Response Surface Methodology for Biodiesel Production Using Calcium Methoxide Catalyst Assisted with Tetrahydrofuran as Cosolvent

Table 2

Experimental design with observed and predicted values from transesterification of WCO.

Run number	A: methanol-to-oil; molar ratio	B: catalyst concentration; (wt%)	C: reaction time; (min)	D: THF; concentration; (v/v%)	Observed FAME; (%)	Predicted FAME; (%)
1	8 (−1)	2 (−1)	60 (−1)	6 (−1)	71.17	68.98
2	12 (+1)	2 (−1)	60 (−1)	6 (−1)	71.43	71.99
3	8 (−1)	3 (+1)	60 (−1)	6 (−1)	84.85	86.73
4	12 (+1)	3 (+1)	60 (−1)	6 (−1)	91.94	92.26
5	8 (−1)	2 (−1)	120 (+1)	6 (−1)	73.83	73.79
6	12 (+1)	2 (−1)	120 (+1)	6 (−1)	78.71	77.14
7	8 (−1)	3 (+1)	120 (+1)	6 (−1)	93.25	94.02
8	12 (+1)	3 (+1)	120 (+1)	6 (−1)	95.87	99.88
9	8 (−1)	2 (−1)	60 (−1)	9 (+1)	83.44	80.06
10	12 (+1)	2 (−1)	60 (−1)	9 (+1)	84.3	81.59
11	8 (−1)	3 (+1)	60 (−1)	9 (+1)	89.76	89.38
12	12 (+1)	3 (+1)	60 (−1)	9 (+1)	92.74	93.41
13	8 (−1)	2 (−1)	120 (+1)	9 (+1)	84.56	82.30
14	12 (+1)	2 (−1)	120 (+1)	9 (+1)	85.4	84.16
15	8 (−1)	3 (+1)	120 (+1)	9 (+1)	94.02	94.09
16	12 (+1)	3 (+1)	120 (+1)	9 (+1)	98.22	98.46
17	6 (−2)	2.5 (0)	90 (0)	7.5 (0)	81.03	83.15
18	14 (+2)	2.5 (0)	90 (0)	7.5 (0)	91.34	90.54
19	10 (0)	1.5 (−2)	90 (0)	7.5 (0)	50.57	56.33
20	10 (0)	3.5 (+2)	90 (0)	7.5 (0)	92.83	88.38
21	10 (0)	2.5 (0)	30 (−2)	7.5 (0)	81.72	83.68
22	10 (0)	2.5 (0)	150 (+2)	7.5 (0)	94.19	93.54
23	10 (0)	2.5 (0)	90 (0)	4.5 (−2)	91.94	89.41
24	10 (0)	2.5 (0)	90 (0)	10.5 (+2)	95.24	99.08
25	10 (0)	2.5 (0)	90 (0)	7.5 (0)	97.75	95.02
26	10 (0)	2.5 (0)	90 (0)	7.5 (0)	95.61	95.02
27	10	2.5	90	7.5	93.33	95.02
28	10	2.5	90	7.5	96.1	95.02
29	10	2.5	90	7.5	93.16	95.02
30	10	2.5	90	7.5	94.19	95.02