The Characterization of Fulvic Acid Fractionated by Gel Permeation Chromatography

摘要

Fulvic acid, the major component of naturally occurring humic substances in water, is both a precursor of chlorinated organics in drinking water and the source of organic color in surface waters. The purpose of this study was to isolate and characterize components of fulvic acid, and relate these findings to water treatment practices for the removal of color, primarily coagulation with aluminum sulfate. Fulvic acid was fractionated into four fractions by gel permeation chromatography. Chemical characterization of each fraction included carbon, hydrogen, nitrogen, water, and ash analyses. The structures of the fulvic acid fractions were elucidated by the use of infrared, ultraviolet, and nuclear magnetic resonance spectroscopy. An aluminum binding study was performed to gain insight into the mechanism of fulvic acid removal during coagulation. The fractions were isolated and found to be discrete components of fulvic acid with different chemical and strutural characteristics. Test results indicated that the smallest molecular weight fraction was the most homogeneous, being primarily an aromatic substituted with carboxylate functional groups, and was able to complex more aluminum than any other fraction. It was concluded that fulvic acid cannot be completely nor selectively removed during coagulation with aluminum sulfate, and thus, trihalomethanes will always be produced during disinfection with hypochlorous acid.