Studies on Processes for the Reduction in Acidity of Some Vegetable Khln Htwe Nyunt', Khln Setn' , Bo BoThet] Abstract. Plant oils are a promising alternative energy source offering a variety of economical and ecological advantages. Blodiesel is an alternativefuel produced from vegetable oils or through transesteriflcaUon reaction with methanol and sodium hydroxJde as catalyst. The ectdtty of these raw materials is given by free fatty acids that are transformed into in the presence of a base and water. Since the formation of cause problems In the steps of washing and puriflcatJon of blodlesel. and decrease of yield. vegetable oils or fats with high acidity could not be used for the conventional process of aIkaUne catalysts. If free fatty adds are present, they can be removed or transformed into blodlesel using special pretreatment technologies. In this research two methods of deacidIfication such as neutralization andextraction were being explored for the reduction of acidity of some vegetable oils such as rice bran. palm and oils having different acidities. The oUs were first pretreated by Illtratlon. degumming and winterization. The pretreated oils were then deacldtfled by either neutralization or extraction. It was found that neutralizatlon gave more reduction in acidity but percent yield was low. Stepwiseextraction made more yield of oils having low acidity less than 2.0.

Keywords: biodtesel. rransestenftcanon. free fatty acids. deacidification, neutralization. extraction

INTRODUCTION Oils. fats. and belong to the class of compounds called lipids. which are insoluble in water, but soluble in ether and other organic solvents. The lipids have long been considered important as one of the three major classes of food materials. They differ from the other two, proteins and carbohydrates, in that they provide more than twice the number of calories per unit weight when converted to carbon dioxide and water. Hence. they were thought to be primarily products for storage of energy in plants and animals. Oils and fats are usually distinguished from one another by their melting points and. to some extent. by their sources. OHs are generally liquid at ordinary temperatures while fats are solid or semi-solid. The fats are usually of animal origin while oils are extracted from plant tissue. fish. or marine animals. Fats and oils ohtalned from animal or vegetable tissue are predominantly triglycerides with traces of mono- and dfglycendes. free fatty acids. phospholipids.

I Dr.• Professor and Head. Department of Industria.l Chemistry. West YangonUniversity 2Associate Prof.....-(ReuL).lJeponment of!nduslrial Cberusry, W.,.Yangon UnMoslty 3 Demonstrator. Department oflndustrial Chemistry. WestYangon University WYU Research Journa12014. Vol.4 177

sterols, and other minor constituents. Procedures for refining and processing crude oils remove most of the trace constituents (Kent 1974). Fats and oils have always had an essential role as food for humankind. In addition. however. our modern industrial world has found many important applications for them. The largest consumption of fats forchemical raw materials is in making fattyacids. Oils are saponified. hydrogenated. epoxidized, and sulfonated to a great number of usable products. and fats are isomerized and interesterified, all to produce upgraded and more useful oils and fats (Austin 1984). Btodlesel fuel can also be made from new or used vegetable oils and animal fats. which are non-toxic, biodegradable. renewable resources. The most common process for making blodiesel is known as transesteriflcation. This process involves combining any natural (vegetable or animal) wtth virtually any alcohol. and a catalyst. The oils or fats with high acidity could not be used for the conventional process of alkaline catalysis. If free fatty acids are present, they can be removed or transformed into using special pretreatment technologies. The main objectives of this research work are to explore suitable methods for the reduction of acidity of somevegetableoils such as rice bran. palmand palm kernel oils and to give moreyield of oils having low acidityyieldingmorebiodiesel.

MATERIALS AND METHODS Raw Materials Crude samples with different acidities obtained from (01) Rice Bran all Plant, Kamayut Township and palm kernel oil samples with different acidities obtained from Soap Factory No. (I), Hlalng Township

Chemical Reagents Potassium hydroxide (SDH, Ana lar grade), dlethyl ether, phenolphthalein indicator (Laboratory chemicals, May & Baker Ltd.), ethyl alcohol (95 percent alcohol) and n-Hexane wereused.

Apparatu s 100 ml, 250 ml conical flasks, analytical balance, pipette (25 ml), burette (25 ml wtth graduation in 0.05 ml divisions), hot-plate with temperature control, volumetric flasks (100 ml, 250 ml. 500 ml), water-bath (stainless steel), 500 ml separating funnels; desiccators and oven. 178 WYU Research Jouma 12014 . VolA

Experimental Procedure The acid value is defined as the number of milligrams of potassium hydroxide required to neutralise the free in one gram of oil. 1 gm of oil was weighed into a 100 m1 conical flask and dissolved in 30 ml of I:1 v/v mixture of previously neutralized ethanol and diethyl ether solution. While shaking. it was titrated with 0.1 N ethanolic potassium hydroxide solution until the pink colour did not change for at least 30 sec. The acid value of the oil sample was calculated as follows (Horwitz 1980). Vxfx 5.6l AV= weight of sample where V = volume orO.IN KOH solution f • factor of O.IN KOH solution

Pretreatmemt of Oils Pretreatment of crude oil includes filtration. degumming and winterization. Rice bran oil. palm oil and palm kernel oil samples with different acidities were pretreated in these experiments.

Materials Crude oil samples with different acidities Hot water (90'C) Concentrated phosphoric acid

Apparatus 250 ml volumetric flask 2L beaker. IL beaker Magnetic stirrer Centrifuge machine 500ml se parating funnel Buchner funnel

Filtration of Crude Oil 1000 ml of rice bran oil sample with acidi ty of AV 30.3 was filtered for the separation of impurities such as sludges , carbo hydrates and waxes by Buchner funnel. The same experiments for rice bran oil. palm oil and palm kernel oil samples with different acidities were also carried out. Acidities before and after filtration were detennined by me AOeS (American Oil Chemists' Society) method. The results are shown in Table 1. WYU Research Journal 2014 , VolA 179

Degumming of Filtered Oil with Hot Water at 90°C 500 ml of filtered rice bran oil sample with known acidity was carried out by using 2.5%v/v hal water (90'C) as degumming agent. The amount of all taken (500 mil. the amount of degumming agent used (2.5% v/v) . the agitation rate (200 rpm) and time (I5 minutes) were kept constant throughout the experiment. After the flocculated gums had been separated by centrifugation. the oil was washed and dried . The acidity. the volume and % yield of oil were also recorded. The same experiments for filtered palm oil and palm kernel oil samples with different acidities were also carried out by using 2.5%v/v hot water (9OOC) as degumming age nt. The results are shown in Table 2.

Degumming of Filtered, Partially degummed Oil with Phosphoric Acid at 90°C 450 mi of filtered and partially degummed rice bran all sample with known acidity was taken and concentrated phosphoric acid (0.1 % v/v) was used as degumming agent at 900 e. The amount of oil taken (450 ml), the agitation rate (200 rpm) and time (1 5 minutes) were kept constant throughout the experiment. After the flocculated gums had been separated by centrifugation, the degummed oil was washed and dried . The acidity, the volume and % yield of oil were also record ed. The same experiments for filtered and partially degummed palm oil and palm kernel oil samples with different acidities were also carried out by using 0.1 % v/v phosphoric acid as degumming agent. The results are shown in Tab le 3.

Winterization of Degummed Oil 400 ml of filtered and degummed rice bran oil sample was dewaxed by winterization at 12°C. The sample was placed in a It pyrex beaker and a gradual cooling to a temperature of 12°C was achieved by passing thermosta tically controlled cool water (9 ± 1°C) into the water j acket. A close tempe rature control was maintained with the aid of the two therm ometers and continuous stirring was provided throughout for 3 hours. After 3 hours. the acidity. the volume and % yield of the dewaxed oil were also recorded. The same experiments for filtered and degummed palm oil and palm kerne l oil samples with different acidities were also carried out. The results are shown in Table 3.

Neutralization of Pretreated Oils 100 ml of pretreated palm oil sample with known acidity was preheated to 90°C. A calculated amount of caustic soda solution (20°Be) prepared (amount of caustic soda required was calculated for neutralizing the acidity of the degummed oil sample) was gradually added and the sample was kept under co nstant agitation for 15 min. The soa p and neutral oil formed were separated in the separating funneL Refined 180 WYU Research Jouma12014. VolA oil was washed with hot water. The washed solution was constantly checked with phenolphthalein indicator to ensure that the neutral all was free from soap. The washed oil was dried in the oven at llOOC. The addity and the yield percentage of neutralized. washed and dried oil sample were determined. The same experiment for pretreated palm kernel oil sample with different acidity was also carried out. The results areshown in Table 4.

Extraction ofPretreated Oil Using Various Ratio DrOll to Solvent 50 ml of pretreated (filtered. fully degummed and winterized) rice bran 011 sample having an acidity of AV 42.3 was extracted with 95% ethanol using ihe 011 to solvent ratio of 1:6. After addition of ethanol, the sample was kept under constant agitation at 300 rpm for 1 hour. The sample was transferred into a separating funnel. When two layersseparatedsharply. the bottom fraction was drawn off. Afterdistilling ofT the ethanol the acidity of 011 was then detenolned. The same experiments were also carried out for rice bran oil with the varying ratio of the oil to solvent ratio of 1:8. 1:10 respectively. Theyield percentage and the acidity of theoil sample before and after eachextraction were determined. The results are shown in Table 5.

Extraction of Pretreated Oil Having AV Range (30 - 50) Pretreated oils having AV Range (30 - 50) were extracted with 95% ethanol using the oil to solvent ratio of 1:10. Stepwise extraction of the samples obtained was then continued. The yield percentage and the acidity of the oil sample before and after each extraction were determined. The results are shown in Table 6. The effects of stepwise extraction on acid value and percent yield of pretreated oil samples having AV Range (30 - 50) are shown in Figure I and 2.

Extraction of Pretreated 011 Having AV Range (16 - 20) Pretreated oils having AV Range (16 - 20) were extracted with 95% ethanol using the oil to solvent ratio of 1:10. The yield percentage and the acidity of the 011 sample before and after each extraction were determined. The results are shown in Table 7. The effects of stepwise extraction on acid value and percent yield of pretreated oil samples having AV Range (16 - 20) are shown in Figure 3 and 4.

RESULTS AND DISCUSSION In this work, studies were conducted with three types of oils: rice bran oil. palm oil and palm kernel oil. with high acidities. corresponding to developments made for producing biodlesel. WYU Research.Journal znfe , \\>1.4 181

Plant oils-ere a promising alternative energy source offering a variety of economical and ecological advantages. Btodlesel is an alternative fuel produced from 'vegetable.' oils "or fats like through transestertftcatton reaction with methanol and sodium hydroxide as catalyst, The acidity of these raw materials is given by free fatty acids that are transformed into soaps in the presence of a base and water. Since the formation of soap cause problems in the steps of washing and purification of blodlesel, and decrease of yield. vegetable oils or fats with high addity could not be used for the conventio nal process of alkaline catalysts. If free fatty acids are present, they- can - be removed or transformed Into biodl esel using special pretreatment technologies. The .yteld of blodl esel produced is higher if the oil is dried and pretreated first. (hl!P'!IIoumeyto[orever.orgJ) •.•. In this study. pretreatment including filtration, degumming and winterization were carried out. Two-samples of crude rice bran oil having acid val ue 33 .4 and 39 .8. palm oil,having acid value 10.91 and 23.93. and palm kernel oil samples having acid value 22.1 and 8.69 were collected from (01) Rice Bran Oil Plant. Kamayut Township and -from Soap Factory No.Uk Hlaing Township . Crude oil may contain relailvely small and variable amounts of nonglyceride lmpurtnes. Some of the impurities have an effect-on the oil 'squality for food and industrial uses and thus need to be removed. These. impurities influence both the way the oil responds in the various processing steps employed to produce a finished product and the yield of fln1shed oil. ·The insoluble fmpurttles-consist of seed fragments. excess moisture. and a waxy fraction that appears in refrigerated oil. thus making it appear rurbld or cloudy. Impurities-such as seed fragments and meal fines are normally and readily removed 'by flltratlon. ' " ,.., ., • '..

pretreated. oils stepwise extraction was required to take low acidity with less than 2.0. The results were reported in terms of acidity and percent yield of different oils. Pretreated rice bran oil sample having AV 42.3 gave 70.8 percent yield and AV 6.55 for first extraction and 69.8 percent yield and AV 1.22 for second extraction. Also after second extraction pretreated rice bran oil sample having AV 48.25 gave 60.8 percent yield and AV 1.95, pretreated palm oil sample having AV 32.5 gave 65.0 percent yield and AV 1.42 and pretreated palm kernel oil sample having AV 30.48 gave 56.0 percent yield and AV 1.60 respectively. Figure I and Figure 2 show the effects of stepwise extraction on acid value and on percent yield of pretreated oil samples having AV Range (30-50). Although pretreated oils having AV range (Jo­ SO) could not be economically refined using neutralization the reduction In their acidities could be made bystepwise extraction methods. Stepwise extraction methods were also used for deacidification of pretreated various oils having AV range (16 - 20) by using 95% ethanol solution at 70°C as shown in Table 7. It could be observed that after second extraction pretreated palm oil sample having AV 19.8 gave 68.5 percent yield and AV 1.42 and pretreated palm kernel 011 sample having AV 16.4 gave 71.8 percent yield and AV 1.35 after first extraction respectively. Figure 3 and Figure 4 show theeffects of stepwise extraction on acid value and on percent yie ld of pretreated 011 samples having AV Range (16 - 20).

Table I Filtration ofDifferent Crude Oils

Rice Bran Oil Palm a ll Palm Kernel Oil Crude Olls Characteristics Sample Sample Sample Sample Sample Sample I 2 3 4 5 6 Vol. before flJoatlon (mI) 1000 1000 1000 1000 1000 1000 Vol. after _ (ml) 977 982 985 979 976 986 AV before Illtratlon (mg KOH Ig oti) 33.4 39.8 10.91 23.93 22.10 8.69

AV after filtratlon . (mg KOH Ig oU) 35.2 42.0 12.73 25.75 23.92 10.36 % Yield (vlv) 97.7 98.2 98.5 97.9 97.6 98.6 184 WYU Research Joumal 2014 , VoL4

Table 2 Degumming of Filtered Oils with 2.5% Hot Water at 90°C Agitation time (min.) - 15 A-\R1 Itat Ion rate - 200,rpm Rice Bran Oil PalmOil Palm Kernel Oil Crude Oils Cbaracrertsncs Sample Sample Sample Sample Sample Sample 1 2 3 4 5 6 Vol. of Oil before 500' , . degumming (ml) 500 500 500 500 500

Vol. of Oil after Degumming (ro!) 493 492 495.5 493.5 493.0 496.0

AV beforedegumming 35.2 42.0 12.13 25.75 23.92 10.36 (mg KOHIg 011) AV afterdegumming 36.5 43.25 14.35 27.30 25.65 11.95 (mg KOHIg 011 ) %Yield (v/v) 98.6 98.4 99.1 98.7 98.6 99.2

Table 3 Degumming of Filtered, Partially Degummed Oil with 0.1 % Phosphoric Acid at 90°C and Winterization at 12°C Agilation time (min.) - 15 AAananon rate - 200J rpm Rice Bran Oil PalmOil PalmKe"mel Oil CrudeOils Charactertsucs Sample Sample Sample Sample Sample Sample 1 2 3 4 5 6 befor~ l~ pgumml ng AV (mg 36.5 43.25 KOH I. 011 14.35 27.30 25.65 11.95 AV after degumming (mg KOHI. Dill" 38.80 45.35 16.20 29.50 27.58 13.90 % Yield (v/v) 98.5 98.9 98.6 98.5 98.5 99.2 AV before winterization 38.8 45.35 16.60 29.50 27.58 . 13.90 (me KOHIe Dill , ~ w in tei ;~zallo n V after 42.3 48.25 19.8 32.5 30.48 16.4 me KOH /0 oil % Yield (v/v) 97.5 95.2 98.2 97.2 97.6 98.5 WYU Research Journal 2014 • VolA 185

Table 4 Neutralization of Pretreated Oil with 200Be Caustic Soda Solution at 900 e Agitation time {mln.) - 15 A'\w,"tation rate - 200.mm Crude Oils PalmOil PalmKernel 011 Characteristics Samele3 Sample 6 Vol. of Oil before Neutra lization (ml) 100 100 Vol. of Oil after Neutralization (ml) 58.5 62.3

AV before Neutralization 19.8 16.4 I (m. KOHI. otll AV after Neutra lization 0.50 0.48 I (rna KOHI. otll % Yield (v/v) 58.5 62.3

Table 5 Extraction of Pretreated Rice Bran Oil using Various Ratio of Oil to Solvent Agitationtime [hr) - 1 A",utation" rate- 300, rpm Before Deacidification After Deacidification Oilto. Acid Valueof Acid Valueof Yield 95% Volume Volume Extraction Oil LAV Fraction (% Ethanol of Oil of Oil (mg KOH /g (mg KOH/g vlv) Ratio (ml) (ml) oil) oil) 1:6 First 50 42 .3 36.3 10.25 72.6 1:8 First 50 42.3 36.1 8.50 72.2 1:10 First 50 42.3 35.4 6.55 70.g

Table 6 Deacidification of Pretreated Various Oils Having AV Range (30 - 50) by Using 95% Ethanol Solution at 70°C Agitation time (hr) - 1 Agitation rate - 300 rpm Oil to 95% Ethanol Ratio - 1.' 10 Before Deacidification After Deacidification Acid Value Volume Acid Valueof Volume of LAV Yield Oils Extraction of Oil Oil of Oil Fraction (% vlv) (ml) (mg KOHIg 011) (ml) (mg ~~ H I. oil Rice Bran Oil First 100 42.3 70.8 6.55 70.8 Sample I Second 71.0 6.55 69.8 1.22 69.8 Rice Bra n Oil First 100 48.25 68.35 9.52 68.2 Sample2 Second 68.35 9.52 60.8 1.95 60.8 Palm Oil First 100 32.5 68.5 6.35 70.10 Sample 4 Second 68.5 6.35 65.0 1.42 65.0 Palm Kernel Oil First 100 30.48 60.0 6.50 60.0 Sample 5 Second 60.0 6.50 56.0 1.60 56.0 186 WYU Research Joumal 20 l4 , VolA

Table 7 Deacidification of Pretreat ed Var ious Oils Having AV Ra nge ( 16 - 20) by Using 950/. Ethanol Solution at 70°C Agitation lime (hr) - I Agitation rate - 300 rpm Oil to 95% Ethanol Ratio - 1'10 Before Deacidification Arter Deacidification Acid Value of Yipld Extrac- Volume Acid Value of Volume Oils LAV Fraclion lion Oil (mg KOH of Oil (% v/v) eron (mg KOHIg (mil Ig o;l) (ml) oill Palm Oil First 100 19.8 72.0 6.28 72.0 Sample 3 Second 72.0 6.28 68.5 1.42 68.5 Palm Kernel First 100 16.40 71.80 1.35 71.8 Oil Sample 6

:: ': 60 o Before Ext ract io n .. 50 • First Extraction " o SeCOlXJ Extraction ":l! 40 "e 30 -~ 20 -; .. 10 [l ~ 0 LL RBO RBO PO PKO Sample 1 Sample 2 Sam ple 4 Sample 5

Figure I Effect of Stepwise Extraction on Acid Value (Ra nge 30-50) of Dlffcrcnt Oil Sa mples

80 o First Extraction

-> 70 • Second Extraction ;; 60 -~ 50 ;;: 40 -~ 30 i:" 20 e, 10 o RBO RBO PO PKO Sampl e I Sampl e 2 Sample 4 Sample 5

Figure 2 Effect of Stepwise Extraction on Yield Percent of Different Oil Samples ( AV Range 30 - 50) WYU Research Jouma12014 . VolA 187

D Before Extraction ::: 25 • • First Extraction -'" 20 o Second Extraction -0 :.:: 15 E ~'" =~ 10 >= ::! 5 ~ -< 0 PO Sample 3 PKO Sample 6

Figure 3 Effect of Stepwise Extrac tion on Acid Value (Ra nge 16-20) of Different Oil Samples

73 o First Extractio n • Second Extraction 72 .------t- > 71 --e 70 ..;;: 69 -•~ 68 ~" 67 66 PO Sample 3 PKO Sample 6

Figure 4 Effect of Stepwise Extractio n on Yield Percent of Different O il Sa mplesf AV Range 16 - 20)

CONCLUS ION

Thi s research work has explored two methods: neutralization and stepwise extraction for deacidification of rice bran . palm and palm kernel oils. It was found that neutralization gave more reduction in acidity but percent yield was low. Stepwise extraction made more yield of oils having low acidity less than 2.0 yielding not only more biodiesel but also more other industrial prod ucts such as soaps. paints. detergents. lubricants. . etc. 188 WYU Research Joumal zula , VolA

AC~OW L E DGEJ\lENTS

The authors would like ( 0 express sincere thanks to Dr. Khine Mye. Rector. West Yangon University for his permission to submit this paper. Thanks are also extended to the staff members of Quality Control and Research Laboratory of Soap Factory No.(l) , Hlaing Township, Ministry of Industry (1 ); (01) Rice Bran Oil Plant. Kamayut Township . Ministry of Commerce for their kind assistance In providing crude ells with different acldilies.

References

Austin.G.T. (1 984). Shreve's Chemical Process Industries. Fifth Edition. Horwitz.W. (1 980). Official Method of Analysis of the Association ofOffictal Analytical Chemicals. Kent. j .A. (1974). Rigel's Handbook of Industrial Chemistry. Seventh Edition. Kyl Kyi Wynn. (1984). Separation ofEdible Oil from High Acid Crude Rice Bran Oil by Fractional Crystallization. (Unpublished) MSc (Thesis). Department of Industrial Chemistry.University of Yangon. Pequot. C. (1979) . Standard Methods for the Analysis of Oils. Fats and Derivatives, 6th Edition. Oxford. Pergamon Press. hftp:l!loumeytoforever.org!