【摘要】 采用光谱法研究了聚乙烯亚胺(PEI)与钴离子在水溶液中络合的行为。研究了不同温度下水溶液中生成的PEI-Co络合物浓度随时间的变化,发现随温度升高,达到络合平衡所需要的时间缩短,而生成的PEI-Co络合物浓度增加。分别在钴离子或PEI中亚胺基过量的情况下,研究了PEI与钴离子络合的初始速率与亚胺基或钴离子浓度的关系,发现PEI与钴离子的络合反应对钴离子和PEI中亚胺基均是一级反应。求出了不同温度下PEI与钴离子络合反应和解络合反应的速率常数,以及络合反应的平衡常数。根据Arrhenius方程计算得到PEI与钴离子络合反应的活化能为21.2kJ·mol-1。基于Van’tHoff方程,求出了络合反应的摩尔反应焓和熵,其值分别为55.3kJ·mol-1和218J·mol-1·K-1。更多还原

【Abstract】 The kinetic and thermodynamic characteristics of the complexation reaction of polyethyleneimine (PEI) with cobalt ions were studied. According to the relation between the absorbance and concentration of PEI-Co complexes, the concentration of PEI-Co complex formed in aqueous solutions was measured by the spectroscopic method. With the increase of temperature, the time needed for the complexation reaction to reach its equilibrium is shorter, and the corresponding equilibrium concentration of PEI-Co complex is higher. The complexation reaction was found to be a first order reaction for both the cobalt ions and imine groups, it indicates that the complexation reaction of cobalt ions with imine groups is stepwise. The rate constants and equilibrium constants of the complexation reaction at various temperatures were obtained, and according to the Arrhenius equation, the activation energy of the complexation reaction was calculated to be 21.2 kJ·mol-1. Furthernore, based on the Van’t Hoff equation, the enthalpy and entropy of the complexation reaction were determined to be 55.3 kJ·mol-1 and 218 J·mol-1·K-1, respectively.更多还原