Abstract: Na-based bentonite was modified with cetyl trimethyl ammonium bromide（CTMAB）as the modifier.The absorption efficiency of Na-bentonite to chromium ion（Ⅵ） in wastewater before and after organic modification was investigated.The influences of absorption time，solution pH，feeding amount of bentonite，and temperature etc.on the absorption effect were studied.The optimal adsorption conditions for Na-based bentonite were obtained by experiment as follows：40 min，pH=7.0， 15 g/L，and 20～30 ℃；and for organic modified bentonite were as follows：40 min，pH=6.0，10 g/L，and 30 ℃.After modifica- tion the adsorption rate significantly increased from 50% to 95% above.Then the adsorption isotherms of organic bentonite was studied in chromium wastewater and proved the adsorption process met the Langmuir isotherm model.The remediation effect of organic modified bentonite applied to Cr（Ⅵ） contaminated soil was also investigated preliminarily.Results showed organic modified bentonite′s remediation effect to Cr（Ⅵ） contaminated soil was obviously better than that of Na-based bentonite and the removal rates could be up to 90% above.

Key words: Na-bentonite, organic modification, chromium ions, soil remediation