MINERALOGY AND SURFACE-PROPERTIES OF MUNICIPAL SOLID-WASTE ASH

被引:188
作者
KIRBY, CS
RIMSTIDT, JD
机构
[1] Department of Geology, Virginia Polytechnic Institute, State University, Blacksburg, Virginia 24061-0420
关键词
D O I
10.1021/es00041a008
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
Bulk chemical analysis shows most elements enriched over average soil abundances except for Si, which is 60% of the concentration in soils. Eleven minerals were identified using powder X-ray diffraction (XRD). Standard additions using XRD gave the following weight percent of minerals (+/-2sigma) in combined bottom and fly ash: gypsum, 1.8 +/- 1.9; hematite, 3.7 +/- 1.7; quartz, 2.3 +/- 1.0; spinel, approximately 3.5; halite, 0.5 +/- 0.4; calcite 3.5 +/- 1.9; rutile, 1.1 +/- 1.3. Mullite, sylvite, anhydrite, and wustite were also identified. The ash contains 18% minerals. 9% structural and adsorbed water, and 72% glass. An estimated composite glass composition is reported. Chemical sequential extraction showed that most Cr is present in phases resistant to chemical weathering, while significant Cd and Pb are sequestered in acid-soluble (carbonate) phases. Little of these toxic trace metals are water soluble or in exchangeable surface sites. The ash has a pH-dependent cation exchange capacity of 25-55 mequiv/100 g, suggesting surface sites are available to sequester metals.
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页码:652 / 660
页数:9
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