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Islam et al / Physical Chemistry 19(1) (2019) 23-27

Evaluation of Wild Olive Plant Oil as a Potential Feedstock for BiodieselProduction

using Homogeneous Catalyst

Muhammad Noman, Muhammad Farooq*, Muhammad Rahim, Juma Sahar, Fouzia Perveen, Ain-Ul Shams, Dur Muhammad, Ghazala Abid

National Centre of Excellence in Physical Chemistry University of Peshawar, Pakistan. 25120

*Corresponding author E-mail: Muhammadnomanktk740@gmail.com A R T I C L E I N F O A B S T R A C T Article type The rapid increase in the industrialization and motorization are the major

cause of environmental pollution and diminishing petroleum reservoir in the world. Therefore, it is necessary to find out some sustainable and renewable sources of energy for smooth economic growth and development. Biodiesel, being a renewable and environmental friendly characteristic, is considered one of the most suitable alternative energy source to substitute petroleum derived diesel in the near future. In the present study, wild olive plant oil has been employed in biodiesel production at selected conditions in the presence of NaOH as homogeneous catalyst and methanol to study its feasibility for sustainable biodiesel production. The results showed that NaOH successfully transestrified the olive oil at selected reaction parameters and provided maximum biodiesel yield of 97wt% at methanol to oil molar ratio of 9:1, reaction temperature of 650C, catalyst loading of 0.6wt% in reaction time of one hour. Moreover, the various physical and chemical properties of the synthesized biodiesel were in the range as prescribed by international standards of ASTM and EN. Thus, the present study clearly portrayed that the wild olive oil has the immense potential to be used as a sustainable feedstock for profitable biodiesel production in Pakistan.

Research article

History

Received 09-11-2018

Accepted 29-05-2019

October 2019 Issue 1

Keywords

Bio diesel

Olive plant oil

NaOH catalyst

Transestrification

© 2019 NCEPC, University of Peshawar: All rights reserved

Cite This Article As: Muhammad Noman, Muhammad Farooq*,Muhammad Rahim, Juma Sahar,Fouzia Perveen, AinUl Shams,Dur Muhammad, Ghazala AbidEvaluation of Wild Olive Plant Oil as a Potential Feedstock for BiodieselProduction using Homogeneous Catalyst. Physical Chemistry 19(1) (2019) 23-27

INTRODUCTION Worldwide, the only main energy reservoir is the fossils fuels, which unfortunately are now limited because of the rapid increase in world population with increasing industrialization and motorization.[1] In this scenario, the rapid dwindling of petroleum reservoir is one of the

biggest problems nowadays, to face such a situation, an alternate source of energy that is renewable, environmental friendly, nontoxic and socio-economic. Since biodiesels the best choice and has become popular worldwide among all the renewable sources ofenergy,the advantages of biodiesel are their renewability, biodegradability in term of environmental

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benefits, also reducing exhaust emissions and safe handling due tohigh flash point because of these advantages biodiesel industries are now expending globally.[1], [2] In this context, improving the yield and quality of biodiesel, research has been focused to increase the number of available raw material for them but however biodiesel does not pecked such a high popularity among them because of the price per liter.[3]The price of biodiesel can be reduced by using waste material as a feedstock for biodiesel production and also by using byproduct of biodiesel such as glycerol, carbohydrate and bioethanol from vegetable oil, which makes the process more economical for the welfare of society.[4][5][6] Glycerol can also be used for traditional applications (food industries, pharmaceuticals and cosmetics). The recent applications of glycerol are in the field of carbon feedstock in fermentation, polymer, animal feed, surfactants, intermediate and lubricants.[7][8]For biodiesel production various types of processes are usedsuch as the blending pyrolysis micro emulsion and transestrification. Transestrification is the best among these because of their advantages on other processes.[9][10] Chemically, biodiesel are mono alkyl ester that can be produced through the process transestrification of oil with short chain alcohol (ethanol or methanol) in the presence of catalyst.[11][1]The demand for catalysts is increasing to improve the efficiency or to reduce waste production or by reducing energy consumption or increasing the yield of biodiesel and selectivity.[12] The energy demand of most energy intensive sector can be reduced by 20-40% by the chemical industry through the catalyst.[12][13] Recently, both ethanolysis and methanolysis of oil with homogeneous catalyst for biodiesel have been wildly investigated. The criteria for the selection of alcohol are the performance and the cost.[14]Here acid catalyst slow down the rate of reaction and also corrode the equipment’s, that is why we prefer a basic homogeneous catalyst.For commercial biodiesel production, the most widely used method is the base catalyzed Trans esterification process. [15]Currently, the following homogeneous base catalysts (CH3OK, CH3ONa, KOH, NaOH,) used for the production of biodiesel are effective and have proven specialty, such as a smooth reaction condition, high reaction rate and the production of high yield methyl ester. [2][16] In this article, for biodiesel production, we used wild olive plant oil as a feedstock to produce large quantity of biodiesel in Pakistan.[17] Usually, olive oil is not viable to use for biodiesel production due to relatively high price and high value of edible oil. But we selected wild olive seeds as a feedstock for biodiesel production because of high fatty acid contents up to 15% thus olive oil indicate a high amount of methyl ester present in them which are considered to be more suitable for biodiesel engine.[17][18] Further moreover wild olive bitter taste and are not used for edible purposes that are grown in the hilly areas of district Karak and the northern areas of Pakistan. In order to produce high quality biodiesel from wild olive plant oil that are used as a feedstock for the transestrification of biodiesel, which is effected by a number of factors, such as temperature moisture

contents,[19] type of catalyst,[12] free fatty acid contents [1][17]and alcohol oil molar ratio.[11] For maximum conversion of oil into methyl ester, usually maximum alcohol is used. The stoichiometry of complete transestrification requires one mole of triglycerides and three mole of alcohol to give 3 mole of methyl fatty ester and 1 mole of glycerol. Reaction are shown in the figure number 1.[9][16]

This figure shows that the process of transestrification is completed in three consecutive steps including mono, diglycerides intermediate and methyl ester with byproduct of glycerol. After completion of transestrification process, it gives two main products that are glycerol and biodiesel. The biodiesel phase is lighter than glycerol, due to this reason glycerol settled down at the bottom of the vessels, which can easily separate from biodiesel. [20][21] Experimental Chemicals The chemicals used in the current study for the production of biodiesel were methanol [Sigma-Aldrich], NaOH [Sigma-Aldrich], n-hexane [Sigma-Aldrich], and KOH [Merck]. Equipment’s Electric grinder , Soxhlet extractor, condenser, 200mL round bottom flask, hot plat, magnetic bar, vacuum adopter, distilling head, thermometer, thermometer adopter, three necked round bottom flask, separating funnel, thimble, thistle funnel, balance watch glass and oven. Feedstock collection Wild olive plant oil were used as a feedstock for biodiesel production. The seed of selected plant were collected from the hilly areas of district Karak Saber

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Abad. Wild olive seeds were crushed and then treated with n-hexane in Soxhlet extractor for 3 hour at 1300C.[22] And the oil percentage in this selected plant was 30%.[23] Procedure The transestrification of olive plant oil was performed in a three necked 250mL round bottom glass reactor fitted with a water cooled condenser and thermometer. The transestrification reaction was performed using methanol and NaOH catalyst under different reaction conditions, such as reaction time, reaction temperature, catalyst amount methanol to oil molar ratio and agitation speed to obtain optimum condition for biodiesel production. The catalyst was dispersed in methanol in order to activate it. After catalyst activation, the required olive plant oil (heated it 1000C for 6 hour prior to the reaction) was added to the reactor and the reaction was carried out under the identified reaction condition..[21][24] After the completion of reaction in the way then transferred to a separating funnel and allowed to stand for 24 hours the bottom layer of (glycerol) was drainedOut and the upper layer consisting of biodiesel (methyl ester) was collected carefully. Finally the biodiesel was dried at 800C in a vacuum oven for 24 hours and stored in an air tight bottle for further investigation. The biodiesel yield was calculated by using this equation.[23]

[Eq 1] Feedstock characterization Determination of Acid Value The acid value (AV) of the Olive oil was determined using the European standard EN14104 method. According to this method, 10 g of oil placed in a 250 mL conical flask were weighed accurately. A 50 mL solvent mixture of 1:1 dehydrated ethanol and diethyl ether was added into the flask and slightly agitated to dissolve the oil sample in the solvent mixture completely. A few drops of phenolphthalein indicator (1%) were added to the mixture of flask and then titrated against 0.1 N standard aqueous solution of KOH with vigorous stirring until a definite pink colour persisted for 10 sec. The acid value (mg KOH per g of oil sample) was calculated according to the following formula:[25][24]

[Eq 2] Where, 56.1 = Molecular weight of KOH (g/mole) N Normality of KOH (mEq/mL) A Volume of the KOH (mL) used for titration W = Mass of the oil sample (g). Determination of Saponification Value

Saponification value is one of the physiochemical property that affect the quality of oil. Saponification number is defined as the amount of alkali required to saponify a definite quantity of oil sample. It is expressed as, milligrams of KOH required to saponify 1 g of the oil sample. Saponification process involves the breaking down of oil with alkali into glycerol and fatty acids as represented in Eq. 3

[Eq 3]

Saponification value (SV) was determined using the AOCS method Cd 3a-94. According to this method, 2 g of oil was weighed accurately in a 250 mL conical flask. About 25 mL of ethanolic solution of KOH (0.5 N) was added into the flask with constant stirring. About 4 mL of a solvent mixture of 1:1 dehydrated ethanol and diethyl ether was added later to the flask and slightly agitated to dissolve the oil sample in the solvent mixture. The mixture was heated gently for 1 h to saponify the oil according to Equation 3. The mixture was cooled down to room temperature. A few drops of phenolphthalein indicator (1%) were added to the cooled mixture and then titrated against standardized (0.5 N) HCl with vigorous stirring until the pink colour disappeared for at least 30 seconds. Another experiment was performed under similar conditions without adding the oil sample to the mixture. The SV was then calculated according to the following formula.

[Eq 4] Where, B Volume of titrant (mL) used for blank sample (Oil free mixture) S = Volume of titrant (mL) used for sample N Normality of HCl (mEq/mL) 56.1 Molecular weight of KOH (g/mol) W = Mass of the oil sample (g). The average molecular weight of the selected WCO was calculated from the saponification value using following Eq. 3.15 (Zhu et al. 2006).

356.1 1000Average molecular weightSV AV

Where, SV = Saponification value (AOCS method Cd 3a-94) AV = Acid value (European Standard EN 14104) Results and discussion Physicochemical Properties of the selected wild olive oil The quality of oil depends on its physio-chemical properties, such as acid value and saponification value. The various physio-chemical properties of the selected oil were determined as given in the Table .1 The average molecular weight (M) was calculated on the basis of the acid value (AV) and saponification value

56.1Acid value (mg KOH/g of oil) A NW

HeatTriacylglycerol +3KOH Glycerol+3Potassiumsalt of fattyacids

( ) 56.1Saponification value (mg KOH/g of oil) B S NW

[Eq. 5]

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(SV) of wild olive oil obtained using the following correlation as following Eq [6] below.

356.1 1000Average molecular weightSV AV

Table 1. Physicochemical properties of the selected wild olive oil. Property Unit Value Testing

method Acidic value mg

NaOH/ g 4.14 1404

Kinematic viscosity at 400C

Cst 44.2 ASTMD-455

Specific gravity at 300C

0.89 ASTMD-7042

Mean molecular mass

g/mole 948.13 GB 530-85

Saponification value

mg NaOH/g

180.12 AOCS Cd 3a-94

Feedstock Pretreatment Since the acid value of the olive oil is higher than 1 wt. %, olive oil could not be directly transferred into biodiesel using base catalyst. Therefore, the selected oil was first treated with H2SO4 to lower the acid value. The acid value was found to be 0.88 mg KOH/g when 0.5wt% H2SO4 was employed for esterification reaction at 65 °C and 10:1 methanol to oil molar ratio in reaction time of 60 min. Transestrification of selected oil into biodiesel The transestrification reaction of the selected olive oil was performed in three necked flask reactor using NaOH homogeneous catalysts with pre-determined optimized reaction conditions i.e. at methanol to oil molar ratio of 9:1, reaction temperature of 650C, catalyst loading of 0.6wt%, in reaction time of one hour. It was noted that, NaOH successfully transestrified the wild olive oil providing maximum biodiesel yield of 97wt% under the selected reaction parameters.[21][26] The biodiesel yield was determined using the formula given in equation.[25]

Yield (%) = x 100% Physiochemical properties of biodiesel from selected wild olive plant oil Important physicochemical properties of the biodiesel produced from wild olive oil, such as viscosity, density, acid value, flash point, moisture content, calorific value etc. were determined according to the well-established methods. The physicochemical properties of the biodiesel were found to be within the limits set by the ASTM D-6751 and the European Standard EN 14214 (Table 2). This shows that the wild olive plant oil used in this study has the potential to be used in large scale biodiesel production in Pakistan with a suitable catalytic system.[25][26][19]

Table 2. Physicochemical properties of the synthesized biodiesel

Properties Unit ASTM D-6751

EN 14214

Prepared biodiesel

Ester content

% 96.5 96.5 97.91

Density (15 0C)

kg/m3 860-894

860-900

863

Viscosity (400C)

mm2/s 1.9e6.0 3.50-5.00

3.49

Conclusion In the present investigation, oil was successfully extracted from wild olive plant seeds and transestrified to biodiesel using NaOH homogeneous catalyst. Wild olive plant seeds contains sufficient amount of oil, therefore has the immense potential to be used for profitable biodiesel production. The highest biodiesel yield of 97wt% was achieved with methanol to oil molar ratio of 9:1, reaction temperature of 65oC, catalyst loading of 0.6wt% in reaction time of one hour. Furthermore, the physicochemical properties of the synthesized biodiesel were evaluated by following international standard methods. The properties of the synthesized biodiesel meet the requirements as defined by the ASTM and EN.Thus, the use of wild olive oil could open a new sustainable way for benefitable biodiesel technology in Pakistan. Recommendation Further research should be done on the following areas Nowadays, the bio-diesel cost is 1.5 to 3 times higher than the fossil diesel cost because the largest share of production cost of bio-diesel is the feedstock cost. Therefore, biodiesel is not competitive with fossil diesel under the current economic conditions, where the positive externalities, such as impacts on environment, employment, climate changes and trade balance are not reflected in the price mechanism. However, biodiesel can be made from other feedstock of low cost oils and fats such as restaurant waste and animal fats that can be converted into biodiesel. The problem with the processing of these low-cost oils and fats is that they often contain large amounts of free fatty acids (FFA) that cannot be converted into biodiesel using an alkaline catalyst. Further experiments should be done in the laboratories, such as producing the biodiesel from pure or waste vegetable oil and make it undergo under all the additional steps once the transestrification is completed as to get a biodiesel of high quality as for commercial biodiesel. And also further research should be done to use heterogeneous catalyst for biodiesel production. References A. Demirbas, “Progress and recent trends in biodiesel fuels,” Energy Convers. Manag., vol. 50, no. 1, pp. 14–34, 2009.

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