Biodiesel synthesis from Ricinus communis and Pongamia pinnata oil blends by injecting superheated methanol – isopropanol mixtures: Optimization through CCD and ANN approaches

Abstract

In the current study, blends of castor and karanja oils were subjected to uncatalysed alcoholysis with superheated mixtures of 2-propanol and methanol for their rapid conversion into fuel-grade esters. Optimizable ranges identified from batch studies for 6 parameters: alcohol preheat temperature, castor oil to karanja oil ratio, initial oil mass, methanol to 2-propanol ratio, reaction temperature and retention duration were fed into a spherical central composite design (CCD-S, used for identifying process conditions for optimal biodiesel yield. It was noted that a maximum biodiesel yield of 98.79 % could be obtained when 650g castor and karanja oil blend at a ratio of 2:1 was charged into the reactor. The alcohols at a ratio of 3:5 for methanol: 2-proanol had to be pre-heated to 140 °C to achieve desired energy, reactivity and flow. The reaction provided best results when allowed to occur at 260 °C for a duration of 8 min. The experimentally obtained data were verified for reliability through ANOVA studies and ANN was used to validate the data as well as develop a model capable of predicting output accurately, with a 6-10-1 algorithm giving an R² of 0.987, indicating high reliability.