Understanding Production and Regeneration Of Hybrid Fiber-Ferric Hydroxide Adsorbents For Arsenic Removal From Drinking Water

Persistent Link:
http://hdl.handle.net/10150/337308
Title:
Understanding Production and Regeneration Of Hybrid Fiber-Ferric Hydroxide Adsorbents For Arsenic Removal From Drinking Water
Author:
Chaudhary, Binod K.
Issue Date:
2014
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Drinking water contaminated with arsenic is a worldwide problem, especially in developing nations. The research presented in this dissertation describes two major goals: development of hybrid homopolymer polyacrylonitrile (PAN)-based sorbents for arsenate removal from drinking water and understanding regeneration of arsenate from ferric hydroxide-based adsorbents. The homopolymer PAN fiber was chemically modified to introduce functional groups using NaOH and hydrazine hydrate (HH) separately, or in combination of both. The modified fibers were characterized using Fourier transform infrared spectroscopy (FTIR) and ion exchange measurements. The ferric hydroxides were impregnated onto functionalized fibers using two iron loading procedures. The best arsenate removal performance was obtained using the simplest pretreatment procedure of soaking in 10% NaOH at 95 °C for ninety min, followed by precipitation coating of ferric hydroxide. This suggests that adsorbents based on a low-cost PAN fabric may be produced in developing areas of the world where commercial products may not be available. A density functional theory (DFT) molecular modeling was used to compare free energies of reactions and activation barriers in the formation of arsenate-ferric hydroxide complexes. Slow kinetics associated with arsenate adsorption and desorption attributed to the high activation barriers in forming and breaking bonds with the ferric hydroxides. Another aspect of regeneration study focused on the effects of underlying properties of the ferric hydroxides-loaded adsorbents on arsenate recovery. The arsenate loaded ferric hydroxide adsorbent containing no or weak base functionalities can be regenerated using NaOH, while addition of NaCl to NaOH solution is required for same recovery of arsenate from the adsorbents containing strong base anion exchange functionalities. Moreover, the irreversible fraction of arsenate on the adsorbent can be reduced by increasing the concentration of NaOH. Thus, understanding arsenate desorption kinetics and effects of support properties of ferric hydroxide-based adsorbents are important for environmental fate of arsenate and in designing adsorption systems for removing arsenate from potable water.
Type:
text; Electronic Dissertation
Keywords:
DFT Modeling; Ferric Hydroxide; Homopolymer Polyacrylonitrile; Kinetics; Regeneration; Environmental Engineering; Arsenic
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Environmental Engineering
Degree Grantor:
University of Arizona
Advisor:
Farrell, James

Full metadata record

DC FieldValue Language
dc.language.isoen_USen
dc.titleUnderstanding Production and Regeneration Of Hybrid Fiber-Ferric Hydroxide Adsorbents For Arsenic Removal From Drinking Wateren_US
dc.creatorChaudhary, Binod K.en_US
dc.contributor.authorChaudhary, Binod K.en_US
dc.date.issued2014-
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractDrinking water contaminated with arsenic is a worldwide problem, especially in developing nations. The research presented in this dissertation describes two major goals: development of hybrid homopolymer polyacrylonitrile (PAN)-based sorbents for arsenate removal from drinking water and understanding regeneration of arsenate from ferric hydroxide-based adsorbents. The homopolymer PAN fiber was chemically modified to introduce functional groups using NaOH and hydrazine hydrate (HH) separately, or in combination of both. The modified fibers were characterized using Fourier transform infrared spectroscopy (FTIR) and ion exchange measurements. The ferric hydroxides were impregnated onto functionalized fibers using two iron loading procedures. The best arsenate removal performance was obtained using the simplest pretreatment procedure of soaking in 10% NaOH at 95 °C for ninety min, followed by precipitation coating of ferric hydroxide. This suggests that adsorbents based on a low-cost PAN fabric may be produced in developing areas of the world where commercial products may not be available. A density functional theory (DFT) molecular modeling was used to compare free energies of reactions and activation barriers in the formation of arsenate-ferric hydroxide complexes. Slow kinetics associated with arsenate adsorption and desorption attributed to the high activation barriers in forming and breaking bonds with the ferric hydroxides. Another aspect of regeneration study focused on the effects of underlying properties of the ferric hydroxides-loaded adsorbents on arsenate recovery. The arsenate loaded ferric hydroxide adsorbent containing no or weak base functionalities can be regenerated using NaOH, while addition of NaCl to NaOH solution is required for same recovery of arsenate from the adsorbents containing strong base anion exchange functionalities. Moreover, the irreversible fraction of arsenate on the adsorbent can be reduced by increasing the concentration of NaOH. Thus, understanding arsenate desorption kinetics and effects of support properties of ferric hydroxide-based adsorbents are important for environmental fate of arsenate and in designing adsorption systems for removing arsenate from potable water.en_US
dc.typetexten
dc.typeElectronic Dissertationen
dc.subjectDFT Modelingen_US
dc.subjectFerric Hydroxideen_US
dc.subjectHomopolymer Polyacrylonitrileen_US
dc.subjectKineticsen_US
dc.subjectRegenerationen_US
dc.subjectEnvironmental Engineeringen_US
dc.subjectArsenicen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineEnvironmental Engineeringen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorFarrell, Jamesen_US
dc.contributor.committeememberFarrell, Jamesen_US
dc.contributor.committeememberArnold, Boben_US
dc.contributor.committeememberReyes, Sierraen_US
dc.contributor.committeememberChorover, Jonen_US
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