SDBS the current response was increased about 14.5 times compared to that obtained without SDBS. The peak current was directly proportional to the concentration of vanadium (V) in the range from 0.5ng/mL to 120ng/mL and the linear regression equation is ip-0. 027+0.031+[V5+] (ng/mL), r = 0.9991. The detection limit was 0.lng/mL and the method was applied to determination of vanadium in hair and in waste water with satisfactory results. In addition, the experiment examined the correlation between peak current of complex and the oxygen in the solution in a preliminary manner.4. In potassium hydrogen phthalate medium at pH4-5 containing Perron and SDBS, a sensitivy current of uranium (VI) in second derivative oscillopolarography was observed at -0.48V (vs. SCE). With SDBS the current response was increased about 7 times compared to that obtained without SDBS. The peak current was directly proportional to the concentration of uranium (VI) in three ranges from 8ng/mL to 100ng/mL, 100ng/mL to 600ng/mL and 600ng/mL to 1000ng/mL. The detection limit was 0.5ng/mL and the correlation between peak current of complex and the oxygen in the solution was also examined in a...