An Investigation to Assess Storage Stability of Pomelo Seed Oil Biodiesel

Transcription

1 Journal of Energy and Power Engineering 12 (2018) doi: / / D DAVID PUBLISHING An Investigation to Assess Storage Stability of Pomelo Seed Oil Biodiesel Madhurjya Saikia, Dilip K. Bora and Kalyan Kalita Mechanical Engineering Department, Assam Engineering College, Guwahati , India Abstract: Biodiesel is a biomass-based renewable and clean fuel. It can be used directly in existing diesel engines without any modification. In spite of having so many advantages, it has an issue regarding long-term storage stability. Biodiesel oxidizes when it comes in proximity of light, temperature, humidity, metals etc. The oxidation causes precipitation and sedimentation in the fuel. Such biodiesel is unfit to use in engines. Hence, this study aims to assess the storage stability of pomelo seed oil (Citrus maxima) biodiesel over a period of five months upon storage both in open and closed condition. Storage stability of biodiesel is determined in terms of acid value, peroxide value and viscosity at regular interval of time. It is observed that there is a strong relationship between oxidation and outside factors such as light, temperature fluctuations and humidity level. Upon exposure to these factors, oxidation in biodiesel accelerated greatly. Key words: Biodiesel, storage stability, acid value, peroxide value, viscosity. 1. Introduction Bio-diesel refers to a biomass based fuel having short chain alkyl esters, made by transesterification of vegetable oil or animal fat which can be used in existing diesel-engines [1-3]. It is considered to be a naturally oxygenated fuel with inherent oxygen in itself about 9-10% [3, 4]. Recent researches suggest that biodiesel is a clean fuel with less contribution to the net increase of carbon monoxide, carbon dioxide, other hydrocarbons and sulphur dioxide [5-7]. Moreover, biodiesel from various non-edible oil resources has been used successfully without requiring any engine modification [8-10]. As a fuel, biodiesel is engine friendly but its storage stability is a concern. When biodiesel is stored for a long time, it degrades rapidly in contact with sunlight, moisture, and humidity. This is a common problem faced by all biomass-based liquid fuels [11-19]. Ultimately, oxidized biodiesel becomes unfit to use in modern engines and causes trouble by clogging fuel injection and multiple another failures due to precipitation and sedimentation problem [12, 13, Corresponding author: Madhurjya Saikia, research scholar, ME Deptt., research fields: solid & liquid fuels and biodiesel. 20]. Hence, quality should be maintained all the time to ensure longevity of engines. Some of the tests based on which storage stability can be ascertained are peroxide value, acid value and viscosity of the fuel. The present study tries to assess storage stability of pomelo seed oil biodiesel (Citrus maxima) over a period of five months both in open and closed condition. 2. Materials and Methods The experimental study is carried out in Mechanical Engineering Department Engine Laboratory, Dibrugarh University, India. 2.1 Biodiesel Production The vegetable oil from pomelo seeds had been extracted by using a mechanical expeller. Pomelo seed oil is converted to biodiesel via transesterification process. Fig. 1 depicts the steps of laboratory scale biodiesel production steps. Two hundred ml of methyl alcohol was mixed with 14.5 gm of KOH (catalyst) to form a potassium methoxide solution. Then, this solution of sodium methoxide was mixed with pomelo oil (1,000 ml). The mixture was held at a temperature

2 12 An Investigation to Assess Storage Stability of Pomelo Seed Oil Biodiesel Fig. 1 Biodiesel production process. Table 1 Physical and chemical properties of pomelo biodiesel (Citrus maxima). Sl No. Properties Pomelo biodiesel Diesel 1 Density (kg/m 3 ) Kinematic viscosity (cst) Pour point ( C) Cloud point ( C) Calorific value (MJ/kg) Flash point ( C) Fire point ( C) FFA% Acid number of 60 C for 90 minutes with a constant agitation speed of 300 rpm. Then, the mixture was allowed to cool and settle in a separating flask for 12 hours. Two layers were formed in the separating flask; bottom layer of glycerol and top layer of biodiesel. The top layer of biodiesel has been separated by using a separating flask. The properties of biodiesel are listed in Table Determination of Storage Stability of Biodiesel Storage stability studies were conducted on two biodiesel samples. The biodiesel samples were stored in sealed glass vessels. One of these glass vessels was placed normally in a room. The other one was placed in a wooden cabinet to resemble closed condition. Storage stability of the samples is assessed in terms of acid value, peroxide value and viscosity at an interval of one month for five months Acid Value It is the mass of potassium hydroxide (KOH) in milligrams that is required to neutralize one gram of chemical substance. Precisely, five gram oil was taken in a conical flask and isopropyl alcohol was added till the oil dissolves completely. This solution was titrated against 0.1 N KOH solution after adding 1 or 2 drops of phenolphthalein indicator. The appearance of pink colour indicates the endpoint. Then, the acid value was calculated using the formula given below. Acid value = (A B) N 56.1/W where, A = amount of 0.1 N KOH required for titration with oil; B = amount of 0.1 N KOH required for titration without oil; W = weight of oil, N = normality of KOH.

3 An Investigation to Assess Storage Stability of Pomelo Seed Oil Biodiesel Peroxide Value Peroxide value is a measure of the concentration of peroxides and hydroperoxides formed in the initial stages of lipid oxidation. Milliequivalents of peroxide per kg of fat are measured by titration with iodide ion. To measure peroxide value, 5 gm of oil was taken in a flask. A mixture of 20 ml of acetic acid and 10 ml of chloroform was added to oil sample. The mixture was swirled at low speed. After proper mixing, 0.5 ml of freshly prepared potassium iodide solution was added to the solution and stirred at a low speed. Then, the solution was treated with 30 ml of distilled. This solution was titrated against 0.1 N sodium thiosulphate, using 0.5 ml starch solution as indicator. The amount of sodium thiosulphate solution required for titration was recorded. Peroxide value was determined by the following method: S = Titration of sample; B = Titration of blank; N = Normality of sodium thiosulphate solution. Peroxide value: Determination of Viscosity The viscosity was measured in redwood viscometer. Precisely, 50 ml of biodiesel was heated at 80 ºC in the viscometer. By opening the aperture at the bottom of the viscometer, the oil was allowed to flow and the time was recorded. The kinematic viscosity was determined by using the formula, Kinematic viscosity = At B/t. The constants: (1) A = 1.79, B = for 34 t 100; (2) A = 0.59, B = for t Results and Discussions The acid values, peroxide values and viscosities had been determined both conditions at an interval of one month for five month duration. During the experimentation period, the average ambient temperature and humidity had been recorded and given in Table 2. The variations of acid values, peroxide values and viscosities with storage time have been shown in Figs. 2-4 for both open and closed conditions. The results were distinctly divided in two phases; first from September to November 2016 and second from December 2016 onwards till the end of the experiment. During the first phase, the acid values, peroxide values and viscosities for both conditions tended to decrease as the ambient temperature, humidity and sunlight tended to fall progressively on the advent of winter. This indicated the slowing of oxidations reactions and improvement in stability. The lowest acid values, peroxide values and viscosities reached by both the open and close samples had been 1.22 & 0.561, 20 & 2 meq/kg and 1.26 cst & 0.85 cst respectively for the month of November In the second phase, the ambient temperature and humidity levels rose. This expedited oxidation reactions in biodiesel samples. As result, acid values, peroxide values and viscosities had increased with storage time for both the samples in open and closed conditions. Another important observation during this phase was that the biodiesel in close condition degraded at a higher rate than that of Table 2 Stability status. Peroxide value Acid Value Viscosity (cst) (meq/kg) Temp ( C) Humidity (%) Open Close Open Close Open Close 30/09/ /10/ /11/ /12/ /01/

4 14 An Investigation to Assess Storage Stability of Pomelo Seed Oil Biodiesel Acid value Acid value open Acid value close 30/9/ /10/ /11/ /12/ /1/2017 Fig. 2 Acid value vs.. Peroxide value (meq/kg) 45 Peroxide value open Peroxide value close /09/ /10/ /11/ /12/ /01/2017 Fig. 3 Peroxide value vs.. Viscosity(cSt) Fig. 4 Viscosity open Viscosity close /09/ /10/ /11/ /12/ /01/2017 Viscosity vs..

5 An Investigation to Assess Storage Stability of Pomelo Seed Oil Biodiesel 15 open one. Unlike the open condition, the temperature and humidity level were intact in the closed condition and were slightly higher than that of open one. This small temperature gradient resulted higher oxidation that sample. 4. Conclusions In this study, storage stability of pomelo seed oil biodiesel is evaluated on terms of acid value, peroxide value and viscosity. The behaviour of parameters can be divided into two phases. During the first phase (September to November 2016), the parameters showed a decreasing trend indicating lower oxidation due to low ambient temperature and humidity level. As the surrounding temperature and humidity increased slightly in the second phase, there was rapid oxidation in biodiesel and acid values, peroxides values and viscosities rose with storage time. The oxidation of biodiesel can be reduced by applying antioxidants such as TBHQ, PrG, BHA and BHT. References [1] Peterson, C. L., Feldman, M., Korus, R., and Auld, D. L Batch Type Transesterification Process for Winter Rape Oil. Applied Engineering in Agriculture 7 (6): [2] Ma, F., Clements, L. D., and Hanna, M. A The Effects of Catalyst, Free Fatty Acids, and Water on Transesterification of Beef Tallow. Trans. Am. Soc. Agric. Eng. 41 (5): [3] Balaji, G., and Cheralathan, M., Potential of Various Sources for Biodiesel Production. Energy Sources, Part A 35: [4] Ilkilic, C., and Behçet, R The Reduction of Exhaust Emissions from a Diesel Engine by Using Biodiesel Blend. Energy Sources, Part A 32 (9): [5] Canakci, M., and Van Gerpen, J. H Comparison of Engine Performance and Emissions for Petroleum Diesel Fuel, Yellow Grease Biodiesel, and Soybean Oil Biodiesel. ASAE 46 (4): [6] Karaosmanoglu, F Vegetable Oil Fuels: A Review. Energy Sources 21 (3): [7] Canakci, M., and Hooz, M., Energy and Exergy Analyses of a Diesel Engine Fuelled with Various Biodiesels. Energy Sources, Part B 1 (4): [8] Rajan, K., and Kumar, K. R. S Improvement of Performance and Emission Characteristics of a DI Diesel Engine with Turbulence Induced Piston (Internal Jet Piston) Using Biodiesel Blends. SAE International 28 (December): [9] Bora, D Performance of Single Cylinder Diesel Engine with Karabi Seed Biodiesel. Journal of Scientific & Industrial Research 68 (11): [10] Bora, D Biofuel Production from Mesua Ferrea L Seed Oil. International Journal of Engineering and Technical Research (IJETR) 2 (9): [11] Du Plessis, L. M., De Villiers, J. B. M., and Van der Walt, W. H Stability Studies on Methyl and Ethyl Fatty Acid Esters of Sunflower Seed Oil. Journal of the American Oil Chemists Society 62 (4): [12] Bondioli, P., Gasparoli, A., Lanzani, A., Fedeli, E., Veronese, S., and Sala, M Storage Stability of Biodiesel. Journal of the American Oil Chemists Society 72 (6): [13] Bondioli, P., Gasparoli, A., Della Bella, L., and Tagliabue, S Evaluation of Biodiesel Storage Stability Using Reference Methods. European Journal of Lipid Science and Technology 104 (12): [14] Bondioli, P., Gasparoli, A., Della Bella, L., Tagliabue, S., and Toso, G Biodiesel Stability under Commercial Storage Conditions over One Year. European Journal of Lipid Science and Technology 105 (12): [15] Middlemarch, M., and Schober, S The Influence of Antioxidants on the Oxidation Stability of Biodiesel. Journal of the American Oil Chemists Society 80 (8): [16] Serrano, M., Bouaid, A., Martinez, M., and Aracil, J Oxidation Stability of Biodiesel from Different Feedstocks: Influence of Commercial Additives and Purification Step. Fuel 113 (November): [17] Serrano, M., Martinez, M., and Aracil, J Long-Term Storage Stability of Biodiesel: Influence of Feedstock, Commercial Additives and Purification Step. Fuel Processing Technology 116 (December): [18] Knothe, G., and Dunn, R. O Dependence of Oil Stability Index of Fatty Compounds on Their Structure and Concentration and Presence of Metals. Journal of the American Oil Chemists Society 80 (10): [19] Dilip, B Storage Stability of Mahua Oil Methyl Ester. Journal of Scientific & Industrial Research 68 (2): [20] Madhurjya, S Effect of Antioxidant on Storage Stability of Citrus Maxima Biodiesel. International Journal of Mechanical and Production Engineering 5 (2):