Hsi H C, Rood M J, Rostam-Abadi M, Chen S, Chang R
Department of Civil and Environmental Engineering, 205 North Mathews Avenue, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Environ Sci Technol. 2001 Jul 1;35(13):2785-91. doi: 10.1021/es001794k.
Laboratory studies were conducted to determine the role of sulfur functional groups and micropore surface area of carbon-based adsorbents on the adsorption of Hg0 from simulated coal combustion flue gases. In this study, raw activated carbon fibers that are microporous (ACF-20) were impregnated with elemental sulfur between 250 and 650 degrees C. The resulting samples were saturated with respect to sulfur content. Total sulfur content of the sulfur impregnated ACF samples decreased with increasing impregnation temperatures from 250 and 500 degrees C and then remained constant to 650 degrees C. Results from sulfur K-edge X-ray absorption near-edge structure (S-XANES) spectroscopy showed that sulfur impregnated on the ACF samples was in both elemental and organic forms. As sulfur impregnation temperature increased, however, the relative amounts of elemental sulfur decreased with a concomitant increase in the amount of organic sulfur. Thermal analyses and mass spectrometry revealed that sulfur functional groups formed at higher impregnation temperatures were more thermally stable. In general, sulfur impregnation decreased surface area and increased equilibrium Hg0 adsorption capacity when compared to the raw ACF sample. The ACF sample treated with sulfur at 400 degrees C had a surface area of only 94 m2/g compared to the raw ACF sample's surface area of 1971 m2/g, but at least 86% of this sample's surface area existed as micropores and it had the largest equilibrium Hg0 adsorption capacities (2211-11,343 micrograms/g). Such a result indicates that 400 degrees C is potentially an optimal sulfur impregnation temperature for this ACF. Sulfur impregnated on the ACF that was treated at 400 degrees C was in both elemental and organic forms. Thermal analyses and CS2 extraction tests suggested that elemental sulfur was the main form of sulfur affecting the Hg0 adsorption capacity. These findings indicate that both the presence of elemental sulfur on the adsorbent and a microporous structure are important properties for improving the performance of carbon-based adsorbents for the removal of Hg0 from coal combustion flue gases.
进行了实验室研究，以确定碳基吸附剂的硫官能团和微孔表面积对模拟煤燃烧烟气中Hg0吸附的作用。在本研究中，将具有微孔结构的原始活性炭纤维（ACF-20）在250至650摄氏度之间用元素硫进行浸渍。所得样品的硫含量达到饱和。硫浸渍ACF样品的总硫含量随着浸渍温度从250升高到500摄氏度而降低，然后在650摄氏度时保持恒定。硫K边X射线吸收近边结构（S-XANES）光谱分析结果表明，浸渍在ACF样品上的硫以元素态和有机态两种形式存在。然而，随着硫浸渍温度的升高，元素硫的相对含量降低，有机硫的含量随之增加。热分析和质谱分析表明，在较高浸渍温度下形成的硫官能团具有更高的热稳定性。一般来说，与原始ACF样品相比，硫浸渍降低了表面积，但提高了Hg0的平衡吸附容量。在400摄氏度下用硫处理的ACF样品的表面积仅为94平方米/克，而原始ACF样品的表面积为1971平方米/克，但该样品至少86%的表面积为微孔，并且具有最大的Hg0平衡吸附容量（2211 - 11343微克/克）。这一结果表明，400摄氏度可能是该ACF的最佳硫浸渍温度。在400摄氏度下处理的ACF上浸渍的硫以元素态和有机态两种形式存在。热分析和CS2萃取试验表明，元素硫是影响Hg0吸附容量的主要硫形态。这些发现表明，吸附剂上元素硫的存在和微孔结构都是提高碳基吸附剂从煤燃烧烟气中去除Hg0性能的重要特性。
