PRODUCTION AND PERFORMANCE APPRAISAL OF BIODIESEL DERIVED FROM USED COOKING OIL ON COMPRESSION IGNITION ENGINE

The present study is concerned with the production of biodiesel produced from used cooking groundnut oils using alkali trans-esterification reaction. Gas chromatography-mass spectrometry (GC-MS) and Fouriertransform infrared spectroscopy (FTIR) analyses were carried out on the biodiesel produced and the presence of methyl esters and their various functional groups were detected. The Physico-chemical properties of the biodiesels produced were also carried out and most of the properties conformed to ASTM standards. The biodiesel samples were tested in a 165FHorizontal Single Cylinder Direct Injection Diesel Engine at Bayero University Kano (BUK), Kano State, Nigeria, investigating parameters such as: Brake power, Specific fuel consumption and Brake mean effective pressure. The exhaust gas was analysed in an NHA-506EN automotive gas analyzer, from Nigerian Institute of Transport Technology, Zaria, Kaduna State, where parameters such as hydrocarbon (HC), nitrogen oxide (NOx), carbon monoxide (CO) and carbon (IV) oxide (CO2) were all analyzed. The results showed that the oil from frying yam yielded 87.5% while that from frying fish yielded 94% and the biodiesels produced conformed to most of the Physico-chemical properties according to the ASTM standards. Also, the engine results demonstrated that there was improved brake power and mean effective pressure but the specific fuel consumptions were higher than that of the control sample. Lastly, the exhaust gas emissions results showed that there were significant reductions in carbon monoxide (CO), nitrogen oxide (NOx), carbon IV oxide (CO2) and hydrocarbon emissions showing us that biodiesel is more eco-friendly.


INTRODUCTION
Insufficient energy is a major factor responsible for the setback of industrialization in developing economies, especially in Nigeria. Recently in Nigeria, pipeline vandalism has been responsible for the decrease in electricity supply with economic hardship. Oil spills, diesel and greenhouse gas emissions are the primary cause of health and environmental challenges in the society (Okere, 2016). Energy shortage across the globe has necessitated the search for a viable and sustainable source (Chang, et al., 2013). According to Roger (2014), diesel fuel and other greenhouse gas emissions are potential causative agents of most chronic diseases such as chronic cancer, heart attack and arrhythmias which often leads to an untimely death. These consist of carbon IV oxides (CO2), carbon II oxides (CO) sulfur IV oxides (SO2), oxides of Nitrogen (NOx) and Polyaromatics Hydrocarbons (PAHs), Ozone (O3) and Particulates Matters (PM). In Nigeria, the rate at which energy demand is increasing is very alarming. To meet this increased demand in energy, alternative energy sources should be researched. A biofuel is a form of fuel derived from plant and animal oils; it can be produced through agricultural and biological processes such as fermentation and anaerobic digestion as a variant from geological processes in the formation of fossil fuel. The common biofuels are mostly ethanol and biodiesel (Roos, 2012). Trans-esterification method has been widely used to produce biodiesel. It is essentially a chemical process where vegetable oils and fats react with alcohol to produce fatty acid alkyl esters and glycerol. The most common catalyst used to enhance the production process is sodium and potassium hydroxide, sodium methylate and methanol (Anita and Dawn, 2010). Methanol offers several advantages over other catalysts such as low cost, ease to react with vegetable oil and the ease at which NaOH dissolves in it. The transesterification method requires a specific molar ratio of alcohol to triglycerides in which 3:1 was widely reported. The ratio can be higher for maximum yield at the expense of other factors (Aydin et al., 2012;Raja et al., 2011). The triglycerides react with alcohol using a particular catalyst under controlled temperature for a certain period. Alkyl esters and glycerin are obtained as the final yield. The alkyl esters are desirable and the glycerin is a byproduct (Jaichandar and Annamalai, 2011). The used cooking oil produced via transesterification was appraised based on some important physico-chemical properties. The most common examples of physicochemical properties of methyl ester are flash point, kinematic viscosity, total sulfur, copper strip corrosion, moisture contents, carbon residue, acid value, total glycerol and distillation profile (Gerpen et al., 2004). Many used cooking oils from restaurants, canteens and street sellers are often dumped into the streets which leads to the pollution of the environments. One of the ways of treating these used oils is by converting them to biodiesel and research is limited in this regard (Kawentar, 2013). Han, F. F. B., & Alrabadi, S. (2018) produced biodiesel from waste cooking oil using a Jordan Zeolite catalyst. A yield of about 95 % was recorded and the properties of the biodiesel conform to the ASTM standard. Jacobson, et al., (2008) assessed the suitability of various catalysts to produce biodiesel from used cooking oil. The yield could reach 98 wt. %. Gashaw, A. and Abile, T. (2014) provided an overview of biodiesel production methods and highlighted some important factors influencing the production of biodiesel. Biodiesel produced from various feedstock has similar properties with the mineral diesel fuel and could serve as a reliable substitute to diesel oil. Recently, liquid fuels like biodiesel obtained from used cooking oil which is mainly produced via the trans-esterification process have been identified as one of the good alternative to mineral diesel. However, the available biodiesel comes mainly from vegetable oils and animal fats, problem exists that the feedstock strongly competes with edible materials and the yield for the non-edible is not appreciable (Gashaw and Abile, 2014). Thus, this research is aimed at utilizing the used cooking oils obtained from household activities to investigate its performance and emissions behaviour in a diesel engine.

MATERIALS [b1]AND METHODS Production of biodiesel
The used cooking oil from frying yam and the used cooking oil from frying fish were bought from NIHARI restaurant Samaru Branch; biodiesels were produced from each sample through an alkali transesterification reaction. A mass of (1.44 g[b2][WU3]) hydroxide (NaOH) was added to 99 ml of methanol and were both kept at a temperature of 60 0 C before been stirred with a hot plate and a magnetic stirrer for about an hour then poured into a separating funnel (Kaisan et al., 2017 a.). After three hours when no clear separation occurred, the mixture was left for another 24-hours, two layers were formed: glycerol and biodiesel (Zhang et al., 2003). The washing process was then commenced by introducing water to the mixture until the biodiesel was completely separated and bottled in a well labeled bottle termed sample A for the biodiesel produced from used cooking oil for frying yam. The same procedure was carried out for the used cooking oil from frying fish and the biodiesel gotten was termed as sample B. Plate 1 and 2 [H4]depicts the biodiesel production process. the quantification of fatty acid methyl ester functional group in the produced biodiesel. Also, the FTIR was carried out at the Multi-User Laboratory, Department of Chemistry, Ahmadu Bello University Zaria using 5977B MSD CARY 630 FTIR equipment.
[b6] Free fatty acid content (FFA) Free fatty acid is defined as the percentage of fatty acid of specified molecular weight. The fatty acid is expressed as a milliliter of sodium hydroxide solution of specified normality, which will neutralize the fatty acid in 100 g of test oil sample. The Free fatty acid is a direct function of acid value. The acid number and the FFA of the samples were determined. The acid value were calculated from equation (1[H7]) below as stated by Kaisan et al., (2017 a[b8]) and Kaisan et al., 2014. Acid value =

5.61
(1) Where T = volume in ml of 0.5M NaOH required for titration; W = weight in gram for sample taken. The FFA is half of the acid value. The FFA value for sample A was 2.2, while that of sample was 0.8.

Blending
The blending of the biodiesel fuels produced to pure fossil diesel fuel was done in the ratio of 20:80 and the biodiesel fuel and pure fossil diesel fuel samples were kept for control purposes. The biodiesel blend from sample A was denoted as sample A B20 and the biodiesel blend from sample B was denoted as sample B B20 while the pure biodiesel sample from used oil from frying yam was denoted as sample A B100 and the pure biodiesel sample from used oil from frying fish was denoted as sample B, B100 and finally, the pure fossil diesel was denoted as B0.

Determination of physico-chemical properties of the fuel samples
The following properties were determined in accordance to the ASTM D6571 standard for the biodiesel produced from the used cooking oils; The calorific value We used bomb calorimeter to note the calorific value of the biodiesel. A quantified amount of the fuel was placed in the crucible. The crucible was then placed over a ring and a fine magnesium wire touching the fuel sample was stretched across the electrodes. The lid was firmly screwed on and O2 at 25 atm pressure was contained in the bomb. Thereafter, the initial temperature was noted. A battery source of 6 V was connected to the electrodes thereby completing the circuit. The source was then put on, the fuel in the crucible burnt with heat released. The heat released raised the temperature of the water, and the maximum temperature realized was noted (Kaisan et al., 2017 a).

Cetane number
A portable cetane/octane meter was used to determine the cetane number of the fuel based on ASTM D613 guideline. This approach was utilized to ascertain the fuel cetane number rating. The meter scale ranges from 0 -100 (Kaisan et al., 2017a[b9]).

Flash point
The flash point of the biodiesel was determined by the ASTM D93 method using a Pensky -Martens closed-cup tester. The determination of the flash point of biodiesel was done in a temperature range of 60 to 190 0 C with an automated Pensky-Martens closed-cup apparatus according to the standard method of testing flash point. The flash point determination was carried out by heating a sample of the fuel in a stirred container and passing a flame over the surface of the liquid (Kaisan et al., 2017 a).

Kinematic viscosity
The kinematic viscosity of the fuel samples was determined in accordance with the ASTM D445 standard. This will involve using a calibrated Viscometer with a calibration constant of 0.1057 to determine the viscosity at 40 0 C.

Specific gravity
To measure the specific gravity of the fuel, a Fisher brand hydrometer (size 0.795-0.910, accuracy 0.001) was used. The procedure adopted was in accordance with Kaisan et al., (2017 a[b10]).

Cloud point
The cloud point was determined in accordance with the ASTM D2500 standard. This method necessitate that the fuel be transparent in layers of 40 mm thickness This test method covers only petroleum products and biodiesel fuels that are transparent in layers 40mm in thickness, and the cloud point value be less than 49 0 C.

Pour point
The pour point was determined in accordance with the ASTM D97 standard method. The summary of some standard code requirements and methods for testing these properties are listed according to American Society for Testing and Materials, ASTM D 6751 in Table 1.0 (Gerpen et al., 2004). Report in 0 C ASTM D 97 (Gerpen et al., 2004) Engine test and exhaust gas analysis Some parameters of the engine performance such as: brake specific fuel consumption, brake power, brake thermal efficiency and exhaust gas temperature as well as the emission characteristics were investigated in a horizontal single cylinder direct injection diesel engine run on biodiesel fuel made from used cooking oils in accordance with Kaisan et al.,(2017 b) method. The engine was tested under full loading conditions at varying torques of 10 N-m, 6 N-m and 2 N-m for each of the blends. The exhaust gas analysis was achieved by using the NHA-506EN automotive gas analyzer, the exhaust gas was passed into the analyzer through a probe link to the condensation trap and to the particulate filter where the gas particles were removed before they were passed into the analyzer's sensor chamber where the result values of; carbon dioxide CO2, carbon monoxide CO, nitrogen oxide NOx and hydrocarbon were recorded. Engine performance parameters Several factors play an important role in the performance of an engine, hence an engine is selected based on certain criteria but the considerations often being its power/speed characteristics. The performance of an engine can be determined if some characteristics or parameters of such engines can be evaluated. Hence, if some of these parameters are known, there will be an opportunity to compare the performance of an engine type to the other. The engine parameters are being obtained by measuring the qualities concerned while the results are mostly represented in the form of performance curves (Adeyemo et al., 1998). In this literature, the major parameters considered were: brake power, brake mean effective pressure, thermal efficiency, brake thermal efficiency, specific fuel consumption and diesel engine emissions. The expressions for these parameters are given below: -Brake power is mathematically given by Eastop and McConkey, (2009) Where, Torque (T) is given as: (3) Where T = Torque, in Newton meter (Nm), N = rotational speed (rpm), bP = brake power (kW), W = Load on dynamometer power (N), R = arm radius of the dynamometer power (m). Brake mean effective pressure (Bpmef) is given by Eastop and McConkey, (2009) as: Bpmef = bP60/LANK (4) Where bP = Brake Power (W), A = Area of the piston (m 2 ), N = Rotational Speed (rpm), K=Number of Cylinders, L = Stroke length (m) -Brake thermal efficiency (ȠmbTh) is given by Kumar, (2013) as: ȠmbTh = bP/mf x Qnet,v (5) Where mf = fuel consumption rate (kg/s or kg/hr), Qnet,v = net calorific value of the fuel (kJ/kg), bP=brake power (kW) Specific fuel consumption (SFC) is given by (Kumar, 2013) as: SFC = mf/bP (6) Where SFC = (kg/kWhr), Mf = fuel consumption rate (kg/hr)

RESULTS AND DISCUSSIONS Gas chromatography and mass spectroscopy (GC-MS) results
The results of methyl esters percentage contents of the biodiesel products were analyzed by the Gas Chromatrography and Mass Spectroscopy (GC-MS) of the biodiesel produced from used cooking oil from frying yam as "sample A" and used cooking oil from frying fish as "sample B". The interpretation of the peaks of the chromatogram was given in figures 1 [H12]and 2, paying more attention to the methyl esters present in each chromatogram only.  figure 1 indicate that, the most abundant ester in Sample A is mono saturated methyl octadecanoate. It is an important compound responsible for the stability of the biodiesel, this is because, a higher degree of unsaturation in the fatty acid methyl esters limits its suitability for use as a fuel due to high polymerization tendency, which is caused by peroxidation (Bamgboye and Hensen, 2008). The esters present in Sample A is similar to that of the work of Kaisan et al., (2017 b). Sample B methyl ester From figure 2, the methyl ester composition of biodiesel produced from Sample B confirmed the presence of Pentadecanoic acid, 14-methyl-methyl ester (C17H34O2), 9-Octadecenoic acid (Z)-, methyl ester (C19H36O2), Heptadecanoic acid, 16-methyl-, methyl ester (C19H38O2), Methyl 9eicosenoate (C21H40O2) and Methyl 11-docosenoate (C23H44O2). Their respective percentages are: 37.87%, 37.87%, 13.40%, 1.96% and 4.76%. The profile shows that, Pentadecanoic acid, 14-methyl-methyl ester (C17H34O2) and 9-Octadecenoic acid methyl ester (C19H36O2) are the predominant compounds in the mixture having the highest percentages of 37.87%. The results in figure 2 [H14]indicate that, the most abundant ester in Sample B is mono saturated methyl octadecanoate. It is a very good compound that has the tendency of assigning stability to the biodiesel, this is because, a higher degree of unsaturation in the fatty acid methyl esters limits its suitability for use as a fuel due to high polymerization tendency, which is caused by peroxidation (Bamgboye and Hensen, 2008). The results of our findings is in line with the work of Kaisan et al., (2017 b).

Fourier transform infrared spectroscopy (FTIR) analysis resul[b15]t[WU16]s
The FTIR analysis results of the two samples were discussed in this section.  The results of the pour points indicate that they have good cold flow characteristics which are in line with the work of Encinar, et al. (2007) and Kaisan et al. (2017a).

PRODUCTION AND PERFORMANCE APPRAISAL … Suleiman et al
[b21]

Figure 8: Pour points of different biodiesel samples Cloud point
The cloud point is the temperature at which wax crystals first stat to form in a fuel. Figure 9 shows the cloud points for the biodiesel samples and it can be deduced that all the samples conform to the ASTM range. All the biodiesel samples have very low cloud point of below 0 0 C, which is similar to the work of Kaisan et al. (2017a).  Figure 10 shows the different cetane numbers of the biodiesel samples. All the samples considered conforming to the ASTM standards. The results are similar to that of Encinar et al. (2007) and Kaisan et al. (2017a).
[b23] Figure 10: Cetane number of different biodiesel samples Engine performance results Brake power Figures 11, 12 and 13 depict the brake powers of the biodiesel samples. A similar experiment was reported by Kaisan et al. (2017b) whose result showed that at a speed of 1000 rpm the blend from Jatropha and diesel (B10) had the maximum brake power. From the experimental results herein presented, at a Torque of 10 N-m, the maximum brake power was that of sample A. generally, the two biodiesel samples have brake power values higher than that of the pure fossil diesel. This finding agrees with that of Anitha and Dawn, (2010). diesel. It can be seen that pure fossil diesel has a better fuel consumption rate. Also, sample A displays a good consumption rate similar to that of the fossil diesel at torques 10 and 8 N-m. The result is similar to that of Sudhir et al. (2007).
[b27] Figure Kaisan et al. (2017a) and this is as a result of the brake powers.

CONCLUSIONS
After a carefully carried out research, conclusions were drawn that the biodiesels produced from the transesterification of used cooking oil from frying yam which yielded 87.5% and used cooking oil from frying fish which yielded 94% are viable sources of renewable energy because the trans-esterified used cooking oils met the necessary criteria for standard biodiesel as defined by the American Society for Testing and Materials ASTM D6751. It is also important to state the fact that the  biodiesels produced from used cooking oils conform to most of the physicochemical properties standards and related past works.
Although the performance of the biodiesels produced from used cooking oils on a 165 F horizontal single-cylinder directinjection engine varied at different torques generally had a good brake power, better brake mean effective pressure but the specific fuel consumptions were higher than that of the pure fossil diesel especially that of the biodiesel produced from used cooking oil from frying yam which was termed as sample A. Also, for the exhaust gas analysis carried out on the biodiesels from used cooking oils, the biodiesel produced from used cooking oil from frying yam demonstrated a higher value in terms of carbon monoxide (CO), nitrogen oxide (NOx), carbon IV oxide (CO2) and hydrocarbon emissions while the biodiesel produced from used cooking oil from frying fish termed as sample B generally showed a reduction in values in terms of carbon monoxide (CO), nitrogen oxide (NOx), carbon IV oxide (CO2) and hydrocarbon emissions compared to sample A and the pure fossil diesel. Lastly, it can be seen that the biodiesel produced from used cooking oil from frying fish had a higher yield than the biodiesel produced from used cooking oil from frying yam and is generally better than the fossil diesel because it's environmentally friendly.