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1546710 
Journal Article 
Measurement of Complexation Stability Constant and Coordinating Number of Poly(ethylenimine) with Metals 
Huang Jia-Hua; Gong Zhen-Bin; Lin Ji-Jun; Duan Hua-Ling 
2012 
1 
Gaodeng Xuexiao Huaxue Xuebao / Chemical Journal of Chinese Universities
ISSN: 0251-0790 
33 
12 
2633-2637 
WOS:000313544300007 
A rapid and accurate method using polymer complexation ultra-filtration (PC-UF) technique and inductively coupled plasma mass spectrometry(ICP-MS) for the measurement of the complexation stability constant and the average coordination number of poly (ethylenimine) (PET) groups participating in the complex formation of PEI with metal ions was proposed. The method was applied to determine the stability constant and the average coordination number of PEI and Cd2+ complex. Firstly the mixture of various initial concentration ratios of PEI and Cd2+ solution were prepared, respectively, then the mixture reacted until the complexation equilibrium reached, and at last Cd2+ and small components were permeated into the solution and PEI-Cd complex was hold back with centrifugal ultra-filtration kit. Then ultra-filtration followed was completed so as to decompose PEI-Cd complex and obtain Cd2+ species using 10 mL 3% (volume fraction) HNO3. With the help of chemical model inferred in the study, the complexation stability constant and the average coordinating number of PEI-Cd could. be calculated. Effect of pH value(pH = 4. 0-5. 9) on the equilibrium was investigated. The results showed that the complexation stability constant and the average coordinating number of PEI-Cd became larger as pH value increases. This may due to the protonation of PEI reduces as pH values increase, then the binding ability of PEI with metals become stronger. 
Poly(ethylenimine); Complexation stability constant; Coordinating number; Ultrafiltration technique; Inductively coupled plasma mass spectrometry