Fig. 5From: Facile synthesis of reduced graphene oxide by Tecoma stans extracts for efficient removal of Ni (II) from water: batch experiments and response surface methodologyPlots of externally studentized residuals with (a) predicted response; Ni (II) removal, (b) the number of runs in BBD design. (c) Box-Cox plot, (d) validation model by the relationship between predicted and actual values of the response. (e) The effect of perturbation of each process variable, (f) Cook’s distance for each experimental runBack to article page