SPECIATION OF ARSENIC AND CHROMIUM IN COAL AND COMBUSTION ASH BY XAFS SPECTROSCOPY
SPECIATION OF ARSENIC AND CHROMIUM IN COAL AND COMBUSTION ASH BY XAFS SPECTROSCOPY
复制标题
DOI：
10.1016/0378-3820(94)90171-6
复制
发表时间：
1994-08-01
影响因子：
7.5
通讯作者：
ZHAO, JM
中科院分区：
文献类型：
--
作者：
HUFFMAN, GP;HUGGINS, FE;ZHAO, JM
虽然有多种方法来确定煤和灰分中微量元素的浓度，但很少有人尝试确定这些元素的种类。 在本文中，它表明，X射线吸收精细结构（XAFS）光谱是能够提供形态的信息，在现实的浓度水平为10-100 ppm，提供了一个固态多元素锗探测器。 最初的研究集中在砷和铬。 砷在煤中主要有两种赋存形式：黄铁矿中的砷和砷酸盐（AsO 4（-3））中的砷（V）。 在一种煤（匹兹堡#8，德克斯-12）中，As以毒砂形式存在。 黄铁矿中的砷在环境条件下容易氧化为砷酸盐形式。 在燃烧灰中，所有的砷都是以砷酸盐的形式存在，至少有两种形式的砷酸盐存在;铝硅酸盐渣和原砷酸钙中的砷是可能的。 煤和灰中的铬主要以Cr+3状态存在（>95%）。 羟基氧化铬是标准化合物，其XAFS光谱最接近于煤中的铬，而灰分中的铬可以掺入铝硅酸盐渣相中。
While there are a variety of methods to determine the concentration of trace elements in coal and ash, there have been few attempts to determine the specication of these elements. In this paper, it is demonstrated that X-ray absorption fine structure (XAFS) spectroscopy is capable of providing speciation information at realistic concentration levels of 10-100 ppm, provided a solid-state multielement germanium detector is used. The initial studies have concentrated on arsenic and chromium. For arsenic, two principal forms of occurrence are observed in coal: As contained in pyrite and As(V) in arsenate (AsO4(-3). In one coal (Pittsburgh #8, DECS-12), the As is present as arsenopyrite. The As in pyrite is readily oxidized under ambient conditions to the arsenate form. In combustion ashes, all arsenic is in the form of arsenate, with at least two forms of arsenate present; As in aluminosilicate slag and calcium orthoarsenate are possibilities. Chromium in coal and in ash is observed to be present predominantly (>95%) in the Cr+3 state. Chromium oxyhydroxide is the standard compound whose XAFS spectrum most closely resembles that of the chromium in coal, while the chromium in ash may be incorporated into the aluminosilicate slag phase.