Table 1.

Variables involved in the Central Composite Design (CCD) and response obtained.

Time (min/coded)		Power (W/coded)		NVOC Yield (%)	VOC Yield (%)
20	−1	200	−1	24	0.6
40	0	200	−1	24.6	1.2
60	1	200	−1	25	1.4
20	−1	550	0	24.9	0.6
40	0	550	0	24.1	1.2
60	1	550	0	25.9	1.4
20	−1	900	1	23.1	0.6
40	0	900	1	23.3	1.4
60	1	900	1	23.2	1.4
40	0	550	0	25.1	1.2
40	0	550	0	24.7	1.2
40	0	550	0	24.2	1.2
40	0	550	0	24.7	1.2
40	0	550	0	24.9	1.2