Volume 4 No. 4, April 2014 ISSN 2224-3577 International Journal of Science and Technology ©2014 IJST. All rights reserved http://www.ejournalofsciences.org 66 A Search for Alternative Solvent To Hexane During Neem Oil Extraction Ayoola A.A., Efeovbokhan V.C., Bafuwa O.T. and David O.T Chemical Engineering Department, Covenant University, Ota, Nigeria ABSTRACT The growing environmental concerns on the toxicity and flammability of hexane motivate the need to obtain a more environmentally friendly solvent capable of extracting as much oil as hexane or even more, while giving acceptable oil quality. This study therefore investigated the possibility of replacing Hexane with either Ethanol or the mixtures of both in the extraction of Neem Oil from Neem seed. It was observed that as the extraction time increased, oil yield increased, though there was little or no increase in oil yield at 5hours and 6 hours of operations. At different extraction time, Hexane produced oil yields greater than that obtained from Ethanol. Hence, Ethanol did not prove to be a good replacement for Hexane, even at higher temperature of 75 0 C for Ethanol. Optimum temperature of extraction was found to be 55 0 C. Surprisingly, mixtures of Ethanol and Hexane gave commendable results. Particularly, Ethanol-Hexane mixtures of 60/40, 50/50, and 40/60 % (volume proportions) gave better oil yields of 44%, 43% and 41.2% respectively than that of Hexane (40.25%) at the 6 hours of operation, thereby making the combinations good substitutes for Hexane. Keywords: Ethanol, Hexane, Neem Oil, Soxhlet Extraction. I. INTRODUCTION Neem Oil is a vegetable oil gotten from the fruits, leaves and seeds of neem tree. The tree is a member of the Mahogany family, with generic name Azadirachta Indica A. Juss, it is an evergreen tree which is endemic to the Indian subcontinent and has been introduced to many other areas in the tropics. It has also been found to thrive in the semi tropics, arid and semi arid climates in some countries including Nigeria where it is known as Dongoyaro, meaning “tall boy”. [1,2,3] Neem oil is generally light to dark brown in colour. It has a bitter taste and an offensive odour similar to the combined odours of garlic and peanut. It comprises mainly of triglycerides (esters formed from a molecule of glycerol and three molecules of fatty acids), and is very rich in azadirachtin- the key component acting as insect repellent, anti-feedant, anti-fungal and anti-viral, among others, it is perhaps the most important commercial product of neem for organic farming and medicines.[4,5,6] Also, it is being increasingly used in manufacturing a large number of skin products: body soaps, body lotions, and beauty care facial packs in combination with other natural ingredients.[7] Research reveals three ways in which neem oil may be extracted from its seeds and they are: mechanical pressing, supercritical fluid extraction and solvent extraction. Mechanical pressing involved crushing of neem seed to extract oil. Though oil obtained by cold pressing preserves the key components of the oil (particularly azadirachtin), but reports however show that such oil has low yield and poor market value (quality) as the oil is turbid and has high water and metal contents.[1,2] Supercritical fluid extraction process utilizes carbon dioxide at critical temperatures and pressures to extract the active ingredients of the neem leaves or seeds. It produces high quality oil but it is very expensive to operate and involves the release of CO2 to the atmosphere.[8] The use of solvent extraction for the extraction of neem oil is generally the preferred choice. This is due to very high oil yield and less turbid oil obtained than that from mechanical pressing. And also due to the relatively low operating cost compared to supercritical extraction.[2] The vast usefulness and applications of the neem oil progressively places an increasing demand for the availability of the extracted and processed oil.[9,10,11,12,13,14,15] The pharmaceutical industry and, particularly, the agro-allied industry, where neem oil is rapidly finding relevance in plant protection make the need for the extracted oil be on the increase.[9,16] Hexane is the most commonly used, as well as preferred choice in extraction of oils from seed, even in neem oil solvent extraction. This is largely due to its availability at a reasonable cost and its suitable functional characteristics for oil extraction. Amongst such characteristics is its high solvent power for triglycerides at fairly low temperatures, non-reactivity with oil and oil miscella, as well as with equipment.[7] However, the interest in alternate solvents to hexane has continued and is motivated by one of a combination of factors: the desire for a non flammable solvent, a more efficient and less hazardous and environmentally friendly solvent. An average of one major accident associated with the use of hexane occurs per year.[7] In addition, n-Hexane, the main component of