Optimization to Hydrothermal Liquefaction of Low Lipid Content Microalgae Spirulina sp. Using Response Surface Methodology

Table 3

Experimental design and the results.

	Variables			Volume (mL)	Maximum pressure (MPa)	Yield (%)
	1	1	1				1	80	12.03	40.8 ± 0.88
2	1	1	−1	100	11.89	43.5 ± 1.21
3	1	−1	1	150	11.33	38.1 ± 1.06
4	1	−1	−1	150	11.12	38.9 ± 1.13
5	−1	1	1	80	11.91	38.7 ± 0.95
6	−1	1	−1	100	11.78	40.3 ± 0.90
7	−1	−1	1	150	10.98	37.5 ± 1.15
8	−1	−1	−1	150	10.62	38.8 ± 0.95
9	1.682	0	0	120	11.34	43.3 ± 1.35
10	−1.682	0	0	120	11.57	38.2 ± 1.11
11	0	1.682	0	80	12.75	42.6 ± 1.35
12	0	−1.682	0	180	10.91	37.2 ± 0.72
13	0	0	1.682	120	11.86	38.8 ± 0.74
14	0	0	−1.682	120	11.12	39.2 ± 0.86
15	0	0	0	120	11.32	43.6 ± 1.23
16	0	0	0	120	11.51	44.2 ± 1.02
17	0	0	0	120	11.33	43.9 ± 0.99
18	0	0	0	120	11.36	43.3 ± 1.06
19	0	0	0	120	11.48	44.4 ± 1.56
20	0	0	0	120	11.22	42.9 ± 0.89

, concentration; , temperature; , holding time.