▎ 摘　　要

In this paper, we found that the presence of sodium chloride (NaCl) can effectively inhibit the diffusion of graphene oxide (GO) in water. Based on this discovery, we reported a simple preparation method of GO paper regulated by Na ions. By adjusting the drying temperature and the mass fraction of NaCl solution, the preparation and complete stripping of GO paper can be easily completed, thereby obtaining free-standing GO paper. Further, we also found that the introduction of sodium ions would cause changes in the microwave irradiation spectrum of GO paper, and the change was related to the mass fraction of NaCl solution used, which could be used to detect sodium ions and the concentration of NaCl solution. Besides, our study also showed that MWRGO paper with NaCl solution treatment can more effectively remove methylene blue in water, compared with MWRGO paper without NaCl solution treatment. This study provides the possibility of the preparation of GO paper based on seawater and also provides a new method for the detection of sodium ions and determination of sodium chloride solution concentration. It has important application prospects in the preparation of GO paper, sensor and water treatment.