Production and Optimization of Bio-Based Silica Nanoparticle from Teff Straw (Eragrostis tef) Using RSM-Based Modeling, Characterization Aspects, and Adsorption Efficacy of Methyl Orange Dye

Table 5

Coefficients in terms of coded factors.

Factor	Coefficient estimate	df	Standard error	95% CI low	95% CI high	VIF
Intercept	68.69	1	0.1745	68.32	69.07
A-temperature	3.45	1	0.0872	3.27	3.64	1.0000
B-NaOH concentration	−2.05	1	0.0872	−2.24	−1.87	1.0000
C-RPM	2.96	1	0.0872	2.77	3.14	1.0000
D-time	2.42	1	0.0872	2.24	2.61	1.0000
AB	−2.46	1	0.1069	−2.69	−2.24	1.0000
AC	−0.9000	1	0.1069	−1.13	−0.6722	1.0000
AD	−0.2087	1	0.1069	−0.4365	0.0190	1.0000
BC	−1.72	1	0.1069	−1.95	−1.50	1.0000
BD	−0.2075	1	0.1069	−0.4353	0.0203	1.0000
CD	1.21	1	0.1069	0.9785	1.43	1.0000
A^2	0.6681	1	0.0816	0.4942	0.8421	1.05
B^2	1.70	1	0.0816	1.52	1.87	1.05
C^2	0.0394	1	0.0816	−0.1346	0.2133	1.05
D^2	−0.5594	1	0.0816	−0.7333	−0.3854	1.05