Removal of Cr (VI) and Cr (III) From Polluted Water and Soil Sown with Beet ( ) or Celery ( ) after the Addition of Modified Zeolites

Clinoptilolite, which was modified with hexa de-cyltrimethyl
ammonium-bromide solution (HDTMA-Br) in a proportion of
1/8 w/v (Ζ1), was applied for the adsorption of chromate anions
from aqueous solutions. Different initial concentrations of
chromate anions from 0 to 145 ppm were added as K2Cr2O7 to
1 g of modified zeolites adsorbent. Zeolites (clinoptilolite, Z)
was also used for comparison reasons. The kinetic analysis of
both adsorbents (Z, Z1) was studied at 25°C. Equilibrium
isotherms of chromate anions were studied for Clinoptilolite
and modified zeolites at 25, 40 and 60°C. According to the
kinetic analysis, the chromate anions adsorption capacity
reached at 1115.10 mg Cr (VI)/kg adsorbent for Z1 and 35.05
mg Cr (VI) kg for Z. According to isotherms, the adsorption of
Cr (VI) on Z1 and Z did not increase with the increase of
temperature indicating that the whole adsorption mechanism is
controlled by chemisorptions and not by physical adsorption.
Modified zeolites and zeolites were tested to two different soils,
i.e. a soil amendments. The modification of Clinoptilolite with
HDTMA-Br leads to the creation of positively charged surface
sites of zeolites increasing the adsorption of Cr (VI) as
chromate anions. Such adsorbents can be applied for the
removal of heavy metals and dyes in an anionic form from
wastewater and soil solutions where negative charged sites of
Clinoptilolite present low adsorption capacity.

Author(s): Zacharias Ioannou, Evangelia Brozou and Anthoula Dimirkou

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