利用分光光度法测定混合电解质溶液中铁氰化钾的浓度

摘要

The limiting-current electrochemical method, based on K3Fe (CN)6-K4Fe (CN)6-NaOH electrolyte system, is often used to investigate experimentally wall transport characteristics in power and chemical engineering fields. Accurate measurement of ferricyanide ion concentration is crucial for determining wall mass transfer coefficient. In this paper, the process of measuring ferricyanide concentration in K3Fe (CN )6-K4Fe (CN )6-NaOH electrolyte utilizing UV-VIS spectrophotometry is presented, including the measurement of absorption spectral curves, determination of the optimum absorption wavelength and the calibration of standard working curve. Results indicate that the maximum absorption (302 nm) for ferricyanide is unsuitable for concentration measurement because of the interference of ferrocyanide. The linear correlation between ferricyanide concentration and absorbance at wavelength of 420 nm is proposed and can be used to determine the ferricyanide concentration through UV-VIS spectrophotometry. In addition, the physical properties of 0. 01 mol · L-1 K3Fe(CN)6-0. 02 mol · L-1 K4Fe(CN)6-0. 5 mol · L-1 NaOH electrolyte are measured and the correlations of density, kinetic viscosity and molecular diffusive coefficient vs temperature are presented. Both the concentration measurement of ferricyanide and the physical properties of K3Fe(CN)6-K4Fe(CN)6-NaOH electrolyte may offer valuable reference for the application of limiting-current electrochemical method.%基于K3Fe(CN)6-K4Fe(CN)6-NaOH电解质体系的极限电流电化学方法被广泛用于壁面传质系数的测量,准确测定混合溶液中铁氰离子浓度是获得壁面传质系数的关键.详细介绍了利用紫外可见分光光度法(UV-VIS)测量K3Fe(CN)6-K4Fe(CN)6-NaOH电解质体系中K3Fe(CN)6浓度的过程,包括吸收光谱曲线测定、最佳吸收波长的确定、标准曲线标定等.还给出了0.01 mol·L-1K3Fe(CN)6-0.02mol·L-1K4Fe(CN)6-0.5mol·L-1NaOH混合电解质溶液的物性(包括密度、运动黏度、扩散系数)计算关联式,为极限电流电化学方法的应用提供参考.