In-Situ Regeneration of Granular Activated Carbon (GAC) Using Fenton's Reagents

Persistent Link:
http://hdl.handle.net/10150/195619
Title:
In-Situ Regeneration of Granular Activated Carbon (GAC) Using Fenton's Reagents
Author:
De Las Casas, Carla
Issue Date:
2006
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:
Fenton-dependent recovery of carbon initially saturated with one of several chlorinated aliphatic contaminants was studied in batch and continuous-flow reactors. A specialty carbon, URV-MOD 1 (Calgon) was employed to minimize non-productive H2O2 demand - that which does not yield hydroxyl or superoxide radicals.Enhancement of PCE degradation kinetics by ferric iron addition is limited by iron solubility, even at relatively low pH. Quinone addition increased the pseudo-first-order rate constant for PCE loss temporarily. Only copper addition sustainably enhanced the specific rate of PCE loss. For copper-to-iron molar ratios of 0.25 to 5, the pseudo-first-order rate constant for PCE transformation was increased by a factor of 3.5. It is apparent that the effect of copper addition on Fenton-dependent reaction rates is complex, and involves a shift in chemical mechanism, as indicated by the differing slopes in the Arrhenius plot (with and without copper).A mathematical model was developed to evaluate the effect of operational parameters ([Fe(III)]T:[H2O2]o ratio and pH) on degradation kinetics and optimize the PCE degradation process in homogeneous reaction mixtures. The model simulated experimental degradation of the organic target in a homogeneous Fenton-reaction system. The model requires further refinement to simulate Fenton's systems in which ions in solution (such as sulfate and chloride) play significant roles.In continuous-flow reactors, Fenton's reagents were cycled through spent GAC in columns to degrade one of seven chlorinated compounds tested. The contaminant with the weakest adsorption characteristics, methylene chloride, was 99% lost from the carbon surface during a 14-hour regeneration period. At the field site, the GAC was saturated with gases containing TCE and PCE from a soil vapor extraction (SVE) system. In the field, up to 95% of the sorbed TCE was removed from GAC during regeneration periods of 50-60 hours. Recovery of PCE-loaded GAC was significantly slower. Column experiments show that there is minimal loss of carbon adsorption capacity during Fenton treatment and that the rate of GAC regeneration is compound specific. Scoping-level cost estimates indicated that field use of Fenton regeneration is not cost effective without optimization and/or iron surface amendments, except in the case of the most soluble VOCs.
Type:
text; Electronic Dissertation
Keywords:
Fenton; Regeneration; GAC; carbon; PCE; degradation
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Environmental Engineering; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Ela, Wendell P.
Committee Chair:
Ela, Wendell P.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleIn-Situ Regeneration of Granular Activated Carbon (GAC) Using Fenton's Reagentsen_US
dc.creatorDe Las Casas, Carlaen_US
dc.contributor.authorDe Las Casas, Carlaen_US
dc.date.issued2006en_US
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.abstractFenton-dependent recovery of carbon initially saturated with one of several chlorinated aliphatic contaminants was studied in batch and continuous-flow reactors. A specialty carbon, URV-MOD 1 (Calgon) was employed to minimize non-productive H2O2 demand - that which does not yield hydroxyl or superoxide radicals.Enhancement of PCE degradation kinetics by ferric iron addition is limited by iron solubility, even at relatively low pH. Quinone addition increased the pseudo-first-order rate constant for PCE loss temporarily. Only copper addition sustainably enhanced the specific rate of PCE loss. For copper-to-iron molar ratios of 0.25 to 5, the pseudo-first-order rate constant for PCE transformation was increased by a factor of 3.5. It is apparent that the effect of copper addition on Fenton-dependent reaction rates is complex, and involves a shift in chemical mechanism, as indicated by the differing slopes in the Arrhenius plot (with and without copper).A mathematical model was developed to evaluate the effect of operational parameters ([Fe(III)]T:[H2O2]o ratio and pH) on degradation kinetics and optimize the PCE degradation process in homogeneous reaction mixtures. The model simulated experimental degradation of the organic target in a homogeneous Fenton-reaction system. The model requires further refinement to simulate Fenton's systems in which ions in solution (such as sulfate and chloride) play significant roles.In continuous-flow reactors, Fenton's reagents were cycled through spent GAC in columns to degrade one of seven chlorinated compounds tested. The contaminant with the weakest adsorption characteristics, methylene chloride, was 99% lost from the carbon surface during a 14-hour regeneration period. At the field site, the GAC was saturated with gases containing TCE and PCE from a soil vapor extraction (SVE) system. In the field, up to 95% of the sorbed TCE was removed from GAC during regeneration periods of 50-60 hours. Recovery of PCE-loaded GAC was significantly slower. Column experiments show that there is minimal loss of carbon adsorption capacity during Fenton treatment and that the rate of GAC regeneration is compound specific. Scoping-level cost estimates indicated that field use of Fenton regeneration is not cost effective without optimization and/or iron surface amendments, except in the case of the most soluble VOCs.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectFentonen_US
dc.subjectRegenerationen_US
dc.subjectGACen_US
dc.subjectcarbonen_US
dc.subjectPCEen_US
dc.subjectdegradationen_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineEnvironmental Engineeringen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorEla, Wendell P.en_US
dc.contributor.chairEla, Wendell P.en_US
dc.contributor.committeememberSaez, A. Eduardoen_US
dc.contributor.committeememberArnold, Robert G.en_US
dc.identifier.proquest1963en_US
dc.identifier.oclc659746541en_US
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