钴-亚硝基R盐体系的电化学研究

钴(Ⅱ)与亚硝基红盐(NRS)、氯代十四烷基吡啶(TPC)所形成的三元络合物在示波器极谱仪上产生一灵敏的二阶导数极谱波,比没有TPC存在时,峰高增加近20倍.在7.0×10-10～6.0×10-6mol/L的范围内,钴(Ⅱ)的浓度与峰电流有良好的线性关系,检出限为1.4×10-10 mol/L(8.0 ng/L).研究了络合物的电化学行为,经计算得到Co(Ⅲ)-NRS-TPC三元络合物的配比为136,稳定常数为6.5×1037,三元络合物在电极表面的吸附符合福兰克林方程,吸附系数(β)为1.21×105 L/mol,饱和吸附量(Гs)为9.8×10-10 mol/cm2,吸引因子(v)为0.96.

Investigation on the Electrochemical Behavior of Cobalt-Nitroso R Salt System

A sensitive oscillopolarographic method for the determination of trace cobalt based on the complex adsorptive current of the cobalt-Nitroso R salt (1-nitroso-2-naphthol-3,6-disulfonic acid disodium salt, NRS) system with a cationic surfactant, tetradecyl pyridinium chloride (TPC) was developed. With TPC the current response was increased about 20 times compared to that obtained without TPC. Under optimum experimental conditions, the peak current was directly proportional to the concentration of cobalt (7. 0 × 10-10 ～6.0× 10-6 mol/L), with the detection limit of 1.4× 10-10 mol/L(8. 0 ng/L). The electrochemical behavior of NRS with cobalt in the presence of TPC was investigated. The composition of the Co( Ⅲ )-NRS-TPC complex was estimated to be 1: 3: 6, and the apparent stability constant was 6.5 × 1037. The adsorption of Co(Ⅲ)(NRS)3 (TPC)6]on the mercury electrode obeyed the Frumkin adsorption isotherm. The adsorption coefficient (β=1.21 × 105 L/mol), the amount of saturated adsorption( Гs = 9.8 × 10-10 mol/cm2)and the attractive factor (v=0.96) were evaluated. The mechanism of the reaction was discussed.