کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4982360 | 1453857 | 2017 | 9 صفحه PDF | دانلود رایگان |
- Polyampholytic latex samples were synthesised containing weak acid and weak base groups.
- These latex particles can be used as a model to explain polyampholytic resin ion-exchange behaviour.
- Surface charge densities at different pH values were determined from zeta potential measurements.
A polystyrene based polyampholytic (zwitterionic) latex was synthesised with an isoelectric point (IEP) of 6.9 and particle size of about 110Â nm. Ion-exchange (IEX) ability of this latex with sodium chloride and ammonium bicarbonate (AB) was studied and it was found that Na+, NH4+, Clâ and HCO3â ions exchange with the surface groups following the law of mass action. The latex typically had an adsorption capacity of about 0.11Â mmol/m2, for both NaCl and NH4HCO3 electrolyte solutions. Surface adsorption constants, i.e. KNH2 and KCOOH, were assumed to be similar to solution values, that is: 1Â ÃÂ 10â9Â M and 1Â ÃÂ 10â6Â M, respectively. Precise ionization ability of the active groups is specific for the type of polymer used to form the latex particles. Calculated surface charge densities, obtained from zeta potential studies, shows that the best pH range for IEX studies with this polyampholytic latex was in the range 6.8-8.0. The average affinity of HCO3â ions was found to be higher than Clâ during the IEX process. This latex was used to demonstrate an ion adsorption model which could be applied to the IEX properties of polyampholytic resins containing the same weak acid (WA) and weak base (WB) groups.
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Journal: Colloids and Surfaces A: Physicochemical and Engineering Aspects - Volume 516, 5 March 2017, Pages 39-47