Presentation from international conference Zeolite 2014 in Belgrade.

1. Removal of chromium(VI) from aqueous
solutions using zeolites modified with
HDTMA and ODTMA surfactants
Barbara Szala, Tomasz Bajda, Anna Jeleń
www.agh.edu.plwww.agh.edu.pl
AGH University of Science and Technology
Faculty of Geology, Geophysics and Environmental Protection
08. 06. – 13. 06. 2014 Belgrade, Serbia

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Outline
 Aim
 Natural or synthetic?
 Applications
 Materials
 Modification and sorption experiments
 Cr(VI) removal
 Conclusion

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Aim
The aim of this study was to compare the chromate
adsorption capacities of natural and synthetic organo-zeolites
modified with hexadecyltrimethylammonium bromide (HDTMA)
and octadecyltrimethylammonium bromide (ODTMA)
surfactants.

4. Natural or
synthetic?

5. Environmental
protection
 Wastewater treatment
 Sorption of heavy metals
Agriculture
 Soil treatment
Water moderators
Hygiene
 Cosmetic products
 Detergents
Medicine
 Pharmaceuticals
Construction
 Concrete additive
 Water softlening
 Pozzolan
Nuclear industry
Petrochemistry
 Catalysis
 Adsorbents
 Desiccant
Gas treatment
 Drying of gases
 Air decomposition
Solvent recovery
Application

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Materials

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Materials

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Materials

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Materials

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Surface modification
http://www.ees.nmt.edu/bowman/resarch/SMZ/ZeoSurfInt.html

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Modification
HDTMA / ODTMA solution
24.4 mmol/100g for Na-P1 Zeolite
11.45 mmol/100g for natural
80°C
Mechanical stirrer (80°C) – 6h
Centrifugation and drying

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Modification
In the adopted conditions, the formation of the double layer
of surfactant (2.0 ECEC) was not possible. The surfactant has
been adsorbed onto the surface in an amount of
approximately 1.2 of ECEC for all modifications.
HDTMA ODTMA
Natural clinoptillolite 0.94 0.93
Synthetic Na-P1 1.01 0.98

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Sorption
Static condition
 pH 1-10 (5 mmol/L)
 0.05-50 (pH 4, clinoptilolite)
(pH 1, Zeolite Na-P1)
 24 h of shaking
 10 min of contrifuging
Dynamic condition
 Flow technique
 Column 50 cm, Φ2.5 cm
 10g of zeolite + 500 ml
 pH =3.5
 C0=0.4 mmol/L
The chromate concentration in the supernatant was determined
spectrophotometrically (UV–VIS Hitachi U-1800) using the
biphenylocarbazide method (ASTM, 1992).

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Results
Cr(VI) sorption on HDTMA- modified: Clinoptilolite and Na-P1 synthetic zeolite as a
function of pH.

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Results
Cr(VI) sorption on ODTMA- modified: Clinoptilolite and Na-P1 synthetic zeolite as a
function of pH.

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Results
Cr(VI) sorption on HDTMA- modified: Clinoptilolite and Na-P1 synthetic zeolite as a
function of concentration.

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Results
Cr(VI) sorption on HDTMA- modified: Clinoptilolite and Na-P1 synthetic zeolite as a
function of concentration.

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Results
Breakthrough curves for selected organo-zeolites modified in amount of 1.0 ECEC over
the regenerated reactive adsorbent at 25ºC.

19. Conclusion
Cr(VI) ads. /HDTMA Cr(VI) ads. /ODTMA
1.0 ECEC 1.2 ECEC 1.0 ECEC 1.2 ECEC
Clinoptilolite 0.71 0.77 0.75 0.75
Na-P1 zeolite 0.49 0.58 0.47 0.51
 Organo-zeolites modified by HDTMA have an almost equal sorption capacity
to ODTMA- modified zeolites.
 The molar ratio clearly indicates that in the adoptedconditions, the natural
zeolite’s sorption capacity is utilized to a greater extent.
 Surfactants adsorbed on the zeolite’s surface are used to a lesser extent by
the Na-P1 zeolite than clinoptilolite in Cr(VI) sorption experiments.

20. bszala@geol.agh.edu.pl
Conclusion
 Organo-zeolites used in this work show a significant ability to remove chromium(VI)
contamination from aqueous solutions.
 The conducted experiments showed that the amount of Cr(VI) removed either by
organically modified natural zeolites or synthetic zeolites is high at a low pH (2-7).​​
 The sorption of chromate is more efficient with the organo-zeolites modified with
HDTMA than the ODTMA surfactant.
 All experiments have shown that the modified synthetic zeolite is a better sorbent for
anionic forms of chromium(VI) than modified natural zeolites.
 The results of this research can be used in environmental protection as well as for
further study into the properties of surfactant-modified zeolites and their potential
applications in environmental protection.

21. Thank you for your attention