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Title page for ETD etd-03182016-113514


Type of Document Dissertation
Author Barpaga, Dushyant
Author's Email Address dushyant.barpaga@vanderbilt.edu
URN etd-03182016-113514
Title Synthesis and Characterization of Novel Nanoporous Materials for Acidic and Basic Gas Adsorption
Degree PhD
Department Chemical Engineering
Advisory Committee
Advisor Name Title
M. Douglas LeVan Committee Chair
G. Kane Jennings Committee Member
Peter N. Pintauro Committee Member
Sandra J. Rosenthal Committee Member
Keywords
  • adsorbent materials
  • NH3
  • SO2
  • MOFs
  • metal salts
  • CSC
  • MCM-41
Date of Defense 2016-03-14
Availability unrestricted
Abstract
Adsorbent technology employing specificity towards a broad range of target molecules is becoming increasingly important for a variety of applications such as filtration, separation, purification and/or storage of fluids. The development of newer, more efficient adsorbent materials is a growing concern for civilian, first responder, and military uses. This dissertation is focused on the synthesis and characterization of novel, nanoporous adsorbents incorporated with metal salts either by further functionalization of pre-synthesized substrates or as precursors in the formation of porous composites like metal-organic frameworks (MOFs).

The biphasic substrate primarily used in this work was made up of mesoporous silica derived from MCM-41 and a microporous carbon made from a polymerized alcohol. This carbon silica composite (CSC) was further functionalized by various water-soluble metal salts through single salt impregnations as well as dual salt incorporation. The effectiveness of salt-functionalized CSCs was measured via breakthrough capacities for low concentrations of NH3 and SO2. Materials with high adsorption performance for both of these targets, representative of acidic and basic gases, were obtained with potential broad-scale, commercial applicability for a diverse set of adsorbates. In brief, the incorporation of potassium carbonate increased the alkalinity of the adsorbent thereby promoting SO2 adsorption. Similarly, the incorporation of zinc chloride increased the acidity of the adsorbent resulting in enhanced NH3 adsorption. The addition of K2CO3 and ZnCl2 on the same adsorbent was shown to consolidate high adsorption performance for both of these toxic industrial chemicals (TICs). Interestingly, upon incorporation of the two water-soluble impregnants, a reaction to form an insoluble precipitate within the substrate via in-pore synthesis occurs. This dual salt functionalization leading to the in-pore synthesis of insoluble precipitates was also performed using various combinations of metal chlorides with potassium salts. Differences in the pH of salt-incorporated substrates provided an understanding of cation and anion dependence in functionalized materials for NH3 and SO2 adsorption. With MOFs, a characterization analysis was performed to interpret the degradation (or lack thereof) of chemical bonds within the framework that were susceptible to water adsorption.

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