The search for innovation and biotechnological strategies in the biodiesel production chain have become a topic of interest for scientific community owing the importance of renewable energy sources. This work aimed to implement an enzymatic transesterification process to obtain biodiesel from waste frying oil (WFO). The transesterification was performed by varying reaction times (8 h, 12 h and 16 h), enzyme concentrations of lipase XX 25 split (14%, 16% and 18%), pH of reaction media (6, 7 and 8) and reaction temperature (35, 38 and 40 °C) with a fixed alcohol–oil molar ratio of 3:1. The optimum operating conditions were selected to quantify the amount of fatty acid methyl esters (FAMEs) generated. The highest biodiesel production was reached with an enzyme concentration of 14%, reaction time of 8 h, pH of 7 and temperature of 38 °C. It was estimated a FAMEs production of 42.86% for the selected experiment; however, best physicochemical characteristics of biodiesel were achieved with an enzyme concentration of 16% and reaction time of 8 h. Results suggested that enzymatic transesterification process was favorable because the amount of methyl esters obtained was similar to the content of fatty acids in the WFO.

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Enzymatic Transesterification of Waste Frying Oil from Local Restaurants in East Colombia Using a Combined Lipase System

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Physicochemical study of used frying oil as feedstock for the production of biodiesel

The biodiesel production was analyzed by chemical and enzymatic processes, from used cooking oil (UCO), evaluating the quality and yield of the product obtained in each method. For the chemical process, an acid esterification followed by a basic transesterification was developed, (reaction temperature: 60 °C, oil:methanol 1:6 molar ratio, concentration of KOH catalyst: 1% w/w reaction times: 55 and 70 min); and enzymatic transesterification (temperature: 38 °C, oil:methanol 1:3 molar ratio, enzyme concentration lipase XX 25 split liquid: 5%, reaction times: 3 and 6 hours). Physicochemical properties (i.e. density, kinematic viscosity, moisture content, fatty acid profile, percentage of acidity, peroxides index and saponification) of the raw material were determined. Results showed the presence of oleic acid (42.45%) and palmitic acid (33.52%). The highest yield obtained was from the chemical transesterification under the conditions of 60 °C, 1% KOH and 70 min with a conversion percentage of 96.15% and an acid number of 1.33 mmKOH/g, compared to the enzymatic transesterification which registered a high acid number of 6.91 mmKOH/g and conversion percentage of 48.81% under the conditions of 38 °C, 5% of enzyme lipase and 3 hours.

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Astrid Zuleima Acevedo-Rodríguez

Papers

Study of the production of biodiesel by enzymatic and chemical processes from used cooking oil