Ultrasonication Assisted Production of Biodiesel from Sunflower Oil by Using CuO: Mg Heterogeneous Nanocatalyst

Biodiesel is a clean, renewable, biodegradable, eco-friendly and alternative fuel used in the diesel engine. The present work was carried out at constant operational conditions such as methanol to oil molar ratio 6:1, catalyst concentration 0.25%, 30 minute reaction time and the reaction temperature at 60°C. Biodiesel was synthesized by transesterification of sunflower oil (SFO) with methanol, using CuO: Mgas nanocatalyst. This nanocatalyst was prepared by quick precipitation method. The biodiesel yield of 71.78% was achieved under reaction condition. The presence of methyl ester groups at the produced biodiesel was confirmed using the Gas Chromatography-Mass Spectrometry (GC-MS). The FAME conversion yield up to 82.83 % could be obtained under the operating conditions.


INTRODUCTION
The need for a renewable fuel source grows due to the ever-increasing demand for energy and depletion of fossil fuels. There are many options in this area, but unlike other energy sources, biofuels such as biodiesel have the capability of providing a fuel source perfectly suited to existingdiesel engines [1].Biodiesel is a clean, renewable, biodegradable, nontoxic produced from various oil feed stocks, including edible and non-edible vegetable oils, animal fats, microalgae and even from restaurant waste oils [2][3][4].
The most common way to produce biodiesel is the transesterification method, which refers to a catalyzed chemical reaction involving vegetable oil and alcohol to yield fatty acid alkyl esters (biodiesel) and glycerol. A catalyst is usually used to improve the reaction rate and the yield [5].Recent research demonstrated that the use of different nanomaterials as a catalyst can be considered as an efficient way for the production of biodiesel [6,7]. The catalysts after the reaction maintain their physical and chemical properties, and it can be reused without any loss in activity with the maximum yield [8].
Recent studies were focused more on ultrasonic-assisted method as it is one of the simplest methods and capable way to reduce reaction time compared to the conventional stirred procedure for the production of biodiesel [9].Most researchers believe that the effect of ultrasonication on enhancing transesterification lies mainly in intensifying the mixing of the immiscible methanol and triglyceride phases [10][11][12].It was demonstrated that ultrasonication also enhances heterogeneous catalyst activities in transesterification of plant oils [13]. In this study, the ultrasonic-assisted catalytic transesterification using CuO: Mg nano catalyst was studied for sunflower oil.GC/MS analysis was studied accurately to identify and confirm the presence of fatty acid methyl esters.

Materials
Methanol, Copper Acetate [Cu (CH 3 COO) 2 ], Magnesium chloride (MgCl 2 ), PVP and Sodium hydroxide (NaOH), were purchased from Merck Specialties Private Ltd, India. The Sunflower oil samples were purchased from local market of Trichy.

2.2.Preparation of CuO: Mg Nanocatalyst
In this quick precipitation method two separate solutions, aqueous Copper acetate (5M) and aqueous NaOH were used separately.About 1 wt. % of PVP is added to copper acetate solution and the NaOH solution is added drop by drop and the stirring continued until the formation of a suspension. In order to dope, the dopant solution (MgCl 2 ) was added to the same precursor solution at 5wt % concentration.Afterthe completion of reaction, a large amount of black precipitate was formed which were collected by centrifugation dried in an oven for 3 hours.
The studies such asXRD,UV-Vis spectroscopy, FE-SEM and EDX analysis which were confirming the formation of CuO: Mg nano particles.(The characterization studies arenot included in this paper since which has already published).

BiodieselProduction by UltrasonicationMethod
For ultrasonic-assisted transesterification procedure, the 60 ml of sunflower oil was added to the premixed solution of methanol and catalysts (CuO: Mg). The mixture was then subjected to the ultra-sonication under a matrix of conditions: methanol to oil molar ratio of 6:1; catalyst concentrations in 0.25 wt. % of oil; at a time (30 min) with constant reaction temperature.
The product formed was then allowed to settle overnight to enhance separation in a separating funnel. The remaining water and unreacted methanol in the methyl esters were removed by heating at 110 o C until the bubbles disappeared. The biodiesel was then collected and stored in an air-tight bottle at room temperature.  Fig.1 displays the color of synthesized SFO biodiesel by using CuO: Mg nano catalyst.

GC-MS Analysis
The synthesized biofuel products were examined by gas chromatography to determine the composition of fatty acid methyl esters (Fig.2). Each peak corresponds to a fatty acid methyl ester component of SFO and was identified using the library match software. The identities of the FAME were verified by comparing the respective retention time data with mass spectroscopic analysis.

Fig.3GC Chromatogram of FAMEs of SFO biodiesel
The chemical composition of GC-MS result for SFO pure oil and biodiesel is briefly given in the table1&2 respectively. The fatty acid profiles showed that the major compound present in the SFO is 9, 12-Octadecadienoic acid. The FAME is mainly of 9-Octadecenoic acid, methyl ester. The maximum FAME conversion calculated is 82.83 % in the ultrasonicator based method.  Other FAME components ( total)

28.54
Total FAME conversion

3.3.Biodiesel Yield (%)
The volume of biodiesel product was first measured and the volume yield percentage was calculated according to the following: The total yield from the biodiesel was finally calculated according to the formula: [14] % = % ! * The yield of 71.78 % is obtained under the operating conditions.

CONCLUSION
The production of biofuel from sunflower oil with methanol was successfully synthesized using CuO: Mg nanoparticle as a heterogeneous catalyst by ultrasonication methods. This nanocatalyst was prepared by quick precipitation method. The biodiesel yield of 71.78% was achieved under reaction condition. The presence of FAME groups in the produced biofuel was confirmed using the GC-MS analysis.The FAME conversion yield up to 82.83 % could be obtained under reaction conditions.Hence the biodiesel, synthesized from the above given studies can be considered as a better source of energy and fuel over the conventional diesel.