Evaluation of the Effective Charge Density on Low
Pressure Nanofiltration with the Separation Characteristics
of Monovalent and Divalent Solutes in the Production of
Drinking Water |
Jeongik Oh1†, and Urase Taro2 |
1Green Growth Research Team, Land & Housing Institute, Yuseong 305-731, Korea 2Department of Civil Engineering, Tokyo Institute of Technology, Tokyo 152-8550, Japan |
Corresponding Author:
Jeongik Oh ,Tel: +82-42-866-8454, Fax: +82-42-866-8472, Email: ojijp@lh.or.kr |
Received: October 7, 2010; Accepted: February 28, 2011. |
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ABSTRACT |
The electric charge on a membrane was investigated by analyzing the experimental rejection of various monovalent and divalent
ionic solutes. The characteristics of the separation of ionic solutes using various nanofiltration membranes were obtained from an
experimental nanofiltration set-up, with a surface area of 40 cm2 under the operational pressures between 0.25-0.3 MPa. The state of
the membrane electric charge was observed using separation coefficients, i.e., the permeation ratio of monovalent to divalent ions.
To confirm the state of the membrane charge observed via the separation coefficient, a calculation using the extended Nernst-Planck
equation, coupled with the Donnan equilibrium, assuming different electric charge states of the membrane, was compared with the
experimental rejection of ionic solutes. The examination of the characteristics of separation using three types of nanofiltration membranes
showed that one of the membranes carried a negative/positive double charge density inside, while other two membranes carried
either a positive or negative charge density. |
Keywords:
Effective charge density | Ionic solutes | Low pressure | Nanofiltration | Separation coefficient |
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