钛催化十六烷基三甲基溴化铵活化H2O2氧化甲基绿褪色动力学光度法测定痕量Ti（Ⅳ）

基于在稀H2SO4介质中及90℃条件下,痕量Ti(Ⅳ)对十六烷基三甲基溴化铵活化H2O2氧化甲基绿褪色反应有明显的催化作用,据此建立了催化动力学光度法测定痕量Ti(Ⅳ)的分析方法。优化了实验条件。非催化反应(吸光度为A0)与催化反应(吸光度为A)在波长631nm处的吸光度差值△A与Ti(Ⅳ)的质量浓度ρ在0.03～1.50μg/25 mL范围内呈良好的线性关系,检出限为7.488×10-10g/mL。在25 mL溶液中对1.0μg Ti(Ⅳ)标准溶液测定12次,相对标准偏差为1.3%。测定了动力学参数,反应为准一级反应,表观速率常数为5.72×10-4/s,表观活化能为41.78 kJ/mol。该分析方法用于炼钢烧结矿中痕量Ti(Ⅳ)的测定,样品中钛含量与对照值吻合较好,RSD(n=6)为0.18%和0.22%,回收率在98%～101%,符合痕量分析要求。

Determination of trace Ti（Ⅳ） by kinetic spectrophotometry in titanium catalyzing activation action of cetyl trimethyl ammonium bromide on fading of methyl green oxidized by H2O2 system

Trace Ti(Ⅳ) had significant catalytical action on the activation action of cetyl trimethyl ammonium bromide on the fading reaction of methyl green oxidized by hydrogen peroxide in diluted sulfuric acid medium at 90℃.On the basis of this fact,a catalytic kinetic spectrophotometric determination method of trace Ti(Ⅳ) was proposed.The optimized experimental conditions were studied.At 631 nm,the absorbance difference(△A) between non-catalytic system(A0) and catalytic system(A) showed good linear relationship with the mass concentration(ρ) of Ti(Ⅳ) in the range of 0.03~1.50 μg/mL,with a detection limit of 7.488×10-10 g/mL.The standard deviation was 1.3% by 12 times determination of 1.0μg of Ti(Ⅳ) standard in 25mL of solution.Kinetic parameters were determined and the catalytic reaction was found as pseudo first order reaction.The apparent reaction rate constant was 5.72×10-4 /s,and the apparent activation energy was 41.78 kJ/mol.The proposed method had been applied to the determination of Ti(Ⅳ) in two steelmaking sinter ore samples,and results were consistent with the reference values.The relative standard deviations(RSD)(n=6) were 0.18% and 0.22%,respectively.The recoveries of standard addition were in the range of 98%~101%.