Development of Waste Cooking Oil Methyl Esteras Potential Electrical Insulating Fluid for Power Transformer

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DEVELOPMENT OF WASTE COOKING OIL METHYL ESTERAS POTENTIAL ELECTRICAL INSULATING FLUID FOR POWER TRANSFORMER

Imran Sutan Chairul, Norazhar Abu Bakar, Md Nazri Othman, Sharin Ab Ghani and Muhammad Nazori Deraman High Voltage Engineering Research Laboratory, Centre for Robotics and Industrial Automation, Fakulti Kejuruteraan Elektrik, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, Durian Tunggal, Melaka, Malaysia Email: [email protected]

ABSTRACT Due to toxicity and non-biodegradability of petroleum-derived mineral insulating oil, the use of vegetable-based oils such natural esters as insulating liquid is on grow. Although natural esters have higher flash point compared to mineral insulating oil, its high viscosity is not suitable for existing distribution transformer with natural cooling system. Thus, low- viscosity esters derived from various vegetable-based oils have been developed. In this study, waste cooking oil methyl ester (WCOME) is proposed as potential low-viscosity insulating fluid for transformer. Waste cooking oil (WCO) is cheaper vegetable-based oil relative to crude vegetable oil. It is also abundantly available as 50,000 tonnes were reported being produced in Malaysia each year. WCOME is produced via catalysed transesterification reaction between WCO and methanol usingpotassium hydroxide (KOH). The physical (density, flash point, pour point, viscosity), chemical (water content, acidity) and electrical (breakdown voltage) properties of WCOME are presented and discussed. Results indicated that transesterification reaction produced a low viscosity WCOME fluid (14.19 mm2/s) that possessed a dielectric breakdown voltage (BdV) of 30 kV, which is 50% above the IEEE C57.147 BdV’s requirement for new natural ester fluids. Hence, the WCOME has a potential to be used as electrical insulating liquid for transformer.

Keywords: breakdown voltage, low viscosity fluid, waste cooking oil, transesterification, waste cooking oil methyl ester.

INTRODUCTION down voltage of the produced PKOEME insulating oil is Natural ester insulating (NEI) fluids are derived 42.58 kV while its kinematic viscosity is 6.14 mm2/s. from seed oils [1]-[3], therefore the properties of NEI oils Other than that, H. B. H. Sitorus et al. [12] produced are reflects to the fatty acids composition of the NEI jatropha curcas methyl ester oil (JMEO) through based-oil. NEI oils have good dielectric properties [2], neutralization and alkali base catalyzed esterification [4], [5] and can extend the life of cellulose material [6]- reaction followed by water treatment process. The average [8] but it’sviscosity is higher compared to mineral AC breakdown voltage and kinematic viscosity for JMEO insulating oil. Thus, NEI’s required modification to lower are 87 kV and 10.45 mm2/s. respectively. Other its viscosity such as through chemical modification [3]for researchers, M.C. Menkiti et al.[13] produced a modified application upon existing operated distribution terminalia catappa kernel oil (MTCKOc) through acid transformer. catalyzed esterification followed by base catalyzed Several researchers had proposed esterification transesterification reaction. As for oxidation prevention, reaction method to reduce the viscosity of an ester oil. P. acetic acid (AA) and citric acid (CA) additives were Thomas et al. [9] developed a dielectric liquid from added into MTCKOc, thus creating two more varieties of karanji oil. The oil was esterified with methanol and insulating liquid; (1) MTCKOc blended with 0.2% AA is refluxed for 8 to10 hours using a base catalyst. Methyl labeled as MTCKOd while (2) MTCKOc blended with ester of karanji oil (MEKO) produced from this 0.15% AA and CA is named MTCKOe. The dielectric esterification was then refined by passing it through strength for MTCKOc, MTCKOd and MTCKOe are 33.95, alumina and earth material. As results, MEKO properties 41.08 and 48.55 kV respectively while the viscosity is obtained were 65 kV for electric strength and 8 mm2/s for 14.1, 11.84 and 10.29 mm2/s in the same order. The kinematic viscosity. On the other hand, Y. Bertrand and P. physicochemical and electrical properties of the reported Lauzevis [10]produced a low viscosity insulating liquid modified ester oils is tabulated as in Table-1. (LVIL) for distribution transformers by using a mixture of As per author’s knowledge, although efforts on oleic rapeseed oil, fatty mono-esters and 0.3% 2, 6-ditert- developing a low viscosity insulating fluid from butyl-p-cresol (DBPC). The fatty mono-esters were vegetable-based oil have been reported, a survey of produced via transesterification reaction between rapeseed literatures showed that there is no work have been done oil and 2-ethyl-1-hexanol. The breakdown voltage and thus far regarding the use of waste cooking oil (WCO) as kinematic viscosity of the developed LVIL are 74 kV and based-liquid for a low viscosity insulating oil. Therefore, 17 mm2/s respectively. Alternatively, A. A. Abdelmalik et this paper presents waste cooking oil methyl ester al. [11] synthesized a palm kernal oil epoxy methyl ester (WCOME) as a potential insulating liquid for transformer. (PKOEME) from an epoxidized palm kernel oil through base catalyzed transesterification reaction. The break

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WASTE COOKING OIL processing cost. WCO is also abundantly available since it WCO is obtained after edible vegetable oils were is estimated that 50, 000 tonnes of WCO [16] were being used several times for frying. WCO is selected for this produced in Malaysia annually while European countries study because it is 2 to 3 times cheaper [14] compared to generates approximately up to 10 million tonnes of WCO crude vegetable-based oil [15], which could reduce the each year [17].

Table-1. Properties of modified ester oils.

Reference [9] [10] [11] [12] [13] [13] [13] Property Unit MEKO LVIL PKOEME JMEO MTCKOc MTCKOd MTCKOe Density g/cm3 0.870 0.890 - 0.896 0.852 0.840 0.840 Flash point °C 295 175 - 191 255 265 275 Pour point °C - -30 -10 0 -5 -5 -5 Viscosity mm2/s 8 17 6.14 10.45 14.1 11.84 10.29 Water content mg/kg - - - 64.91 1 0.9 0.9 Acidity mg KOH/g - 0.12 - 0.0708 0.857 0.845 0.844 Breakdown voltage kV 65 74 42.58 87 33.95 41.08 48.55

The availability of WCO are due to increment of transesterification should be applied because these food consumption which parallel to the growth of human techniques are independent of % FFA. Other than population [17]. In addition, the use of WCO could choosing an effective technique, there are four (4) mitigate the issues of "competing for food with mankind" parameters that should be controlled [23] to ensure high and "excessive logging of primitive forest for planting yield of the produced esters. The parameters are (1) ratio crops"[18] that raised while using edible and non-edible of alcohol to triglyceride, (2) catalyst concentration vegetable-based oils respectively. (wt%), (3) reaction temperature (°C) and (4) reaction time Environmentally, waste cooking oil discarded (hours). into drain can possibly pollute the water resources and A. V. Tomasevic and S. S. Siler-Marinkovic [19] clogged the sewage system. Thus, by utilizing waste obtained methyl esters from used frying oils through cooking oil, it could reduce water pollution [19] and homogeneous transesterification reaction via alkali reduce the cost of treating sewage [20]. catalyst. It is found that, at 1wt% of potassium hydroxide (KOH), reaction temperature at 25 °C, molar ratio of 6 to TRANSESTERIFICATION 1 between methanol and used frying oil as well as 30 Transesterification reaction is a process to minutes of reaction temperature; the used frying oils were separate fatty acids of triglyceride (vegetable-based oil) sufficiently transesterified. It is also found that methyl that attached to a glycerol, thus forming fatty acid esters esters have much lower viscosities than the used frying and glycerol. A molecular representation of a trans- oils. On the other hand, Y. Wang et al. [24] transesterified esterification reaction is shown in Figure-1 [21]. The fatty WCO producing methyl esters via acid catalyst. The acids of triglyceride are represented as R1, R2 and R3. methyl esters yield was 90% at 4 wt% of sulphuric acid, molar ratio of 20 to 1 between methanol and WCO, 10

CH2-O-CO-R1 CH2-OH R-O-CO-R1 hours and 95 °C of reaction time and temperature Catalyst respectively. Alternatively, F. H. Alhassan et al. [25] CH-O-CO-R2 + 3 ROH CH-OH + R-O-CO-R2 obtained 96.5% methyl ester yield via transesterification

CH2-O-CO-R3 CH2-OH R-O-CO-R3 of used frying oil using solid acid catalyst. The optimum reaction parameters are 3 wt% of ferric–manganese doped Triglyceride Alcohol Glycerol Esters sulphated zirconia nanoparticle solid acid catalyst, 20 to 1 of molar ratio between methanol and used frying oil, 3 Figure-1. Molecular representation of a transesterification reaction [21]. hours of reaction time and 180 °C of reaction temperature. Additionally, the reaction was done at agitation speed of

600rpm. Several techniques of transesterification reaction It can be seen that alkali catalyst via catalyst have been developed [22], [23]. Basically, transesterification required small amount of catalyst, low two (2) type of catalyst are used, either alkalior acid. The selection of an effective technique for transesterification ratio of methanol to oil, low reaction temperature as well reaction is depends on the percentage of free fatty acids as low reaction time compared to acid and solid acid transesterification reaction provided that the %FFA of oil (%FFA) of vegetable-based oil used. This is because an under investigation is less than 5%. Therefore, in this alkali catalyzed transesterification is effective if %FFA is study, WCO with less than 5% of %FFA will be selected less than 5% [22]Otherwise, the acid and solid catalyzed

www.arpnjournals.com whereas transesterification reaction via alkali catalyst will be adapted. Start

METHODOLOGY Methodology adapted in this study is summarized Selection of waste cooking oil in a flow chart, as shown in Figure-2. (WCO): % FFA < 5%

Sample preparation of waste cooking oil Initially, a liter of WCO was filtered through a filter paper via filtration process. The filter paper pore size Transesterification reaction is 0.2µm while the %FFA of the WCO is 1.41%; less than using alkali catalyst: 5%. %FFA can be calculated via WCO's acidity by using potassium hydroxide (KOH) the following equation (1) [26]:

Acidity Waste cooking oil methyl ester %FFA  (1) (WCOME) .1 99

Then, the filtered WCO were heated at 120 °C for 10 minutes to reduce its water content. The low %FFA Physicochemical properties and reduction of water content in WCO are necessary to measurement: (1) density, (2) ensure an effective alkali catalyzed transesterification flash point, (3) pour point, (4) reaction [22]. After that, the WCO were cooled down to viscosity and (5) acidity 60 °C prior to transesterification reaction.

Transesterification reaction Water content measurement In this study, transesterification reaction using alkali catalyst is adapted. Initially, 7g of KOH were dissolved into 250ml of methanol in a 500ml erlenmeyer flask forming a potassium methoxide solution. Next, the Water < 200 cooled down WCO at 60 °C and the potassium methoxide treatment ppm? solution were mixed in a 2L beaker. The mixture then was process stirred for 5 minutes. After that, the 2L beaker were wrapped in aluminium foil and stored in a thermos for 48 hours so that the transesterification reaction could be continued. After 48 hours of reaction, there were 2 layers Breakdown voltage of liquid being formed in the 2L beaker. Top layer was measurement waste cooking oil methyl esters (WCOME) whereas bottom layer was glycerol. There were also excessive methanol and KOH in both layers. End

Figure-2. Flow chart of the methodology adopted in this study.

As methanol and KOH are soluble in water, the top layer WCOME were washed using hot water (>90°C) to discard the excessive methanol and KOH from WCOME. The washing process were repeated six times. Next, the washed WCOME were heated at 120 °C for 10 minutes to reduce its water content followed by being cooled down to room temperature. The cooled WCOME properties were then assessed according to IEEE Guide for Acceptance and Maintenance of Natural Ester Fluids in Transformers (IEEE C57.147).

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Physicochemical and electrical properties Density Density of WCO and WCOME are 0.9136 g/cm3 Physical properties (density, flash point, pour point and 0.8966 g/cm3 respectively as shown in Figure-4. Both and viscosity) values satisfy the density requirement as per IEEE C57. Density, flash point, pour point and viscosity of 147 which is the density should be less than or equal to the oil samples were measured based on ISO 12185, ISO 0.96 g/cm3. 2719, IEC 3016 and ASTM D7042 respectively at a laboratory that accredited to ISO/IEC 17025. All Flash point measurements were done in the best knowledge of the Figure-5 shows the flash point of WCO and personal concern by following very stringent procedures. WCOME. Flash point of WCO is 269 °C whereas the Superior then verified the measurement results as such WCOME is 184 °C. Although these values do not satisfy they were undeniable and disputed. the flash point requirement as per IEEE C57.147 which is the flash point should be more than or equal to 275 °C; Chemical properties (acidity and water content) but both values are above 145 °C; fulfilling the flash point Acidity or total acid number (TAN) was requirement based on ASTM D3487. measured based on the amount of potassium hydroxide (in mg) required to neutralize hydrogen ions (H+) in 1 g of Pour point oil sample. Acidity for all oil samples was measured in Both pour point of WCO and WCOME are -28 accordance with ASTM D974 [27] by using 848 Titrino °C as shown in Figure-6. These values satisfy the pour Plus (Metrohm). Water content of oil sample was point requirement as per IEEE C57. 147 which is the pour determined using a coulometer based on the Karl Fischer point should be less than or equal to -10 °C. titration method. The method is based on the oxidation of sulphur dioxide by iodine in methanolic hydroxide Viscosity solution. Measurement of water content in oil was done Figure-7 shows the viscosity at 40 °C of WCO based on ASTM D1533[28] by using899 Karl Fischer and WCOME the viscosity of WCO is 40.84mm2/s coulometer (Metrohm). whereas WCOME is 14.19 mm2/s. Hence, both values satisfies the viscosity at 40 °C requirement as per IEEE Electrical property (breakdown voltage) C57.147 which is should be less than or equal to 50 Breakdown voltage (BdV)of oil sample was mm2/s. measured according to ASTM D1816[29] by usingOTS60PB Portable Oil Tester (Megger). Two (2) Acidity semi-spherically capped VDE electrodeswith a gap Acidity of WCO is 2.7972 mgKOH/g whereas distance of 1.0 mm was used for the measurement. The WCOME has a lower acidity of 0.2561 mgKOH/g as voltage was increased gradually at a rate of 0.5 kV/s until shown in Figure-8. It is notice that both values do not breakdown occurs. The minimum volume of oil sample is satisfies the acidity requirement of new natural ester 350 ml. In this study, fives (5) BdV measurements were fluids as per IEEE C57. 147 which is the acidity should be performed on each oil samples. less than or equal to 0.06 mg KOH/g.

Water treatment process Water content A low value of BdV primarily indicates the Figure-9 shows the water content of WCO, existence of contaminants[30]such water in a liquid. Thus, WCOME and WCOME (after water treatment). The water a water treatment process on the liquid is necessary so content of WCO is 1,036.5 ppm whereas WCOME is that the measured BdV will reflected the liquid’s ability to 257.6 ppm. On the other hand, the water content of withstand electric stress. Hence, in this study, water WCOME (after water treatment) is 156.4 ppm. As the treatment process on WCOME was done by bubbling water content’s requirement as per IEEE C57.147 is nitrogen gas (N2) [31]into WCOME for 30 minutes. should be less than or equal to 200 ppm; it is notice that only WCOME (after water treatment) fulfilled the water RESULTS content limits. Results in this study are focusing on the appearances, physicochemical and electrical properties of Breakdown voltage WCO and WCOME. The results were assessed according The average BdV of WCO sample is7kV. In to the IEEE C57.147. contrast, the average BdV of WCOME (after water treatment) sample is 30kV as shown in Figure-10. Appearances According to IEEE C57. 147, the acceptable BdV of new Figure 3(a) and 3(c) show colour of WCO and natural ester fluids is should be more than or equal to 20 WCOME respectively. Notice that the colour of WCO is kV. Hence, it is found that WCOME (after water dark brown while WCOME is light brown. On the other treatment) is fulfilled the requirement whereas WCO is hand, Figure-3(b) shows 2 layer of liquids. The top layer not. is WCOME whereas bottom layer is glycerol with both layers consist of KOH and excessive methanol.

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DISCUSSIONS 0.915 The results obtained from the measurements on physicochemical and electrical properties of WCO and 0.91 ) WCOME are summarized in Table-2. 3 As WCO was exposed to repeated frying and 0.905 oxidation processes, the by-product such dissolved decay 0.9 product from these processes can be indicated by darker colour such dark brown as shown in Figure-3(a). 0.895 WCO and WCOME is a vegetable-based oils, Density (g/cm 0.89 hence its composition normally consists five (5) main types of chains. 0.885 WCO WCOME

Figure-4. Density (g/cm3) of WCO and WCOME.

300 250 200 150 100

(a) (b) (c) Flash point (°C ) 50

Figure-3. (a) WCO, (b) layer of raw WCOME (top) and 0 glycerol (bottom), (c) WCOME. WCO WCOME

Figure-5. Flash point (°C) of WCO and WCOME.

0 WCO WCOME -5

-10

-15

-20 Pourpoint (°C ) -25

-30

Figure-6. Pour point (°C) of WCO and WCOME.

The chains are palmitic, stearic, oleic, linoleic, and linolenic [23]. The unsaturated (double bond) alkyl chains esters such oleic and linoleic acids correlates well with the cold flow performance [32]. Therefore, the WCO and WCOME has low pour point.

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Table-2. Physicochemical and electrical properties of WCO and WCOME samples.

Specification for Specification for Property Unit Mineral Insulating Oil Natural Ester Fluids WCO WCOME [33], [34] [30], [35] Density g/cm3 ≤ 0.91 ≤ 0.96 0.9136 0.8966 Flash point °C ≥ 145 ≥ 275 269 184 Pour point °C ≤ -40 ≤ -10 -28 -28 Viscosity mm2/s ≤ 12 ≤ 50 40.84 14.19 Acidity mg KOH/g ≤ 0.03 ≤ 0.06 2.7972 0.2561 Water content mg/kg ≤ 35 ≤ 200 1036.5 156.4a Breakdown voltage kV ≥ 20 ≥ 20 7 30a

a: after water treatment

50 1200 1000

C 40 800

30/s) 600 2 20 400 (mm 200

10 Watercontent (ppm) Viscosity Viscosity at 40° 0 0 WCO WCOME WCOME WCO WCOME (after water

treatment) 2 Figure-7. Viscosity at 40 °C(mm /s) of WCO and WCOME. Figure-9. Water content (ppm) of WCO, WCOME and WCOME (after water treatment).

3 40 2.5 2 30 1.5 20 1 (kV) 10 0.5 Acidity Acidity (mg KOH/g) Breakdown Breakdown voltage 0 0 WCO WCOME (after WCO WCOME water treatment)

Figure-8. Acidity (mg KOH/g) of WCO and WCOME. Figure-10. Breakdown voltage (kV) of WCO and

WCOME (after water treatment).

According to F. Ma and M. A. Hanna[36], transesterification is a sequential reaction. Initially, triglycerides are reduced to diglycerides followed by the diglycerides are reduced to monoglycerides. Finally, the monoglycerides are reduced to fatty acid esters. In this study, the viscosity of WCOME (fatty acid esters) is lower than WCO (triglycerides) by 62.25%. The low viscosity of WCOME might be resulting from the decrement of ester chain length [37] because the glycerol of triglycerides have been discarded thus only fatty acid esters remained. On the other hand, it is expected that the

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WCO show higher viscosity due to oxidation process that Melaka (UTeM) under the grant:(FRGS/1/2017/TK04/ has changed its composition [38]. FKE-CERIA/F00332). The authors amiably thank Ms Nur It can be seen that the acidity difference between Lidiya Muhammad Ridzuan and Ms Siti Nadzirah Binti WCO and WCOME is 2.5411 mgKOH/g, which Norhan from Faculty of Electrical Engineering, UTeM, corresponds to 90.84% difference due to Malaysia for providing assistance on the preparation and transesterification reaction. According to IEEE C57.147, measurements of the materials used in this study. it is found that the acidity of WCOME (2.7972 mg KOH/g) is higher than the prescribed limit for new natural REFERENCES ester fluids which is should be less than or equal to 0.06 mg KOH/g. Fortunately, the acidity of WCOME is within [1] D. Gnanasekaran and V. P. Chavidi. 2018. Chapter 6 suggested limits for continued use of in-service natural Vegetable Oil: An Eco-friendly Liquid Insulator. in ester fluids in oil-immersed transformer which is should Vegetable Oil based Bio-lubricants and Transformer be less than or equal to 0.30 mg KOH/g[30]. Fluids: Applications in Power Plants., Springer. pp. It is notable that the water content of WCO is 1,036.5 ppm. On the other hand, WCOME's water content 101-124. is 257.6 ppm, a reduction of 75.15% relative to the water content of WCO. Alas, both oil samples' water content is [2] I. Fernández, A. Ortiz, F. Delgado, C. Renedo and S. higher than 200 ppm; a maximum limit for new natural Pérez. 2013. Comparative evaluation of alternative ester fluids [30]. Thus, water content of WCOME were fluids for power transformers. Electr. Power Syst. then being reduced via water treatment process producing Res. 98: 58-69. WCOME (after water treatment) with 156.4 ppm of water content, a value below 200 ppm. [3] S. Ab Ghani, N. A. Muhamad, Z. A. Noorden, H. The transesterification reaction and water Zainuddin, N. Abu Bakar and M. A. Talib. 2017. treatment process have resulting in higher BdV of Methods for improving the workability of natural WCOME (after water treatment): 30 kV compared to ester insulating oils in power transformer applications: BdV of WCO: 7 kV). The low BdV of WCO is expected because the WCO has high water content (1,036.5 ppm). A review. Electr. Power Syst. Res. As for WCOME (after water treatment), 30kV is 50% higher than the minimum dielectric breakdown voltage [4] M. Rafiq, Y. Z. Lv, Y. Zhou, K. B. Ma, W. Wang, C. required for new natural ester fluids which is 20 kV[30]. R. Li and Q. Wang. 2015. Use of vegetable oils as Thus, the finding shows the advantage of transformer oils-A review. Renew. Sustain. Energy transesterification reaction in enhancing the dielectric Rev. 52: 308-324. breakdown voltage of oil. [5] M. Rycroft. 2014. Vegetable oil as insulating fluid for CONCLUSIONS transformers. Energize, no. April. pp. 37-40. WCOME was obtained viaalkali catalysed transesterification reaction between methanol and WCO [6] A. A. Abdelmalik, J. C. Fothergill, and S. J. Dodd. using KOH. The reaction resulting in change of oil 2013. Aging of Kraft Paper Insulation in Natural Ester colour; from dark brown (WCO) to light brown (WCOME). It is also found that the reaction has resulting Dielectric Fluid. in 2013 IEEE International to a lower physicochemical property (density, flash point, Conference on Solid Dielectrics, ICSD. pp. 541-544. pour point, viscosity, acidity and water content) of WCOME relative to WCO; the original based-oil used in [7] M. L. Coulibaly, C. Perrier, M. Marugan, and A. the reaction. Water treatment process has resulting the Beroual. 2013. Aging Behavior of Cellulosic WCOME (after water treatment) to have a water content Materials in Presence of Mineral Oil and Ester of 156.4 ppm, an acceptable value according to IEEE Liquids under Various Conditions. IEEE Trans. C57.147. Hence, as the water content is low, it is found Dielectr. Electr. Insul. 20(6): 1971-1976. that the BdV of WCOME (after water treatment) is 30 kV, 50% more than the minimum requirement as per IEEE [8] B. García, T. García, V. Primo, J. C. Burgos and D. C57.106.Based on the results obtained in this study, it can be suggested that the WCOME has a potential to be Urquiza. 2017. Studying the loss of life of natural- insulating fluids for transformers since it helps tackle ester-filled transformer insulation: Impact of moisture issues related to high viscosity of aged NEI oils – on the aging rate of paper. IEEE Electr. Insul. Mag. however, much work is needed to reduce the acidity value 33(1): 15-23. of WCOME. [9] P. Thomas, S. Sridhar and K. R. Krishnaswamy. ACKNOWLEDGEMENT 1995. Dielectric Liquid from Vegetable Origin-Indian The authors gratefully acknowledge the financial Beech Oil. in International Symposium on Electrical support provided by the Ministry of Higher Education Insulating Materials. pp. 507-510. Malaysia (MoHE) and Universiti Teknikal Malaysia

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[10] Y. Bertrand and P. Lauzevis. 2013. Development of a optimization and quality assessment of biodiesel from Low Viscosity Insulating Liquid Based on Natural waste vegetable oil. Int. J. Environ. Sci. Technol. Esters for Distribution Transformers. in CIRED 22nd 5(1): 75-82. International Conference on Electricity Distribution. pp. 1-4. [21] P. Felizardo, M. J. N. Correia, I. Raposo, J. F. Mendes, R. Berkemeier and J. M. Bordado. 2006. [11] A. A. Abdelmalik, A. P. Abbott, J. C. Fothergill, S. Production of biodiesel from waste frying oils. Waste Dodd and R. C. Harris. 2011. Synthesis of a Base- Manag. 26: 487-494. stock for Electrical Insulating Fluid Based on Palm Kernel Oil. Ind. Crops Prod. 33(2): 532-536. [22] A. Talebian-Kiakalaieh, N. A. S. Amin and H. Mazaheri. 2013. A review on novel processes of [12] H. B. H. Sitorus, R. Setiabudy, S. Bismo and A. biodiesel production from waste cooking oil. Appl. Beroual. 2016. Jatropha Curcas Methyl Ester Oil Energy. 104: 683-710. Obtaining as Vegetable Insulating Oil. IEEE Trans. Dielectr. Electr. Insul. 23(4): 2021-2028. [23] D. Y. C. Leung, X. Wu and M. K. H. Leung. 2010. A review on biodiesel production using catalyzed [13] M. C. Menkiti, C. M. Agu, P. M. Ejikeme and O. E. transesterification. Appl. Energy. 87(4): 1083-1095. Onyelucheya. 2017. Chemically Improved Terminalia Catappa L. Oil: A Possible Renewable Substitute for [24] Y. Wang, S. Ou, L. Pengzhan, F. Xue and S. Tang. Conventional Mineral Transformer Oil. J. Environ. 2006. Comparison of two different processes to Chem. Eng. 5(1): 1107-1118. synthesize biodiesel by waste cooking oil. J. Mol. Catal. A Chem. 252: 107-112. [14] Anonymous. 2017. Bagaimana Anda Boleh Buat Duit Dengan Minyak Masak. The Vocket, 2017. [Online]. [25] F. H. Alhassan, U. Rashid, and Y. H. Taufiq-Yap. Available: https://www.thevocket.com/bagaimana- 2015. Synthesis of waste cooking oil-based biodiesel anda-boleh-buat-duit-dengan-minyak- masak/. via effectual recyclable bi-functional Fe2O3-MnO- [Accessed: 13-Jan-2018]. SO42-/ZrO2 nanoparticle solid catalyst. Fuel. 142: 38-45. [15] Anonymous. 2017. Palm Oil Price Today. Markets Insider, 2017. [Online]. Available: [26] 2009. AOCS Official Method Ca 5a-40 Free Fatty http://markets.businessinsider.com/commodities/palm Acids. pp. 1-2. -oil-price. [Accessed: 30-Oct-2017]. [27] ASTM D974. 2014. Standard Test Method for Acid [16] L. S. Kheang, C. Y. May, C. S. Foon, and M. A. and Base Number by Color-Indicator Titration. pp. 1- Ngan. 2006. Recovery and Conversion of Palm Olein- 7. derived Used Frying Oil to Methyl Esters for [28] ASTM D1533. 2012. Standard Test Method for Water Biodiesel. J. Oil Palm Res. 18: 247-252. in Insulating Liquids by Coulometric Karl Fischer [17] Z. Yaakob, M. Mohammad, M. Alherbawi, Z. Alam Titration. pp. 1-5. and K. Sopian. 2013. Overview of the production of [29] ASTM D1816. 2012. Standard Test Method for biodiesel from Waste cooking oil. Renew. Sustain. Dielectric Breakdown Voltage of Insulating Liquids Energy Rev. 18: 184-193. Using VDE Electrodes. pp. 1-5. [18] Y. Lin and H. Lin. 2010. Study on the spray [30] IEEE Std C57.147TM. 2008. IEEE Guide for characteristics of methyl esters from waste cooking Acceptance and Maintenance of Natural Ester Fluids oil at elevated temperature. Renew. Energy. 35: 1900- in Transformers. 1907. [31] J. Wada, G. Ueta, S. Okabe and T. Amimoto. 2013. [19] A. V. Tomasevic and S. S. Siler-Marinkovic. 2003. Techniques to inhibit transformer insulating oil Methanolysis of used frying oil. Fuel Process. degradation - Effectiveness evaluation of the removal Technol. 81: 1-6. of degradation products using adsorbents. IEEE [20] A. A. Refaat, N. K. Attia, H. A. Sibak, S. T. El Trans. Dielectr. Electr. Insul. 20(6): 2307-2316. Sheltawy, and G. I. ElDiwani. 2008. Production

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[32] E. Lotero, Y. Liu, D. E. Lopez, K. Suwannakarn, D. A. Bruce and J. G. Goodwin Jr. 2005. Synthesis of biodiesel via acid catalysis. Ind. Eng. Chem. Res. 44: 5353-5363.

[33] ASTM D3487-16. 2016. Standard Specification for Mineral Insulating Oil Used in Electrical Apparatus. pp. 1-5.

[34] IEEE Std C57.106TM. 2015. IEEE Guide for Acceptance and Maintenance of Insulating Mineral Oil in Electrical Equipment.

[35] ASTM D6871-03. 2003. Standard Specification for Natural (Vegetable Oil) Ester Fluids Used in Electrical Apparatus. pp. 1-4.

[36] F. Ma and M. A. Hanna. 1999. Biodiesel production: A review. Bioresour. Technol. 70(1): 1-15.

[37] M. J. Pratas, S. Freitas, M. B. Oliveira, S. C. Monteiro, A. S. Lima and J. A. P. Coutinho. 2010. Densities and Viscosities of Fatty Acid Methyl and Ethyl Esters. J. Chem. Eng. Data. 55: 3983-3990.

[38] J. M. Dias, M. C. M. Alvim-Ferraz and M. F. Almeida. 2008. Comparison of the performance of different homogeneous alkali catalysts during transesterification of waste and virgin oils and evaluation of biodiesel quality. Fuel. 87: 3572-3578.

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