pH effect on the zeta potential of GO, GO-CS, and GO-EDTA.

pH	Zeta potential (mV)
	GO	GO-CS	GO-EDTA
4	−34.80	−30.46	−33.33
6	−39.14	−36.15	−46.25
7.4 (physiological pH)	−30.30	−35.78	−46.09
9	−24.66	−34.16	−45.87