新型中性载体硫氰酸根离子选择电极研究

系统研究了新型Schiff碱[N,N'-双-(4-苯偶氮水杨醛)缩邻苯二胺]过渡金属配合物的阴离子响应行为.实验结果表明,配合物中心金属原子的结构与电极的响应行为之间有非常密切的构效关系,其中Mn(Ⅱ)的配合物对硫氰酸根有优良的电位响应性能和选择性,该电极的线性范围为0.14.3×10^-6mol/L,斜率为-58.0mV/dec.,其反Hofmeister选择性次序为SCN^->I^->Sal^->PhCO₂^->ClO₄^->NO₂^->Br^->Ac^->NO₃^->Cl^-.通过交流阻抗和膜相中荷电离子的添加实验证实,该电极对阴离子的响应系中性载体作用机制.该电极具有读数稳定,选择性和重现性好等优点,可直接应用于废水中硫氰酸盐的测定.

Studies on Thiocyanate-selective Electrodes Based on Novel Neutral Carriers

The anion response characteristics of transition metal chelates of a new Schiff base was systematically investigated in this paper. The results show that the electrode response characteristics have close relationship with the properties of the central metals, the electrodes based on the Mn(Ⅱ) chelate exhibited an excellent potentiometric response and selectivity towards thiocyanate. The linear response range of the electrode was (0.1~4.3)×10^-6 mol/Lwith a slope of-58.0 mV/dec., the anti Hofmeister selectivity pattern was: SCN^->I^->Sal^->PhCO₂^->ClO₄^->NO₂^->Br^->Ac^->NO₃^->Cl^-. The response mechanism was investigated by A.C. impedance and the effect of charged additives on the response characteristics and selectivity of the electrodes. It can be concluded that the electrodes exhibited Nernstian response to thiocyanate via a neutral carrier-based mechanism. The novel electrodes have advantages of being fast, accurate and stable, and can be used for the determination of thiocyanate in actual samples.