CARBON-ZEOLITE COMPOSITE MATERIALS IN ADVANCED DRINKING WATER TREATMENT

摘要

The presence of humic substances in waters can cause various environmental problems. Humic acid (HA) is one of the major components of humic substances which contain both hydrophilic and hydrophobic molecules as well as phenolic, carboxyl and hydroxyl groups connected to the skeleton of aliphatic or aromatic units. Nowadays, special attention has been given to humic substances, following the discovery of trihalomethanes in water supplies. It is believed that these suspected carcinogens can be formed in the presence of humic substances during the disinfection of raw municipal drinking water by chlorination. The formation of trihalomethanes can be,' therefore, reduced by removing as much of the humic material as possible prior to chlorination.1'2 Several processes, such as sand filtration, coagulation followed by filtration or activated carbon filtration are the most commonly used technologies to remove natural organic compounds from water. In recent years, there has been a great deal of interest in the use of advanced treatment processes for the removal of hazardous and refractory organic compounds.3"6 The advanced oxidation processes (AOP), using the combination of ozone with other oxidant agents (UV radiation and hydrogen peroxide), allow only the oxidation of dissolved organic compounds that are commonly refractory to the direct attack of ozone.7'8 hi fact, UV radiation and hydrogen peroxide addition lead to the ozone demolition and the OH. radical formation; the OH. radicals are particularly aggressive with respect to the organic compounds, advancing their chemical degradation.9