Characterization of 15N-TNT Residues After an Anaerobic/Aerobic Treatment of Soil/Molasses Mixtures by Solid-State 15N NMR Spectroscopy. 1. Determination and Optimization of Rele

详细信息    查看全文

• 作者：Heike Knicker ; Dirk Bruns-Nagel ; Oliver Drzyzga ; Eberhard von Lö ; w ; and Klaus Steinbach
• 刊名：Environmental Science & Technology
• 出版年：1999
• 出版时间：January 15, 1999
• 年：1999
• 卷：33
• 期：2
• 页码：343 - 349
• 全文大小：76K
• 年卷期：v.33,no.2(January 15, 1999)
• ISSN：1520-5851

文摘

Solid-state ¹⁵N NMR was applied to a humic acid,extracted from ¹⁵N-2,4,6-trinitrotoluene (TNT) enriched soiltreated in an anaerobic/aerobic composting system tocharacterize the nitrogen functionality of the transformationproducts bound to the soil organic material. Signalsassignable to aniline derivatives and condensation productswere identified, indicating that the anaerobic/aerobictreatment caused a reduction of nitro groups followed bycondensation reactions with the soil organic material.Relevant parameters for routine application of the crosspolarization magic angle spinning technique were determinedand optimized. The proton spin-lattice relaxation times ofall peaks in the ¹⁵N NMR spectrum of the humic acid did notexceed 30 ms. Due to the fast relaxation, the applicationof ¹⁵N NMR spectroscopy to soils with lower enrichment of¹⁵N-TNT is feasible. The influence of spinning sidebandson the intensity distribution was shown to be minimal atspinning speeds between 5.5 and 6.5 kHz. Contact timesbetween 0.7 and 1 ms resulted in spectra with representativeintensity distribution of all visible ¹⁵N-TNT transformationproducts. However an underestimation of unreacted TNTmust be considered. The results imply that CPMAS ¹⁵N NMRis a valuable tool for the examination of bound residuesof TNT in soils. (Figure 1).