Sorption of organobentonites to some organic pollutants in water

Organobentonites were synthesized by placing quaternary ammonium surfactants such as octadecyltrimethylammonium bromide (OTMAB), cetyltrimethylammonium bromide (CTMAB), and dodecyltrimethylammonium bromide (DTMAB) on the bentonite by cation exchange. The properties for organobentonites to sorb naphthylamine, naphthol, nitrobenzene, and aniline in water were investigated in detail. It was indicated that the interlayer spacing and the saturation sorption capacities as well as the removal rates for organobentonites to treat organic compounds in water were positively correlated to the length of alkyl chains and the amounts of cation surfactants exchanged on the bentonite. The removal percentages for organobentonites to treat organic compounds from water were as follows: OTMAB-bentonite > CTMAB-bentonite > DTMAB-bentonite; alpha-naphthylamine similar to beta-naphthylamine similar to naphthol > nitrobenzene > aniline. Naphthylamine/naphthol sorptions to organobentonites were characterized by relatively strong solute uptake and nonlinearity. Nitrobenzene and aniline sorptions to organobentonites were weaker, and the isotherms were approximately linear. The sorption mechanism was also studied by octanol-water partition coefficients of organics.