Ratna Dewi Kusumaningtyas, - (2019) Simplex Lattice Design Method for the Optimization of Non-Edible Oils Mixture Composition as Feedstock for Biodiesel Synthesis Using Reactive Distillation. Journal of Physics: Conference, 1295. pp. 1-9. ISSN ISSN (P): 1742-6588 ISSN (e): 1742-6596

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Abstract

The diminished of fossil fuel becomes a critical issue today. Thus, it is essential to develop alternative energy resources which are renewable and environmental friendly. Among the prospective alternative is biodiesel. Biodiesel (fatty acid methyl ester) is produced by combining vegetable oils with alcohol via transestefication reaction. To avoid conflict between food and energy needs, the uses of non-edible oils as raw material is suggested. Commonly, biodiesel synthesis employs a single type of vegetable oil feed-stock. The dependency on a certain feed-stock could cause an increasing price due to the high demand and low supply. Thus, it is beneficial to apply diversification by employing multiple feed-stocks or mixture of non-edible oils as biodiesel feedstocks. However, the best composition of the multiple feed- stocks is needed to obtain the optimum yield of biodiesel. In this work, mixture of non-edible oils, i.e. jatropha, nyamplung (Calophyllum inophyllum L.) seed, and used cooking oils were applied as biodiesel feedstocks. Non-edible oils are cheap but have high free fatty acid (FFA). The high FFA is not favorable for the alkaline-catalyzed transesterification since it will cause undesired saponification reaction and lower biodiesel yield. Hence, pretreatment to reduce FFA content is crucial prior to transesterification. In this work, esterification of FFA in vegetable oils mixture (jatropha, nyamplung, and used cooking oils) with methanol using reactive distillation in the presence of SnCl2 catalyst was conducted as pretreatment step of biodiesel production. Various compositions of the oils mixture were employed. To determine the best formulation of feed-stocks, Simplex Lattice Design Method (SLDM) was used for the optimization of non-edible oils mixture composition as feedstock for biodiesel synthesis using reactive distillation. The prediction using SLDM was validated with the experimental data. It was found that the optimal composition of oil mixture was the mixture contains 37.291 v/v% jatropha oil + 37.709 v/v% nyamplung oil + 25 v/v% used cooking oil. This composition of feedstocks revealed the FFA conversion of 85.93% (prediction) and 86.03% (experiment). The desirability value was 0.937 which indicated the validity of the SLDM optimization method. The esterified oil mixture was then underwent transesterification reaction to produce biodiesel. The yield of biodiesel demonstrated 99.65 % purity and density of 884 kg/m3 .

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