Preparation and Characterization of Chitosan/Bentonite Composites for Cr (VI) Removal from Aqueous Solutions

Table 4

ANOVA of responsive surface design.

Source	Sum of squares	df	Mean square	value	value
Model	7749.45	9	861.05	108.04	<0.0001	Significant
	196.02	1	196.02	24.60	0.0016
	599.79	1	599.79	75.26	<0.0001
	1241.27	1	1241.27	155.75	<0.0001
	2.19	1	2.19	0.27	0.6163
	5.34	1	5.34	0.67	0.4402
	0.65	1	0.65	0.081	0.7838
	2.26	1	2.26	0.28	0.6106
	192.74	1	192.74	24.18	0.0017
	5348.48	1	5348.48	671.10	<0.0001
Residual	55.79	7	7.97
Lack of fit	46.16	3	15.39	6.40	0.0525	Not significant
Pure error	9.62	4	2.41
Cor total	7805.24	16