Biodiesel Production Using Supercritical Methanol with Carbon Dioxide and Acetic Acid

Table 2

Levels of variables in biodiesel production.

Factors	Parameter	Levels and values
		Low (−1)	Medium (0)	High (1)
𝐴	Temperature (°C)	260	280	300
𝐵	Time (min)	30	60	90
𝐶	Methanol/oil	20	40	60
𝐷	Acetic acid/oil	1	2	3

(𝐴: temperature; 𝐵: time; 𝐶: molar ratio (methanol/oil); 𝐷: molar ratio (acetic acid/oil)).