Photodegradation of humic acids in the presence of hydrogen peroxide

A batch photoreactor was used to evaluate the UV/H2O2 oxidation process for the removal of humic acids in water. A 450-W UV lamp with high-pressure me rcury vapor was employed as the light source. The residues of humic acids a nd hydrogen peroxide were measured for assessment of process performance an d understanding of process reaction behavior. The UV photolysis alone can p lay an important role in the degradation of humic acids. The presence of hy drogen peroxide was found to promote the degradation efficiency. However, e xcessive dosage of H2O2 does not further improve the degradation of humic a cids. On the contrary, the lower the H2O2 dosage the higher the amount of h umic acids which can be removed. Aeration with air does not favor the remov al efficiency of humic acids as the oxidation lasts for a sufficiently long time. The presence of carbonate species deteriorates the humic acids' remo val, whereas it results in a larger amount of H2O2 decomposition. (C) 2000 Elsevier Science Ltd. All rights reserved.