Liu Yilin, Su Jincai, Duan Fei, Cui Xin, Yan Weichao, Jin Liwen
School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, No. 28 Xianning West Road, Xi'an, 710049, China.
School of Life Sciences & Chemical Technology, Ngee Ann Polytechnic, 535 Clementi Road, 599489, Singapore.
Phys Chem Chem Phys. 2022 Jul 13;24(27):16442-16452. doi: 10.1039/d2cp01411d.
Hydrophilic nanocomposite membranes have significant advantages in the separation of water vapor which is the core process in air dehumidification. This paper focuses on exploring the micro-mechanism of enhanced separation using graphene oxide-polyvinyl alcohol (GO-PVA) nanocomposite membranes. The sorption and diffusion behaviors of water vapor and nitrogen in GO-PVA membranes were investigated using molecular dynamics (MD) and Monte Carlo (MC) methods. The study showed that embedding GO into a PVA matrix results in a higher glass transition temperature and fractional free volume. The latter is believed to enhance the diffusivity of gas molecules in polymeric membranes. The interaction between the polymer chains and GO nanoparticles notably promotes the adsorption capacity of water vapor and inhibits nitrogen adsorption in the membrane. A water vapor permeance of 8844.07 Barrer and a separation factor of 3.53 could be achieved with the GO-PVA-0.5 membrane. The analysis confirmed that GO has the same effect on single gas and binary gas mixtures, , increasing the water vapor permeability and selectivity. The calculated water vapor permeance of binary gas is 83% lower than that of single gas permeation. It is expected that this research could provide fundamentals for the optimization and synthesis of gas separation membranes.
亲水性纳米复合膜在水蒸气分离方面具有显著优势，而水蒸气分离是空气除湿的核心过程。本文重点探索氧化石墨烯-聚乙烯醇（GO-PVA）纳米复合膜增强分离的微观机制。采用分子动力学（MD）和蒙特卡罗（MC）方法研究了水蒸气和氮气在GO-PVA膜中的吸附和扩散行为。研究表明，将GO嵌入PVA基体中会导致更高的玻璃化转变温度和自由体积分数。后者被认为可增强气体分子在聚合物膜中的扩散率。聚合物链与GO纳米颗粒之间的相互作用显著提高了水蒸气的吸附能力，并抑制了膜中氮气的吸附。GO-PVA-0.5膜的水蒸气渗透率可达8844.07 Barrer，分离因子为3.53。分析证实，GO对单一气体和二元气体混合物具有相同的作用，即提高水蒸气渗透率和选择性。计算得到的二元气体水蒸气渗透率比单一气体渗透时低83%。预计该研究可为气体分离膜的优化和合成提供基础。
