Statistical Optimization of Operational Parameters for Enhanced Naphthalene Degradation by TiO_𝟐/Fe_𝟑O_𝟒-SiO_𝟐 Photocatalyst

Table 2

The central composite experimental design with three independent variables and results.

Run	Factors (coded value)						Degradation rate y (%)
	Irradiation time	Code	pH	Code	Catalyst loading	Code
	(min)	𝑥1		𝑥2	(g/L)	𝑥3
1	80	+1	1.5	+1	0.8	+1	54.5
2	100	−1	1.5	+1	0.8	+1	81.3
3	80	+1	2.5	−1	0.8	+1	55.3
4	100	−1	2.5	−1	0.8	+1	82.4
5	80	+1	1.5	+1	1.0	−1	71.3
6	100	−1	1.5	+1	1.0	−1	90.3
7	80	+1	2.5	−1	1.0	−1	78.5
8	100	−1	2.5	−1	1.0	−1	92.8
9	90	0	2.0	0	0.9	0	91.0
10	90	0	2.0	0	0.9	0	90.5
11	90	0	2.0	0	0.9	0	91.1
12	90	0	2.0	0	0.9	0	90.2
13	90	0	2.0	0	0.9	0	91.1
14	90	0	2.0	0	0.9	0	91.6
15	73.18	−a	2.0	0	0.9	0	52.6
16	106.82	a	2.0	0	0.9	0	91.4
17	90	0	1.16	−a	0.9	0	78.7
18	90	0	2.84	A	0.9	0	82.0
19	90	0	2.0	0	0.7318	−α	64.3
20	90	0	2.0	0	1.0682	α	90.2