Quantitative characterization of physico-chemical properties of the active layers of reverse osmosis and nanofiltration membranes, and their relation to membrane performance

Coronell Nieto, Orlando

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https://hdl.handle.net/2142/15596 Copy

Description

Title

Quantitative characterization of physico-chemical properties of the active layers of reverse osmosis and nanofiltration membranes, and their relation to membrane performance

Author(s)

Coronell Nieto, Orlando

Issue Date

2010-05-14T20:51:57Z

Director of Research (if dissertation) or Advisor (if thesis)

Mariñas, Benito J.

Doctoral Committee Chair(s)

Mariñas, Benito J.

Committee Member(s)

• Cahill, David G.
• Elimelech, Menachem
• Strathmann, Timothy J.

Department of Study

Civil & Environmental Eng

Discipline

Environ Engr in Civil Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• membranes
• reverse osmosis
• Nanofiltration
• water treatment
• functional groups
• Rutherford backscattering spectrometry
• carboxylic groups
• amine groups
• steric effects
• stoichiometry of association
• active layer
• membrane characterization

Abstract

The main objectives of this dissertation were: (i) to develop experimental and analytical procedures to quantify different physico-chemical properties of the ultra-thin (~ 100 nm) active layers of reverse osmosis (RO) and nanofiltration (NF) membranes and their interactions with contaminants; (ii) to use such procedures to evaluate the similarities and differences between the active layers of different RO/NF membranes; and (iii) to relate characterization results to membrane performance. Such objectives were motivated by the current limited understanding of the physico-chemical properties of active layers as a result of traditional characterization techniques having limitations associated with the nanometer-scale spatial resolution required to study these ultra-thin films. Functional groups were chosen as the main active layer property of interest. Specific accomplishments of this study include the development of procedures to quantify in active layers as a function of pH: (1) the concentration of both negatively and positively ionized functional groups; (2) the stoichiometry of association between ions (i.e., barium) and ionized functional groups (i.e., carboxylate and sulfonate); and (3) the steric effects experienced by ions (i.e., barium). Conceptual and mathematical models were developed to describe experimental results. The depth heterogeneity of the active layer physico-chemical properties and interactions with contaminants studied in this dissertation was also characterized. Additionally, measured concentrations of ionized functional groups in the polyamide active layers of several commercial RO/NF membranes were used as input in a simplified RO/NF transport model to predict the rejection of a strong electrolyte (i.e., potassium iodide) and a weak acid (i.e., arsenious acid) at different pH values based on rejection results at one pH condition. The good agreement between predicted and experimental results showed that the characterization procedures developed in this study serve as useful tools in the advancement of the understanding of the properties and structure of the active layers of RO/NF membranes, and the mechanisms of contaminant transport through them.

Graduation Semester

2010-5

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http://hdl.handle.net/2142/15596

Copyright and License Information

Copyright 2010 Orlando Coronell Nieto. Chapter 2 - Copyright 2008 American Chemical Society. Chapter 3 - Copyright 2009 American Chemical Society.

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