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Soil Science Society of America Journal Abstract -

A Dual Function Organoclay Sorbent for Lead and Chlorobenzene


This article in SSSAJ

  1. Vol. 63 No. 1, p. 73-78
    Received: Feb 11, 1998

    * Corresponding author(s): boyds@pilot.msu.edu
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  1. Guangyao Sheng,
  2. Stephen A. Boyd  and
  3. Shihe Xu
  1. Dep. of Crop and Soil Sciences, Michigan State University, East Lansing, MI 48824-1325
    Health and Environmental Sciences, Dow Corning Corporation, Midland, MI 48686-0994



To demonstrate the concept of organoclays with dual sorptive properties, carboxylic group-bearing carboxydecyltriethylammonium [(HOOC)C10H20N(C2H5)3]+ cations (CDTEA) were used to substitute exchangeable inorganic cations of montmorillonite. Sorption of Pb2+ and chlorobenzene was examined as a function of pH and over a range of equilibrium concentrations at constant pH. The dual sorptive properties of CDTEA-montmorillonite were compared with those of its nonfunctionalized analogue, decyltrimethylammonium(DTMA)-montmorillonite, and with Na-montmorillonite. The infrared spectra showed bands corresponding to the carboxylic acid group and alkyl chain of CDTEA in CDTEA-montmorillonite. Titration of CDTEA-montmorillonite with NaOH indicated the existence of two distinct types of acidity originating from the native acid groups of the clay and the carboxylic groups of CDTEA. Sorption of Pb2+ by CDTEA-montmorillonite was much higher than that by Na-montmorillonite. Complete removal of 0.00724 cmol L-1 (15 mg L-1) of Pb2+ by CDTEA-montmorillonite occurred at pH 5 and above, but this was not achieved by Na-montmorillonite, regardless of pH. Pb2+ sorption by DTMA-montmorillonite was lower than that by Na-montmorillonite. These results indicate that Pb2+ is effectively bound to carboxylic groups of CDTEA. Sorption of chlorobenzene by CDTEA-montmorillonite was comparable to that by DTMA-montmorillonite. These results indicate that CDTEA-montmorillonite possesses dual sorptive properties for both heavy metals and organic contaminants. Neither Na- nor DTMA-montmorillonite were effective sorbents for both types of contaminants. The simultaneous removal of Pb2+ and chlorobenzene by CDTEA-montmorillonite and the non-competitive nature of the sorption processes each suggest the potential utility of such functionalized organoclays in the treatment of water contaminated by both heavy metals and organic chemicals.

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