Design and development of a portable biodiesel reactor using aeration-assisted alkali catalyzed transesterification of waste cooking oil

Abstract

The 21^st century is an era where the world’s transportation is powered by fossil fuels. Due to the said fact, the emission from using these fuels is a huge factor in contributing to the pollution of the world and climate change. This research aimed to produce a greener and more eco-friendly fuel that can be utilized as an alternative for today’s fuel. It focused primarily in presenting a design which introduces aeration technology, a heating element and air-atomized spraying of catalyst for the continuous production of biodiesel from waste cooking oil. The transesterification of the biodiesel reactor comprises 4 stages: pre-heating, synthesis, washing and polishing. An amount of 15.88 L of waste cooking oil (WCO) was reacted with 3.96 L of CH₃OH and 66.67 g of NaOH as catalyst. The CH₃OH and NaOH were mixed in the methoxide tank by a stirrer. The temperature was controlled at 55^oC for 1 h of preheating. The aerator and the pump were then simultaneously turned on for the reaction to begin. The reaction lasted for 3 h and 15 min which includes the settling of glycerol. The biodiesel was washed three times using 10.4 L of H₂O per washing. Finally, the biodiesel was heated at 105^oC for 3 h for the purpose of polishing. The parameters that affected the production of biodiesel were CH₃OH to biodiesel ratio, catalyst concentration, and reaction time. These parameters were experimentally varied to determine the most economical for the pilot-scale production. The economic CH₃OH to biodiesel ratio was tested to be 6:1, which was the same as the optimum ratio. The lowest catalyst concentration achieved was 0.5 wt% of the straight vegetable oils (SVO). As for the reaction time, the shortest period achieved was 3 h. The biodiesel yield of 97.7 %, was considered a relatively good result at this stage of the technology. The properties of the waste cooking oil strongly suggested its efficient conversion into biodiesel. Optimal aeration, characterized by the formation of smaller bubbles that increase surface area, resulted in the highest biodiesel yield. The settling time after the reaction considerably decreased contributing to less energy utilization. On the other hand, the automation of the reactor reduced the need for manual labor which greatly improved the reactor’s operation.

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*Corresponding author

Email address: rejie.magnaye@g.batstate-u.edu.ph