Quantification of interfacial polymerization covalent organic framework membrane physicochemical composition and performance

Lawrence, Gabrielle Adrienne

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https://hdl.handle.net/2142/114056 Copy

Description

Title

Quantification of interfacial polymerization covalent organic framework membrane physicochemical composition and performance

Author(s)

Lawrence, Gabrielle Adrienne

Issue Date

2021-11-11

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

Marinas, Benito J

Doctoral Committee Chair(s)

Marinas, Benito J

Committee Member(s)

• Dichtel, William R
• Espinosa-Marzal, Rosa M
• Cusick, Roland D

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)

• nanofiltration
• covalent organic framework
• Rutherford backscattering spectrometry
• membrane chlorination
• physicochemical characterization
• membrane performance

Abstract

Forty percent of the world suffers from water scarcity and a lack of safe drinking water due to record population growth, accelerated development, and climate change, making it essential to start emphasizing sustainable and efficient water treatment technologies. Pressure driven membrane systems are a promising technology that can be used effectively to recycle freshwater, seawater, municipal wastewater effluent or industrial water to potable quality. Commercial membrane products typically consist of an asymmetric thin-film composite (TFC) structure: a polymeric thin active layer supported by an ultrafiltration membrane and a thick fiber backing. While this structure allows reverse osmosis (RO) and nanofiltration (NF) membrane systems to remove a wide range of water contaminants with no chemical additives or thermal input, the relatively limited polymeric surface chemistry currently available restricts the range of water permeability and solute selectivity achieved. An alternative to conventional polymeric membrane materials are two-dimensional covalent organic frameworks (COFs). 2D COFs have a crystalline structure created by strong covalent bonds made through synthetic reactions of organic building units. This structure provides a well-organized layer, reducing surface roughness, with pore size control based on chosen building units, allowing the user more control over membrane performance. Utilizing the up-scalable TFC structure formation of commercial membrane products, an ultrathin COF film can form on an ultrafiltration membrane support by interfacial polymerization (IP), creating a novel NF TFC membrane. This research presents a robust analysis of IP COF NF membranes, utilizing novel materials characterization techniques to quantify film composition and structure. Key material properties of COF films are assessed including modularity, crystallinity, and chemical stability. The impact of COF monomer selection was assessed through a comparative analysis of three imine-linked COF films, ultimately showing that COF building units significantly influence membrane performance. The performance of these three materials illuminated critical questions about the IP COF membrane configuration, motivating an in-depth analysis to quantify the degree of COF formation. Using Rutherford backscattering spectrometry (RBS) and heavy counterion probe solutions, COF material properties were obtained and lead to the realization that IP COF films were made up of small platelets rather than large sheets. This experimental method provided pathways to understand other material characteristics of the COF films, including oxidation tolerance, an important parameter for a water treatment application. A key takeaway from each of these studies is although the COF formation and performance is not ideal, the resulting films still exhibit properties that when controlled will result in extraordinary attributes for the next generation of membrane materials.

Graduation Semester

2021-12

Type of Resource

Thesis

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Copyright 2021 Gabrielle Lawrence

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