Molecular simulation of layered GO membranes with amorphous structure for heavy metal ions separation

• Published in: Journal of membrane science 2022-10, Vol.660, p.120863, Article 120863
• Main Authors: Chen, Yankai, Yang, Xiaoning
• Format: Article
• Language: English
• Subjects: Amorphous structure; Graphene oxide; Heavy metal ions; Membrane separation; Molecular simulation
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2022.120863

Currently, layered graphene oxide (GO) membranes have gained considerable attention due to their high separation efficiency in water treatment. However, a molecular-level separation mechanism remains elusive due to the complex irregular stacking feature of GO nanoscale flakes in actual GO membranes. Most existing molecular simulation studies using idealized GO membrane models might largely ignore the membrane structural heterogeneity. In this work, a molecular simulation protocol was applied to construct a non-idealized amorphous GO membrane model, and its structural morphology and property fit well with the realistic GO membranes. For the first time, the actual structure-oriented GO membrane model was used to study the separation behavior of heavy metal ions from aqueous solutions. The effects of the stacking structures and morphologies for the amorphous membranes on the water permeation and ion rejection were investigated. The constituent GO flakes with varied sheet sizes and oxidization degrees were considered. Our simulations demonstrate that the GO-based amorphous membranes with different-sized GO sheets can exhibit distinct ion rejection mechanisms and water penetration behavior. This finding has not been observed in previous idealized membrane models. Our simulation study provides novel insight into the separation mechanisms and improves the microscopic understanding of layered GO membranes. [Display omitted] •Layered GO membrane models with amorphous structure were constructed by molecular simulation procedure.•The realistic-oriented membrane models were firstly used to simulate the separation of heavy metal ions.•The simulated structures and properties of GO amorphous membranes agree well with experimental data.•A new separation mechanism for the amorphous GO membranes has been presented.