Highlights Hydrosonic and ultrasonic reactors were compared in two-step biodiesel process. Key part is utilizing the 3D-printed rotor–stator. Methyl ester 99.163 wt% was produced using rotor–stator hydrodynamic reactor. Maximum yields 97.51 vol% purified biodiesel was achieved using HC reactor. The total average energy consumption of using HC reactor was 0.049 kW h/L.

This research focuses on the feasibility of using diesel–palm fatty acid distillate ethyl ester (PFADE)–ethanol in a direct injection diesel engine without any major modifications. Hydrous ethanol was selected for blending in diesel to produce diesohol. The palm fatty acid distillate (PFAD) and PFADE were directly blended in ethanol and diesel. A comparative study of the phase stability in diesel–PFAD–hydrous ethanol and diesel–PFADE–hydrous ethanol was performed with varied blend proportions. The fuel properties, emissions (CO, CO 2 , NO x , O 2 , exhaust gas temperature), and fuel consumptions of diesel, PFADE, diesel–PFADE–hydrous ethanol were compared to evaluate the feasibilities of these fuel blends in a diesel engine at the engine speeds 1100, 1400, 1700, 2000, and 2300 rpm. At 2300 rpm, the maximum CO 2 emission with 10 wt % hydrous ethanol in the blend was approximately 2%. With regard to fuel consumption, clearly, 20 wt % diesohol gave higher consumption than 10 wt % ethanol at a maximum engine speed of 2300 rpm. The blend D50PE40E10 gave the lowest fuel consumption, while the maximum fuel consumption was with the D10PE70E20 blend. Therefore, both 10 and 20 wt % hydrous ethanol in the diesel fuel are alternatives usable in a diesel engine without modifications.

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In this study, Amberlyst-15 as heterogeneous catalyst was used for the reduction of free fatty acid (FFA) from the palm oil mill effluent (POME) for biodiesel production with acid-catalyzed esterification process. The objective of this study was to decrease a high FFA in POME to less than 2 wt.% FFA, for used as a raw material to produce biodiesel in the second-step transesterification process. Amberlyst-15 as an eco-friendly catalyst with non-toxic wastes after reactions, when compared to homogeneous catalysts such as sulfuric acid. Therefore, an esterification reaction with a heterogeneous acid catalyst was carried out to examine the FFA conversions. The conditions of two parameters of Amberlyst-15 catalyst (10–40 wt.%), and 1–8 h reaction time were varied, whereas the methanol to oil molar ratio and the speed of the stirrer were fixed at 5:1 and 300 rpm, respectively. As a result, the FFA sharply decreased from 89.16 wt.% to 1.75 wt.% under the conditions of 40 wt.% of Amberlyst-15, 5 h reaction time, 5:1 molar ratio methanol to oil, speed of the 300 rpm stirrer. The Amberlyst-15 had the potential to reduce high FFA in POME using the esterification reaction.