老化过程中铜形态变化的X射线吸收精细结构谱的(XAFS)初步研究

利用X射线吸收精细结构谱(XAFS)对老化过程中土壤中铜的分子形态进行初步表征。以硫酸铜、氧化铜和硫化铜的X射线吸收扩展边结构(EXAFS)谱为参比,对土壤样品中Cu的EXAFS谱进行拟合,得到不同老化阶段与参比物质相对应的结合态Cu的百分含量,并与连续提取法表征进行比较。XAFS分析结果表明,老化阶段土壤样品中铜的主要结合形态是CuSO_4,同时还有部分CuS,基本不含有CuO。随着时间的推移,土壤中CuSO_4百分含量呈现出下降的趋势,CuS百分含量呈现出上升的趋势。这与连续提取法研究结果中其可交换态的百分比下降,残渣态上升的趋势相似。

Study on the Cu Speciation in Soil during the Aging Process with XAFS

The speciation of copper in soil during the aging process was studied by x-ray absorption fine structure (XAFS) spectroscopy. Theoretical fitting of the EXAFS spectra from the soil was done using the extended x-ray absorption edge structure (EXAFS) spectra of copper sulfate, copper oxide and copper sulfide as references. Then, the concentrations of the copper during the aging process were obtained and compared with the date obtained from the sequential extraction methods. The results proposed that the copper in the soil existed as CuSO₄ and CuS, with CuSO₄ predominating. No CuO was found in the soil. During the aging process, the content of CuSO₄ in soil increased gradually, while that of CuS decreased. The result is in agreement with the conclusion that obtained from the sequential extraction analysis.