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This article in JEQ

  1. Vol. 31 No. 1, p. 168-175
    Received: Oct 24, 2000

    * Corresponding author(s): man@kvl.dk
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Adsorption of Cadmium, Copper, Nickel, and Zinc to a Poly(tetrafluorethene) Porous Soil Solution Sampler

  1. M.K. Andersen *a,
  2. K. Raulund-Rasmussenb,
  3. B.W. Strobela and
  4. H.C.B. Hansena
  1. a Chemistry Department, Royal Veterinary and Agricultural University, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark
    b Danish Forest and Landscape Research Institute, Hoersholm Kongevej 11, 2970 Hoersholm, Denmark


Suction cups made of poly(tetrafluorethene) (PTFE) are widely used for sampling of soil solution. A brand (Prenart) of PTFE cups was tested for adsorption of Cd, Cu, Ni, and Zn at low concentrations under different conditions. In a laboratory experiment adsorption from a 10 μg L−1 heavy metal solution with a 0.01 M NaCl background electrolyte was investigated at pH 3.6, 4.5, and 5.8 by pumping the solutions through the cups. The effect of three different ionic compositions was also investigated using 0.01 M CaCl2, 0.01 M NaCl, and no background electrolyte at pH 4.5. In 0.01 M NaCl electrolyte at pH 5.8 the cups acted as effective filters. At pH 3.6 after 300 mL of solution had passed through the cup, equivalence between the Cd and Ni concentrations in influent and effluent was found. No equivalence between effluent and influent concentrations was found for Zn and Cu at pH 4.5 and 5.8. With Ca as the electrolyte, no adsorption of Cd, Ni, or Zn was found. In Na electrolyte, equivalence between influent and effluent concentrations for Cd, Ni, and Zn was reached. The difference between effluent and influent concentrations of Zn, Ni, and Cd remained significant in the absence of electrolyte. For all pH values and electrolytes the difference between effluent and influent concentrations of Cu was significant. It is concluded that PTFE cups affect the concentrations of heavy metals sampled at low soil solution concentrations. Cadmium, Cu, Ni, and Zn adsorb to the cup at pH > 4.5 and low ionic strength.

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Copyright © 2002. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyPublished in J. Environ. Qual.31:168–175.