热处理调控氧化石墨烯薄膜层间距与离子筛分

Heat treatment regulates the interlayer spacing of the graphene oxide membrane and ion sieving

采用热处理方法,通过改变热处理时间和温度来调控氧化石墨烯(GO)薄膜的层间距,并考察了Cs^(+)、K^(+)、Na^(+)、Li^(+)、Sr^(2+)、Mg^(2+)和Al^(3+)离子在不同层间距的GO薄膜中的渗透性.结果发现:热处理后得到的GO薄膜在湿润状态下的层间距范围为0.57~1.31 nm,当薄膜层间距在0.55 nm左右时,水分子很难在薄膜中输运;此外,在不同层间距的GO薄膜中离子渗透性除了与离子水合直径有关之外,还与离子所带电荷以及离子脱水作用有关.该方法实现了Li^(+)/Mg^(2+)和Na^(+)/Sr^(2+)的分离,为离子的精确筛分、促进如盐湖提锂以及核废液处理等提供了参考.

The heat treatment method was used to control the interlayer spacing of the GO membrane by changing the heat treatment time and temperature,and the permeability of Cs^(+),K^(+),Na^(+),Li^(+),Sr^(2+),Mg^(2+)and Al^(3+)in GO membranes with different interlayer spacing was investigated.The interlayer spacing of the GO membranes obtained after heat treatment in the wet state was 0.57-1.31 nm.When the interlayer spacing was about 0.55 nm,it was difficult for water molecules to transport in the membrane.It was found that the ion permeability of GO membranes with different interlayer spacing was related not only to the hydration diameter of the ions,but also to the charge and the dehydration of the ions.We have achieved the separation of Li^(+)/Mg^(2+)and Na^(+)/Sr^(2+),which provides a reference for precise sieving of ions,promotion of lithium extraction from salt lakes,and nuclear waste liquid treatment.