权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

LFER Approach to predict the Gibbs free energy of oxoanion Adsorption by the isotype Fe/Al hydroxides goethite and diaspore

LFER 方法预测同型 Fe/Al 氢氧化物针铁矿和水铝石吸附含氧阴离子的吉布斯自由能

基本信息

批准号：
314328699
负责人：
Professor Dr.-Ing. Michael Kersten
金额：
--
依托单位：
Institute of Surface Chemistry
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/314328699?language=en
关键词：
LFER Approach predict Gibbs free

项目摘要

The importance and demand in environmental geochemistry on thermodynamic data for aqueous systems at elevated temperatures has increased over the last decade. This is due to an intense debate on potential groundwater contamination with regard to geothermal power generation, carbon capture and sequestration, hydrofracking, and nuclear waste repositories. Deep aquifer brines recharged within the framework of these geo-engineering activities often contain elevated concentrations of toxic oxyanions such as arsenate and vanadate. However, the factors controlling the mobility of these oxyanions in geothermal waters at depth and with the pipe scales is not fully known. There is concern that they are more mobile at these than at ambient surface conditions, and may thus contaminate the shallower groundwater aquifer systems upon contact. In principle, much is known about water-rock interaction (adsorption, precipitation, etc.) processes governing retardation of the toxic oxyanions at room temperature, but much less about the processes controlling their solid-water partitioning along the temperature gradient. The hypotheses for this proposal are that (i) the adsorption behavior at elevated temperatures for all oxyanions can be predicted by a linear free energy relationship (LFER) between their Gibbs free energy of adsorption and of their aqueous protonation reaction, and that (ii) the entropy term can be predicted on basis of molecular level information on the surface complex structure. The data yet gained in the PIs lab for selenate, arsenite, and silicic acid do not suffice to validate these hypotheses. The purpose of the current work proposal is (1.) to perform experiments on the three binary adsorbate-adsorbent systems bromate-goethite (FeOOH), chromate-goethite and arsenate-goethite at higher temperatures to verify these hypotheses with the most critical data points identified by the LFER, and (2.) to extent by additional experiments the approach to the binary oxyanion-diaspore (AlOOH) system. The latter is even of greater importance with respect to water-rock interaction related to the geo-engineering activities. The aim is to set the LFER and entropy hypotheses on a reliable basis for prediction of standard molar Gibbs free energies of adsorption of all other oxyanions, for which no experimental data are available or difficult to obtain. This aim can be reached only with extensive experimental laboratory work to vary adsorbate/adsorbent ratio, pH value, ionic strength, and even temperature in a 4-D parameter space matrix suitable for the equilibrium thermodynamic modelling of the surface complexation reactions.

在过去的十年中，环境地球化学对高温下水体系热力学数据的重要性和需求有所增加。这是由于关于地热发电、碳捕获和封存、水力压裂和核废料储存库方面潜在的地下水污染的激烈辩论。在这些地球工程活动的框架内重新补给的深层含水层卤水往往含有高浓度的有毒氧离子，如砷酸盐和钒酸盐。然而，控制这些氧阴离子在地热水中深度和管道结垢的流动性的因素并不完全清楚。令人担忧的是，它们在这些条件下比在周围地表条件下更具流动性，因此在接触时可能会污染较浅的地下水含水层系统。原则上，人们对水-岩相互作用(吸附、沉淀等)有很多了解。控制有毒氧阴离子在室温下的延迟的过程，但关于控制其沿温度梯度的固水分配的过程要少得多。提出的假设是：(I)所有含氧阴离子在高温下的吸附行为可以通过它们的吉布斯吸附自由能和它们的水溶液质子化反应自由能之间的线性自由能关系(LFER)来预测；(Ii)可以根据表面络合物结构的分子水平信息来预测熵项。在PIS实验室中获得的亚硒酸盐、亚砷酸盐和硅酸的数据还不足以验证这些假设。当前工作提案的目的是(1)。在较高温度下对溴酸盐-针铁矿(FeOOH)、铬酸盐-针铁矿和砷-针铁矿三种二元吸附-吸附剂体系进行实验，以用LFER确定的最关键数据点验证这些假设，以及(2)通过额外的实验，扩展了对一水硬铝石(AlOOH)二元体系的探讨。后者在与地球工程活动有关的水-岩相互作用方面更为重要。其目的是将LFER和熵假设建立在可靠的基础上，以预测所有其他没有实验数据或难以获得实验数据的其他氧离子的标准摩尔吉布斯自由能。这一目标只有通过广泛的实验室实验工作才能实现，即在适合于表面络合反应的平衡热力学模拟的四维参数空间矩阵中改变吸附/吸附剂比、pH值、离子强度、甚至温度。