微乳液增敏动力学光度法测定试样中的铁

Kinetic spectrophotometric determination of iron(Ⅲ) in the sample by the enhancing sensitivity of microemulsion

在n-C7H16/n-C4H9OH/CPC/H2O微乳液介质中,以邻菲啰啉(Phen)为活化剂时,Fe(Ⅲ)对H2O2氧化亚甲基蓝褪色反应具有催化作用,据此建立了动力学光度法测定Fe(Ⅲ)的新方法。该方法的最佳实验条件为0.6mL亚甲基蓝溶液(1.0×10-3mol/L),0.2mLH2O2(20%),1.4mLPhen(1.0×10-3mol/L),1.8mL微乳液,2.0mLHAc-NaAc缓冲溶液(pH=4)。对Fe(Ⅲ)测定的线性范围为1.0～40μg/L,检出限为8.4×10-7g/L。100℃时的反应速率常数为0.0280min-1,表观活化能为36.22kJ/mol,可用于环境水样中Fe(Ⅲ)的测定。

A new kinetic spectrophotometric method for the determination of trace Fe （ Ⅲ ） has been studied. It is based on the catalytic effect of Fe（ Ⅲ ） on the decolouring reaction of MB by H2O2 in the presence of microemulsion n-C7H16/n-C4H9OH/CPC/H2O and 1,10-phenanth roline（Phen） as activator. The optimum conditions are 0.6 mL 1.0× 10^-3 mol/L MB,0.2 mL 20% H2O2, 1.4 mL 1.0× 10^-3 mol/L Phen, 1.8 mL microemulsion,2.0 mL HAcNaAc（pH=4）. The linear calibration curve from 1.0 to 40 μg/L of Fe（ Ⅲ ） and the detection limit of 8.4× 10^-7 g/L are reported. The speed constant of the reaction at 100 ℃ is 0.028 0 min^-1 and the apparent activation energy is 36.22 kJ/mol. The method has been used to determine Fe（ Ⅲ ） in water samples with satisfactory results.