Removal of Zinc from Aqueous Solution by Optimized Oil Palm Empty Fruit Bunches Biochar as Low Cost Adsorbent

Table 3

Analysis of variance (ANOVA) for response surface quadratic model for yield.

Source of data	Sum of squares	Degree of freedom (DF)	Mean square	-value	value; Prob >	Comment
Model	125.62	9	13.96	46.44	<0.0001	Significant
	77.90	1	77.90	259.18	<0.0001
	20.69	1	20.69	68.84	<0.0001
	5.13	1	5.13	17.05	0.0020
	1.30	1	1.30	4.31	0.0646
	0.43	1	0.43	1.44	0.2580
	0.39	1	0.39	1.29	0.2828
	19.09	1	19.09	63.50	<0.0001
	0.85	1	0.85	2.81	0.1244
	0.038	1	0.038	0.13	0.7302
Residual	3.01	10	0.30
Lack of fit	2.46	5	0.49	4.51	0.0618	Not significant
Pure error	0.55	5	0.11