中文摘要：

H-酸萘环上含有的两个磺酸基团，在水溶液中可以解离一个或者两个．pH2．5条件下，主要有一个磺酸基团解离，此时，H-酸通过一个磺酸基团吸附在TiO2表面，占位小，饱和吸附量大，但吸附键较弱，吸附较可逆．pH5．0条件下，主要有两个磺酸基团解离，此时，H-酸通过两个磺酸基团吸附在TiO2表面，占位大。饱和吸附量小，但吸附键较强，吸附不可逆性较强．这种吸附模式的差异是导致H．酸在不同pH条件下饱和吸附量和吸附不可逆性差异的根本原因，也是导致不同pH条件下H-酸具有不同光催化降解途径的重要原因．

英文摘要：

H-acid has two sulphonic groups, which can be dissociated in aquatic solutions. At pH 2.5, only one of them dissociated. H-acid adsorbed onto TiO2 surface through one sulphonic group, which occupied less surface area leading to higher adsorption capacity, weaker adsorption bond, and less adsorption irreversibility. At pH 5.0, two of the sulphonic groups all dissociated. H-acid adsorbed onto the TiO2 surface by the two dissociated sulphonic groups, which occupied more surface area leading to lower adsorption capacity, stronger adsorption bond, and bigger adsorption irreversibility. These differences are the fundamental reasons why the adsorp- tion capacity and adsorption irreversibility and hence photo-degradation pathways for H-acid were different un- der different pH conditions.