. The predicted and experimental molar conversions of fatty acid methyl esters (FAME) were 80 and 79 , respectively. Keyword phrases: biodiesel; lipase; magnetic nanoparticles; response surface methodology; waste cooking oil1. Introduction Biodiesel is defined as the fatty acid alkyl monoesters derived from renewable feedstocks which include vegetable oils and animal fats [1]. It draws a lot consideration as an option fuel because it isInt. J. Mol. Sci. 2013,biodegradable, non-toxic, and can be applied straight or blended with traditional petrodiesel in unmodified diesel engines. As compared to petrodiesel, biodiesel has a higher cetane quantity, no aromatics, practically no sulfur, and consists of ten ?1 oxygen by weight [2], hence decreasing the emission of carbon monoxide, hydrocarbon, and particulate matter inside the exhaust gas. Biodiesel is generally made by transesterification of virgin vegetable oils with quick chain alcohols applying alkaline catalysts. Nonetheless, the process needs high good quality food-grade vegetable oils with low degree of free fatty acids (FFA) to prevent saponification, which results in low biodiesel conversion and causes difficulties inside the separation of glycerol. A major hurdle inside the commercialization of biodiesel is its higher manufacturing cost, primarily from virgin vegetable oils. Thus, waste cooking oil (WCO) has turn into a promising feedstock for biodiesel production. WCO is significantly significantly less high priced than pure vegetable oils from soybean, sunflower or canola, and it is actually presently utilised as animal feed or is basically discarded. Nevertheless, the harmful compounds of WCO could return into the meals chain when utilised as animal feed plus the disposal of WCO normally results in contamination of recipient waters [3]. Also to the benefit of reduced cost, utilization of WCO as a feedstock for biodiesel production partly solves the problem of disposing WCO. Biodiesel attained out of animal fat and WCO has a lower value than those derived from refined vegetable oils and fossil diesel [4].1823379-92-5 Purity Lipases (E.Formula of 1421473-07-5 C.PMID:33478300 three.1.1.three) are capable of catalyzing a variety of reactions which include hydrolysis, alcoholysis, esterification, transesterification, and hence are extensively applied in sector [5]. Biodiesel also can be synthesized through lipase-catalyzed transesterification; the procedure produces high purity items and enables easy separation on the glycerol byproduct [6]. The enzymatic process is compatible with low top quality feedstocks with higher levels of FFA. In addition, it demands much less power input due to lower reaction temperature than the akali-catalyzed course of action. Even so, there has been really limited commercial success as a result of high expense of lipases. A single prevalent approach for decreasing the price of lipases is usually to recycle the biocatalyst via immobilization [7]. Numerous immobilization methods have already been applied to lipases for the production of biodiesel. Help supplies for example Celite [8], acrylic resin [9], and ion exchange resins [10,11] were made use of for attaching lipases through adsorption. The adsorption technique is easy to execute, however it suffers from desorption of enzyme molecules. Immobilization by way of covalent bonds has the benefit of minimal enzyme leakage, and support like electrospun polyacrylonitrile was reported [12]. Cross-linked enzyme aggregates can be formed by implies of bifunctional or multifunctional reagents for instance glutaraldehyde [13]. Lipases might be also entrapped in polymeric matrix like phyllosilicate sol-gel [14] and silica gels [15] or encapsulated in silica aerogel [.