Production of biodiesel from used Edible oils optimization and Validation

Abstract

Fatty acid methyl esters (FAME) were synthesized from the Waste Cooking Oil (WCO) by direct transesterification with methanol. The WCO was pretreated to increase the efficiency of FAME production with 1% of potassium methoxide as a catalyst. The free fatty acid of the raw source was reduced using 2% of activated charcoal as adsorbent. Transesterification of WCO was done by microwave-assisted with KOH, Ultrasonication with KOH and Nanobiocatalyst. The process variables were optimized using Box Behnken design of Response Surface Methodology (RSM) and Artificial Neural Network (ANN) model was developed to predict the FAME yield. The highest percentage of conversion (95%) was achieved by microwave-assisted transesterification at optimum conditions, for the catalyst concentration of 1%, lcohol to oil ratio of 6:1 (v/v), temperature of 75°C and time of 60 s. The yield of biodiesel was estimated by higher R2 values of RSM (0.98) and ANN (0.99), respectively. The produced FAME from pretreated WCO at 75°C by microwave irradiation was examined by proton nuclear magnetic resonance (1H NMR), carbon nuclear magnetic resonance (13C NMR), Fourier Transform Infrared (FT-IR) spectroscopy and Gas Chromatography-Mass Spectrometry (GC MS). The esters exhibited their two characteristically strong absorption bands arising from carbonyl (CO) at 1741 cm 1 of fresh oil and C=O stretching between 1300 and 1000 cm 1 in the FT-IR spectra. The spectrum of 13C NMR for the FAME from WCO confirmed that the presence of methyl esters in the biodiesel, ester carbonyl (-COO-) and C-O functional group were established at the peak value of 174.2 ppm and 51.4 ppm, respectively newline