Abstract
Organo-bentonites have been synthesized through ion-exchange reaction using benzyl dimethyl dodecyl ammonium (BDMDA), dioctadecyl dimethyl ammonium (DODMA) chloride; tetraphenyl phosphonium (TPP) and hexadecyl pyridinium (HDP) bromides. The unmodified and modified samples were studied with Fourier transform infrared (FT-IR) spectroscopy, Xray diffraction (XRD) technique, and Scanning electron microscopy (SEM). The
basal spacing of the unmodified bentonite was 17.123Å and after modification it increased to 22.071Å and 20.066Å
at 1.0CEC for BDMDA and DODMA respectively. With 1.5CEC of TPP and 2.0CEC of HDP the basal spacing
increased to 20.250Å and 18.205Å respectively. The FT-IR studies also revealed structural differences between
the modified and unmodified bentonite samples. The IR spectra of the modified bentonite showed C-H asymmetric stretching at 2928cm -1 for BDMD 2920cm-1 for DODMA and 2918cm-1 for HDP, symmetric stretching at 853cm-1 for BDMD, 2851cm-1 for DODMA and 2851cm-1 HDP and bending vibrations at 1460cm -1 for BDMDA, 469cm-1 for DODMA and 1469cm-1 for HDP with respect to long alkyl chains in BDMDA, DODMA and HDP. The vibration associated with pyridinium was observed at 1490cm-1 in HDP modified bentonite. The C=C stretching vibrations in the phenyl ring were at 1587cm-1 and 1441cm-1 while attachment of the phenyl rings to phosphonium ion were observed at 1587cm-1 , 1441cm-1 , and 1438cm-1 with respect to TPP modified sample. Results
of the SEM revealed a tendency towards flakes/grain like formation and agglomeration.