Solar Photocatalytic Degradation of Azo Dye in Aqueous TiO_𝟐 Suspension Assisted by Fresnel Lens

Table 2

Experimental range and levels of the process independent variables in this study.

Independent variable	Factor		Range and level
		−1	0	+1
Initial pH	X 1	5.0	7.0	9.0
TiO2, g/L	X 2	0.5	1.0	1.5
Reaction time, hr	X 3	1.0	1.5	2.0
Y (response)—COD or; TOC degradation, %