Process Optimization for Acid Hydrolysis and Characterization of Bioethanol from Leftover Injera Waste by Using Response Surface Methodology: Central Composite Design

Table 1

Coefficients in terms of coded factors.

Factor	Coefficient estimate	Df	Standard error	95% CI low	95% CI high	VIF
Intercept	26.75	1	0.0476	26.65	26.86
A—temperature	1.70	1	0.0315	1.63	1.78	1.0000
B—acid concentration	−1.30	1	0.0316	−1.37	−1.23	1.0000
C—hydrolyzing time	1.67	1	0.0316	1.60	1.74	1.0000
AB	−0.5650	1	0.0412	−0.6569	−0.4731	1.0000
AC	−0.2200	1	0.0412	−0.3119	−0.1281	1.0000
BC	−1.19	1	0.0412	−1.28	−1.10	1.0000
A^2	0.4419	1	0.0307	0.3736	0.5102	1.02
B^2	0.1035	1	0.0308	0.0350	0.1721	1.02
C^2	−1.02	1	0.0307	−1.09	−0.9561	1.02