REMOVING 2,4-D FROM WATER BY ORGANO-CLAYS

Decylammonium-montmorillonite (C10M) and decylammonium-vermiculite (C10V) were assayed as sorbent for the weak acid herbicide 2,4-D (2,4-dichlorophenoxy acetic acid) and were compared with untreated clays and activated carbon. Langmuir and Freundlich sorption parameters were calculated from the sorption isotherms. These indicated an increase of sorption capacity for 2,4-D of clays after decylammonium exchange. The sorption at different pH showed that molecular forms were preferentially adsorbed on C10M whereas anionic forms were on C10V. The C10V sample showed much higher and stronger sorption capacity than C10M. The different behaviour of both organic sorbents was related to the different arrangement of decylammonium cations in the interlayer of both minerals, as a consequence of their different layer charge.