Intercorrelations among Degree of Geochemical Alterations, Physicochemical Properties, and Organic Sorption Equilibria of Kerogen
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- 作者：Chen Yang ; Weilin Huang ; Baohua Xiao ; Zhiqiang Yu ; Ping'an Peng ; Jiamo Fu ; and Guoying Sheng
- 刊名：Environmental Science & Technology
- 出版年：2004
- 出版时间：August 15, 2004
- 年：2004
- 卷：38
- 期：16
- 页码：4396 - 4408
- 全文大小：649K
- 年卷期：v.38,no.16(August 15, 2004)
- ISSN：1520-5851
文摘
Recent studies reported that kerogen is an importantnatural organic material dominating sorption of relativelyhydrophobic organic contaminants (HOCs) by topsoils andriver sediments collected from industrialized regions.Due to its chemical and structural heterogeneity, kerogenis expected to exhibit a spectrum of sorptive phenomenafor HOCs. The goal of this study is to establish correlationsbetween heterogeneous physicochemical properties ofkerogen and its sorptive characteristics for HOCs. In thisstudy, we simulated diagenetic alterations under laboratoryconditions by thermally treating a low-grade lignite at200, 250, 300, 350, 400, 450, and 500 
C, yielding a seriesof type III kerogen samples having the same parental materialbut different maturations and physicochemical properties.The treated samples and the original lignite weresystematically characterized using different methods andwere used as the sorbents for sorption equilibrium study. Theresults of characterization revealed that black carbon orchar was formed at 450 C or above and that, as the treatmenttemperature (T) increases, both O/C and H/C atomicratios decrease whereas aromaticity and reflectance indexincrease. The sorption and desorption isotherms measuredfor 1,3,5-trichlorobenzene and phenanthrene are nonlinearand hysteretic. The nonlinearity and apparent desorptionhysteresis increase as a function of T and correlate well withrigidity and aromaticity of the organic matrix. The sorptioncapacity for each sorbate increases initially as Tincreases, reaches a maximum at 300-350 C, and thendecreases rapidly as T increases beyond 350 C. This studysuggests that the highly heterogeneous kerogen-basedcoal materials may have varied elemental compositions,functionalities, and matrix rigidity and that they could playmajor roles in the isotherm nonlinearity and the apparentsorption-desorption hysteresis exhibited by soils andsediments.
C, yielding a seriesof type III kerogen samples having the same parental materialbut different maturations and physicochemical properties.The treated samples and the original lignite weresystematically characterized using different methods andwere used as the sorbents for sorption equilibrium study. Theresults of characterization revealed that black carbon orchar was formed at 450 C or above and that, as the treatmenttemperature (T) increases, both O/C and H/C atomicratios decrease whereas aromaticity and reflectance indexincrease. The sorption and desorption isotherms measuredfor 1,3,5-trichlorobenzene and phenanthrene are nonlinearand hysteretic. The nonlinearity and apparent desorptionhysteresis increase as a function of T and correlate well withrigidity and aromaticity of the organic matrix. The sorptioncapacity for each sorbate increases initially as Tincreases, reaches a maximum at 300-350 C, and thendecreases rapidly as T increases beyond 350 C. This studysuggests that the highly heterogeneous kerogen-basedcoal materials may have varied elemental compositions,functionalities, and matrix rigidity and that they could playmajor roles in the isotherm nonlinearity and the apparentsorption-desorption hysteresis exhibited by soils andsediments.