Highly-polar layered double hydroxides are efficient adsorbents of low-concentrated trihalomethanes present in water

. Replacement of (Al(OH)6)3- blocks by (AlF6)3- was explored as a strategy to modify the dipolarity of layered double hydroxides materials (LDHs). The presence of fluorine augments the dipolarity/polarizability of LDHs. LDHs were tested as adsorbents of the trihalomethanes CHCl3 and CHBr3 that are present (low concentrated) in water. Fluorinated LDHs were significantly more efficient compared to that without fluorine. Thermal treated fluorinated LDHs are able to remove 95% and 90% of CHCl3 and CHBr3, respectively, present in low concentrated aqueous solutions. The effect of concentration of triahalomethanes, time of contact and structure of adsorbent were explored.  Linear isotherms were obtained when un-fluorinated adsorbents were used but the isotherm turns to match that of Freundlich-type when adsorbent contains fluorine. Resumen. La sustitucion de iones  de (Al (OH)6) 3- por (AlF6)3- se investigo como una estrategia para modificar la dipolaridad de los hidroxidos dobles laminares (HDL). La presencia de fluor aumenta la dipolaridad / polarizabilidad de los HDL. Los HDL se probaron como adsorbentes de los trihalometanos CHCl3 y CHBr3 presentes a bajas concentraciones en agua. Los HDL fluorados fueron significativamente mas eficientes en comparacion con los que no contenian  fluor. Los HDL fluorados tratados termicamente pueden eliminar 95% y 90% de CHCl3 y CHBr3, respectivamente, presentes en soluciones acuosas a baja concentracion. Se examino el efecto de la concentracion de trihalometanos, el tiempo de contacto y la estructura del adsorbente. Se obtuvieron isotermas lineales cuando se usaron adsorbentes no fluorados; en contraste, cuando el adsorbente contiene fluor la isoterma coincide con la de tipo Freundlich.