Abstract：
The surface charge of calcite in aqueous environments is essential to many industrial and environmental applications. Electrokinetic measurements are usually used to assess the calcite charging behavior and characterize its electrical double layer (EDL). Numerous surface complexation models (SCMs) have been proposed to interpret the effect of different surface interactions on the zeta potential. Because of their versatility, SCMs have also become important tools in reactive transport modeling. The research on enhanced oil recovery within the last decade has led to an increased number of publications reporting both zeta potential measurements and SCMs for calcite. Nonetheless, the measurements are often inconsistent and the reasons for choosing one model over another are unclear. In this work, we review the models proposed for calcite and address their main differences. We first collect a large number of published zeta potential measurements and then we fit a Diffuse Layer, Basic Stern, and Charge-Distribution Multi-Site Complexation models to a selected reliable dataset. For each model, we maintain a similar number of adjustable parameters. After optimizing the parameters of the models, we systematically compare their prediction capabilities against data obtained in monovalent and divalent electrolyte systems containing calcium, magnesium, sulfate, or carbonate. We show that, often, the discrepancies between the models and the experimental data can be explained by different levels of disequilibrium. Nonetheless, assumptions used in the development of the models may significantly reduce their extrapolability to variable chemical conditions. The poor agreement between the models tuned to electrokinetic data with surface charge measurements and dynamic retention from single-phase flowthrough tests show that zeta potential may not be the best type of data to characterize ion binding at the calcite surface. Including the effect of mineral impurities and temperature on the calcite surface speciation and electrokinetic behavior prevail as main challenges for reactive transport modeling.
摘要：
方解石在水性环境中的表面电荷对于许多工业和环境应用是必不可少的。电动测量通常用于评估方解石的充电行为并表征其双电层（EDL）。已经提出了许多表面络合模型（SCM）来解释不同表面相互作用对ζ电位的影响。由于它们的多功能性，SCM也已成为反应性传输建模中的重要工具。在过去十年中，关于提高石油采收率的研究导致越来越多的出版物报道了方解石的zeta电位测量和SCM。尽管如此，测量结果通常不一致，选择一个模型而不是另一个模型的原因尚不清楚。在这项工作中,我们回顾了方解石的模型，并解决了它们的主要差异。我们首先收集大量已发布的zeta电位测量值，然后拟合扩散层，基本斯特恩，和电荷分布多站点复合模型到选定的可靠数据集。对于每个模型，我们保持类似数量的可调参数。优化模型参数后,我们系统地比较了它们的预测能力与在含钙的单价和二价电解质系统中获得的数据，镁，硫酸盐,或碳酸盐。我们证明,经常,模型和实验数据之间的差异可以用不同程度的不平衡来解释。尽管如此，模型开发中使用的假设可能会大大降低其对可变化学条件的外推性。通过表面电荷测量和单相流过测试的动态保留，调整为电动数据的模型之间的一致性较差，这表明zeta电位可能不是表征方解石表面离子结合的最佳数据类型。包括矿物杂质和温度对方解石表面形态和电动行为的影响是反应输运建模的主要挑战。
