Compositions and Sorptive Properties of Crop Residue-Derived Chars
详细信息 查看全文
- 作者：Yuan Chun ; Guangyao Sheng ; Cary T. Chiou ; and Baoshan Xing
- 刊名：Environmental Science & Technology
- 出版年：2004
- 出版时间：September 1, 2004
- 年：2004
- 卷：38
- 期：17
- 页码：4649 - 4655
- 全文大小：104K
- 年卷期：v.38,no.17(September 1, 2004)
- ISSN：1520-5851
文摘
Chars originating from the burning or pyrolysis of vegetationmay significantly sorb neutral organic contaminants(NOCs). To evaluate the relationship between the charcomposition and NOC sorption, a series of char sampleswere generated by pyrolyzing a wheat residue (Triticumaestivum L.) for 6 h at temperatures between 300 
C and700 C and analyzed for their elemental compositions, surfaceareas, and surface functional groups. The samples werethen studied for their abilities to sorb benzene andnitrobenzene from water. A commercial activated carbonwas used as a reference carbonaceous sample. The charsamples produced at high pyrolytic temperatures (500-700 C) were well carbonized and exhibited a relatively highsurface area (>300 m2/g), little organic matter (<3%),and low oxygen content (
10%). By contrast, the charsformed at low temperatures (300-400 C) were only partiallycarbonized, showing significantly different properties(<200 m2/g surface area, 40-50% organic carbon, and>20% oxygen). The char samples exhibited a significantrange of surface acidity/basicity because of their differentsurface polar-group contents, as characterized by theBoehm titration data and the NMR and FTIR spectra. TheNOC sorption by high-temperature chars occurredalmost exclusively by surface adsorption on carbonizedsurfaces, whereas the sorption by low-temperature charsresulted from the surface adsorption and the concurrentsmaller partition into the residual organic-matter phase. Thechars appeared to have a higher surface affinity for apolar solute (nitrobenzene) than for a nonpolar solute(benzene), the difference being related to the surface acidity/basicity of the char samples.
C and700 C and analyzed for their elemental compositions, surfaceareas, and surface functional groups. The samples werethen studied for their abilities to sorb benzene andnitrobenzene from water. A commercial activated carbonwas used as a reference carbonaceous sample. The charsamples produced at high pyrolytic temperatures (500-700 C) were well carbonized and exhibited a relatively highsurface area (>300 m2/g), little organic matter (<3%),and low oxygen content (10%). By contrast, the charsformed at low temperatures (300-400 C) were only partiallycarbonized, showing significantly different properties(<200 m2/g surface area, 40-50% organic carbon, and>20% oxygen). The char samples exhibited a significantrange of surface acidity/basicity because of their differentsurface polar-group contents, as characterized by theBoehm titration data and the NMR and FTIR spectra. TheNOC sorption by high-temperature chars occurredalmost exclusively by surface adsorption on carbonizedsurfaces, whereas the sorption by low-temperature charsresulted from the surface adsorption and the concurrentsmaller partition into the residual organic-matter phase. Thechars appeared to have a higher surface affinity for apolar solute (nitrobenzene) than for a nonpolar solute(benzene), the difference being related to the surface acidity/basicity of the char samples.