Table 2.

GO preparation conditions [14,19].

Symbol	Base Acid	Oxidizing Mixture (Reagents)	Time
Method A	H2SO4 (20 mL)	HNO3 (15 mL), KMnO4 (3 g)	24 h
Method B	H2SO4 (30 mL)	NaNO3 (3 g), KMnO4 (3 g)	2 h
Method C	H2SO4 (22.5 mL)	NaNO3 (0.5 g), KMnO4 (3 g)	0.5 h
Method D	H2SO4 (45 mL), H3PO4 (5 mL),	KMnO4 (5 g), KNO3 (1.5 g)	5 h