Table 1 Coded levels for variables used in the experimental design
From: Optimization of algal methyl esters using RSM and evaluation of biodiesel storage characteristics
Factors | Symbol | Coded levels | ||
|---|---|---|---|---|
−1 | 0 | +1 | ||
Oil:alcohol ratio (v/v) | A | 4 | 6 | 8 |
Catalyst amount (w/w) | B | 0.1 | 0.3 | 0.5 |
Time (min) | C | 30 | 90 | 150 |
Temperature (° C) | D | 50 | 70 | 90 |