Sorption and cosorption of 1,2,4-trichlorobenzene and tannic acid by organo-clays

Organo-clay sorbents were prepared by treating montmorillonite with four different quaternary ammonium compounds. The sorbents were then evaluated for the ability to remove a lower molecular weight hydrophobic organic, 1,2,4-trichlorobenzene (TCB), from water in the presence of larger, more hydrophilic organics such as tannic acid. Removal of each sorbate species was characterized separately, then the organo-claysʹ removal of TCB was assessed in the presence of the tannic acid. The quaternary ammonium compounds used were tetramethylammonium chloride (TMA), hexadecyltrimethylammonium bromide (HDTMA), hexadecylbenzyldimethylammonium chloride (HDBDMA), and dioctodecyldimethylammonium bromide (DDDMA). The adsorption isotherms of tannic acid onto the organo-clays were all nonlinear; the TMA-modified clay led to unfavorable curvature, while the long-chain surfactants all produced favorable curvature. The ability of the organo-clays to remove tannic acid increased in the order TMA