COMPARISON OF TWO DIFFERENT PROCESSES TO SYNTHESIZE BIODIESEL BY WASTE COOKING OIL

Abstract The traditional acid and the new two-step catalyzed processes for synthesis of biodiesel expressed as fatty acid methyl ester (FAME) were comparatively studied to achieve an economic and practical method for utilization of waste cooking oil (WCO) from Chinese restaurants. WCO samples with the acid value of 75.92 ± 0.04 mgKOH/g mixed with methanol were catalyzed under 95 °C for various reaction time, followed by methanol recovery under vacuum (10 ± 1 mmHg) at 50 °C with a rotational evaporation. FAME analyzed by gas chromatography (GC) was obtained directly from sulfuric acid catalyzed reaction in the traditional acid method, whereas in the two-step method it was produced from ferric sulfate (2.0%) catalyzed reaction followed by alkali (1.0% potassium hydroxide) transesterification. The conversion of free fatty acids of WCO into FAME in the two-step method was 97.22% at the reaction time of 4 h, mole ratio of methanol to TG of 10:1, compared in the acid method with 90%, 10 h, and 20:1, respectively, showing much higher catalyzed activity of ferric sulfate. This new two-step process showed advantages of no acidic wastewater, high efficiency, low equipment cost, and easy recovery of catalyst compared with the limitations of acidic effluent, no reusable catalyst and high cost of equipment in the traditional acid process.

[1]  K. Steemers,et al.  Energy policy and standard for built environment in China , 2005 .

[2]  F. Karaosmanôglu,et al.  Optimization of Base-Catalyzed Transesterification Reaction of Used Cooking Oil , 2004 .

[3]  M. Sharma,et al.  Prospects of biodiesel production from vegetable oils in India , 2005 .

[4]  Yomi Watanabe,et al.  Continuous production of biodiesel fuel from vegetable oil using immobilized Candida antarctica lipase , 2000 .

[5]  Ali O. Al-Shyoukh,et al.  Experimental evaluation of the transesterification of waste palm oil into biodiesel. , 2002, Bioresource technology.

[6]  M. P. Dorado,et al.  Optimization of alkali-catalyzed transesterification of Brassica carinata oil for biodiesel production , 2004 .

[7]  Ghassan Tashtoush,et al.  Experimental study on evaluation and optimization of conversion of waste animal fat into biodiesel. , 2004 .

[8]  A. Demirbas,et al.  Biodiesel fuels from vegetable oils via catalytic and non-catalytic supercritical alcohol transesterifications and other methods: a survey , 2003 .

[9]  G Antolín,et al.  Optimisation of biodiesel production by sunflower oil transesterification. , 2002, Bioresource technology.

[10]  Yomi Watanabe,et al.  Conversion of degummed soybean oil to biodiesel fuel with immobilized Candida antarctica lipase , 2002 .

[11]  Yoshio Tominaga,et al.  Enzymatic conversion of waste edible oil to biodiesel fuel in a fixed-bed bioreactor , 2001 .

[12]  H. Noureddini,et al.  Improved conversion of plant oils and animal fats into biodiesel and co-product , 1996 .

[13]  M. Haas,et al.  Simple, high-efficiency synthesis of fatty acid methyl esters from soapstock , 2000 .

[14]  W. Körbitz,et al.  Biodiesel production in Europe and North America, an encouraging prospect , 1999 .

[15]  M. Dubé,et al.  Biodiesel production from waste cooking oil: 2. Economic assessment and sensitivity analysis. , 2003, Bioresource technology.

[16]  Yi-Hsu Ju,et al.  A two-step acid-catalyzed process for the production of biodiesel from rice bran oil. , 2005, Bioresource technology.

[17]  J. H. Van Gerpen,et al.  A pilot plant to produce biodiesel from high free fatty acid feedstocks. , 2003 .

[18]  M. Dubé,et al.  Biodiesel production from waste cooking oil: 1. Process design and technological assessment. , 2003, Bioresource technology.