Atrazine sorption by hydroxy-interlayered clays and their organic complexes.
This study examined the sorption of atrazine by hydroxy-Fe interlayered montmorillonite (FeMt) and its hydroquinone (FeMtHQ), citrate (FeMtCt) and catechol (FeMtCC) complexes as well as by hydroxy-Al interlayered montmorillonite (AlMt) and its hydroquinone (AlMtHQ) and citrate (AlMtCt) complexes. Found among the clays were sorption distribution coefficients (K(d)) ranging from 24 to 123 mL g(-1) and maximum sorption (M) ranging from 2.2 to 16.8 microg g(-1). Both K(d) and M decreased in the order of FeMtCC > FeMtHQ > AlMtHQ > (AlMt = FeMt) > (AlMtCt = FeMtCt). The pH was negatively correlated with both K(d) (r = -0.90, p < 0.001) and M (r = -0.81, p < 0.001). When interlayered clays were associated with humified material (FeMtCC, FeMtHQ, AlMtHQ), both K(d) (r > 0.96, p < 0.01) and M (r > 0.94, p < 0.01) were highly positively correlated with total organic C and alkali-soluble C. However, clays with non-humified organic compounds (FeMtCt and AlMtCt) sorbed less atrazine than clays without any organic C (FeMt and AlMt). This suggests that functional groups of Fe-OH and Al-OH in FeMt and AlMt reduced the available sorption sites for atrazine by making complexes with citrate ions while forming FeMtCt and AlMtCt. The atrazine was sorbed through the hydrophobic interactions with organic compound surfaces as well as through H-bonding and ionic bonding with clay-mineral surfaces.
Indraratne
Srimathie P
SP
Department of Soil Science, University of Manitoba, Winnipeg, Manitoba, Canada.
Farenhorst
Annemieke
A
Goh
Tee Boon
TB
D000327:Adsorption; D000536:Aluminum Hydroxide / Q000032:analysis / Q000737:chemistry; D000538:Aluminum Silicates / Q000032:analysis / Q000737:chemistry*; D001280:Atrazine / Q000032:analysis / Q000737:chemistry*; D001546:Bentonite / Q000032:analysis / Q000737:chemistry; D002396:Catechols / Q000032:analysis / Q000737:chemistry; D019343:Citric Acid / Q000032:analysis / Q000737:chemistry; D000077215:Clay; D005290:Ferric Compounds / Q000032:analysis / Q000737:chemistry; D006540:Herbicides / Q000032:analysis / Q000737:chemistry*; D006812:Humic Substances / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010084:Oxidation-Reduction; D012989:Soil Pollutants / Q000032:analysis*
D000538:Aluminum Silicates; D002396:Catechols; D005290:Ferric Compounds; D006540:Herbicides; D006812:Humic Substances; D012989:Soil Pollutants; D001546:Bentonite; D019343:Citric Acid; C021024:ferric hydroxide; D000536:Aluminum Hydroxide; C034221:catechol; D001280:Atrazine; D000077215:Clay