Date of Award

Fall 2003

Document Type


Degree Name

Master of Science (MS)


Ocean & Earth Sciences



Committee Director

Joseph H. Rule

Committee Member

Robert F. Dias

Committee Member

Dennis A. Darby

Call Number for Print

Special Collections LD4331.G4 D54 2003


Humic (HA) and fulvic (FA) acids participate in many geochemical processes and the mechanisms of their sorption to colloidal surfaces are numerous, indicating these substances are complex and heterogeneous. The current study focuses on the interactions of the Fe hydroxide (FE), Al hydroxide, Kaolinite (KA) and Smectite (SM) and these naturally occurring organic acids using Fourier Transform Infrared Spectroscopy (FTIR) and DOC analysis at pH 4. FTIR was used for the initial functional group characterization, as well as the comparison of before and after adsorption spectra of the HA and FA. DOC examined the amounts of HA and FA adsorbed to the four colloids.

An important finding was the spectral patterns of both FA and HA changed when the sample was characterized from a concentrated versus a diluted solution. Concentrated solutions are usually produced by the most common isolation techniques and samples are subsequently diluted for experimental procedures. These results underscore the importance of conducting FA and HA spectral characterization under exact experimental conditions.

Generally, the peaks associated with carboxyl groups showed a decrease in intensity after exposure to FE and only slightly with AL. The peaks corresponding to phenolic groups decreased after exposure to SM and AL. Contrary to other viewpoints, H-bonding seemed be a major type of adsorption mechanism based on changes in the recorded spectra. From the DOC analysis two important observations were made, more HA was adsorbed by all four colloids compared to FA and FE adsorbed more HA and FA than the other three colloids.


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