Processing and Characterization of Cotton Seed Methyl Ester

Research Article

Austin Chem Eng. 2015; 2(2): 1020.

Processing and Characterization of Cotton Seed Methyl Ester

Gopal BV¹*, Sridevi V ², Sarma AJN³ and Rao PV4

¹Research Scholar, Department of Chemical Engineering, Andhra University, India

²Professor, Department of Chemical Engineering, Andhra University, India

³Post-Graduate Student, Department of Chemical Engineering, Andhra University, India

4Associate Professor, Department of Mechanical Engineering, Andhra University, India

*Corresponding author: B Venu Gopal, Department of Chemical Engineering, Andhra University, India

Received: November 16, 2015; Accepted: November 30, 2015; Published: December 01, 2015


Production of cotton seed methyl ester (biodiesel) from non-edible vegetable oils for diesel substitute is particularly important because of the decreasing trend of economical oil reserves, environmental problems caused due to fossil fuel use and the high price of petroleum products in the international market. Present work reports an optimized protocol for the production of methyl ester through alkaline catalyzed transesterification of cotton seed oil. Three principal variables, molar ratio of methanol to oil, amount of catalyst, and reaction temperature affecting the yield of alkaline catalyzed production of methyl ester from cotton seed oil were investigated. The reaction variables used were methanol/oil molar ratio (4:1–8:1), catalyst concentration (0.5–2%), temperature (50–70°C), and catalyst type. The rate of transesterification in a batch reactor increased with temperature up to 60°C. The methyl ester with best yield and quality was produced with cotton seed methyl ester at 6:1 mole ratio and 1 wt% of catalyst (NaOH) the yield was 93 %. It was noted that greater or lower the concentration of NaOH or methanol than the optimal values, the reaction either fully occur or lead to soap formation. Physical and chemical properties of cotton seed methyl ester are compared to that of petroleum diesel. The produced methyl ester was found to exhibit fuel properties within the limits prescribed by the American Standards for Testing Material (ASTM) and European EN standards.

Keywords: Cotton seed oil; Methyl ester; Physicochemical properties; Renewable sources; Transesterification


Biodiesel is an alternative fuel for diesel engines that is produced by chemically reacting a vegetable oil or animal fat with an alcohol such as methanol [1,2,3]. The reaction requires a catalyst, usually a strong base, such as sodium or potassium hydroxide, and produces new chemical compounds called methyl esters. It is these esters that have come to be known as biodiesel. Because its primary feedstock is a vegetable oil or animal fat, biodiesel is generally considered to be renewable [4,5]. Since the carbon in the oil or fat originated mostly from carbon dioxide in the air, biodiesel is considered to contribute much less to global warming than fossil fuels [4]. Diesel engines operated on biodiesel have lower emissions of carbon monoxide, unburned hydrocarbons, particulate matter, and air toxics than when operated on petroleum based diesel fuel [6,7]. The use of edible vegetable oils and animal fats for biodiesel production has recently been of great concern because they compete with food materials. As the demand for vegetable oils for food has increased tremendously in recent years, it is impossible to justify the use of these oils for fuel use purposes such as biodiesel production. Moreover, these oils could be more expensive to use as fuel. Hence, the contribution of non-edible oils such as cottonseed and coconut will be significant as a non-edible plant oil source for biodiesel production [8]. In recent years, there exist active researches on biodiesel production from cottonseed oil of which the conversion between 72% and 94% was obtained by enzyme catalyzed transesterification when the refined cottonseed oil reacted with short-chain primary and secondary alcohols [9,10,11]. The application of solid acid catalysts on cottonseed oil transesterification. The results showed that the yield of methyl ester was above 90% after 8 hours of reaction [12]. In Contrast, transesterifying cottonseed oil by microwave irradiation could produce a biodiesel yield in the range of 89.5-92.7% [13]. No matter what kind of catalysts or approaches were applied, all those studies aimed to produce high yield of biodiesel by optimized reaction conditions based on optimized parameters in terms of alcohol/oil molar ratio, catalyst concentration, reaction temperature, and time. However, nearly in all studied cases, there existed complex interactions among the variables that remarkably affected the biodiesel yield [14,15,16].

The most common way of producing biodiesel is the transesterification of vegetable oils. The methyl ester produced by transesterification of vegetable oil has a high cetane number, low viscosity and improved heating value compared to those of pure vegetable oil which results in shorter ignition delay and longer combustion duration and hence low particulate emissions [17]. Its use results in the minimization of carbon deposits on injector nozzles [18]. The main Objectives of the work are to study the processing parameters which effecting the production yield of biodiesel from cotton seed oil and to evaluate the physical and chemical characteristics of biodiesel produced.

Materials and Methodology

In the present investigation experimental work was carried out in two levels. In the first level process development studies using cotton seed vegetable oil were undertaken. In the second level biodiesel samples obtained in the experimental work were evaluated.

The process development studies are divided into three steps:

1. Preconditioning of oil

2. Transesterification reaction

3. Purification of products

The procedure of biodiesel from cotton seed oil is from flowchart shown in (Figure 1).