Oxidation, Thermal, and Storage Stability Studies of Jatropha Curcas Biodiesel

Table 5

Independent variable and levels used for CCD in oxidation process with respect to time for all the metals.

Variables	Symbols	Levels
		−1.68179 (−𝛼)	−1	0	+1	+1.68179 (+𝛼)
Antioxidants concentration (ppm)	𝐴	0	150	300	450	600
Metal contaminants concentration (ppm)	𝑀	0	0.5	1	1.5	2
Storage time (months)	𝑇	0	1.5	3	4.5	6