Precise evaluation the effect of microwave irradiation on the properties of palm kernel oil biodiesel used in a diesel engine

Palm kernel oil (PKO) has an appropriate oil content which can be utilized for biodiesel production. Sparse studies have been performed on its ability as well as the produced biodiesel properties and performance in the diesel engine. Further, no study has been performed on the conversion of PKO via microwave irradiation and comparing the PKO biodiesel abilities combusted in diesel engines with those prepared by conventional methods. For this purpose, PKO was directly extracted from date palm fruits (Phoenix dactylifera) with microwave and conventional heating systems utilized for conversion of PKO to biodiesel. In addition to optimization of microwave-assisted transesterification reaction conditions, variations of temperature during each run were carefully monitored. The results revealed that palm kernel has 10 wt% of oil containing high unsaturated fatty acids and free fatty acid (FFA). The transesterification reaction was sharply accelerated by microwave power such that the reaction time diminished from 90 min for conventional method to 2.5 min. The results of temperature monitoring confirmed great elevation in the reaction temperature (over boiling point of methanol) with the rise of microwave power and methanol/oil ratio. Moreover, reduction of temperature occurred with more loading of catalyst due to greater formation of soap. Both high and low temperatures showed negative effects on the yield of transesterification reaction. The performance and emissions gas evaluation of the engine fueled by PKO biodiesel produced by microwave and conventional heating system indicated that the fuel produced by microwave irradiation can sharply reduce the CO and HC and insignificantly increase NOx in exhaust emission as compared to fuel produced by the conventional method. Also, higher amounts of microwave-assisted produced PKO biodiesel can be blended with net diesel fuel to use in diesel engines. The results suggested that microwave irradiation can considerably influence the phytochemical properties of biodiesel and improve its combustion profile in the diesel engine and exhaust gas emissions. (C) 2019 Published by Elsevier Ltd.