Nanoporous Materials As Advanced Adsorption Media

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Nanoporous Materials As Advanced Adsorption Media

• Marshall McDaniel
• Dr. Sabatini
• Edgar Acosta

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Nanoporous Materials As Advanced Adsorption Media

• Overview
• Background
• Adsorption
• Activated Carbon
• Motivation for Research
• Nanoporous Material Studies
• Porous Polymers
• Hypothesis I
• Hypothesis II
• Modified Alumina
• Further Research

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Adsorption

• Vocabulary
• Adsorbent (ex. soil, activated carbon, etc.)
• Adsorbate (ex. solute, contaminant, etc.)
• Isotherms
• Adsorption capacity (mg/g) vs. Equilibrium
  Concentration (mg/L)
• Better adsorbents greater adsorption capacity

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Activated Carbon (AC)

• What is activated carbon?
• How is it made?
• High Temp, Low O2
• Characteristics
• AC can be up to 800m2 per gram (The size of a
  soccer field!).
• What is it used for?
• Water filtration
• Air filtration
• Does it have limits?

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Motivation

• Problem
• Polar organic contaminants are difficult to
  remove from water using traditional adsorbents
  (AC).
• Examples
• Pharmaceuticals
• Acetaminophen
• non-ionic surfactants
• Phenols
• Endocrine disruptors

Acetaminophen
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Hypotheses

• Polar organic molecules (POMs) show less tendency
  to adsorb to activated carbon because of the lack
  of polar adsorption sites.
• Therefore, by synthesizing an adsorbent with more
  polar adsorption sites we will expect an
  increased adsorption of POMs.

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Hypothesis I Methods

• Measure adsorption of alcohols and acetaminophen
  on activated carbon.
• Sampling Equipment Gas Chromotograph
• Analyze Data

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Hypothesis I Results

• Adsorption Isotherms
• Hypothesis I confirmed.

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Hypothesis II Restated

• Synthesizing an adsorbent with more polar
  adsorption sites we will expect an increased
  adsorption of POMs.

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Hypothesis II Introduction

• GOAL Create a porous polymer with
• Comparable surface area to AC
• More polar adsorption sites

polymer
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Hypothesis II Methods

• MATERIALS USED FOR POLYMER SYNTHESIS
• Methyl methacrylate (monomer)
  - AIBN (initiator)
• - Ethylene glycol dimethacrylate (crosslinker)
• 2-Hydroxyethyl methacrylate - 3-Sulfopropyl
  methacrylate, potassium salt

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Hypothesis II Methods

• Synthesis of porous polymer F22
• 5.5 ml of H2O, 4ml of HEMA, 0.5 ml of EGDMA
• Add Initiator
• Place in Hot Bath (60o C) for 1 day
• Place in Acetone
• Dry in Oven
• Grind up dried polymer

Acetone / H2O / Air
Polymer
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Hypothesis II Results

• Adsorption of F22 and F41 compared with AC

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Porous Polymer Observations

• Two Possible Reasons for Poor Adsorption
• Not enough surface area?
• Test polymers using surface area equipment
• Surface is not appropriate? (too polar?)
• Look at surface area probes
• Inconclusive results change in approach

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Nanoporous Modified Alumina

• Introduction
• aluminum oxide (Al2O3), activated
• 300m2/gram surface area
• Positively charged below pH 9.3
• Ave. pore size of 5.8nm diameter
• Goal
• To modify the Al2O3 by adsorbing negatively
  charged organic molecules to its surface.

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Adsorption on Modified Alumina

• Procedure
• Adsorb Bridging-Organics onto Alumina
• Measure adsorption on Al2O3
• tannic acid (TA), humic acid (HA), lignosulfonic
  acid sodium salt (LA), sodium dodecylbenzenesulfon
  ate
• Sample using UV Spectrophotometer
• Use organo-modified alumina to adsorb POMs.

bridge molecule
polar organic molecule (alcohol)
Al2O2 surface
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Adsorption on Modified Alumina

• Procedure STEP 1

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Further Research

• Follow through on the Adsorption on Modified
  Alumina STEP 2
• use organo-modified alumina to adsorb POMs.
• Test competitive adsorption studies where two
  POMs are placed in the same vial.
• Measure surface area of adsorbents.

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Special Thanks to

• Dr. Sabatini Edgar (for putting up with me)
• Denae for the great job of directing REU this
  summer.
• All the OU CEES faculty and Grad students for a
  great summer.
• The National Science Foundation for funding.