Acid-base properties of organosmectite in aqueous suspension

Surfactant modified smectite was prepared using hexadecyltrimethylammonium bromide (HDTMAB) at three CEC levels (0.5, 1 and 2 CEC). Potentiometric titration behavior of Na-smectite and organosmectites was investigated and interpreted according to surface complexation theory. The point of zero charge (PZC) was determined by both the methods potentiometric and mass titrations. The PZC of Na-smectite is about 6.2 and that of the organosmectites (H0.5, H1 and H2) is 6.8, 7.7 and 8, respectively. The titration data was modulated using the ProtoFit program in order to determine the PZC and the equilibrium constants (pKas). The results give a good agreement between the experimental and modeling study.