Facile synthesis of reduced graphene oxide by Tecoma stans extracts for efficient removal of Ni (II) from water: batch experiments and response surface methodology

Table 2 Experimental factors and levels used for the optimum Ni (II) removal onto rGO-X-25

Factors (Independent variables)	Units	Levels
Factors (Independent variables)	Units	-1	0	+1
pH	(−)	3	4.5	6
Ni (II) initial concentration (Conc.)	(mg L^− 1)	2	6	15
rGO-X-25 dose (Dose)	(g L^− 1)	0.06	0.13	0.20

ISSN: 2468-2039