| Summary: | 碩士 === 國立中興大學 === 土壤環境科學系所 === 96 === Pyrogenic carbon particles such as carbon black, soot and charcoal et al., collectively termed black carbon (BC), have been reported to exhibit an extremely strong sorption of organic compounds in the environment. The sorption process dominated the fate and transport of organic contaminants in the soil and sediment environments. This study aims to analyse the characterization of black carbon and study the sorption behaviors and sorption mechanisms of several organic compounds in these black carbons in an aqueous phase. The results demonstrate that produced process and starting material are potential factors that can explain the sorptive variability of black carbons. Sorption kinetics of organic contaminants into black carbons revealed that around several hours were enough to reach sorption equilibrium.
Sorption isotherms of organic compounds can be described by sorion models including linear equation, Freundlich equation, and Langmuir equation. The results showed that use Freundlich equation can describe the sorption of organic compounds on black carbon form aqueous solutions well. The surface properties of black carbons controlled by their production conditions and depend on their starting material. Because of the surface area of BC1 is more than BC3 and BC4, the sorption coefficients of aromatic compounds without functional groups on BC1 were larger than those on BC3 and BC4. Sorption behaviors of black carbons were affected by functional groups, so sorption capacity of aromatic compounds with functional groups on BC4 is more than BC3 due to more functional groups observed on BC 3. The surface properties of these pyrogenic carbon particles such as surface area and functional groups affected the sorption behaviors of these compounds.
The sorption coefficients of organic compounds including polar and non-polar chemicals on black carbons have been obtained via a reversed-phase liquid chromatography (RP-LC) method. Because of the surface area of BC1 is more than the other black carbons, the sorption coefficients of organic chemicals on BC1 were larger than those on the other four black carbons. The effect of sorption behaviors on black carbons also depended suface functional groups, so sorption of aromatic compounds with functional groups on BC3 is larger than that of BC4. Five black carbons have mostly non-polar surface, the observed sorption coefficients of organic compounds on black carbons increased with their octanol-water partition coefficient values (Kow). The results obtained that sorption coefficients of chloroethylenes and chlorophenols on the black carbons became larger with more chloro atoms on the molecular structures of chloroethylenes and chlorophenols and larger with more carbon atoms on the benzene compounds.
By the regression of the sorption coefficients of organic compounds on these black carbons with the properties of organic compounds, several linear solvation energy relationship (LSER) equations were built. The analysis of the interactions based on these LSERs indicated that the London dispersion force and interaction through π- and n- elactrons were the major adsorption interaction in the sorption process on black carbons. The effects of the dipolarity / polarisability, the hydrogen bond acidity, and the hydrogen bond basicity were less. For selected organic chemicals, some specific interactions occur during the sorption process. Several LSERs equations were developed to facilitate the prediction of different organic chemicals on black carbons. The better understanding of the sorption behaviors of organic chemicals into pyrogenic carbon particles can facilitate the fate transport and risk assessment processes of contaminants in the environment.
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