Date of Award

6-2013

Document Type

Thesis

Degree Name

Master of Science in Petroleum Engineering (MSPE)

Department

Chemical Engineering

First Advisor

Dr Sulaiman Al-Zuhair

Second Advisor

Dr Ismameldin H ashim

Third Advisor

Prof. Abdulrazag Y. Zekri

Abstract

Due to the reduction in fossil fuel reserves and associated environmental impacts from using petroleum fuels, biodiesel has been presented as a feasible alternative because it is sustainable and environmentally friendly. In this study, it is proposed to investigate the feasibility of enzymatic production of biodiesel from waste animal fats using supercritical fluid technology for the extraction and reaction. The operating conditions that resulted in the optimum extraction and biodiesel production yield were identified. To the best of my knowledge of the investigators, the waste animal fat extracted by supercritical CO2 (SC-CO2) for the production of biodiesel in SC-CO2 media has never been investigated.

Waste fat extracted from lamb meat was selected as feedstock for the transesterification reaction using Novozym 435 as a biocatalyst for biodiesel production and SC-CO2 as an extraction solvent and reaction medium. Fatty acid methyl ester (FAME) analysis was accomplished using gas chromatography equipped with ionization detector (GC-FID). The effect of temperature in the range of 35-55 °C, pressure in the RANGE OF 300-500 bar and SC-CO2 flow rate in the range of 3-5 ml min-1 on the fat extraction effectiveness and yield were investigated and optimized using response surface methodology. To evaluate the feasibility of using Supercritical fluid extraction (SFE) as an alternative extraction method, its fat extraction yield was compared to that using soxhlet extraction. Statistical analysis was done using Minitab 15 software. In addition, the effect of temperature in the range of 35-60°C, methanol molar ratio in the range of 3:1-6:1 and enzyme loading in the range of 10-50%, on reaction rate and yield were also tested. The experimental results were used to fit a suitable reaction kinetic model to estimate the model parameters using non-linear regression analysis.

The result indicated that effective SFE requires dry meat sample at moderate temperature. At optimum conditions, the system was capable of extracting up to 87.4% of the total fat content from freeze-dried and grind meat sample at 45°, 500 bars and 3 ml min-1. The statistical analysis indicated that the yield was a function temperature and SC-CO2 flow rate, whereas that extraction pressure showed insignificant effect.

Biodiesel production by enzymatic transesterification of extracted lamb meat fat with methanol, using Novozym 435 proved to be of high potential, with a conversion of almost 40%. Effect of reaction conditions and reaction kinetics were investigated. The optimal conditions for transesterification of lamb meat using Novozym 435 in SC-CO2 reaction medium were: 50 °C, 30% loading, 4:1 methanol to fat molar ratio and 25 hr. reaction. When subjected to repeated uses, Novozym 435 showed significant loss in its activity. The experimental results were used to fit simplified model based on Ping Pong Bi Bi with methanol inhibition to determine kinetic parameters using non-linear regression technique.

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