Table 4 The levels of variables chosen for the Box–Behnken optimization experiment for biodiesel yield
From: Production and statistical optimization of biodiesel from kitchen chimney dump lard
Variables | Variable code | −1 | 0 | +1 |
|---|---|---|---|---|
Methanol | X 1 | 40 | 50 | 60 |
NaOH | X 2 | .5 | 1.5 | 2.5 |
Temperature | X 3 | 52 | 62 | 72 |
Time | X 4 | 80 | 90 | 100 |