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Assessment of Modeling Uncertainties Using a Multistart Optimization Tool for Surface Complexation Equilibrium Parameters (MUSE)
ACS Earth and Space Chemistry ( IF 2.9 ) Pub Date : 2018-12-27 00:00:00 , DOI: 10.1021/acsearthspacechem.8b00125
Nefeli Maria Bompoti 1 , Maria Chrysochoou 1 , Michael L. Machesky 2
Affiliation  

The MUlti-start optimization algorithm for Surface complexation Equilibrium (MUSE) algorithm has been developed to optimize the fitting of thermodynamic constants for surface complexation modeling (SCM). Although there is a plethora of software to perform data fitting and determine intrinsic equilibrium constants, the algorithms used are highly dependent on initial values and choice of parameters. This limits their transferability to model other systems, for example, reactive transport processes. With this in mind, a hybridized optimization approach, based on a multistart algorithm combined with a local optimizer, has been developed to allow the simultaneous optimization of SCM parameters and to assess the sensitivity of these parameters to changes in the model assumptions. In this study, the CD–MUSIC formalism with a Basic Stern electrostatic model is utilized to model chromate adsorption on ferrihydrite, although the MUSE algorithm can be applied to any adsorption data set and be implemented in any model formulation. This study offers two innovative components to the inverse SCM modeling approach: (a) determination of the true global optimum by performing multiple minimizations of the mean squared error between the simulated and observed data using a large number of initial starting points and (b) quantitative simulation of spectroscopic pH-dependent profiles for two chromate surface complexes. We demonstrate that when MUSE is implemented to determine chromate log Ks, their dependence on other adjustable parameters such as specific surface area (SSA) and capacitance is relatively small (i.e., less than one unit difference for chromate log Ks on ferrihydrite) and can be accounted by mathematical functions determined through the MUSE algorithm. The robustness of the algorithm is demonstrated in the absence of the spectroscopy data as well, with traditional batch tests yielding similar thermodynamic constants as the spectroscopic profiles.

中文翻译:

使用针对表面络合平衡参数(MUSE)的Multistart优化工具评估建模不确定性

已经开发了用于表面络合平衡的MUlti-start优化算法(MUSE)算法,以优化用于表面络合建模(SCM)的热力学常数的拟合。尽管有很多软件可以执行数据拟合和确定固有平衡常数,但所使用的算法高度依赖于初始值和参数的选择。这限制了它们的可移植性以建模其他系统,例如反应性运输过程。考虑到这一点,已经开发了一种基于多启动算法和局部优化器的混合优化方法,可以同时优化SCM参数并评估这些参数对模型假设变化的敏感性。在这项研究中,尽管MUSE算法可以应用于任何吸附数据集并可以在任何模型公式中实现,但具有Basic Stern静电模型的CD-MUSIC形式主义可用于模拟铬酸盐在三水铁矿上的吸附。这项研究为逆SCM建模方法提供了两个创新组成部分:(a)通过使用大量初始起点对模拟数据和观测数据之间的均方误差进行多次最小化来确定真实的全局最优值;以及(b)定量的两个铬酸盐表面配合物的pH依赖性光谱的模拟。我们证明了当实施MUSE来确定铬酸盐对数时 尽管MUSE算法可以应用于任何吸附数据集,并可以在任何模型公式中实现。这项研究为逆SCM建模方法提供了两个创新组成部分:(a)通过使用大量初始起点对模拟数据和观测数据之间的均方误差进行多次最小化来确定真实的全局最优值;以及(b)定量的两个铬酸盐表面配合物的pH依赖性光谱的模拟。我们证明了当实施MUSE来确定铬酸盐对数时 尽管MUSE算法可以应用于任何吸附数据集,并可以在任何模型公式中实现。这项研究为逆SCM建模方法提供了两个创新组成部分:(a)通过使用大量初始起点对模拟数据和观测数据之间的均方误差进行多次最小化来确定真实的全局最优值;以及(b)定量的两个铬酸盐表面配合物的pH依赖性光谱的模拟。我们证明了当实施MUSE来确定铬酸盐对数时 (a)使用大量初始起点,通过对模拟数据和观测数据之间的均方误差进行多次最小化,确定真正的全局最优;以及(b)对两种铬酸盐表面配合物的pH依赖性光谱进行定量模拟。我们证明了当实施MUSE以确定铬酸盐对数时 (a)使用大量初始起点,通过对模拟数据和观测数据之间的均方误差进行多次最小化,确定真正的全局最优;以及(b)对两种铬酸盐表面配合物的pH依赖性光谱进行定量模拟。我们证明了当实施MUSE来确定铬酸盐对数时K s对其他可调参数(例如比表面积(SSA)和电容)的依赖性相对较小(即,对于三水铁矿上的铬酸盐log K s小于一个单位差),并且可以通过MUSE算法确定的数学函数来解释。该算法的鲁棒性在没有光谱数据的情况下也得到了证明,传统的批处理测试产生的热力学常数与光谱图相似。
更新日期:2018-12-27
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