Management of groundwater resources and remediation of groundwater pollution require reliable quantification of contaminant dynamics in natural aquifers, which can involve complex chemical dynamics and challenge tradi...Management of groundwater resources and remediation of groundwater pollution require reliable quantification of contaminant dynamics in natural aquifers, which can involve complex chemical dynamics and challenge traditional modeling approaches. The kinetics of chemical reactions in groundwater are well known to be controlled by medium heterogeneity and reactant mixing, motivating the development of particle-based Lagrangian approaches. Previous Lagrangian solvers have been limited to fundamental bimolecular reactions in typically one-dimensional porous media. In contrast to other existing studies, this study developed a fully Lagrangian framework, which was used to simulate diffusion-controlled, multi-step reactions in one-, two-, and three-dimensional porous media. The interaction radius of a reactant molecule, which controls the probability of reaction, was derived by the agent-based approach for both irreversible and reversible reactions. A flexible particle tracking scheme was then developed to build trajectories for particles undergoing mixing-limited, multi-step reactions. The simulated particle dynamics were checked against the kinetics for diffusion-controlled reactions and thermodynamic wellmixed reactions in one-and two-dimensional domains. Applicability of the novel simulator was further tested by(1) simulating precipitation of calcium carbonate minerals in a two-dimensional medium, and(2) quantifying multi-step chemical reactions observed in the laboratory. The flexibility of the Lagrangian simulator allows further refinement to capture complex transport affecting chemical mixing and hence reactions.展开更多
A multi-step reaction route was developed to synthesize boron nitride（BN） nanoparticles via the reactionbetween NaN3 and BC13 in a benzene-thermal solution. By means of this route, the crystallinity of BN nanopartic...A multi-step reaction route was developed to synthesize boron nitride（BN） nanoparticles via the reactionbetween NaN3 and BC13 in a benzene-thermal solution. By means of this route, the crystallinity of BN nanoparticleswas improved via increasing the reaction steps. Meanwhile, a phase transformation from hexagonal BN（hBN） or tur-bostratic BN（tBN） to cubic BN（cBN） occurred, resulting in the increase of cBN content. Moreover, the content ofcBN also slightly increased when the temperature was elevated from 265 ℃ to 280 ℃.展开更多
基金supported by the National Natural Science Foundation of China(Grants No.41330632,41628202,and 11572112)
文摘Management of groundwater resources and remediation of groundwater pollution require reliable quantification of contaminant dynamics in natural aquifers, which can involve complex chemical dynamics and challenge traditional modeling approaches. The kinetics of chemical reactions in groundwater are well known to be controlled by medium heterogeneity and reactant mixing, motivating the development of particle-based Lagrangian approaches. Previous Lagrangian solvers have been limited to fundamental bimolecular reactions in typically one-dimensional porous media. In contrast to other existing studies, this study developed a fully Lagrangian framework, which was used to simulate diffusion-controlled, multi-step reactions in one-, two-, and three-dimensional porous media. The interaction radius of a reactant molecule, which controls the probability of reaction, was derived by the agent-based approach for both irreversible and reversible reactions. A flexible particle tracking scheme was then developed to build trajectories for particles undergoing mixing-limited, multi-step reactions. The simulated particle dynamics were checked against the kinetics for diffusion-controlled reactions and thermodynamic wellmixed reactions in one-and two-dimensional domains. Applicability of the novel simulator was further tested by(1) simulating precipitation of calcium carbonate minerals in a two-dimensional medium, and(2) quantifying multi-step chemical reactions observed in the laboratory. The flexibility of the Lagrangian simulator allows further refinement to capture complex transport affecting chemical mixing and hence reactions.
基金Supported by the National Natural Science Foundation of China(Nos.21073107,51102151 and 50990061)the Natural Science Foundation of Shandong Province,China(No.2R2011EMQ002)+1 种基金the Independent Innovation Foundation(No.2010TS039)the Postdoctoral Foundation of Shandong University,China
文摘A multi-step reaction route was developed to synthesize boron nitride（BN） nanoparticles via the reactionbetween NaN3 and BC13 in a benzene-thermal solution. By means of this route, the crystallinity of BN nanoparticleswas improved via increasing the reaction steps. Meanwhile, a phase transformation from hexagonal BN（hBN） or tur-bostratic BN（tBN） to cubic BN（cBN） occurred, resulting in the increase of cBN content. Moreover, the content ofcBN also slightly increased when the temperature was elevated from 265 ℃ to 280 ℃.
