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Atrazine sorption by hydroxy-interlayered clays and their organic complexes
Srimathie P Indraratne1, Annemieke Farenhorst, Tee Boon Goh
1Department of Soil Science, University of Manitoba, Winnipeg, Manitoba, Canada.
Summary
The sorption of atrazine by modified clays depends on organic matter. Humified organic compounds enhanced atrazine sorption, while non-humified compounds reduced it, impacting contaminant removal strategies.
Area of Science:
- Environmental Chemistry
- Soil Science
- Mineralogy
Background:
- Montmorillonite clays are key soil components influencing contaminant fate.
- Interlayer modification of montmorillonite with metal hydroxides (Fe, Al) alters its sorption properties.
- Understanding atrazine sorption mechanisms is crucial for environmental risk assessment.
Purpose of the Study:
- To investigate the sorption behavior of atrazine on hydroxy-Fe and hydroxy-Al interlayered montmorillonite (FeMt, AlMt).
- To evaluate the influence of complexation with hydroquinone, citrate, and catechol on atrazine sorption.
- To determine the relationship between clay properties, organic matter content, and atrazine sorption.
Main Methods:
- Sorption experiments were conducted using various modified montmorillonite clays.
- Sorption distribution coefficients (K(d)) and maximum sorption (M) were determined.
- Statistical analyses (correlation) were used to assess relationships between variables.
Main Results:
- Sorption coefficients (K(d)) ranged from 24 to 123 mL g(-1) and maximum sorption (M) from 2.2 to 16.8 microg g(-1).
- Sorption decreased in the order FeMtCC > FeMtHQ > AlMtHQ > (AlMt = FeMt) > (AlMtCt = FeMtCt).
- Atrazine sorption was negatively correlated with pH and positively correlated with organic carbon content for humified complexes.
Conclusions:
- Humified organic matter significantly enhances atrazine sorption on modified montmorillonites.
- Non-humified organic compounds (citrate) can reduce atrazine sorption by complexing with metal hydroxide groups.
- Atrazine sorption involves hydrophobic interactions, H-bonding, and ionic bonding with clay surfaces.
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