Biodiesel preparation from high acid value phoenix seed oil using Eversa transform 2.0 as a novel catalyst

Biodiesel is one kind of renewable energy. In this paper, phoenix seed oil (PSO) with high acid value (60.3 mgKOH/g) from waste phoenix tree seed, an undeveloped woody oil seed was used as a new feedstock to prepare biodiesel. A low-cost liquid lipase Eversa transform 2.0 was firstly used to simultaneously catalyze the transesterification of PSO and the esterification of free fatty acids. Effects of reaction temperature, time, enzyme load, and substrate ratio on biodiesel yield were investigated and optimized by response surface methodology with a Box-Behnken design (BBD). Results showed that Eversa transform 2.0 can simultaneously catalyze the transesterification of PSO and the esterification of free fatty acids to produce biodiesel. The optimal experimental conditions were 9.9% enzyme load with 4.2:1 molar ratio of methanol to oil at 29 °C for 4.2 h. Under these optimized conditions, the maximum biodiesel yield was 94.1 ± 0.6%. According to Ping-Pong Bi-Bi mechanism, this reaction was inhibited by methanol. K^′_m, K_IA, and V_max were 1.98 × 10⁻¹ mol/L, 7.08 × 10⁻¹ mol/L, and 5.44 × 10⁻³ mol/(L·min), respectively. Biodiesel from PSO was in accorded with ASTM D6751 standard.