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This article in JEQ

  1. Vol. 36 No. 4, p. 1069-1075
     
    Received: Oct 6, 2006


    * Corresponding author(s): pzhang@sci.ccny.cuny.edu
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doi:10.2134/jeq2006.0432

Removal of Perchlorate from Contaminated Waters Using Surfactant-Modified Zeolite

  1. Pengfei Zhang *a,
  2. David M. Avudzegaa and
  3. Robert S. Bowmanb
  1. a Dep. of Earth and Atmospheric Sciences, City College of New York, New York, NY 10031
    b Dep. of Earth and Environmental Science, New Mexico Inst. of Mining and Technology, Socorro, NM 87801

Abstract

We investigated the potential of using surfactant (hexadecyltrimethylammonium)-modified zeolite (SMZ) as an inexpensive sorbent for removing perchlorate (ClO4 ) from contaminated waters in the presence of competing anions. In batch systems, the presence of 10 mM OH (i.e., pH 12), CO3 2−, Cl, or SO4 2− had little effect on the sorption of ClO4 by SMZ, indicating that the sorption of ClO4 by SMZ was very selective. The presence of 10 mM NO3 , however, reduced the sorption of ClO4 at low initial concentrations. The maximum sorption capacity for ClO4 by the SMZ remained relatively constant (40–47 mmol kg−1), in the absence or presence of the competing ions. In flow-through systems, ClO4 broke through the SMZ columns much later than other anions present in an artificial ground water. The affinity of the anions for SMZ followed the sequence of ClO4 > > NO3 > SO4 2− > Cl Perchlorate loading under dynamic flow-through conditions was 34 mmol kg−1, somewhat less than the maximum loading of 40 to 47 mmol kg−1 determined by the batch method. Less than 1% of previously sorbed ClO4 was leached out by ultra-pure water, by extraction fluid #1 of the standard toxicity characteristic leaching procedure (TCLP), or by a solution of 0.28 M Na2CO3/0.5 M NaOH. About 40% of the previously sorbed ClO4 was leached out from SMZ by a 0.5 M NO3 solution. The exchange of ClO4 with NO3 corroborated results of the batch tests where NO3 was shown to compete with ClO4 sorption.

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