Sapienza University of Rome, Dept. of Chemical Engineering Materials Environment, Via Eudossiana 18, 00184, Rome, Italy.
Sapienza University of Rome, Dept. of Chemical Engineering Materials Environment, Via Eudossiana 18, 00184, Rome, Italy.
Chemosphere. 2019 Apr;220:590-599. doi: 10.1016/j.chemosphere.2018.12.175. Epub 2018 Dec 26.
The aim of this paper is to show the results obtained by investigating the reduction of hexavalent Chromium [Cr(VI)] by iron nano-particles in aqueous solution, interpreted in light of the particle-grain model. The diffusional and geometric parameters that govern and describe the reacting system were estimated from the evidences deriving from the characterization and the experiments conducted, allowing assumptions based on physical principles. Such procedure rendered the particle-grain model a valid choice for the interpretation of the results obtained. The model, used in its dimensionless form, was tested according to a preliminary procedure aimed at analyzing the sensitivity of the system, by varying within wide ranges the ratio between the reaction rate, the diffusive mass transfer rate, and the particle-grain radius, to show how reliable its potential application may be. Subsequently, a non-linear regression procedure was used to estimate the two main parameters of the model that affect the reduction process: (i) the diffusion coefficient within the solid layer produced along with the reaction, D (6.02 E-13 m s), and (ii) the kinetic constant of the surface reaction, k (0.21 m s). The values found for the parameters were perfectly in line with theoretical considerations and experimental evidences.
本文旨在展示通过在水溶液中用铁纳米颗粒还原六价铬[Cr(VI)]所获得的结果，并用颗粒-晶粒模型对其进行解释。从表征和实验中得出的证据中估算了控制和描述反应系统的扩散和几何参数，这些参数基于物理原理进行了假设。这种方法使得颗粒-晶粒模型成为解释所得结果的有效选择。该模型以无量纲形式进行了测试，根据旨在分析系统灵敏度的初步程序进行了测试，通过在较宽范围内改变反应速率、扩散传质速率和颗粒-晶粒半径之间的比例，以展示其潜在应用的可靠性。随后，使用非线性回归程序来估计影响还原过程的模型的两个主要参数：（i）与反应一起在固体层内的扩散系数，D（6.02×10-13 m s）和（ii）表面反应的动力学常数，k（0.21 m s）。发现的参数值完全符合理论考虑和实验证据。
