NMR spectroscopic investigation of hydrogen bonding in atrazine

Welhouse, Gereon J.; Bleam, William F.

doi:10.1021/es00029a014

Cited by 42 publications

(35 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The three possible protonation structures (at low pH) based on derealization of lone‐pair electrons from the electron‐abundant isopropylamino, ethylamino nitrogen, and chlorine atoms into the adjacent π‐electron system in the triazine ring have been given by Pospisil et al [32]. Welhouse and Bleam [33] reported delocalization to be more predominant in a polar solvent and in acid solution. Thus, not surprisingly, the highest initial rate was found to be at pH 2.6 (Fig.…”

Section: Discussionmentioning

confidence: 99%

Abiotic dealkylation and hydrolysis of atrazine by birnessite

Shin

Cheney

2005

Enviro Toxic and Chemistry

View full text Add to dashboard Cite

Atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) and its degradation products are important contaminants of world water systems and have effects on aquatic life. These effects are modulated by the degradation of atrazine, which depends, in part, on its reactivity with soil minerals. We have studied the degradation reaction of atrazine on synthetic birnessite (delta-MnO2) in the aqueous phase using a batch reactor and a developed high-performance liquid chromatography method. The reaction was studied in the absence of light at 25 degrees C and between pH 2.3 to pH 8.3. The reaction rates increased with decreasing pH and increasing delta-MnO2 loading, and they did not follow simple first-order kinetics. The major products are hydroxylated and mono- and didealkylatrazine. Ammeline and cyanuric acid also were detected. The half-life (t 1/2) for the degradation of atrazine was approximately 16.8 d and independent of oxygen. Manganese(II) evolution was a minor product. The mechanism of dealkylation involved proton transfer to Mn(IV)-stabilized oxo and imido bonds, with no net oxidation and reduction. Oxidation was a secondary reaction. The proposed abiotic pathway for the transformation of atrazine on delta-MnO2 was identical to the reported biotic pathway. Thus, delta-MnO2, a common soil component, facilitated the efficient N-dealkylation and hydrolysis of the herbicide atrazine at 25 degrees C, possibly via a nonoxidative mechanisms. The N-dealkylation has been attributed strictly to a biological process in soils.

show abstract

Section: Discussionmentioning

confidence: 99%

Abiotic dealkylation and hydrolysis of atrazine by birnessite

Shin

Cheney

2005

Enviro Toxic and Chemistry

View full text Add to dashboard Cite

show abstract

“…The side chain amino groups are even less electronegative because of delocalization of their lone-pair electrons into the atrazine ring (Welhouse and Bleam 1992). Thus, H-bonding at NH groups with the exchange-cation solvating water is unlikely.…”

Section: Methodsmentioning

confidence: 99%

Sorption of Atrazine by Al- and Ca-Saturated Smectite

Sawhney

1997

Clays and clay miner.

View full text Add to dashboard Cite

Abstract--Because of the large surface area and common occurrence of smectites in the clay fractions, they are important in sorption/desorption reactions of organic pollutants entering soils and sediments. Results of sorption and desorption of atrazine by A1-and Ca-saturated smectite reported here showed that Al-saturated smectite sorbed much higher amounts of atrazine than Ca-saturated smectite. Al-saturated smectite sorbed 3820 mg kg -1 as compared to 1902 mg kg ~ by the Ca-saturated smectite during 5 consecutive sorptions from 10 ppm atrazine solution. Sorption isotherms over 2-10 ppm atrazine concentration range were nonlinear in all cases. Freundich coefficients, Kf, obtained from the sorption isotherms were much higher for A1-than Ca-saturated smectite; Kf varied from 405 to 3035 for Al-saturated and 100 to 306 for Ca-saturated. The pH values of A1-and Ca-saturated smectites were 3-4 units higher than the pK a (1.68) of atrazine, which suggests that atrazine was sorbed as neutral molecules. Stronger H-bonding between the more polarized H20 associated with the trivalent A1 ion than the divalent Ca ion is likely responsible for the greater sorption by Al-smectite.

show abstract

“…Atrazine is a neutral, moderately polar organic compound based on a triazinin ring structure (Welhouse and Bleam, 1992). Using sediment samples, Sun et al, 2010, found that atrazine has a log Koc value between 1.79 and 1.95, indicating the potential for a relatively high mobility within the environment.…”

Section: Introductionmentioning

confidence: 99%

Atrazine leaching from biochar-amended soils

2014

View full text Add to dashboard Cite

The herbicide atrazine is used extensively throughout the United States for weed control, and is a widespread ground water and surface water contaminant. Biochar has been shown to strongly sorb organic compounds, and could provide a way to reduce atrazine leaching. Using lab and field experiments, we studied how biochar impacts atrazine leaching under increasingly heterogeneous soil conditions. Lab-scale soil columns dosed with biochar, atrazine, and simulated rain demonstrated that biochar application does reduce atrazine leaching. Both homogenized and undisturbed soil cores demonstrated lower atrazine leaching with biochar addition, though the increased variability in results for the undisturbed cores masked the statistical significance of this finding. We attribute increased variability to the increased complexity of the soil pore structure. Field plot treatments included biochar, acidified biochar, peat plus biochar mixture, and peat moss. Mean groundwater atrazine concentrations were 34% and 53% lower for biochar and acidified biochar plots, respectively, relative to the control plots; the acidified biochar plots were significantly lower (p=0.0056). Plots receiving peat plus biochar showed no reduction, indicating that organic matter may compete for biochar sorption sites. Peat moss alone had no effect on atrazine leaching. We conclude that biochar application has the potential to decrease atrazine leaching, but heterogeneous soil conditions may reduce this impact.iii

show abstract

NMR spectroscopic investigation of hydrogen bonding in atrazine

Cited by 42 publications

References 6 publications

Abiotic dealkylation and hydrolysis of atrazine by birnessite

Abiotic dealkylation and hydrolysis of atrazine by birnessite

Sorption of Atrazine by Al- and Ca-Saturated Smectite

Atrazine leaching from biochar-amended soils

Contact Info

Product

Resources

About