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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >ATR-FTIR studies on the adsorption/desorption kinetics of dimethylarsinic acid on iron-(Oxyhydr)oxides
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ATR-FTIR studies on the adsorption/desorption kinetics of dimethylarsinic acid on iron-(Oxyhydr)oxides

机译：ATR-FTIR研究二甲基ar酸在氧化铁（羟基）上的吸附/解吸动力学

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摘要

Dimethylarsinic acid (DMA) is an organoarsenical compound that, along with monomethylarsonic acid, poses a health and an environmental risk, and a challenge to the energy industry. Little is known about the surface chemistry of DMA at the molecular level with materials relevant to geochemical environments and industrial sectors. We report herein the first in situ and surface-sensitive rapid kinetic studies on the adsorption and desorption of DMA to/from hematite and goethite at pH 7 and I = 0.01 M KCl using ATR-FTIR. Values for the apparent rates of adsorption and desorption were extracted from experimental data as a function of spectral components, flow rate of the aqueous phase, film thickness of hematite, and using chloride and hydrogen phosphate as desorbing agents. The adsorption kinetic data show fast and slow rates, consistent with the formation of more than one type of adsorbed DMA. Apparent adsorption and desorption rate constants were extracted from the dependency of the initial adsorption rates on [DMA(aq)]. Desorption rate constants were also extracted from desorption experiments using hydrogen phosphate and chloride solutions, and were found to be higher by 1-2 orders of magnitude than those using chloride. In light of the complex ligand exchange reaction mechanism of DMA desorption by phosphate species at pH 7, apparent desorption rate constants were found to depend on [hydrogen phosphate] with an order of 0.3. The impact of our studies on the environmental fate of DMA in geochemical environments, and the design of technologies to reduce arsenic content in fuels is discussed.
机译：二甲基砷酸（DMA）是一种有机砷化合物，与单甲基砷酸一起构成健康和环境风险，对能源行业构成挑战。 DMA在分子水平上与地球化学环境和工业相关的材料的表面化学知之甚少。我们在此报告了使用ATR-FTIR对DMA在赤铁矿和针铁矿中pH值为7且I = 0.01 M KCl的DMA吸附和脱附的第一个原位和表面敏感性快速动力学研究。根据光谱成分，水相的流速，赤铁矿的膜厚以及使用氯化物和磷酸氢盐作为解吸剂，从实验数据中提取表观吸附和解吸速率的值。吸附动力学数据显示出快和慢的速率，与形成一种以上的吸附DMA一致。从初始吸附速率对[DMA（aq）]的依赖性中提取表观吸附和解吸速率常数。还从使用磷酸氢盐和氯化物溶液的解吸实验中提取了解吸速率常数，发现其比使用氯化物的解吸速率常数高1-2个数量级。根据pH值为7的磷酸盐物质解吸DMA的复杂配体交换反应机理，发现表观解吸速率常数取决于[磷酸氢]，为0.3量级。讨论了我们的研究对DMA在地球化学环境中的环境命运的影响，并讨论了降低燃料中砷含量的技术设计。

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