Modeling the Sorption of Ni²⁺ and Co²⁺ on Saprist Peat Using the Response Surface Methodology

Table 3

ANOVA for response surface reduced^* quadratic model for Ni²⁺ and Co²⁺.

Source	Sum of squares	Degrees of freedom	Mean square	value	value; prob. >	Comments
-Ni^2+ conc.	616	1	617	10	0.0050
-peat dose	2204	1	2205	35	<0.0001
-pH	9413	1	9414	150	<0.0001
	402	1	403	6	0.0194
	694	1	694	11	0.0032
	499	1	500	8	0.0102
	8449	1	8450	134	<0.0001
Residual	1319	21	63
Lack of fit	1096	17	65	1	0.4939	Not significant
Pure error	222	4	56
Cor. total	23198	28
-Co^2+ conc.	372	1	373	97	<0.0050
-peat dose	7777	1	7778	2030	<0.0001
-pH	726	1	727	190	<0.0001
	26	1	26	7	<0.0194
	45	1	45	12	<0.0032
	24	1	24	6	<0.0102
	2357	1	2357	615	<0.0001
	216	1	216	56	<0.0001
Residual	77	20	4
Lack of fit	72	16	4	4	0.0955	Not significant
Pure error	4	4	1
Cor. total	11994	28

Reduced means factors and interactions were eliminated when their values were > 0.05.