Table 2.

The Box–Behnken design for the three independent variables and predicted values

Runs	X1	X2	X3	Response Value/g/L
1	−1	−1	0	2.78
2	−1	1	0	2.45
3	1	−1	0	2.85
4	1	1	0	1.96
5	0	−1	−1	1.55
6	0	–1	1	2.82
7	0	1	−1	1.20
8	0	1	1	2.02
9	−1	0	−1	1.20
10	1	0	−1	1.55
11	−1	0	1	2.75
12	1	0	1	2.20
13	0	0	0	2.99
14	0	0	0	2.96
15	0	0	0	3.11