Figure 2.

Outline of the sample preparation process. (a) Addition of sodium perchlorate monohydrate until the salinity meter reading reached 3%, followed by addition of the GO dispersion, and adjustment of the pH to 6. (b) Stirring of the sample solution. (c) Collection of GO using a membrane filter. (d) The membrane filter bearing the collected GO. (e) Placement of the GO collection membrane filter onto the lined mount. (f) Folding of the filter into 1/3 of its size in the vertical direction. (g) Folding of the filter into 1/3 of its size in the horizontal direction. (h) Sealing using a circular sealing material.