SOIL FULVIC-ACID DEGRADATION BY OZONE IN AQUEOUS-MEDIUM

Armadale soil fulvic acid (SFA) was found to contain several loosely bound organic impurities which could be removed by ethyl acetate extraction. The ozonation of purified Armadale SFA at a variety of dosages was characterized by monitoring the UV absorbance, weight loss, pH changes, total acidity, molecular weight and elemental composition. SFA could only be partially degraded even under ozone dosages as high as SFA/O3 (W/W) of 1:6. At high ozone dosages (SFA/O3 1:6) mostly aliphatic compounds rich in oxygen were produced, whereas at low ozone dosages (SFA/O3 < 1:0.5) mainly benzene polycarboxylic acids and polyhydroxy benzene polycarboxylic acids were found. The solid material isolated from the chlorination (0.5 mg/L residual level) of residues from the ozonation (SFA/O3 1:0.2 to 1:0.5) of Contech SFA did not contain any chlorinated products.