Химия и химические технологии/ 5.Фундаментальные проблемы создания новых материалов и технологий

Ph.d. Student, Sadeq Muneer Shawkat

National technical university "Kharkov polytechnic institute", Ukraine

From waste animal fats and vegetable oils to production biodiesel

Biodiesel is a renewable, biodegradable, environmentally benign, energy efficient, substitution fuel which can fulfill energy security needs without sacrificing engine’s operational performance. Thus, it provides a feasible solution to the twin crises of fossil fuel depletion and environmental degradation.

Any fatty acid source may be used to prepare biodiesel. Thus, any animal or plant lipid should be a ready substrate for the production of biodiesel. The use of edible vegetable oils and animal fats for biodiesel production has recently been of great concern because they compete with food materials - the food versus fuel dispute [1]. As shown in below chart, the world production of feedstocks for biodiesel production can be categorized as conventional vegetable oils, fats of animal origin.

Chart – World production of oils and fats since 2007/2008 (Total 159.4 million tons)

There are concerns that biodiesel feedstock may compete with food supply in the long-term [2]. Hence, the recent focus is the use of non-edible fat and oil sources the feedstock for biodiesel production meeting the international standards. Quality standards are prerequisites for the commercial use of any fuel product. Since the implementation of the European standard specification EN 14214 in 2004, a standardized definition for biodiesel has been agreed as fatty acid methyl esters (FAME) from any kind of feedstock, including waste fats and oils. Biodiesel produced from wastes has the same possibilities to be utilized. The new process technologies developed during the last years made it possible to produce biodiesel from recycled frying oils comparable in quality to that of virgin vegetable oil biodiesel with an added attractive advantage of being lower in price [3, 4].

The term “waste fats and oils” refers to materials which have been used in food production and which is no longer viable for its intended use. Waste of animal fats and vegetable oils arises from many different sources, including domestic, commercial and industrial. This type of waste is a potentially problematic which requires to be properly managed. For example the disposal of waste vegetable oil can be problematic, incorrectly, down kitchen sinks, where it can quickly cause blockages of sewer pipes when the oil solidifies. Properties of degraded used frying oil after it gets into sewage system are conductive to corrosion of metal and concrete elements. It also affects installations in waste water treatment plants. Thus, it adds to the cost of treating effluent or pollutes waterways [5].

Consequently, efforts should be focused on developing technologies capable of using this type of materials. Reusing of these waste greases can not only reduce the burden of government in disposing the waste, maintaining public sewers and treating the oily wastewater, but also lower the production cost of biodiesel significantly. From a waste management standpoint, producing biodiesel is environmentally beneficial, since it provides a cleaner way for disposing these products; meanwhile, it can yield valuable cuts in CO2 as well as significant tailpipe pollution gains. CO2 is the main contributor of global warming and climate change through the enhanced [6].

Regarding the production process of biodiesel from the wastes it is using the transesterification technique as it is the most economical process for treating virgin vegetable oils, also includes reaction between the feedstock with short-chain alcohols (typically methanol or ethanol), as well as catalysts are used to improve the reaction rate and yield. Common catalysts for transesterification include sodium hydroxide, potassium hydroxide, and sodium methoxide. The general transesterification reaction equation is:

But there are some key parameters to identify the viability of the low cost feedstock in biodiesel production (acid value and free fatty acids (FFA) content, moisture content, viscosity and fatty acid profile). Waste greases typically contain ≤ 35% FFAs, this is far beyond the level that can be converted to biodiesel by using an alkaline catalyst. Some researchers recommended using an alternative process for biodiesel production from low- feedstock with a high content of FFA, via use of acid-catalyzed which have claimed are more tolerant of free fatty acids [7]. Previous studies have indicated that acid catalysts are too slow to be practical for converting triglycerides to biodiesel.

However, acid catalysts appear to be quite effective at converting FFAs to esters and this reaction is fast enough to be practical [8]. Thus, an acid–catalyzed pre-treatment step to convert the FFAs to esters followed by an alkali–catalyzed step to convert the triglycerides should provide an effective and efficient method to convert high FFA feedstocks to achieve best results with the high yield and purity of the produced biodiesel. The results of scientific research and the novel technology proposed described a success of using waste fats and oils as an important source for biodiesel production in Ukraine and other countries.

References:

1. Pimentel, D.; Marklein, A.; Toth, M. A.; Karpoff, M. N.; Paul,G. S.; McCormack, R.; Kyriazis, J.; Krueger, T., (2009). Food versus biofuels: Environmental and economic costs. Hum. Eco., 37 (1), 1-12 (13 pages).

2. Metzger, J. O., (2009). Fats and oils as renewable feedstock for chemistry. Eur. J. Lipid Sci. Tech., 111 (9), 865-876 (12 pages).

3. Canakci, M., (2007). The potential of restaurant waste lipids as biodiesel feedstocks. Bioresour. Tech., 98 (1), 183-190 (8 pages).

4. Chhetri, A. B.; Watts, K. C.; Islam, M. R., (2008). Waste cooking oil as an alternate feedstock for biodiesel production. Energies, 1 (1), 3-18 (16 pages).

5. Szmigielski, M.; Maniak, B.; Piekarski, W., (2008). Evaluation of chosen quality parameters of used frying rape oil as fuel biocomponent. Int. Agrophys., 22 (4), 361-364 (4 pages).

6. Tschakert, P.; Huber-Sannwald, E.; Ojima, D. S.; Raupach, M. R.; Schienke, E., (2008). Holistic, adaptive management of the terrestrial carbon cycle at local and regional scales. Glob. Environ. Change, 18 (1), 128–141 (14 pages).

7. Freedman, B., and E. H. Pryde. 1982. Fatty esters from vegetable oils for use as a diesel fuel. In Vegetable Oils Fuels: Proc. of the Intl. Conf. on Plant and Vegetable Oils as Fuels, 117–122. St. Joseph, Mich.: ASAE.

8. Canakci, M.; Van Gerpen, J. Biodiesel production from oils and fats with high free fatty acids. Trans. ASAE 2001, 44, 1429-1436.