Structural Characteristics Of Humic From Different Use Types Of Huang Nitu And Adsorption Of PAHs (Pyrene)

Soil organic matter (SOM) was always a research focus in the soil science and environmental significane. Humic matter was the most important fractions among the SOM, which varied considerably in different soils, and ranged from 60%⁸0%. The Humic was a kind of proper organic matter. In rencent years, soil organic contaminations have attracted increasing attention in the environment. Especially, polycyclic aromatic hydrocarbons (PAHs) are currently of great concern due to their potential carcinogenicity. Lots of studies have been putting up to understand the reciprocity between the soil and contamination. At present, observers have come to the conclusion that SOM play a key role during the adsorption of soil to the organic contaminants. The sorption and desorption of these compounds in soils are primarily regulated by SOM. Therefore, knowledge of sorption behavior by SOM is important for the removal of organic chemicals from soils.The overall objective of this research was to analyse chemical structural constitution characterize of humic matter extracted from three different use types (mulberry field (sy ), metasequoia field (ss ), paddy field (st)) of Huangnitu soils, and humic was grouped fulvic acids (FA), humic acids (HA) and humin acids (HM. In order to elucidate the binding mechanisms of humic to hydrophobic organic compounds. The fractionation and spectroscopic analysis were applied to study the structural characteristics of different humic. On the other hand , pyrene was selected as representative PAHs and equilibrium sorption experiments were carried out to investigate the sorption properties of pyrene with HA, FA and HM. The relationship between the partition coefficient and the structural characteristicswas analyzed to find out the main functional groups affecting the binding capacity in humic. The following were the main results:The results from soils basic physical-chemical properties of analysis showed that different use types had small influences to the mechanical composition and pH of soils , but the soil organic carbon(SOC) and total nitrous (T_N) were varied obviously, and there was the highest CEC in the ss soil. The content of carbon in the HA and FA were sy>st>ss, but in the HM was sy>ss>st. In the same soil, the content of carbon was HM>HA>FA. The ratio of HA/FA was sy>st>ss. E₄/E₆ was sy>ss>st.The fractions of humic from different use types have been studied by elemental composition, FTIR and 1H-NMR, CP/MAS-13C-NMR analysis to provide detailed chemical characterization of the HA. FA and HM. The results indicated that the elemental composition and functional groups in the HA, FA and HM were similar, but the carboxylic groups have great transformation. The content of aromatic carbon in HA: st>ss>sy. The content of carboxyl in FA: sy>ss>st. HA showed higher aromatic character and large-chain alkyl carbons in its structure. FA was characterized by large amount of carboxylic function group. The aliphalic structure were HA>FA. HM contained some aliphalic structure, and owned lots of phenolic hydroxyl in comparison with HA and FA.The adsorption of pyrene by Has, FAs and HMs extracted from three different use types of hunangnitu soils were determined by using high performance lique chromatography (HPLC, Waters 2690)method. The relationship between the partition coefficient (Koc) and the structural characteristics was analyzed to find out the binding mechamiams. The results showed that soils and HMs exhibited closely to linearity sorption isotherms, which were due to partitioning mechanism. What is more, they were both fit for the linear and Freundilich model, but HA and FA exhibited high nonlinearity, the former was fit for the Freundlich model. Langumuir model was not fit to any organic fractions. HM had the highest LogKoc value than HA and FA, which conjectured the soil organic carbon content was an important factor in the binding.To summarize, aromatic carbon and aliphalic structure might play an important role in binding of pyrene in HAs. The high content of carboxylic groups or carbohydrates o...