| Abstract
| - The combination of adsorption and heterogeneousphotocatalysis has been investigated as a promisingtechnology for the removal of organic water pollutants. Alaboratory study of the removal and decomposition of2-chlorophenol (2-CP) as a toxic organic pollutant wascarried out under various conditions with an organophilizedclay mineral (hexadecylpyridinium chloride-modifiedmontmorillonite; HDPM) as adsorbent and Degussa P25TiO2 as photocatalyst. Three different oxidation processesleading to the degradation of 2-CP were compared: direct photolysis, heterogeneous photocatalysis in a TiO2suspension, and the decomposition of substrate adsorbed onHDPM in the presence of TiO2. Both the degradation of2-CP and the formation of intermediates were analyzed byHPLC, the total organic carbon content and the totalorganic and inorganic chloride contents were measuredto monitor the mineralization process, and X-ray diffractionand thermoanalytical measurements were made tocharacterize the hydrophobic clay adsorbent. Theheterogeneous photocatalytic degradation of dissolved(2-CP/UV/TiO2) and desorbed 2-CP (2-CP/HDPM/UV/TiO2)appeared to be equally efficient, whereas direct photolysisof 2-CP was far less efficient in the oxidative destruction.HDPM proved to be a suitable adsorbent, capable ofadsorbing toxic organics from water. It was demonstratedthat the adsorbent (at relatively high concentration) didnot decrease the rate of mineralization of 2-CP. The resultsconfirmed that the adsorbent retains its structure andcomposition during the mineralization process, and thus itcan be reused without regeneration. The combination ofadsorption and heterogeneous photocatalysis studied maybe an efficient and economical means of accumulating,removing, and oxidizing organic water contaminants, andits application is in accordance with the growingenvironmental demands.
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