Abstract: A series of organobentonites synthesized by exchanging organic
cation such as dodecyltri-methylammonium
(DTMA),benzyldimethyltetradecylammonium (BDTDA), cetyltrimethyl-ammonium
(CTMA), octodeyltrimethylammonium (OTMA) on bentonite. The optimal condition,
properties and mechanisms for the organobentonites to sorb phenanthrene,
anthracene, naphthalene, acenaphthene in water were investigated in detail. The
partition behavior was determined for four polycyclic aromatic hydrocarbons
(PAHs), such as naphthalene, phenanthrene, anthracene and acenaphthene, from
water to a series of organobentonites. The interlayer spacings and organic
carbon contents of organobentonites, removal rate and sorption capacities for
organobentonites to treat phenanthrene,anthracene, naphthalene, acenaphthene
were correlated to the length of alkyl chains and the amounts of cation
surfactant exchanged on Foundation item: the bentonite. Phenanthrene,
anthracene, naphthalene, and acenaphthene sorption to organobentonites were
characterized by linear isotherms, indicating solute partition between water
and the organic phase composed of the large alkyl functional groups of
quaternary ammonium cations. PAHs distribution coefficients (K_d)between
organobentonites and water were proportional to the organic carbon contents of
organobentonites. However, the partition coefficients (K_oc) were nearly
constants for PAHs in the system of organobentonite-water. The K_oc of
phenanthrene, anthracene,naphthalene, acenaphthene were 2.621x10^5, 2.106x10^5,
2.247x10^4,5.085x10^4, respectively. The means K_oc values on the
organobentonites are about ten to twenty times larger than the values on the
soils/sediments, what is significant prerequisite for organobentonite to apply
to remediation of pollution soil and groundwater. The sorption mechanism was
also evaluated from octanol-water partition coefficients and aqueous solubility
of PAHs. The correlations between lgK_oc and 1gk_ow, 1gK_oc and 1gS for PAHs in
the system of water/organobenotonites are also discussed.
