Measurement Of Stability Constants And Coordination Numbers Of Polymer-metal Complex By GFC-ICPMS

A new method using gel filtration chromatography (GFC) and inductively coupled plasma mass spectrometry (ICP-MS) was developed for the measurement of complexation stability constants and average coordination numbers of the complex of macromolecular polymers with metallic ions. A novel chemical equilibrium model was also applied to this study. As an example, the binding of poly(ethyleneimine)(PEI) with M2+was shown and investigated. The macromolecular PEI-M complex and micromolecular species of M were separated in accordance with their molecular weights by a low efficiency GFC column with a mobile phase of HAc-NaAc buffer, and then directly introduced into ICP-MS for elemental analysis. The results of complexation stability constants and average coordination numbers characterized by putting the concentration of different species of metallic elements into the equations of the novel chemical equilibrium model which was developed in this study. This online, rapid and accurate method of GFC-ICPMS is a novel technique for the research of polymer-metal complex.This thesis includes five chapters, the details are as follows:Chapter one introduced the properties and harms of metallic elements (Cu, Cd) discharged into environment water, and the removal methods of these metallic ions. Described the properties and application of PEI, which is the common polymers used in Polymer Enhanced Ultrafiltration (PEUF) technique for removing metallic ions. The analysis methods of the complexation stability constants and average coordination numbers of polymer and metal complex was summarized. Finnally elaborated the principle and application of gel filtration chromatography technique.Chapter two developed a chemical model and designed the experimental project of this study. According to the complexation equilibrium theory, the chemical model for determination of stability constants and average coordination numbers of PEI with metallic ions was proposed. Based on the chemical model, combine with GFC and ICP-MS technique, an analysis method to determine the stability constants and average coordination numbers of PEI with metal ions was designed.Chapter three determined the stability constants and average coordination numbers of PEI with Cu2+using GFC-ICPMS technique, which was based on the chemical model from Chapter two. The results shown that the complexation stability constants (KPEI-Cu) were between1096and1010.7and the average coordination numbers (n) were in the range of1.0～1.3when pH was changed from4.1to5.3at25℃. The effect of pH value on the binding ability of PEI with Cu2+was also investigated which suggested that the complexation stability constants and average coordination numbers increased with the increasing of pH. This may due to the decreased protonation of amine groups on the chain of PEI molecule with the increasing of pH value, which is beneficial to the complexation of PEI and Cu2+Chapter four, based on the chemical model built in chapter two, measured the stability constants and average coordination numbers of PEI with Cd2+with the help of GFC-ICPMS technique. The results shown that the complexation stability constants (KPEI-Cd) were between108.7and109.7and the average coordination numbers (n) were in the range of1.0～1.4when pH was changed from4.1to5.3at25℃. The influence of pH value on the complexation of PEI and Cd2+was also investigated, which was shown that the changing trend of binding ability of PEI with Cd2+was the same as PEI with Cu2+, that is, the stability constants and average coordination numbers increased with the increasing of pH. Finally, compared the value of KPEI-Cu with KPEI-Cd under the same conditions, and analysed the mechanism of this results in theory.Chapter five summarized the results achieved in this study, and looked far ahead for further research.