Surface charge formation is relevant in determining the separation efficiency of Nanofiltration membranes with electrolyte solutions. Most of NF membranes show amphoteric behaviour which can depend on feed pH, as well as on type and concentration of ionic species. In this work the “adsorption-amphoteric” (ADS-AMF) model is considered , in which the membrane is modelled through a site-representation as the sum of hydrophobic as well as of hydrophilic groups. The structure of the model is quite general: the relevant phenomena (acid/base dissociation, site-binding and adsorption) occurring in determining the membrane charge can be easily put in evidence and the contribution of each mechanism can be investigated as a function of the operative conditions. Aim of the paper is to study the role of counter-ion site-binding and the contribution of competitive adsorption on the mechanism of charge formation as a function of operative conditions, for the cases of aqueous solutions containing single symmetric as well as non-symmetric salts.
Site-binding and competitive adsorption in determining the membrane charge of nanofiltration membranes / L.Bruni; S.Bandini. - ELETTRONICO. - (2007), pp. 1-4. (Intervento presentato al convegno PERMEA 2007 Membrane Science and Technolgy Conference of Visegrad Countries tenutosi a Siofok (Hungary) nel 2-6 settembre 2007).
Site-binding and competitive adsorption in determining the membrane charge of nanofiltration membranes
BRUNI, LUIGI;BANDINI, SERENA
2007
Abstract
Surface charge formation is relevant in determining the separation efficiency of Nanofiltration membranes with electrolyte solutions. Most of NF membranes show amphoteric behaviour which can depend on feed pH, as well as on type and concentration of ionic species. In this work the “adsorption-amphoteric” (ADS-AMF) model is considered , in which the membrane is modelled through a site-representation as the sum of hydrophobic as well as of hydrophilic groups. The structure of the model is quite general: the relevant phenomena (acid/base dissociation, site-binding and adsorption) occurring in determining the membrane charge can be easily put in evidence and the contribution of each mechanism can be investigated as a function of the operative conditions. Aim of the paper is to study the role of counter-ion site-binding and the contribution of competitive adsorption on the mechanism of charge formation as a function of operative conditions, for the cases of aqueous solutions containing single symmetric as well as non-symmetric salts.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
