Biodiesel production from waste cotton-seed cooking oil using microwave-assisted transesterification: Optimization and kinetic modeling

By Anvita Sharma, P. Kodgire, S. S. Kachhwaha. 2019

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Abstract The current research focuses on process optimization and kinetic study of microwave-assisted transesterification process using KOH and CaO catalyst from waste cotton-seed cooking oil (WCCO). In order to enhance the biodiesel yield, process parameters: methanol to oil ratio (A), catalyst loading (B) and reaction time (C) were optimized by applying response surface methodology based on full factorial design method. It was found that for KOH catalyzed condition, the optimum values for A, B and C are 7:1, 0.65 (w/w) % and 9.6 min, respectively and the model predicted yield is 96.44%. For CaO catalyzed condition, the optimum values for A, B and C are 9.6:1, 1.33 (w/w) % and 9.7 min, respectively and the predicted yield is 89.94%. Experiments were performed using the optimized parameters and the mean biodiesel yield determined for KOH and CaO catalyzed conditions are 96.55 ± 0.23% and 90.41 ± 0.02%, respectively which shows good agreement with model predictions. Analysis of perturbation plots showed that catalyst loading is the most sensitive variable. Considering pseudo-first-order kinetic, the activation energies were obtained and found to be 13.05 kJ mol-1 and 28.93 kJ mol-1 respectively for KOH and CaO catalyzed conditions. The activation energy observed for microwave-assisted method are significantly lower compared to that of conventional method. The scale-up study (with 10 fold batch-size) and energy analysis have been done for KOH and CaO catalyzed conditions whereas reusability was performed with CaO catalyst. It was observed that up to four cycles the biodiesel yield achieved was more than 90%. In microwave-assisted process, efficency factor found to be higher as compared to conventional method. The produced biodiesel properties fulfill fuel specifications designated as per ASTM D6751 standard. The outcome of microwave-assisted transesterification study enhances biodiesel yield and significantly decreases the reaction time, thus making it energy-efficient technique.

Subfields: Biomedical Engineering, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/5281d300f2b14a26bc4d5bda45be6115887b3a28