[Retracted] Synthesis and Optimization of Cr (VI) Removal from Aqueous Solution by Activated Carbon with Magnetic Fe₃O₄Nanoparticles by Response Surface Methodology

Table 2

ANOVA results.

Source	Sum of squares	Df	Mean square	value	value
Model	10291.06	14	735.08	18.27	<0.0001	Significant
A, concentration	167.33	1	167.33	4.16	0.0608
B, adsorption time	434.52	1	434.52	10.8	0.0054
C, dosage	132.4	1	132.4	3.29	0.0912
D, pH	1493.21	1	1493.21	37.11	<0.0001
AB	994.46	1	994.46	24.72	0.0002
AC	688.01	1	688.01	17.1	0.001
AD	504	1	504	12.53	0.0033
BC	1492.28	1	1492.28	37.09	<0.0001
BD	16.81	1	16.81	0.4178	0.5285
CD	2429.5	1	2429.5	60.38	<0.0001
A^2	1294.86	1	1294.86	32.18	<0.0001
B^2	449.15	1	449.15	11.16	0.0048
C^2	74.1	1	74.1	1.84	0.1962
D^2	257.66	1	257.66	6.4	0.024
Residual	563.29	14	40.24
Lack of fit	162.01	10	16.2	0.1615	0.991	Not significant
Pure error	401.28	4	100.32
Cor total	10854.35	28