Table 2.

Box-Behnken design and experimental results.

	Factor
No.	X1	X2	X3	Bioethanol concentration (g/L)
1	−1	−1	0	1.07
2	1	−1	0	0.66
3	−1	1	0	0.56
4	1	1	0	1.11
5	−1	0	−1	0.49
6	1	0	−1	0.93
7	−1	0	1	0.43
8	1	0	1	1.02
9	0	−1	−1	0.63
10	0	1	−1	0.65
11	0	−1	1	0.65
12	0	1	1	0.68
13	0	0	0	1.14
14	0	0	0	1.28
15	0	0	0	1.21
16	0	0	0	1.31
17	0	0	0	1.23