Smectites, modified

Crocker FH, WA Guerin, SA Boyd (1995) Bioavailability of naphthalene sorbed to cationic surfactant-modified smectite clay. Environ Sci Technol 29 2953-2958. 

Alvarez-Cohen et al. [91] explicitly showed that microbial transformation rates of trichloroethylene (TCE) were proportional to the aqueous TCE concentrations and independent from zeolite-sorbed TCE concentrations. Apparently in contrast to these findings, Crocker et al. [92] reported on the direct bioavailability of naphthalene sorbed to hexadecyltrimethylammonium (HDTMA)-modified smectite clay to Pseudomonas putida 17848, but not to Alcaligenes sp. strain NP-Alk. It should be noted that sorption to the hexadecyl chains of HDTMA resembles more the solubilisation by a surfactant than adsorption to a solid surface. Possibly, hydrophobic surface structures of strain 17848 allowed the close contact with HDTMA, thereby facilitating the uptake of naphthalene by a lipophilic pathway. 

Modified smectites (small alkyl-ammonium ions in montmorillonites, hectorites and fluorhectorites)... 

The modified smectite thus has good affinity and selectivity for its target contaminant and is thermally stable, recyclable and economic to use (Fig. 2). 

This property of layer silicate clays has been used to modify smectites so that they can adsorb and retain non-polar pollutants in water, such as chlorinated benzene. 

Pyrene luminescence also has been utilized to probe surfactant-modified smectites. Pyrene and anthracene themselves are poorly adsorbed on the hydrophilic surface of smectites, but they are readily adsorbed by organoammonium-intercalated clays. Intocalation of pyrene, anthracene, and azobenzenes into long-chain quatamary alkylammonium-smectites was successfully achieved by... 

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