Impact of De-Ashing Humic Acid and Humin on Organic Matter Structural Properties and Sorption Mechanisms of Phenanthrene

Organic matter−mineral interactions greatly affect the fate of hydrophobic organic compounds (HOCs) in the environment. In the present study, the impact of organic matter−mineral interaction on sorption of phenanthrene (PHE) by the original and de-ashed humic acids (HAs) and humin (HM) was examined....

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Bibliographic Details
Published in:	Environmental science & technology 2011-05, Vol.45 (9), p.3996-4002
Main Authors:	Yang, Yu, Shu, Liang, Wang, Xilong, Xing, Baoshan, Tao, Shu
Format:	Article
Language:	eng
Subjects:	Adsorption Applied sciences Biological and physicochemical properties of pollutants. Interaction in the soil Correlation analysis Differential scanning calorimetry Earth sciences Earth, ocean, space Engineering and environment geology. Geothermics Environmental Processes Exact sciences and technology Humic Substances - analysis Minerals - chemistry NMR Nuclear magnetic resonance Phenanthrenes - chemistry Pollution Pollution, environment geology Polycyclic aromatic hydrocarbons Soil - chemistry Soil and sediments pollution Sorbents Sorption
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Summary:	Organic matter−mineral interactions greatly affect the fate of hydrophobic organic compounds (HOCs) in the environment. In the present study, the impact of organic matter−mineral interaction on sorption of phenanthrene (PHE) by the original and de-ashed humic acids (HAs) and humin (HM) was examined. After de-ashing treatment, the overall polarity of organic matter in HAs and HM consistently decreased. Differently, the surface polarity of HAs increased but that of HM decreased. No correlation between K oc values of PHE by all tested sorbents and their bulk polarity was observed due to inaccessibility of a portion of interior sorption domains. The inaccessibility of interior sorption domains in HAs and HM was partly due to the crystalline structure in organic matter as indicated by differential scanning calorimetric (DSC) and 13C NMR data and the interference from minerals. A good correlation between surface polarity of the original and de-ashed HAs and HMs and their K oc values for PHE indicated its importance in HOC sorption. Dissimilar changes in surface polarity of HAs and HM after de-ashing treatment can be ascribed to the distinct interactions between organic matter and minerals. The solid-state 13C NMR, XPS, and elemental composition data of all tested sorbents revealed that a larger fraction of O atoms in HAs were involved in organic matter−mineral interaction as compared to HM. Results of this work highlight the importance of soil organic matter (SOM)-mineral interactions, surface polarity, and microscaled domain arrangement of SOM in HOC sorption.
ISSN:	0013-936X 1520-5851