Title:
The distribution of charge and acidic functional groups in natural organic matter: the dependence on molecular weight and pH

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dc.contributor.advisor Perdue, E. Michael
dc.contributor.author Ritchie, Jason Duane en_US
dc.contributor.committeeMember Ching-Hua Huang
dc.contributor.committeeMember Ingall, Ellery
dc.contributor.committeeMember Taillefert, Martial
dc.contributor.committeeMember Michael Bergin
dc.contributor.department Earth and Atmospheric Sciences en_US
dc.date.accessioned 2006-01-18T22:14:21Z
dc.date.available 2006-01-18T22:14:21Z
dc.date.issued 2005-08-25 en_US
dc.description.abstract The Suwannee River natural organic matter (SRNOM) was fractionated by preparative size-exclusion chromatography (SEC) into seven molecular weight (MW) fractions. The SRNOM and its MW fractions were subsequently analyzed for their concentrations of acidic functional groups by direct titrations, average MWs and MW distributions by semi-analytical SEC, and charge-to-MW distributions by capillary electrophoresis. Carboxyl concentrations in the MW fractions were inversely proportional to their average MWs. Conversely, the phenolic concentrations, though smaller than the carboxyl concentrations, were proportional to average MWs. Hysteresisthe non-overlap between sequential forward and reverse titrationswas observed for the SRNOM and its MW fractions, where the reverse titrations predicted a greater concentration of carboxylic acid groups than the forward titration. Because hysteresis is thought to be caused by the base-catalyzed hydrolysis of esters, this suggests that ester groups in the SRNOM are distributed over all MWs. Data for direct titrations, MW distributions, and capillary electrophoresis were evaluated by a computational scheme that solves for the most probable distribution of acidic functional groups and charges on solutes in the SRNOM and the MW fractions as a function of pH. Depending on the MW ranges of the samples, solutes in the SRNOM and the MW fractions are predicted to have from one to a maximum of 25 carboxyl groups per solute. Most phenolic groups are predicted to be on solutes that have a minimum of two carboxyl groups. At low pH, all samples have high relative abundances of solutes with the lowest charges. The charges of solutes are predicted to increase with increasing pH due to the sequential ionization of acidic functional groups. Depending on the MW ranges of the samples, the maximum probable charges of solutes in the SRNOM and the fractions at high pH are -12 to -30. By knowing the most probable distribution of charge and abundances of acidic functional groups, researchers will make better estimates of thermodynamic parameters and models that describe equilibria between metals and natural organic matter in the environment. en_US
dc.description.degree Ph.D. en_US
dc.format.extent 10503527 bytes
dc.format.mimetype application/pdf
dc.identifier.uri http://hdl.handle.net/1853/7476
dc.language.iso en_US
dc.publisher Georgia Institute of Technology en_US
dc.subject Titrations en_US
dc.subject Natural organic matter
dc.subject Electrophoresis
dc.subject Charge distribution
dc.subject Molecular weights
dc.subject.lcsh Organic water pollutants en_US
dc.subject.lcsh Organic geochemistry en_US
dc.subject.lcsh Molecular weights en_US
dc.subject.lcsh Humus Analysis en_US
dc.subject.lcsh Electrophoresis en_US
dc.subject.lcsh Acid-base chemistry en_US
dc.title The distribution of charge and acidic functional groups in natural organic matter: the dependence on molecular weight and pH en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.corporatename School of Earth and Atmospheric Sciences
local.contributor.corporatename College of Sciences
relation.isOrgUnitOfPublication b3e45057-a6e8-4c24-aaaa-fb00c911603e
relation.isOrgUnitOfPublication 85042be6-2d68-4e07-b384-e1f908fae48a
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